Palmitoylethanolamide in the Treatment of Pain and Its Clinical Application Prospects.

PPAR-α is a nuclear receptor that plays an important role in the regulation of inflammation and pain. PEA, as an endogenous ligand of PPAR-α, can activate this receptor and initiate downstream signaling pathways. 20 , 25 PPAR-α and opioid receptors are involved in the interaction between PEA and morphine. 20 Figure 3 The specific regulatory mechanism of PEA on pain relief. PEA can alleviate pain and inflammation, as well as minimizing adverse effects associated with conventional cannabinoids. The specific regulatory mechanism of PEA on pain relief. PEA can alleviate pain and inflammation, as well as minimizing adverse effects associated with conventional cannabinoids. PEA can regulate key signaling molecules such as NF-κB and p38-MAPK by activating PPAR-α. NF-κB is an important transcription factor involved in regulating the expression of various pro-inflammatory factors. PEA inhibits the activation of NF-κB through a PPAR-α dependent pathway, thereby reducing the release of pro-inflammatory factors and alleviating the inflammatory response. 26 , 27 p38-MAPK is another important signaling pathway involved in regulating neuroinflammatory responses. PEA can reduce neuroinflammatory responses and exert analgesic effects by modulating the activity of p38-MAPK. 28 , 29 Both in vitro and in vivo studies have shown that PEA exerts anti-inflammatory and analgesic effects through the PPAR-α dependent pathway. For example, in animal models, PEA can alleviate inflammatory pain and neuropathic pain, and this effect can be blocked by a PPAR-α antagonist. 25 , 26 The endogenous cannabinoid system (ECS) consists of CB1 and CB2 receptors and their endogenous ligands such as N-arachidonoylethanolamine (AEA), playing a significant role in pain and inflammation. The interaction of PEA with ECS does not directly activate CB1/CB2 receptors but achieves the “entourage effect” by indirectly regulating ECS. 30 The “entourage effect” of PEA is mainly reflected in its inhibition of the enzyme fatty acid amide hydrolase (FAAH) that degrades endogenous cannabinoids, thereby increasing the levels of endogenous cannabinoids such as AEA and prolonging their action. 31 Since AEA can activate CB1 and CB2 receptors, PEA indirectly enhances the activity of the ECS by increasing the levels of AEA, thus alleviating pain and inflammation. 25 The synergistic effect of PEA and ECS can relieve pain and inflammation together, while avoiding the side effects of traditional cannabinoids, such as psychoactive effects. 32 In animal models and clinical studies, the interactions between PEA and ECS have demonstrated good analgesic and anti-inflammatory effects. 33 For example, Mabou Tagne et al 34 reported that the combination of PEA with hempseed oil extract showed a synergistic anti-hyperalgesic effect in mouse models of acute and chronic pain. Pharmacokinetic experiments indicate that co-administration of HOE can enhance and prolong the systemic exposure of PEA. Microglia and astrocytes are important glial cells in the central nervous system, playing a key role in chronic pain and neuroinflammation. In the state of chronic pain and neuroinflammation, these glial cells become overactivated, releasing a large amount of pro-inflammatory cytokines, exacerbating neuroinflammation and central sensitization. PEA can alleviate neuroinflammation and central sensitization by inhibiting the excessive activation of glial cells. PEA reduces the release of pro-inflammatory cytokines such as IL-1β and TNF-α, thereby alleviating neuroinflammation. 32 The specific signaling pathways through which PEA regulates glial cell activation include PPAR-α-dependent and non-dependent pathways, such as the TLR4/NF-κB pathway. 25 , 26 In the spinal cord, PEA reduces inflammation, oxidative stress, and p38-MAPK activity. 28 , 29 Both animal models and cell experiments show that PEA has a good regulatory effect on the activation of glial cells. For example, in a spinal cord injury model, PEA can reduce the activation of microglia and astrocytes in the spinal cord, alleviating neuroinflammation and thus relieving neuropathic pain. 35 Oxidative stress, such as the accumulation of reactive oxygen species (ROS), plays an important role in neuropathic pain and chronic inflammation. ROS can damage nerve cells, exacerbate inflammatory responses, and lead to increased pain. 36 , 37 PEA has an antioxidant effect and can enhance antioxidant defenses through multiple mechanisms. PEA can activate the Nrf2/HO-1 pathway, upregulate the expression of antioxidant enzymes, and enhance the antioxidant capacity of cells. In addition, PEA can also directly scavenge free radicals and reduce the accumulation of ROS. 38 In addition to its antioxidant effects, PEA also has anti-inflammatory and metabolic regulatory functions. PEA can regulate mitochondrial function, improve energy metabolism, and block the vicious cycle of inflammation-oxidative stress. For example, PEA affects mitochondrial respiration, mitochondrial membrane potential, and ROS production. PEA improves cellular energy metabolism by regulating the AMPK pathway, thereby alleviating inflammatory responses. 36 PEA regulates various ion channels, including voltage-gated sodium channels and calcium channels. PEA can modulate the activity of ion channels such as Nav1.7 and Cav3.2, thereby inhibiting the hyperexcitability of neurons and exerting an analgesic effect. 39 Through interaction with the Nav1.7 channel, PEA can directly affect sensory neurons and pain transmission. Brain-derived neurotrophic factor (BDNF) is an important neurotrophic factor that plays a key role in neural repair and synaptic plasticity. PEA can upregulate the expression of BDNF, promoting neural repair and synaptic plasticity, and reversing synaptic remodeling associated with chronic pain. 25 Under chronic pain conditions, synaptic plasticity is altered, leading to the abnormal transmission and amplification of pain signals. By regulating synaptic plasticity, PEA can restore normal neural function and reduce pain. In experiments on animal behavior, PEA improves pain behavior and neurological functions through mechanisms such as regulating ion channels and upregulating BDNF expression. 40 PEA treatment alleviates pain and cognitive impairments, thereby restoring LTP and maladaptive changes in synapses within the LEC-DG pathway. 25 NAAA is an intracellular lysosomal enzyme responsible for the degradation of PEA, thereby regulating the levels of PEA in the body. The pathological significance of NAAA in pain lies in its excessive activation, which can lead to a decrease in PEA levels, thereby weakening endogenous analgesic and anti-inflammatory effects. 41 , 42 By inhibiting NAAA, the endogenous levels of PEA can be increased, enhancing its analgesic and anti-inflammatory effects. For example, URB597 is an NAAA inhibitor that exerts its analgesic effect by increasing endogenous PEA levels. Compared to the administration of exogenous PEA, inhibiting NAAA has certain advantages, as it can more precisely regulate PEA levels and may reduce side effects. 42 The mechanism of action of PEA involves multiple targets, including PPAR-α, ECS, glial cells, and ion channels. 43 These targets interact to form a complex regulatory network that collaboratively exerts analgesic, anti-inflammatory, and neuroprotective effects. From the perspective of network pharmacology, PEA has the characteristic of “systemic regulation” and can exert effects through multiple pathways in a collaborative manner. This multi-target synergistic effect is one of the advantages of PEA, which can overcome the limitations of single-target drugs. In contrast, single-target drugs may only focus on a specific pathway or target, while PEA can modulate multiple pathways and targets to more comprehensively intervene in the pathological processes of pain and inflammation. 43

