Bradykinin Receptors Play a Critical Role in the Chronic Post-ischaemia Pain Model

Complex regional pain syndrome type-I (CRPS-I) is a chronic painful condition resulting from trauma. Bradykinin (BK) is an important inflammatory mediator required in acute and chronic pain response. The objective of this study was to evaluate the association between BK receptors (B1 and B2) and chronic post-ischaemia pain (CPIP) development in mice, a widely accepted CRPS-I model. We assessed mechanical and cold allodynia, and paw oedema in male and female Swiss mice exposed to the CPIP model. Upon induction, the animals were treated with BKR antagonists (HOE-140 and DALBK); BKR agonists (Tyr-BK and DABK); antisense oligonucleotides targeting B1 and B2 and captopril by different routes in the model (7, 14 and 21 days post-induction). Here, we demonstrated that treatment with BKR antagonists, by intraperitoneal (i.p.), intraplantar (i.pl.), and intrathecal (i.t.) routes, mitigated CPIP-induced mechanical allodynia and oedematogenic response, but not cold allodynia. On the other hand, i.pl. administration of BKR agonists exacerbated pain response. Moreover, a single treatment with captopril significantly reversed the anti-allodynic effect of BKR antagonists. In turn, the inhibition of BKRs gene expression in the spinal cord inhibited the nociceptive behaviour in the 14th post-induction. The results of the present study suggest the participation of BKRs in the development and maintenance of chronic pain associated with the CPIP model, possibly linking them to CRPS-I pathogenesis.

Chronic pain, Hyperalgesia, Inflammation, Kinins, Inflammatory mediators, Bradykinin receptor antagonists

Complex Regional Pain Syndrome Type-I (CRPS-I) is a chronic multifactorial disorder characterized by severe pain along with sensory, autonomic, motor and trophic impairment (Goh et al. 2017). This condition generally affects women (3–4 times more often than men) in the age group between 50 and 70 years (de Mos et al. 2007; Beerthuizen et al. 2012) and usually develops after tissue injury, surgery or minor trauma, in the absence of peripheral nerve injury (Goh et al. 2017). The pain is disproportionate to degree of tissue injury and persists beyond normal expected time for tissue healing (Guthmiller and Varacallo 2019). According to Bruehl, CRPS-I is distinguished from other chronic pain conditions by the presence of autonomic and inflammatory changes in the affected region (Bruehl 2015). CRPS-I has distinct stages recognized as: acute and persistent or chronic phase (Munnikes et al. 2005). The acute phase involves an exaggerated/aberrant post-traumatic inflammatory response and is characterized by pain, oedema, erythema, increased temperature and impaired function in the CRPS-affected limb (Marinus et al. 2011). In turn, the transition between acute to chronic phase is marked by changes from nociceptive to neuropathic pain characterized by spontaneous, burning pain, allodynia and pain occurring in the area with sensory abnormalities (Gierthmühlen et al. 2014). Considering the complexity of disease, heterogeneity of the clinical presentation and the lack of research into therapies specifically in CRPS-I, the management of symptoms require multidisciplinary approach and the adoption of strategies adapted from neuropathic pain states (Gierthmühlen et al. 2014). Despite, there are some options for pharmacological treatment of CRPS-I, including: glucocorticoids, bisphosphonates, nonsteroidal anti-inflammatory drugs (NSAIDs), anticonvulsants, opioids and anesthetics and topical preparations of anti-oxidants such as dimethyl sulfoxide (DMSO) and N-acetylcysteine (Lee et al. 2018). In this sense, administration of glucocorticoids have been indicated to reduce post-traumatic inflammation during acute phase of CRPS-I (Goh et al. 2017). Additionally, although the most common drug for pain relief are NSAIDs, there is no evidence of its clinically positive effects in CRPS-I, since to date the use of COX-2 selective inhibitors has not been clinically evaluated in the treatment of disease (Bruehl 2015; Lee et al. 2018). How previously cited, the clinical signs of disease during its acute phase suggest that CRPS-I is linked with immunologic and pro-inflammatory responses derived from tissue trauma (Bruehl 2015). In the inflammatory pathways, previous data have linked the development of CRPS-I to mechanisms of peripheral and central sensitisation (Bruehl 2015). In this sense, elevated levels of pro-inflammatory mediators including IL-8, substance P, calcitonin-gene-related peptide (CGRP) and soluble tumour necrosis factor receptor I/II (sTNFR I/II) were identified in blood samples obtained from patients with CRPS-I (Schinkel et al. 2009). Mainly SP and CGRP have been linked to neurogenic inflammation and consequently to most post-traumatic inflammatory changes observed in CRPS-I (acute oedema, vasodilatation and increased sweating) (Wasner et al. 2003; Marinus et al. 2011). In addition, the contribution of hypoxia-inducible factor-1α (HIF-1α) (Hsiao et al. 2016), endothelin (Kim et al. 2015; Millecamps et al. 2015), tumour necrosis factor (TNF) (Sabsovich et al. 2008) and reactive oxygen species (ROS) (Kwak et al. 2009) to chronic nociceptive sensitization in animal models of CRPS were also demonstrated. Altogether, these inflammatory mediators are able to excite nociceptors and induce long-term peripheral sensitization (Ji et al. 2014). In turn, the continuous stimulation of nociceptors leads to an increase of excitability in secondary nociceptive neurons—a process termed central sensitisation (Woolf 2011). These changes contribute to pain processing disorders and consequently pain chronification, an essential feature of CRPS-I (Ji et al. 2003; Cheng and Ji 2008; Latremoliere and Woolf 2009). BK is a common inflammatory mediator in both peripheral and central sensitisation processes (Couture et al. 2001; Ferreira et al. 2002, 2004; Kohno et al. 2008; Wang et al. 2014; Schuelert et al. 2015). This peptide is part of the kinin–kallikrein system (KKS), which comprises the peptide kinins (derived from kininogen precursors), tissue kallikreins, proteolytic enzymes, and the BK receptors B1R and B2R (metabotropic G protein-coupled receptors (GPCRs) of the Gi and Gq family) (Ferreira et al. 2002; Dutra 2016). Kinins are vasoactive peptides represented by BK and Lys-BK peptides (preferred B2R agonists), des-Arg9-BK, and Lys-des-Arg9-BK (metabolites with high affinity and selectivity for B1R) (Dutra 2016; Qadri and Bader 2017). Additionally, enzymes named kininases can degrade these peptides, including kininase angiotensin I-converting enzyme (ACE). Interestingly, while B2R is constitutively expressed and participates in the acute phase of the inflammatory and pain response, the expression of B1R is increased in pathological situations, such as tissue injury (Ferreira et al. 2002; Costa et al. 2011). In this context, BK released from tissue injury binds to kinin receptors, specially B2R, expressed by non-myelinated afferent neurons, promoting polymodal nociceptor activation (hyperalgesia) and reflex responses by the autonomic nervous system (Couture et al. 2001; Marceau and Regoli 2004). The activation of BKRs triggers several well-known signalling pathways to produce depolarization and lowering of the threshold of the nociceptors, particularly, C- and Aδ-primary afferent fibres contributing to the hyperalgesic response. Accordingly, both BKRs were find to contribute to pathogenesis of paclitaxel-induced peripheral neuropathy (Costa et al. 2017), trigeminal neuropathic pain (Luiz et al. 2015), hypersensitivity induced by brachial plexus avulsion (BPA) (Quintão et al. 2019) and fibromyalgia symptoms (Brusco et al. 2019). Thus, pharmacologic modulation of these receptors became an important target for the treatment of chronic pain and inflammatory disorders (Costa et al. 2017). Keeping the above data in mind, the upregulated levels of BK in CRPS-I patients, and the possible participation of these receptors in CRPS-I development, we investigated the role of BKRs in mechanical and thermal cold allodynia during chronic post-ischaemia model (CPIP). Furthermore, we analysed the role of BKRs on oedema development after post-traumatic inflammatory response.

Chemicals Antisense oligonucleotides (ASOs) targeting B1R (5′-AGGTTCCTGTGGATGGCGTCCC-3′), B2R (5′-AGAATTCTGTTCACTGTTTCTTCCCTG-3′), and mismatch (5′-GGTGGAT TTGAGGATTTCGGC-3′) were obtained from GenOne Biotechnologies (Rio de Janeiro, RJ, Brazil) and prepared according to the manufacturer’s instructions (diluted in phosphate-buffered saline (PBS). HOE-140 (B2R antagonist), DALBK (B1R antagonist), Tyr-BK (B2R agonist), DABK (B1R agonist), and captopril (ACE inhibitor) were purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). All other chemicals were of analytical grade and purity and obtained from standard suppliers. The choice of dose for each drug was based on pilot experiments (results not shown) or on previous data described in the literature (Table 1). Table 1. | I.p. route* | HOE-140 (150 nmol/kg) and DALBK (50 nmol/kg) | Brusco et al. (2017) | | I.pl. route | HOE-140 (10 nmol/paw) and DALBK (10 nmol/paw) | Ferreira et al. (2004) | | I.pl. route | Tyr-BK (10 nmol/paw) and DABK (20 nmol/paw) | Ferreira et al. (2004) | | I.t. route | HOE-140 (100 nmol/ sitio) and DALBK (10 nmol/sitio) | Ferreira et al. (2002) | | Antisense | Antisense B2R (2,5 μg/sitio) and B1R (2,5 μg/sitio) | Costa et al. (2011) | | Captopril | 30 mg/kg (p.o.) | Brusco et al. (2017) | *Experiment conducted in male and female Swiss mice Animal Study The experiments were carried out in male and female Swiss mice (40–60 g, 60–120 days of age) obtained from the Federal University of Santa Catarina. Animals (maximum of six mice group-housed in clear-transparent plastic cages with dust-free sawdust bedding) were kept under a 12-h light/dark cycle (artificial light on at 7:00 a.m.) and temperature (22 ± 2 °C). They were fed a pelleted and extruded mouse diet ad libitum and had unrestricted access to drinking water. Animals were acclimatised to laboratory settings for at least 1 h before testing and were used only once throughout the experiments. Mice were randomly assigned before treatment or behavioural evaluation. All procedures in this study were performed in accordance with the National Institute of Health Guide for the Care and Use of Laboratory Animals (National Research Council (US) Committee for the Update of the Guide for the Care and Use of Laboratory Animals., 2011) and were approved by the Animal Ethics Committee of the Universidade Federal de Santa Catarina (CEUA-UFSC, protocol number PP00956/2014). Moreover, the number of animals and the intensity of the noxious stimuli used were the minimum necessary to demonstrate consistent effects. All the experimental procedures were conducted according to the guidelines of CONCEA and CEUA/UFSC, based on the principles of the 3Rs. Mice were euthanised by cervical dislocation. Behavioural evaluations were performed between 8:00 a.m. and 5:00 p.m. All experiments were performed by a blind operator, concerning nociception assessments, paw oedema and statistical analyses. Chronic Post-ischaemia Pain Induction We used CPIP, animal model of CRPS-I standardised by Coderre and colleagues in rats (Coderre et al. 2004), posteriorly adapted to mice (Tang et al. 2017; Dal et al. 2019). Briefly, the protocol consists of an ischaemia–reperfusion (IR) process, which generates an inflammatory cascade, resulting in acute inflammation, oedema, and posterior chronic hyperalgesia. CPIP was induced via IR injury of the left hind paw (Coderre et al. 2004). Concisely, animals were anesthetised over a 3-h period with a bolus (7%, 0.6 ml/kg, i.p.) with chloral hydrate (VETEC, São Paulo, Brazil) and 20% of the initial volume at the end of the first and second hour (Martins et al. 2013). Following induction of anaesthesia, three nitrile 70 durometer O-rings (O-rings West, Seattle, WA, USA) with a 7/32 internal diameter were placed around the left hind limb proximal to ankle joint. The end of the anaesthesia was timed so that mice recovered fully within 30–60 min following reperfusion, which occurred immediately after removal of the O-ring. After 3 h, the O-ring was cut, allowing reperfusion of the hind limb. It is necessary to highlight that during CPIP induction in females we used one O-ring, as CPIP induction with three O-rings promoted an exaggerated inflammatory process accompanied by tissue necrosis and self-mutilation during the pilot experiment. Therefore, we used a humane endpoint to shorten the suffering of these animals according to the guidelines Principles of laboratory animal care. Moreover, our next step was to verify if captopril and selective BKR agonists could exacerbate CPIP-induced hyperalgesia. Thus, considering the results obtained with the application of three O-rings in CPIP induction, in which animals demonstrated hyperalgesia levels close to or equal to 100%, we used one O-ring in these experiments mentioned above, to characterise a submaximal hyperalgesia level. Control (sham) mice were anesthetised, but the O-ring was partially cut so that it only loosely surrounded the ankle and did not occlude blood flow to the left hind paw. Experimental Design To investigate the participation of BKRs in CPIP at peripheral level, we used selective BKR antagonists targeting