This chapter aims to introduce the multifactorial background of pain and inflammation from the perspectives of pathophysiology and molecular biology, while elucidating the fundamental characteristics of Palmitoylethanolamide (PEA), a natural lipid mediator, and its unique role in the regulation of inflammation and pain. It also discusses the limitations of current pain treatments and the potential advantages of natural medicines in terms of safety and tolerance, ultimately clarifying the purpose of this review and its interdisciplinary research perspective. Chronic pain and neuropathic pain are common yet highly complex clinical problems, whose pathophysiological mechanisms involve multiple factors, various signaling pathways, and multi-level regulation 1 , 2 ( Figure 1A ). Pain generation, from peripheral to central, is regulated by a comprehensive array of mechanisms. Peripheral sensitization is primarily manifested under conditions of local tissue damage or inflammation, where inflammatory mediators (such as prostaglandins, interleukins, and other pro-inflammatory cytokines) released from the damaged area directly act on the nerve endings, significantly increasing the sensitivity of ion channels and receptors, thereby lowering the activation threshold and causing abnormal excitability. Meanwhile, central sensitization mechanisms also play a crucial role, where persistent peripheral input stimuli lead to enhanced excitability of neurons in the spinal dorsal horn and higher-level central nervous system, along with changes in synaptic plasticity. 3 , 4 For instance, abnormal accumulation of neurotransmitters like glutamate in the synaptic cleft can activate N-methyl-D-aspartate (NMDA) receptors, triggering a cascade of signal transduction reactions that form neural adaptive changes such as long-term potentiation (LTP), further sustaining and amplifying pain signals. 5 In addition, structural changes of neurons, axonal regeneration, and synaptic remodeling following nerve injury are also significant factors contributing to the chronicity of pain, not only allowing pain signals to persist in the central nervous system for a long time but also posing challenges for subsequent pharmacological interventions. 6 Neuropathic pain, due to its origins often closely related to damage or pathological changes in the nerves themselves, is frequently accompanied by abnormal sensations such as tingling, burning, and electric shock-like feelings. This type of pain often shows inadequate response to analgesic treatments and requires special intervention measures to suppress pathological neuronal discharges and abnormal excitatory states. 7 Figure 1 The relevant mechanisms of pain and their interactions mediated by endocrine-immune-glial cells. ( A ) The diverse mechanism underlying chronic pain and neuropathic pain, including (a) peripheral sensitization, (b) central sensitization, (c) other contributing factors. ( B ) Neuroendocrine-immune-glial crosstalk in pain, including (a) inflammation regulation, (b) multi-target approach, (c) pain modulation. The relevant mechanisms of pain and their interactions mediated by endocrine-immune-glial cells. ( A ) The diverse mechanism underlying chronic pain and neuropathic pain, including (a) peripheral sensitization, (b) central sensitization, (c) other contributing factors. ( B ) Neuroendocrine-immune-glial crosstalk in pain, including (a) inflammation regulation, (b) multi-target approach, (c) pain modulation. In the complex pain and inflammatory response, there exists a close and intricate interplay between the neuroendocrine and immune systems, and this network structure is considered a key factor in maintaining homeostasis and regulating the inflammatory response. Glial cells, including microglia and astrocytes, serve as important support cells in the central nervous system, and their roles in nerve injury, inflammation, and pain signal transmission have garnered increasing attention. ( Figure 1B ) After peripheral or central tissue injury, these glial cells are rapidly activated and secrete a large quantity of pro-inflammatory cytokines (such as TNF-α, IL-1β, IL-6), while they may also produce anti-inflammatory factors like IL-10, thereby participating in regulating the inflammatory process based on the varying local environmental conditions. 8 On the other hand, the hypothalamic-pituitary-adrenal (HPA) axis plays an important role in regulating endocrine and immune balance during stress responses, with hormones released such as cortisol that can inhibit inflammatory responses to some extent; 9 however, in the context of long-term chronic pain, this balance is often disrupted due to excessive activation, further exacerbating local and systemic inflammatory conditions. Moreover, Jiang et al 10 reported that the activation of lymphocytes and monocytes in the immune system is also believed to be closely intertwined with neuroendocrine factors, and together, they regulate the transmission of pain signals and the sensitivity of nerve cells, providing a multi-target and multi-pathway intervention strategy for pain treatment. PEA is an endogenous lipid mediator with a unique chemical structure, scientifically known as N-Palmitoylethanolamine. 