B1 and B2, DALBK and HOE-140 respectively, as well as vehicle, through two different routes: (i) intraperitoneal (i.p.) and (ii) intraplantar (i.pl.) injection (Fig. 1a, b). To determine whether selective BKR agonists can exacerbate CPIP-induced hyperalgesia, we used selective BKR agonists targeting B1R and B2R, DABK and Tyr-BK, respectively, or vehicle by i.pl. injection (Fig. 1b). In the same way, we evaluated if ACE inhibitors such as captopril, which consequently inhibit BK degradation, are also able to exacerbate mechanical allodynia induced by CPIP (Fig. 1c). Thus, on the 14th-day post-ischaemia, we administered captopril (30 mg/kg, p.o.) with and without selective BKR antagonists (DALBK (50 nmol/kg, i.p.) or HOE-140 (150 nmol/kg, i.p.) (Fig. 1c). Intrathecal Injection This experimental protocol was designed to investigate if intrathecal (i.t.) injection of selective BKR antagonists (DALBK and HOE-140) or ASOs targeting B1R and B2R could inhibit CPIP-induced mechanical allodynia in mice (Fig. 1d). We used ASOs targeting B1R (5′-AGGTTCCTGTGGATGGCGTCCC-3′), and B2R (5′-AGAATTCTGTTCACTGTTTCTTCCCTG-3′), as well as mismatch control (5′-GGTGGAT TTGAGGATTTCGGC -3′) administered by i.t. route to verify if inhibition of BKRs gene expression in vivo could modulate mechanical and cold allodynia induced by CPIP. ASOs or vehicle was administered for three consecutive days, every 12 h and 12 h before assessment of mechanical allodynia on the day 14 after induction of CPIP. In another experiment, we administered selective BKR antagonists (DALBK or HOE-140) or vehicle by i.t. route to investigate the participation of BKRs in CPIP at spinal level, also 14 days after CPIP induction. For i.t. drug administration mice were anesthetized with isoflurane and spinal cord puncture was performed between the L5 and L6 level to deliver drug (5 µl) using a 30G needle, according to the technique described by Hylden and Wilcox (Hylden and Wilcox 1980). Mechanical Allodynia Mechanical allodynia was evaluated by von Frey filament (0.4 g) and the frequency of withdrawal method (Bortalanza et al. 2002). Mice were placed individually in clear Plexiglass boxes (9 × 7 × 11 cm) on elevated wire mesh platforms allowing access to the right hind paw ventral surface. Withdrawal response frequency was measured following ten applications (3 s each) of the von Frey filament (VFH; Stoelting, Chicago, IL, USA) at different times (7, 10, 14 and 21 days post-induction) according to the protocol as shown in Fig. 1. In the experiments, animals were acclimatised for at least 1 h before behavioural testing, and to determine the basal tactile thresholds, all of the groups were evaluated prior to CPIP induction. Oedema CPIP-induced hind paw oedema was evaluated through digital micrometre (Digimess, São Paulo, Brazil). The micrometre was positioned with the fixed part on the dorsal surface and moving the part in the ventral plantar surface. Thus, hind paw oedema formation was described as Δpaw thickness = test paw thickness—basal paw thickness. Immediately after removing tourniquet (reperfusion), on day 0, the animals received i.p. administration of DALBK (50 nmol/kg) or HOE-140 (150 nmol/kg). The hind paw oedema was then evaluated between 1 and 8 h after drug administration. Cold Allodynia Test To assess cold allodynia we used the acetone test. Mice were placed under a transparent plastic dome on a metal mesh floor, and acetone was applied to the plantar surface of the paw. The response of the mice to acetone was noted for 20 s and was graded on a 4-point scale as defined by Flatters and Bennett (0, no response; 1, quick withdrawal, flick, or stamp of the paw; 2, prolonged withdrawal or repeated flicking; and 3, repeated flicking of the paw with licking of the paw) (Flatters and Bennett 2004). We evaluated mice cold allodynia at different time points including 8, 11, 15 and 22 days after CPIP induction, how illustrated in the Fig. 1. The results represent a final mean of three repeated measures. Determination of BK Levels The BK-related peptide levels were measured in samples of paw and spinal cord of CPIP and sham mice by a high-sensitivity enzyme immunoassay kit for BK obtained from Peninsula Laboratories International, Inc. (San Carlos, USA). The samples were collected at 22 days post-induction and homogenized with a cocktail of kininase inhibitors (Gewehr et al. 2013; Brusco et al. 2019). The concentration of BK-related peptides was normalized to the protein concentration of the samples (Bradford, 1976) and the results were expressed in ng/mg protein (Bradford 1976; Brusco et al. 2019). Statistical Analysis All data are expressed as the mean ± standard error of the mean (SEM) of 4–6 animals/group and are representative of two independent experiments (n = 8–12 animals/group). A statistical comparison of the data was performed by two-way ANOVA followed by Bonferroni’s post hoc test. P < 0.05, 0.01, and 0.001 were considered significant. Statistical analyses were performing using GraphPad Prism 6 software (GraphPad Software Inc., San Diego, CA, USA). The percentage of inhibition was calculated from the area under the curve.