5 Chemically, this molecule is composed of palmitic acid and ethanolamine, exhibiting certain lipophilicity and biological activity. PEA is primarily endogenously generated through the catalytic action of N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD), while its degradation mainly relies on the action of N-acylethanolamine acid amidase (NAAA), thereby maintaining the balance level of PEA in the body. In addition to endogenous synthesis pathways, PEA can also be obtained from various natural foods such as egg yolks, soybeans, and peanuts, which provides the possibility to regulate the level of PEA in the body through diet 5 , 11 , 12 ( Figure 2A ). Currently, with the development of formulation technology, the metabolic kinetic characteristics of exogenously supplemented PEA have also received widespread attention. Novel formulation forms such as microparticle and ultra-microparticle forms can significantly improve its bioavailability, resulting in more ideal pharmacokinetic properties and therapeutic potential in clinical applications. Figure 2 Sources of PEA, synthesis methods, and its analgesic and anti-inflammatory effects. ( A ) The sources and synthesis methods of PEA. ( B ) The applications of PEA in pain and inflammation treatments. Sources of PEA, synthesis methods, and its analgesic and anti-inflammatory effects. ( A ) The sources and synthesis methods of PEA. ( B ) The applications of PEA in pain and inflammation treatments. As a naturally occurring lipid mediator, PEA not only participates in regular cellular energy metabolism but is also known for regulating inflammatory responses and pain conduction ( Figure 2B ). Its uniqueness lies in being proposed as a “self-repair molecule”-a concept that emphasizes PEA’s role in restoring homeostasis by activating specific receptors and regulating cytokine levels within the body. PEA exerts its anti-inflammatory effects primarily by PPAR-α, a pathway capable of inhibiting the activation of NF-κB and its downstream pro-inflammatory signaling, thereby alleviating inflammatory responses to some extent. 13 Additionally, PEA can indirectly modulate the endocannabinoid system through its “partner effect”, enhancing the activity of substances like anandamide, which in turn reduces neuronal sensitivity to pain stimuli. 14 Furthermore, D’Aloia et al 15 reported that PEA has the significant effects in regulating the activity of glial cells; by attenuating the pro-inflammatory responses of microglia and astrocytes, it can effectively reduce local inflammation and associated pain signaling within the nervous system, providing a solid theoretical basis for its application in various inflammatory and neuropathic pain conditions. Current traditional medications used for pain relief, such as non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, do have certain effectiveness in analgesia; however, their widespread adverse reactions and tolerance issues have long been major concerns in clinical applications. 3 , 4 NSAIDs are often accompanied by gastrointestinal irritation, ulcers, and even cardiovascular side effects, while opioids carry risks of sedation, addiction, and tolerance, which pose significant challenges with long-term use. 3 , 4 In contrast, PEA, as an endogenous lipid mediator, has significant advantages in safety and tolerability. Numerous clinical studies have shown that within an appropriate dosage range, PEA not only exhibits notable anti-inflammatory and analgesic effects, but also has an extremely low incidence of adverse reactions, demonstrating good safety in special populations (such as the elderly and pregnant women). This high safety profile and broad therapeutic window make PEA suitable not only as a standalone therapy but also highly appropriate as an adjunct medication in combination treatments, reducing the dosage of main drugs and the associated risk of side effects. 16 , 17 In addition to safety advantages, PEA also features multi-target and integrative regulatory characteristics in its analgesic mechanisms, demonstrating immense potential in replacing or assisting traditional analgesics. Firstly, PEA can directly intervene in multiple aspects of pain signal transmission and inflammatory responses by activating PPAR-α and regulating the endogenous cannabinoid system, thereby weakening the occurrence and maintenance of pain at the molecular level. Moreover, PEA has been shown to reduce the activation of glial cells and the release of pro-inflammatory cytokines; these mechanisms can exert analgesic effects independently and they also enhance efficacy when used in conjunction with other medications. 18 , 19 For instance, Déciga-Campos et al 20 reported that in the treatment of certain chronic neuropathic pain and fibromyalgia, the introduction of PEA can significantly decrease patients’ dependence on opioids or other potent analgesics, thereby reducing the risks of drug tolerance and addiction; Simultaneously, its combination with other natural antioxidants or anti-inflammatory constituents can further enhance the overall analgesic effect and improve quality of life. This integrative multi-pathway regulatory paradigm provides new ideas and theoretical support for the future development of precision medicine and individualized treatment. 21 , 22 Current research on pain and its related inflammatory responses has achieved a wealth of foundational results, but effectively translating these findings in molecular biology and cellular mechanisms into clinical practice still faces significant challenges. A large amount of basic and animal experimental data reveals the key roles of various cytokines, neurotransmitters, and receptors in the process of pain regulation, yet there remains a clear gap between these data and clinical trials. For example, while many studies indicate that PEA can effectively alleviate inflammation and neuropathic pain by inhibiting NF-κB, reducing pro-inflammatory cytokine levels, and regulating endocannabinoid-related signaling, there is still a lack of systematic integration regarding the specific mechanisms of action and optimal conditions in different pathological states. 23 , 24 Therefore, the primary goal of this review is to explore the effects of PEA in different pain models by consulting and integrating the latest clinical data, randomized controlled trials, as well as systematic reviews and meta-analyses, thereby providing a more comprehensive theoretical basis for the clinical translation of foundational research results, while also revealing current research shortcomings and new targets for further exploration in the future. This article aims to provide readers with a systematic review of the mechanisms of action and clinical applications of PEA in pain relief. The structure of the article is designed to begin with the multifactorial pathological background of pain and inflammation, elaborating in detail on the pathogenesis of chronic pain and neuropathic pain at both peripheral and central levels, as well as the complex interactions between neuroendocrine, immune, and glial cells; secondly, it provides a comprehensive description of PEA’s chemical structure, endogenous production, food sources, and its unique role as a natural lipid mediator in the regulation of inflammation and pain processes; furthermore, it compares the significant differences in safety, tolerability, and multi-target regulatory mechanisms between traditional analgesics and PEA; finally, by integrating basic research and clinical data, it clearly points out the current knowledge gaps and bottlenecks that need to be addressed in the clinical translation process. 16 , 19 This article adopts a multidisciplinary perspective, incorporating neuroscience, immunology, pharmacology, and clinical medicine, aiming to provide a new theoretical framework and practical basis for the field of pain treatment. This interdisciplinary integration writing strategy not only helps readers recognize the complexity of pain generation and regulation from a macro to a micro perspective but also opens possibilities for developing individualized analgesic plans and exploring combination treatment strategies in the future. In summary, this article serves as a systematic review of existing literature, while also providing a solid foundation for future efforts to find new non-addictive analgesics and to facilitate the translation of basic research into clinical applications, with the hope of promoting more high-quality randomized controlled trials and multicenter large-sample studies to clarify the optimal dosing and administration routes of PEA, ultimately achieving the goal of precision medicine.

The clinical studies included in the analysis mainly consist of randomized controlled trials (RCTs) and observational studies, with selection criteria generally including study design, sample size, and clearly defined types of pain. PEA has been widely used in the management of different types of pain, including neuropathic pain and chronic inflammatory pain ( Table 1 ). Commonly used assessment tools include the Visual Analog Scale (VAS), the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), among others. These tools are clinically significant as they can quantify the severity of patients’ pain and functional impairment. 45 , 58 The key research findings are summarized as follows: Numerous studies have shown that PEA monotherapy can significantly reduce pain scores. For example, one study indicated that oral PEA treatment is associated with reduced skin adverse reactions related to interferon-β1a in patients with multiple sclerosis, resulting in improved pain perception. 16 Another study demonstrated that ultramicronized PEA can significantly alleviate pain intensity and neuropathic pain components in patients with chronic low back pain. 59 A meta-analysis of aggregated data on chronic pain showed that PEA can reduce pain intensity by 1.04 points every two weeks. 19 , 47 PEA not only relieves pain but also improves patients’ physical activity and sleep quality. Research shows that the WOMAC functional scores in the PEA group significantly improved, indicating that PEA can effectively enhance patients’ quality of life. 45 In patients with carpal tunnel syndrome, treatment with ultrafine PEA can improve sleep quality, prolong continuous sleep duration, and reduce sleep latency and sleep disorders. 57 Regarding the dose effect of PEA, studies indicate that higher doses (such as 600 mg/day) may be more effective than lower doses (such as 300 mg/day), but the specific dosage should be adjusted according to the individual patient’s condition. 60 Some studies have also examined the differences in efficacy of various treatment durations; for instance, a 12-week trial showed that the combined use of PEA and alpha-lipoic acid can effectively treat chronic prostatitis/chronic pelvic pain syndrome. 58 The benefits of long-term use of PEA have also been observed in other studies, such as in osteoarthritis pain models, where PEA was able to reduce inflammation and pain. 43 In clinical trials, forest plots, curves, and Kaplan–Meier curves are widely used to present and interpret data. The selection of these charts is based on their ability to effectively display the effect sizes and pain relief times of different studies. Forest plots are commonly used to display the effect sizes and confidence intervals of different studies, helping to assess the consistency of PEA treatment effects. For example, a certain forest plot shows that the standardized mean difference (SMD) for the PEA group compared to the placebo is −1.2 (95% CI: −1.5 to −0.9), indicating that PEA has a significant analgesic effect. 47 The curve chart can intuitively show the onset time and duration of effect of PEA. For example, the curve chart shows that patients experience significant pain improvement two weeks after using PEA, and the effect persists. In some studies, Kaplan–Meier curves were used to assess the duration of pain relief and compare the effectiveness of different treatment regimens. 47 The Kaplan–Meier curve can show the duration of pain relief. For example, in one study, the Kaplan–Meier curve indicated that 81% of patients receiving PEA treatment had a pain score of 3 or lower after 60 days of treatment, compared to only 40.9% in the control group. 47 PEA generally has good safety and tolerance, with a low incidence of adverse reactions. Common adverse reactions include gastrointestinal discomfort and dizziness, but they are usually mild and occur at a far lower rate than the risk of gastrointestinal bleeding that traditional analgesics like NSAIDs may cause. Compared to opioids, PEA does not have notable side effects such as constipation and motor coordination disorders. 59 , 61 Some studies have assessed the tolerability of different populations. For example, in elderly patients, PEA has shown good tolerability, making it an attractive option for the management of chronic pain. 60 , 62 In terms of dose-dependent responses, although high doses of PEA may increase the risk of adverse effects in some individuals, overall, the safe dosage range for PEA is broader, with significant individual variability. 16 When analyzing clinical trial data, it is important to pay attention to potential sources of bias that may affect the results, such as study design, patient baseline differences, and so on. Data heterogeneity may arise from differences in patient populations across studies, variations in types of pain, and differences in formulations of PEA. 58 To reduce heterogeneity, subgroup analyses can be conducted, such as stratifying by pain type to separately assess the effects of PEA on neuropathic and inflammatory pain. Additionally, tools like the Cochrane risk of bias assessment tool can be used to evaluate study quality and identify potential bias risks. 35 In terms of data integration, it is important to avoid simply listing research results; instead, one should compare the consistency of conclusions across different studies through tables or textual analysis and conduct critical analysis. It should point out the limitations of current data, such as insufficient sample size and short follow-up duration, and provide direction for future research. For instance, although most RCTs support the analgesic effect of PEA, the negative results of a certain study may be related to the higher baseline pain severity of patients, suggesting the need to optimize inclusion criteria for specific subgroups in future studies. For example, one study included 73 patients with neuropathic pain caused by spinal cord injury, and the results showed no difference in pain intensity reduction between PEA-um and placebo. However, the study also emphasized that PEA did not cause more side effects than placebo, indicating that PEA has good safety. 