Effect of BKR Antagonists Administered by i.p. Injection Immediately Following CPIP Induction We first assessed the role of BKRs during initial stage of CPIP model which happen just after reperfusion injury and last for several hours (Hsiao et al. 2016). As expected, CPIP caused paw oedema when compared to the naïve group, mainly between 1 and 5 h after removing the tourniquet allowing the paw reperfusion (p < 0.001). Immediately after model induction, animals were treated with the selective BKR antagonists DALBK (50 nmol/kg, i.p.) and HOE-140 (150 nmol/kg, i.p.). The Fig. 2 demonstrates that treatment with HOE-140 inhibited the hind paw oedema development when compared to the control group (naïve), especially in the third hour (with inhibition of 11%), after IR induction (Fig. 2a, b). However, DALBK failed to inhibit CPIP-induced paw oedema (Fig. 2). Systemic Administration of BKR Antagonists and the Repercussion in CPIP-Induced Mechanical and Cold Allodynia Next, we investigated the role of BKRs in CPIP-induced mechanical allodynia. As expected, CPIP increased the paw withdrawal frequency upon stimulation with the von Frey filament when compared to naïve animals (p < 0.001) (Fig. 3a). Additionally, this behaviour persisted in the course of the experiment until the 21st-day post-induction (Fig. 3a–d). On the other hand, treatment with selective antagonists targeting BKRs reduced the mechanical allodynia during evaluation days (Fig. 3). Following the 7th and 10th days post-induction, both treatments showed a similar effect (with inhibitions of 56.7% (HOE-140) and 53% (DALBK) on 7th day (Fig. 3a, b). However, HOE-140 showed a more significant effect compared with DALBK on days 10, 14, and 21 post-ischaemia (with inhibitions of 42%, 54%, and 62% respectively, 1 h after drugs administration) (Fig. 3c, d). Furthermore, CPIP mice developed cold allodynia in response to stimulation with acetone when compared to naïve animals (Fig. 3e–h). Nevertheless, treatment with HOE-140 (150 nmol/kg, i.p.) showed a mild effect in the modulation of this signal on the 8th day (with inhibition of 68%) (Fig. 3e) and 15th day (with inhibition of 69.8%) (Fig. 3g), whereas on other days both treatments failed to inhibit cold allodynia compared with CPIP mice (Fig. 3f, h). Local Administration of BKR Selective Antagonists vs. CPIP-Induced Mechanical Allodynia and Cold Allodynia In another set of experiments, we investigated whether i.pl. administration of DALBK and HOE-140 would modulate mechanical and cold allodynia induced by CPIP in mice. We observed that i.pl. injection of HOE-140 (10 nmol/paw) reduced mechanical allodynia when compared to CPIP mice (p < 0.001) on 7th, 14th, and 21st days post-ischaemia (with inhibitions of 66.6%, 56.9% and 61.6% respectively) (Fig. 4a–c). In turn, DALBK (10 nmol/paw) showed an anti-hyperalgesic effect on days 14 and 21 (with inhibitions of 71.6% and 80%, respectively), but this effect was lower when compared to the treatment with HOE-140 (Fig. 4b, c). Furthermore, animals that received HOE-140 showed a moderate reduction of response to acetone on day 8 (with inhibition of 50%) (p < 0.001) and 22 (p < 0.01) (Fig. 4d, f); DALBK did not show this effect (Fig. 4d, f). BKR Selective Agonists vs. CPIP-Induced Mechanical and Cold Allodynia Considering the relevance of kinins to the pain response and inflammatory processes, we next administered selective agonists receptors targeting B1 and B2, DABK (20 nmol/paw) and Tyr-BK (10 nmol/paw), respectively, to verify if i.pl. injection of these agonists would exacerbate mechanical and cold allodynia induced by the CPIP model. Thus, on the 7th-day post-induction, treated with DABK increased hyperalgesia compared with CPIP mice: 0.5 h (p < 0.001) and 4 h (p < 0.01) after administration (Fig. 5a). Additionally, Tyr-BK injection also increased the hyperalgesic response between 0.5 h (p < 0.05) and 3 h (p < 0.01) following agonist application (Fig. 5a). Fourteen days post-ischaemia, only mice treated with Tyr-BK showed increase in mechanical allodynia when compared to CPIP and specifically in the fourth hour post-treatment (p < 0.001) (Fig. 5b). On the 21st day post-induction, there was no significant difference between CPIP mice and animals treated with selective BKR agonists (Fig. 5c). Concerning cold allodynia, there was no difference between the CPIP group and i.pl. treatment with DABK or Tyr-BK on days following CPIP induction (Fig. 5d–f). Silencing of BKRs in the Spinal Cord and its Effect on CPIP-Induced Mechanical and Cold Allodynia Next, to verify the possible involvement of BKRs on spinal pathways following CPIP-induced mechanical allodynia and cold allodynia, separate groups of animals received intrathecal injection of HOE-140 (100 pmol/site) and DALBK (10 pmol/site) on the 14th day post-ischaemia. Both treatments inhibited the mechanical allodynia induced by CPIP for up to 4 h after the initial administration (with inhibitions of 35% and 40%, respectively) (Fig. 6a). Regarding cold allodynia, CPIP mice showed nociceptive response when compared to sham animals, 1, 2 and 4 h after vehicle treatment (Fig. 6d). However, the i.t. treatment with HOE-140 (100 pmol/site) and DALBK (10 pmol/site) failed to inhibit cold allodynia induced by CPIP (p > 0.05) (Fig. 6d). To further confirm the role played by both B1R and B2R in the CPIP model, other groups of mice were subjected to silencing of B1 and B2 by i.t. pre-treatment with B1 (5′-AGGTTCCTGTGGATGGCGTCCC-3′) or B2 (5′-AGAATTCTGTTCACTGTTTCTTCCCTG-3′) AS-ODN following CPIP induction. Interestingly, knockdown of B1R and B2R with AS-ODN blocked mechanical allodynia induced by CPIP induction (with inhibitions of 45% and 42% respectively (Fig. 6b), although failed to prevent cold allodynia induced by CPIP (Fig. 6e). Effect of ACE Inhibitors on Mechanical Allodynia Induced by CPIP Next, we evaluated if captopril administration—antihypertensive ACE inhibitors—would exacerbate CPIP-induced hyperalgesia. On the day 14 post-induction, animals treated with captopril (30 mg/kg, p.o.) showed similar hyperalgesia when compared to CPIP mice (Fig. 6c). However, treatment with captopril reversed the analgesic effect of the BKRs antagonists DALBK (50 nmol/kg, i.p.) and HOE-140 (150 nmol/kg, i.p.) in mechanical allodynia induced by CPIP induction, corroborating the notion that BKRs could participate in CPIP-induced hyperalgesia (Fig. 6c). Interestingly, treatment with captopril plus BKR antagonists reverted anti-hyperalgesic effect of DALBK in cold allodynia induced by CPIP, suggesting a preferential B1R participation (Fig. 6e). Role of BKRs in Female Mice Exposed to CPIP-Induced Pain Considering the higher prevalence of CRPS-I in women (Sandroni et al. 2003; de Mos et al. 2007), we next investigated the role of BKRs in CPIP-induced hyperalgesia in female Swiss mice. Female mice exposed to CPIP showed mechanical allodynia (Fig. 7a–d) and cold allodynia (Fig. 7e–h) when compared to naïve animals. Interestingly, HOE-140 (150 nmol/kg, i.p.) inhibited CPIP-induced mechanical allodynia (with inhibitions of 71.7%, 72% e 72%, on 7th, 10th and 21th post-induction, respectively) (Fig. 7a–d), and DALBK (50 nmol/kg, i.p.) showed antinociceptive effects on the days 10 and 14 post-induction (with inhibitions of 56% and 76% respectively) (Fig. 7c). Finally, BKR-selective antagonists failed to modulate cold allodynia (Fig. 7e–h). BK Tissue Levels in CPIP Versus Sham Mice Next, we investigated the BK tissue levels in sham mice and those submitted to CPIP in the spinal cord and paw 22 day after post-ischaemia induction. As shown in Fig. 8, surprisingly, sham animals showed higher tissue concentrations of BK in the paw compared to CPIP (p < 0.05), while in the spinal cord this difference was not observed (Fig. 8).