35 In terms of clinical translation, explaining the differences in efficacy by combining the mechanism of action of PEA (such as PPAR-α activation) enhances logical coherence. For example, PEA exerts anti-inflammatory and analgesic effects by activating PPAR-α receptors, which may explain why PEA’s efficacy is more significant in certain inflammatory pain models. 26 At the same time, PEA’s influence on the endogenous cannabinoid system may also play a role in the alleviation of neuropathic pain. 31 Overall, clinical trial data and evidence-based analysis indicate that PEA has potential therapeutic value in various types of pain, especially in the management of chronic pain and neuropathic pain. Its good safety and tolerability make it an ideal alternative or adjunct to traditional analgesics. However, future research should still focus on dose optimization, individualized responses, and the impact of different formulations on efficacy to further enhance the clinical application value of PEA.

This chapter mainly discusses the emerging technological applications in the research of the mechanism of PEA in recent years, personalized precision medical strategies, and the future directions of interdisciplinary integration and combined therapy. With the continuous development in the fields of molecular biology, neuroscience, and clinical pharmacology, new technologies and multidisciplinary approaches are providing fresh perspectives and solid evidence to reveal the deeper mechanisms of PEA in anti-inflammatory, analgesic, and neuroprotective effects, while also pointing the way to optimizing clinical medication plans and formulating personalized treatment strategies ( Figure 4 ). In recent years, the rapid development of single-cell sequencing technology (Single-Cell RNA Sequencing) has enabled researchers to analyze complex gene expression profiles in the nervous system and immune cells at the single-cell level ( Figure 4B ). By utilizing this technology, scientists hope to distinguish the expression differences of PEA receptors (such as PPAR-α) and their downstream signaling molecules among different cell subtypes in the context of inflammation, neuropathic pain, and neurodegenerative changes, thereby constructing a more detailed map of cellular regulatory networks. By deeply analyzing the activity of PEA-responsive signaling pathways in different cell populations, not only can the specific mechanisms of PEA in inhibiting key inflammatory signaling pathways such as NF-κB and p38-MAPK be elucidated, but also new targets that have not yet been fully recognized can be discovered, which is of great significance for subsequent drug design and functional validation. 26–29 Meanwhile, the development of real-time live molecular imaging technology has provided unprecedented possibilities for observing the distribution, metabolism, and dynamic effects of PEA in vivo. By utilizing fluorescently labeled probes, near-infrared imaging, and bioluminescent systems, information on the spatiotemporal distribution of PEA in the central and peripheral nervous systems can be directly obtained from live animal models. This technology allows for real-time monitoring of the dynamic regulation process of PEA at inflammation sites and injury areas after administration, providing direct evidence for revealing how PEA transmits signals between cells, regulates glial cell activity, and maintains local immune homeostasis. Additionally, multimodal neuroimaging (such as functional magnetic resonance imaging, positron emission tomography, and diffusion tensor imaging) offers strong data support for assessing the impact of PEA on brain functional networks from a macroscopic perspective. By combining the specific effects at the molecular level with changes in the neural network at the systemic level, a panoramic view of PEA’s effects from micro to macro can be constructed, providing a comprehensive perspective for understanding its role in alleviating chronic pain and cognitive dysfunction. Based on the application of these advanced technologies, future research is expected to achieve breakthroughs in several areas: first, revealing changes in signaling pathways within various cell types regulated by PEA through single-cell sequencing, which will help uncover the sensitivity and response differences of different subtype cells to PEA; second, real-time in vivo molecular imaging technology will be able to reveal the specific dynamic changes of PEA in inflammation and nerve injury areas, assisting researchers in precisely locating the action areas and targeted cells of PEA through the dual information of spatial positioning and temporal resolution; third, the integration of multimodal neuroimaging data can transform molecular biology findings into explanations of their impact on overall nervous system function, thereby better assessing the potential applications of PEA in clinically improving neural functions and alleviating pain ( Figure 4B ). In the context of chronic pain and neuropathic pain, the damage, repair, and plastic changes of nerve cells directly affect patients’ pain experiences and cognitive functions. Numerous experimental studies have shown that PEA not only exerts anti-inflammatory and analgesic effects but may also promote the restoration of the structure and function of the nervous system by regulating neuro-regeneration and synaptic remodeling processes. For example, in nerve injury models, it has been observed that PEA can inhibit the sustained release of inflammatory mediators by activating the PPAR-α signaling pathway, thereby providing a more favorable microenvironment for the regeneration of nerve cells. At the same time, PEA can also regulate the phosphorylation state of AMPA receptor subunits and the expression of postsynaptic density proteins, promoting the reconstruction of synaptic structures and increasing the efficiency of neurotransmission. 24 These effects not only help repair damaged neural circuits but may also improve memory impairments and cognitive decline caused by nerve injuries. Further research can utilize electrophysiological recording techniques, two-photon microscopy, and optogenetic tools to monitor the role of PEA in neurons and glial cells in real time. These techniques can quantitatively analyze neuronal firing patterns, synaptic transmission, and long-term potentiation (LTP) changes, thereby allowing for a more precise assessment of PEA’s role in regulating intracellular signaling processes. Meanwhile, studies based on gene knockout and transgenic animal models can also help clarify the relative contributions of PPAR-α and other potential targets in PEA-mediated nerve repair. The current preliminary research results provide strong support for PEA in neural repair and synaptic plasticity remodeling, but its optimal intervention timing, dose dependence, and interactions with other regulatory factors still need further exploration, laying the theoretical foundation for developing precise treatment plans in the future. In clinical practice, different patients exhibit significant heterogeneity in their responses to PEA treatment due to variations in genetic background, disease progression stage, and inflammatory responses. To achieve precision therapy, patient stratification management has become an important strategy, which focuses on dividing patients into subgroups with similar molecular phenotypes and clinical presentations based on individual characteristics, while exploring biomarkers closely related to the efficacy of PEA. Through high-throughput genomics, proteomics, and metabolomics analysis, researchers can identify a series of candidate biomarkers, such as indicators associated with PPAR-α receptor activity, levels of inflammatory mediators, and neurotrophic factors (like BDNF), which are expected to predict patients’ sensitivity and response level to PEA treatment. The hierarchical management strategy not only helps to optimize treatment plans but also significantly improves the efficacy detection capacity of clinical trials. When designing trials, considering patients’ genetic polymorphisms, disease duration, and inflammatory levels can more precisely define trial inclusion criteria, making the treatment effects more evident. Future research needs to validate the predictive efficacy of these biomarkers in large patient cohorts and establish a patient stratification system based on multivariable models to provide evidence-based support for the clinical implementation of personalized treatment. This classification management based on individual patient characteristics not only aids in enhancing the utilization efficiency of PEA but also reduces unnecessary drug exposure and the risk of side effects. Given the significant differences in efficacy and tolerability of PEA treatment among different individuals, determining its optimal dosage and administration scheme has become an urgent problem to be solved. N-of-1 trials, as a cross-over controlled design method focusing on a single patient, are gradually gaining attention. By alternately using PEA and a placebo in the same patient and continuously recording efficacy indicators (such as pain scores, functional improvements, etc), it is possible to eliminate the interference caused by inter-group differences, providing precise data for individualized administration. Such trials are particularly suitable for patient populations with complex clinical presentations and uncertain results from traditional large sample randomized controlled trials, achieving the goal of precision medicine while ensuring scientific rigor. Corresponding to N-of-1 trials, multi-center large-sample randomized controlled trials can statistically derive the overall dose-response curve and pharmacokinetic characteristics of PEA at the population level. By collaborating across centers and gathering data from patients of different regions and backgrounds, the statistical power of the trials can be significantly enhanced, thereby more accurately capturing the optimal time window, dose range, and administration routes for PEA. In the future, combining the advantages of these two research methods within a design model that is both broadly applicable and considerate of individual differences will undoubtedly establish a scientific and systematic standardized approach for the precise clinical application of PEA ( Figure 4C ). In contemporary medical research, complex diseases such as chronic pain, neuropathic pain, and neurodegenerative diseases often involve multiple mechanisms, multiple signaling pathways, and the synergistic dysregulation of various cell types. A single discipline struggles to comprehensively reveal the pathophysiological processes of these diseases, while multidisciplinary collaboration and integration can overcome this limitation. Molecular biology provides direct evidence for unveiling the microscopic mechanisms of PEA in cellular signaling, gene regulation, and inflammatory intervention; neuroimaging utilizes technologies such as fMRI, PET, and DTI to visually demonstrate the effects of PEA on brain functional networks, neural circuit connectivity, and pathological structural changes; and clinical pharmacology focuses on analyzing the pharmacokinetics, drug metabolism, dosage effects, and safety issues of PEA, which in turn guides practical application. This multidimensional integration of molecules, imaging, and clinical research not only aids in systematically explaining the mechanism of action of PEA from different levels but also facilitates a seamless connection from basic research to clinical application. For example, after revealing the key targets of PEA in regulating inflammation and neuroprotection through molecular biological methods, real-time monitoring of the distribution and changes of these targets in the central nervous system can be carried out using neuroimaging, and further combined with clinical pharmacological data for dosage optimization and efficacy prediction, forming a closed-loop feedback system. In this way, both basic theoretical research can be advanced, and better service can be provided for clinical treatment, ultimately achieving the dual goals of pain management and neurofunctional recovery ( Figure 4 ). Preliminary data that currently exists suggest that changes in PEA-regulated signaling pathways at the molecular level can manifest as functional recovery in specific brain regions on imaging, while clinical pharmacology data show that appropriate doses of PEA can maximize its neuroprotective and analgesic effects. Establishing interdisciplinary communication platforms and data-sharing mechanisms in the future will significantly accelerate in-depth research into this synergistic mechanism and promote the application of comprehensive analysis methods based on multidimensional data in clinical decision-making. Although PEA, as a pure natural lipid mediator, has significant anti-inflammatory, analgesic, and neuroprotective effects, single drug therapy often fails to meet the needs of all patients in the complex pathological processes of chronic pain and neuropathic pain. Recently, the development of new small molecule drugs has provided a broad prospect for combination therapy strategies. Unlike traditional single treatment methods, the combined application of PEA with other small molecule drugs that have complementary mechanisms is expected to enhance therapeutic effects while reducing the dosage of the single drug, thereby minimizing the risk of potential adverse reactions. Certain small molecules that can modulate the activity of the endogenous cannabinoid system, or molecules that enhance antioxidant and anti-inflammatory functions, may exhibit synergistic effects when working in conjunction with PEA. Studies have shown that in animal experiments, the combined use of low doses of opioids or NSAIDs with PEA can significantly enhance analgesic effects without significantly increasing side effects. 