CRPS-I is a debilitating pain disorder, which exhibits several features in common with inflammatory disorders, including a pro-inflammatory profile and elevated levels of BK found in the blood of patients in chronic stages of the disease (Parkitny et al. 2013; Dirckx et al. 2015). Considering the role of BKRs in inflammatory states and the pain process, as well as BKRs harmful effects and relationship with the onset of inflammatory disorders (Soley et al. 2016), herein we investigated the role of the BKRs B1 and B2 in mechanical and cold allodynia associated with CRPS-I using the CPIP experimental model. We demonstrated that BKRs contribute to CPIP-induced mechanical allodynia since HOE-140 and DALBK inhibited the CPIP-induced nociceptive behaviour. Consistent with this, previous studies have also linked BKRs to the development and maintenance of neuropathic pain (Belichard et al. 2000; Fox et al. 2003; Dutra et al. 2013; Luiz et al. 2015; Brusco et al. 2017), as well as the blockade of the reversal of chronic pain (Lai et al. 2006). Yoshino and colleagues recently showed that BKRs are involved in endometriosis-related pain since its activation in endometriotic lesions can induce endothelin-I expression, consequently generating pain (Yoshino et al. 2018). Additionally, we identified different effects of HOE-140 and DALBK in mechanical allodynia. In this context, the analgesic effect of B2R antagonist was more prominent in the initial stage of the model (Hsiao et al. 2016) while B1R antagonist showed to be able to reduce the nociceptive behaviour mainly from 14th day post-induction (chronic phase of disease) (Klafke et al. 2016). In accordance, Levy e Zochdone demonstrated that rats exposed to peripheral nerve injury and treated with DALBK had an analgesic effect only at 14 days following surgery. In contrast mice which received HOE-140 at 48 h post-surgery showed an anti-allodynic response (Levy and Zochodne 2000). It has been shown that B2R antagonist (HOE-140) has analgesic effect mainly in acute phase (Steranka et al. 1988; Rupniak et al. 1997), while B1R antagonist (DALBK) was effective in the persistent phase of inflammatory pain hypersensitivity (Rupniak et al. 1997). Continuing, these differences can be attributed to expression profile of BKRs, since B2R is largely constitutive while B1R is typically inducible upon tissue trauma, inflammation, or nerve injury (Shughrue et al. 2003; Kakoki and Smithies 2009). Consistent with these observations, we also demonstrated that BKR ligands/agonists could exacerbate the CPIP-induced nociceptive response, suggesting that approaches inhibiting the excitatory actions of BKRs may have clinical relevance for the treatment of CRPS-I. Previous studies have reported the constitutive expression of B2R and B1R in the dorsal root ganglion (DRG) and spinal cord of rats, humans, and primates, as well as its association with the sensorial nervous system (Lopes and Couture 1992). From this, it was possible to determine the role of BKRs in pain transmission in the CNS; its activation potentiates glutamatergic synaptic transmission by increasing the release of glutamate and postsynaptic actions by generating activity-dependent central sensitisation and pain hypersensitivity (Wang et al. 2005; Kohno et al. 2008). Ohnishi and colleagues showed that interleukin-1β and BK synergistically increased COX-2 expression in DRG cells, which could result in hyperalgesia and persistent pain (Ohnishi et al. 2019). Previous reports using some animal models have related the antinociceptive effect of BKR antagonists when administered by i.t. route, corroborating our findings (Ferreira et al. 2002; Fox et al. 2003; Wang et al. 2005; Quintão et al. 2008). Thus, we suggest that BKRs expressed on the DRG and spinal cord could be involved in pivotal steps associated with CRPS-I including: (i) wind-up mechanisms in the spinal cord; (ii) maladaptive neuroplasticity with changes in endogenous pain modulation; and (iii) reorganisation of the somatosensory cortex (Bruehl 2010; Gierthmühlen et al. 2014; Reimer et al. 2016). Interestingly, BK is metabolized by the ACE, the same enzyme that is targeted by antihypertensive drugs, which are commonly used in clinical practice for the management of patients with cardiovascular disease (Borsook and Sava 2009). Drugs such as enalapril might block the ACE-dependent degradation of BK, increasing the levels of the active peptide and BK-mediated signalling, consequently worsening pain (Borsook and Sava 2009). De Mos et al. found a positive dose- and duration-dependent association between the use of ACE inhibitors and the risk of CRPS (Mos et al. 2009). More recently, Brusco et al. showed that enalapril could enhance the mechanical allodynia induced by a low dose of paclitaxel (Brusco et al. 2017). In agreement, previous studies have demonstrated that captopril could reduce the pain threshold in non-inflamed rats exposed to noxious thermal stimuli, as well as increase the formalin-induced pain (Corrêa and Calixto 1993; Matsuzaki et al. 2002). Taken together, these reports provide evidence corroborating De Mo's hypothesis regarding ACE inhibitor-induced sensitisation by elevating levels of the neuropeptides BK and substance P (Mos et al. 2009). On the other hand, our results demonstrate that captopril does not increase CPIP-induced mechanical allodynia. However, it is important to highlight that when captopril was co-administered with BKR antagonists, these could not reduce the nociceptive response, confirming that ACE inhibitors also interfere with substance P metabolism (Mos et al. 2009). In turn, elevations in the half-life of substance