20 Furthermore, new small molecule intervention methods also include candidate drugs capable of precisely targeting lesions or regulating the function of specific ion channels, which may complement PEA in their action targets and signaling pathways, promoting nerve repair, enhancing synaptic transmission, and improving intracellular homeostasis. The exploration of combined therapeutic strategies requires multi-layered and multi-angle experimental validation. On one hand, in in vivo and in vitro models, it is necessary to first confirm whether the interactions between different drugs show synergistic or additive effects; on the other hand, through comprehensive assessments of drug metabolism, pharmacokinetics, and pharmacodynamics, the optimal combination ratios, timing of administration, and therapeutic windows between the components must be clarified. Modern pharmacological methods, such as dose-response curves, equivalence trials, and systems biology analytical tools, provide technical support for this process. Future research should integrate chemical synthesis, cell biology, animal model experiments, and preclinical evaluation data to construct a multi-parameter combined evaluation system, thereby providing scientific guidance for the combined application strategies of PEA and novel small molecule interventions. Collectively, through the gradual application of new technologies, continuous optimization of individual stratification and precision medical strategies, and ongoing exploration of interdisciplinary integration and combined treatment models, the future role and clinical application of PEA in the treatment of chronic pain and neuropathic pain will likely see significant breakthroughs. This series of innovative measures will not only help reveal the intrinsic mechanisms of PEA’s multi-target and comprehensive regulation but also promote the development of more scientific and personalized treatment plans, providing patients with safer and more effective new options for pain management.

A large number of foundational experiments and animal model studies have shown that PEA, as an endogenous lipid mediator, plays a unique and extensive role in pain relief, inflammation control, and neuroprotection. It can effectively regulate pain and its related inflammatory responses through the synergistic action of multiple molecular signaling pathways. One of its main mechanisms is to regulate downstream signaling pathways by activating PPAR-α, thereby inhibiting the activity of NF-κB to reduce the expression of pro-inflammatory cytokines (such as tumor necrosis factor-alpha, interferon-gamma, and interleukin-17). 16 This mechanism not only helps to attenuate local inflammatory responses but also reduces pain sensitivity caused by excessive neuronal activation. On the other hand, PEA has a companion effect with the endogenous cannabinoid system; although it does not directly activate CB1 or CB2 receptors itself, it can enhance the effects of endogenous cannabinoids such as AEA, thereby indirectly regulating neurotransmission and pain modulation. Additionally, PEA can reduce the release of inflammatory mediators within the nervous system by regulating the activity of glial cells, particularly microglia and astrocytes, thereby protecting the central nervous system from inflammatory damage. This regulatory mechanism has been validated in many neuropathic pain models, capable of improving synaptic plasticity in neurons, restoring LTP, and enhancing related cognitive functions. 25 , 40 It is worth noting that PEA also has significant protective effects on the peripheral nervous system. In animal models of chronic pain and neuropathic pain, PEA can significantly reduce oxidative stress responses triggered by nerve injury and improve the regeneration and repair of damaged nerves. This process involves not only the inhibition of downstream inflammatory signals (such as the p38-MAPK pathway) but also the regulation of ion channel functions and neurotrophic factors (such as BDNF), enabling neurons to recover normal functions more quickly after external injury. 25 Besides, PEA can also regulate immune cells, particularly its stabilizing effect on mast cells plays a crucial role in inflammatory pain. By reducing the degranulation of mast cells and the release of related inflammatory mediators (such as nerve growth factor and vascular endothelial growth factor), PEA has shown significant anti-inflammatory and analgesic effects in various inflammatory diseases (such as visceral pain induced by the endometriosis model with urinary stones). 63 The synergistic action of multiple targets in this mechanism not only provides a theoretical basis for the application of PEA in acute inflammation and chronic pain but also lays the foundation for its expanded application in nerve repair and disease prevention. Generally, the multiple mechanisms of PEA are reflected in several aspects: Firstly, through the activation of PPAR-α, it inhibits key signaling pathways such as NF-κB and p38-MAPK, reducing the generation of pro-inflammatory factors at the source; Secondly, by acting as a partner of the endocannabinoid system, PEA enhances the endogenous analgesic mechanism; thirdly, PEA reduces local and central inflammation by regulating the activity of glial cells and mast cells, thereby protecting neurons and promoting the recovery of neural plasticity. 16 , 25 , 26 The interplay of these mechanisms gives PEA a significant advantage in improving pain, controlling inflammation, and protecting nerve cells, providing a scientific basis for the future development of novel analgesic and neuroprotective drugs. Based on numerous clinical studies and practical application cases, PEA has shown relatively high safety and good tolerance in the treatment of various pain diseases, giving it a clear advantage over traditional analgesics such as opioids and non-steroidal anti-inflammatory drugs ( Figure 4C ). In some clinical trials involving neuropathic pain, chronic low back pain, and pelvic pain, oral ultra-micronized PEA as an adjunct therapy not only effectively reduced patients’ dependence on conventional analgesics but also significantly improved pain scores and quality of life. 37 , 59 , 60 PEA, as an endogenous lipid that naturally exists in food and the body, has low toxicity, good tolerance, and lacks obvious drug-drug interactions, which is particularly important in complex pathological conditions (such as elderly patients with polypharmacy). For example, the N-of-1 trial method was used to verify the positive effects of PEA in chronic pain management among elderly patients, not only improving pain symptoms but also enhancing functional status and quality of daily life, providing clinicians with a personalized precision treatment plan. 60 , 62 Despite the unique pharmacological advantages of PEA, there are still challenges in its clinical promotion. First, there are certain differences in the dosage forms of PEA used in different clinical trials (such as conventional, microparticulated, ultramicronized, or nanomedicine), which have a direct impact on bioavailability and efficacy. 55 Studies have shown that ultramicronized PEA has higher in vivo distribution efficiency and more lasting analgesic effects. Therefore, how to standardize products through appropriate formulation processes has become an urgent issue that needs to be addressed ( Figure 4A ). Secondly, although several clinical studies have shown that PEA has positive effects on various pain conditions, some studies have limitations such as short follow-up durations and small sample sizes, which pose challenges to the stability and generalizability of the results. In clinical trials for neuropathic pain after spinal cord injury, while some studies failed to observe significant differences compared to the placebo group, overall adverse events were very few, indicating that its safety advantages remain evident. 35 Furthermore, differences among patients, such as genetic background, previous medication history, levels of inflammation, and the complexity of pain types, may all influence the therapeutic effects of PEA, necessitating further exploration of individualized treatment strategies and dose optimization in future clinical research. While the combined application of PEA with other drugs (such as opioids, NSAIDs, alpha-lipoic acid, and other natural antioxidants) has shown synergistic analgesic effects, the optimal combination ratios between different drugs, the mechanisms of interaction, and long-term safety still require more evidence-based research for validation. 20 , 58 , 61 Overall, PEA demonstrates unique and multiple advantages in clinical applications, but it is inevitably restricted by factors such as formulation standards, dosage optimization, patient heterogeneity, and combination medication strategies, all of which point to directions for improvement in future clinical translational research. Future research should build on the existing foundation and conduct large-scale, multi-center, randomized controlled trials to comprehensively verify the efficacy and safety of PEA in various types of pain and neurodegenerative diseases using objective and rigorous evidence-based medical methods. From preliminary mechanistic studies to clinical applications, there is an urgent need to establish a standardized dosage and administration scheme to clarify the optimal application strategies of different formulation products under various pathological conditions. This will not only help improve therapeutic outcomes but also reduce the variability in efficacy and interindividual differences caused by different formulation processes. To achieve this goal, future research needs to closely integrate cutting-edge innovations from multiple disciplines, including molecular biology, neuroimaging, clinical pharmacology, and medicinal chemistry. For example, using single-cell RNA sequencing technology, detailed molecular characterization of pain-related cell populations can be conducted, thereby deepening the understanding of PEA’s regulatory effects on glial cells and immune cells; real-time in vivo molecular imaging technology and multimodal neuroimaging will also provide reliable data for observing the effects of PEA on synaptic plasticity and neural network remodeling in the brain and spinal cord. 25 , 40 Additionally, future research should emphasize interdisciplinary collaboration, integrating data from basic research and clinical trials to create a comprehensive evaluation system that ranges from molecules and cells to organs and overall functions. For instance, the N-of-1 trial method used in some recent randomized controlled trials not only allows for precise efficacy assessment tailored to individual patients but also provides insights for optimizing group treatment plans, making clinical decision-making more personalized and precise. 60 , 62 In terms of combination therapy, exploring the synergistic mechanisms of PEA with other analgesics or anti-inflammatory drugs (such as opioids, gabapentin, natural antioxidants, and plant extracts) will provide possibilities for developing new multi-target combination therapy strategies. This not only helps achieve the desired analgesic effect while reducing the dosage and side effects of traditional drugs, but also promotes the shift from single-drug treatment to multimodal and multi-target therapies, effectively addressing chronic pain and neurodegenerative diseases caused by complex and multifaceted factors. 20 , 58 , 61 Future clinical trials should further expand the sample size and follow-up duration, utilize rigorous randomized controlled designs to eliminate bias, while paying attention to individual differences, and achieve patient stratification management through means such as biomarkers. Only with a more detailed understanding of each patient’s biological status and pain characteristics can the concept of precision medicine be truly implemented. In addition, multi-center cooperation among countries and regions will provide broader data support for the efficacy evaluation of PEA in different populations, thereby accelerating the clinical promotion of PEA worldwide. Collectively, promoting the transition of PEA from basic science to clinical application requires efforts in the following areas: First, conducting large-scale, long-term, multi-center randomized controlled trials to systematically evaluate the efficacy and safety of PEA in different types of pain; Secondly, optimizing the dosage form and preparation process of PEA to ensure sufficient bioavailability in the body; Third, utilizing new technologies to deeply analyze the multiple molecular mechanisms of PEA, particularly its fine roles in neuroprotection and synaptic remodeling; Fourth, strengthening interdisciplinary and international cooperation to integrate advantageous resources from different fields to jointly advance the development of personalized precision medicine. 47 , 55 , 64 With the in-depth clarification of multiple mechanisms, sufficient accumulation of clinical data, and the promotion of interdisciplinary collaborative innovation, PEA is expected to become a safe and effective innovative analgesic and neuroprotective drug with multiple target regulation in the future, opening new therapeutic prospects for patients with chronic pain and neurological diseases.