P can alter pain-signalling through sensitisation of dorsal horn neurons and neurogenic inflammation (Gautam et al. 2015). This consequently might result in hyperalgesia that could not be reversed by HOE-140 and DALBK. Although we did not demonstrate a clear relationship between captopril administration and pain exacerbation in CPIP, we can speculate that continuous use of ACE inhibitors may potentiate the activity of BK and substance P as both appear to be crucial in CRPS pathogenesis, which could reinforce disease development and progression (Borsook and Sava 2009). In the early stage of CRPS-I, patients frequently exhibit prominent oedema and kinins are known to contribute to the oedematogenic response through their vasoactive properties (Bruehl 2010; Dutra 2016). We demonstrated that BKRs are involved in CPIP-induced paw oedema since i.p. injection of HOE-140 (B2R antagonist), but not DALBK (B1R antagonist) immediately after tourniquet removal markedly inhibited the development of paw oedema in male mice. It is in agreement with the role of B2R in acute inflammatory response, since B2R is constitutively expressed is most tissues, while B1R expression is thought to be absent under normal circumstances, but is induced by inflammation or tissue injury (Shughrue et al. 2003; Kakoki and Smithies 2009). Consistent with this, previous studies have also established the participation of BKRs in the oedematogenic response, as well as its relevance in inflammatory processes and tissue injury (Sharma and Buchanan 1994; Beirith et al. 2003; Dobrivojevi and Katarina 2015). Thus, these data provide evidence of the involvement of kinins in CRPS-I pathogenesis, as they are able to induce vasodilation, plasma extravasation, and finally oedema, which is typically associated with the disease (Bruehl 2015). Finally, these findings reinforce the role of inflammatory mechanisms in CRPS-I development, as well as suggest BKRs as a therapeutic target for the management of oedema and inflammation in disease. Cold allodynia is a sensory disturbance characteristic of clinical neuropathic pain states and is consequently commonly associated with CRPS-I (Bruehl 2015). Thus, we investigated the involvement of BK with CPIP-induced cold allodynia. Regarding the intrathecal experiments performed with BKR antagonists and ASOs and the experiment with ACE inhibitor (captopril) with or without BKR antagonists administration, it was not possible confirm the participation of BKRs on CPIP-induced cold allodynia. In agreement with this, Petcu and colleagues also reported that both kinin receptors were not implicated in cold allodynia related to peripheral nerve injury (Petcu et al. 2008). Still, Cobos et al. reported that immune system activation contributes minimally to cold allodynia. However, Brusco et al. recently demonstrated that BKR antagonists are able to mitigate the reserpine-induced cold sensitivity (Brusco et al. 2019). Additionally, there is another important channel involved in BK-induced mechanical hypersensitivity, the transient receptor potential ankyrin 1 (TRPA1), an ion channel receptor belonging to the transient receptor potential (TRP) family, which has been associated to pathological pain and cold hypersensitivity (Yu and Ouyang 2009). Therefore, considering the contribution of TRPA1 to cold hyperalgesia (Koivisto et al. 2018) and its relationship with BKRs, we hypothesized that BKRs could be involved in CPIP-induced cold allodynia, however, the results obtained were not able to confirm this. Despite, De Prá et al. provided evidence regarding the antinociceptive effect of TRPA1 channel antagonist in both mechanical and cold allodynia induced by CPIP model (Dal et al. 2019). Thus, further studies are needed to establish the role of BKRs in CPIP-induced cold allodynia. Finally, we demonstrated that surprisingly, sham animals showed higher tissue concentrations of BK in the paw compared to CPIP, 22 days post-induction. In contrast, it was not observed in spinal cord. Unlike our findings, Brusco et al. identified higher levels of BK-related peptides in the sciatic nerve of mice exposed to fibromyalgia-like pain symptoms (Brusco et al. 2019). Similarly to our results, there was no difference between the levels of BK-related peptides in spinal cord of reserpine group when compared to vehicle (Brusco et al. 2019). Thus, we hypothesize that the lower concentrations of BK in the paw could be related to increased expression of BKRs, since B1R and B2R mRNA and protein levels were markedly enhanced at tibia fracture site associated with severe pain syndrome (Minville et al. 2019). Furthermore, Brusco et al. showed increased levels of B1 and B2 receptors at peripheral tissues of mice exposed to paclitaxel-associated chronic peripheral neuropathy (Brusco et al. 2017). Moreover, it can be suggested that this decrease is partly due to the expression profile of the kinin receptors (such as, higher expression of B2R in the acute phase and B1R during persistent and chronic phase) (Levy and Zochodne 2000) consequently upregulation of BK/des-Arg9-BK level during early stages and downregulation during temporal course of the model. However, future experiments are necessary to compare the levels of BK and des-Arg9-BK in different phases of the CPIP model, as well as it expression. Altogether our results demonstrated the role of BKRs (B1 and B2) in CPIP development and consequently CRPS-I pathogenesis. Furthermore, our data suggest the involvement of BKRs in neuropathic pain, which is typical of CPIP. Thus, BKRs may represent an important target for the treatment of CRPS-I and other neuropathic conditions (Fig. 9).

We thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Apoio a Pesquisa do Estado de Santa Catarina (FAPESC), INCT-INOVAMED Program (Grant 465430/2014-7), and Programa de Pós-Graduação em Neurociências (PGN), all from Brazil, supported this work. E.C.D.G. is a Ph.D. student in neuroscience receiving grants from FAPESC. S.M.O., J.B.C., A.R.S.S., and R.C.D are the recipient of a research productivity fellowship from the CNPq. Author Contributions ECDG designed and performed experiments, wrote the manuscript and supervised the project. GV, TRG, RRS, IB, and SMO performed experiments and analysed data. JBC, MC and ARSS wrote the manuscript. RCD supervised the project, wrote and refined the manuscript. Funding This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Apoio a Pesquisa do Estado de Santa Catarina (FAPESC), INCT-INOVAMED Program (Grant Number 465430/2014-7), and Programa de Pós-Graduação em Neurociências (PGN). Compliance with Ethical Standards Conflict of interest The authors declare no conflicts of interest. Ethical Approval All procedures performed in studies involving animals were in accordance with the ethical standards of the Ethics Committee of Universidade Federal de Santa Catarina (CEUA-UFSC, Protocol Number PP00956/2014). Footnotes Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

- Beerthuizen A, Stronks DL, Van A et al (2012) Demographic and medical parameters in the development of complex regional pain syndrome type 1 (CRPS1): prospective study on 596 patients with a fracture. Pain 153:1187–1192 [DOI] [PubMed] [Google Scholar] - Beirith A, Santos ARS, Calixto JB (2003) The role of neuropeptides and capsaicin-sensitive fibres in glutamate-induced nociception and paw oedema in mice. Brain Res 969:110–116 [DOI] [PubMed] [Google Scholar] - Belichard P, Landry M, Faye P, Bachvarov DR (2000) Inflammatory hyperalgesia induced by zymosan in the plantar tissue of the rat : effect of kinin receptor antagonists. Immunopharmacology 46:139–147 [DOI] [PubMed] [Google Scholar] - Borsook D, Sava S (2009) Pain: do ACE inhibitors exacerbate complex regional pain syndrome? Nat Rev Neurol 5:306–308 [DOI] [PubMed] [Google Scholar] - Bortalanza B, Ferreira J, Hess SC (2002) Anti-allodynic action of the tormentic acid, a triterpene isolated from plant, against neuropathic and inflammatory persistent pain in mice. Eur J Pharmacol 453(453):203–208 [DOI] [PubMed] [Google Scholar] - Bradford M (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72:248–254 [DOI] [PubMed] [Google Scholar] - Bruehl S (2015) Complex regional pain syndrome. Br Med J 29:1–13 [Google Scholar] - Bruehl S (2010) An update on the pathophysiology of complex regional pain syndrome. Anesthesiology 113:713–725 [DOI] [PubMed] [Google Scholar] - Brusco I, Benatti A, Regina C et al (2019) Kinins and their B1 and B2 receptors are involved in fi bromyalgia-like pain symptoms in mice. Biochem Pharmacol 168:119–132 [DOI] [PubMed] [Google Scholar] - Brusco I, Silva CR, Trevisan G et al (2017) Potentiation of paclitaxel-induced pain syndrome in mice by angiotensin I converting enzyme inhibition and involvement of kinins. Mol Neurobiol 54:7824–7837 [DOI] [PubMed] [Google Scholar] - Cheng J-K, Ji R-R (2008) Intracellular signaling in primary sensory neurons and persistent pain. Neurochem Res 33:1970–1978 [DOI] [PMC free article] [PubMed] [Google Scholar] - Coderre TJ, Xanthos DN, Francis L, Bennett GJ (2004) Chronic post-ischemia pain (CPIP): a novel animal model of complex regional pain syndrome-type I (CRPS-I; reflex sympathetic dystrophy) produced by prolonged hindpaw ischemia and reperfusion in the rat. Pain 112:94–105 [DOI] [PubMed] [Google Scholar] - Corrêa CR, Calixto JB (1993) Evidence for participation of B1 and B2 kinin receptors in formalin-induced nociceptive response in the mouse. Br J Pharmacol 110:193–198 [DOI] [PMC free article] [PubMed] [Google Scholar] - Costa R, Bicca MA, Manjavachi MN et al (2017) Kinin receptors sensitize TRPV4 channel and induce mechanical hyperalgesia: relevance to paclitaxel-induced peripheral neuropathy in mice. Mol Neurobiol 55:1–12 [DOI] [PubMed] [Google Scholar] - Costa R, Motta EM, Dutra RC et al (2011) Anti-nociceptive effect of kinin B1 and B2 receptor antagonists on peripheral neuropathy induced by paclitaxel in mice. Br J Pharmacol 164:681–693 [DOI] [PMC free article] [PubMed] [Google Scholar] - Couture R, Harrisson M, Vianna RM, Cloutier F (2001) Kinin receptors in pain and inflammation. Eur J Pharmacol 429:161–176 [DOI] [PubMed] [Google Scholar] - Dal S, De PT, Tatiane C et al (2019) Nociceptive mechanisms involved in the acute and chronic phases of a complex regional pain syndrome type 1 model in mice. Eur J Pharmacol 859:172555 [DOI] [PubMed] [Google Scholar] - de Mos M, de Bruijn AGJ, Huygen FJPM et al (2007) The incidence of complex regional pain syndrome: a population-based study. Pain 129:12–20 [DOI] [PubMed] [Google Scholar] - Dirckx M, Stronks DL, Wesseldijk F, Groeneweg JG (2015) Inflammation in cold complex regional pain syndrome. Acta Anesthesiol Scand Found 59:733–739 [DOI] [PubMed] [Google Scholar] - Dobrivojevi M, Katarina Š (2015) Involvement of bradykinin in brain edema development after ischemic stroke. Pflugers Arch 467:201–212 [DOI] [PubMed] [Google Scholar] - Dutra R (2016) Kinin receptors: key regulators of autoimmunity. Autoimmun Rev 16:192–207 [DOI] [PubMed] [Google Scholar] - Dutra RC, Bento AF, Leite DFP et al (2013) The role of kinin B1 and B2 receptors in the persistent pain induced by experimental autoimmune encephalomyelitis (EAE) in mice: evidence for the involvement of astrocytes. Neurobiol Dis 54:82–93 [DOI] [PubMed] [Google Scholar] - Ferreira J, Campos MM, Araújo R et al (2002) The use of kinin B1 and B2 receptor knockout mice and selective antagonists to characterize the nociceptive responses caused by kinins at the spinal level. Neuropharmacology 43:1188–1197 [DOI] [PubMed] [Google Scholar] - Ferreira J, da Silva GL, Calixto JB (2004) Contribution of vanilloid receptors to the overt nociception induced by B2 kinin receptor activation in mice. Br J Pharmacol 141:787–794 [DOI] [PMC free article] [PubMed] [Google Scholar] - Flatters SJL, Bennett GJ (2004) Ethosuximide reverses paclitaxel- and vincristine-induced painful peripheral neuropathy. Pain 109:150–161 [DOI] [PubMed] [Google Scholar] - Fox A, Wotherspoon G, McNair K et al (2003) Regulation and function of spinal and peripheral neuronal B1 bradykinin receptors in inflammatory mechanical hyperalgesia. Pain 104(683–91):6 [DOI] [PubMed] [Google Scholar] - Gautam M, Prasoon P, Kumar R et al (2015) Role of neurokinin type 1 receptor in nociception at the periphery and the spinal level in the rat. Spinal Cord 54:172–182 [DOI] [PubMed] [Google Scholar] - Gewehr C, Oliveira SM, Rossato MF et al (2013) Mechanisms involved in the nociception triggered by the venom of the armed spider Phoneutria nigriventer. PLoS Negl Trop Dis 7:e2198. 10.1371/journal.pntd.0002198 [DOI] [PMC free article] [PubMed] [Google Scholar] - Gierthmühlen J, Binder A, Baron R (2014) Mechanism-based treatment in complex regional pain syndromes. Nat Rev Neurol 10:518–528. 10.1038/nrneurol.2014.140 [DOI] [PubMed] [Google Scholar] - Goh EL, Chidambaram S, Ma D (2017) Complex regional pain syndrome: a recent update. Burn Trauma 5:2 [DOI] [PMC free article] [PubMed] [Google Scholar] - Guthmiller K, Varacallo M (2019) Complex regional pain syndrome (CRPS), reflex sympathetic dystrophy (RSD). StatPearls Publishing, Treasure Island [PubMed] [Google Scholar] - Hsiao H, Lin Y, Wang JC et al (2016) Hypoxia inducible factor-1 a inhibition produced anti-allodynia effect and suppressed in fl ammatory cytokine production in early stage of mouse complex regional pain syndrome model. Clin Exp Pharmacol Physiol 43:355–359 [DOI] [PubMed] [Google Scholar] - Hylden JLK, Wilcox GL (1980) Intrathecal morphine in mice: a new technique. Eur J Pharmacol 67:313–316 [DOI] [PubMed] [Google Scholar] - Ji RR, Kohno T, Moore KA, Woolf CJ (2003) Central sensitization and LTP: do pain and memory share similar mechanisms? Trends Neurosci 26:696–705 [DOI] [PubMed] [Google Scholar] - Ji RR, Xu Z, Gao Y (2014) Emerging targets in neuroinflammation-driven chronic pain. Nat Publ Gr 13:533–548 [DOI] [PMC free article] [PubMed] [Google Scholar] - Kakoki M, Smithies O (2009) The kallikreinkinin system in health and in diseases of the kidney. Kidney Int 75:1019–1030 [DOI] [PMC free article] [PubMed] [Google Scholar] - Kim Y, Kim I, Yoon M (2015) Neuroscience letters antiallodynic effect through spinal endothelin-B receptor antagonism in rat models of complex regional pain syndrome. Neurosci Lett 584:45–49 [DOI] [PubMed] [Google Scholar] - Klafke JZ, da Silva MA, Rossato MF et al (2016) Acute and chronic nociceptive phases observed in a rat hind paw ischemia/reperfusion model depend on different mechanisms. Pflugers Arch Eur J Physiol 468:229–241 [DOI] [PubMed] [Google Scholar] - Kohno T, Wang H, Amaya F (2008) Bradykinin enhances AMPA and NMDA receptor activity in spinal cord dorsal horn neurons by activating multiple kinases to produce pain hypersensitivity. J Neurosci 28:4533–4540 [DOI] [PMC free article] [PubMed] [Google Scholar] - Koivisto A, Jalava N, Bratty R, Pertovaara A (2018) TRPA1 antagonists for pain relief. Pharmaceuticals 11:1–19 [DOI] [PMC free article] [PubMed] [Google Scholar] - Kwak K, Han C, Lee S et al (2009) Reactive oxygen species in rats with chronic post-ischemia pain 1. Acta Anaesthesiol Scand 53:648–656 [DOI] [PubMed] [Google Scholar] - Lai J, Luo M, Chen Q et al (2006) Dynorphin A activates bradykinin receptors to maintain neuropathic pain. Nat Neurosci 9:1534–1540 [DOI] [PubMed] [Google Scholar] - Latremoliere A, Woolf C (2009) Central sensitization: a generator of pain hypersensitivity by central neural plasticity. Neural Plast 10:895–926 [DOI] [PMC free article] [PubMed] [Google Scholar] - Lee JW, Lee SK, Choy WS (2018) Complex regional pain syndrome type 1: diagnosis and management. J Hand Surg Asian-Pac 23:1–10 [DOI] [PubMed] [Google Scholar] - Levy D, Zochodne DW (2000) Increased mRNA expression of the B1 and B2 bradykinin receptors and antinociceptive effects of their antagonists in an animal model of neuropathic pain. Pain 86:265–271 [DOI] [PubMed] [Google Scholar] - Lopes P, Couture R (1992) Cardiovascular responses elicited by intrathecal kinins in the conscious rat. Eur J Pharmacol 210:137–147 [DOI] [PubMed] [Google Scholar] - Luiz AP, Schroeder SD, Rae GA et al (2015) Contribution and interaction of kinin receptors and dynorphin A in a model of trigeminal neuropathic pain in mice. Neuroscience 300:189–200 [DOI] [PubMed] [Google Scholar] - Marceau F, Regoli D (2004) Bradykinin receptor ligands: therapeutic perspectives. Nat Rev Drug Discov 3:845–852 [DOI] [PubMed] [Google Scholar] - Marinus J, Moseley L, Birklein F et al (2011) Syndrome—current state of the art. Lancet Neurol 10:637–648 [DOI] [PMC free article] [PubMed] [Google Scholar] - Martins DF, Soldi F, Stramosk J et al (2013) High-intensity swimming exercise reduces neuropathic pain in an animal model of complex regional pain syndrome type I: evidence for a role of the adenosinergic system. Neuroscience 234:69–76 [DOI] [PubMed] [Google Scholar] - Matsuzaki S, Hayashi I, Nara Y et al (2002) Role of kinin and prostaglandin in cutaneous thermal nociception. Int Immunopharmacol 2:2005–2012 [DOI] [PubMed] [Google Scholar] - Millecamps M, Laferrière A, Ragavendran JV, Laura S (2015) Role of peripheral endothelin receptors in an animal model of complex regional pain syndrome type 1 (CRPS-I). Pain 151:174–183 [DOI] [PMC free article] [PubMed] [Google Scholar] - Minville V, Mouledous L, Jaafar A et al (2019) Tibial post fracture pain is reduced in kinin receptors deficient mice and blunted by kinin receptor antagonists. J Transl Med 17:1–12 [DOI] [PMC free article] [PubMed] [Google Scholar] - De MM, Huygen FJPM, Stricker BHC et al (2009) The association between ACE inhibitors and the complex regional pain syndrome: suggestions for a neuro-inflammatory pathogenesis of CRPS. Pain 142:218–224 [DOI] [PubMed] [Google Scholar] - Munnikes RJM, Muis C, Boersma M et al (2005) Intermediate stage complex regional pain syndrome type 1 is unrelated to proinflammatory cytokines. Med Inflamm 6:366–372 [DOI] [PMC free article] [PubMed] [Google Scholar] - Ohnishi M, Yukawa R, Akagi M et al (2019) Bradykinin and interleukin-1 β synergistically increase the expression of cyclooxygenase-2 through the RNA-binding protein HuR in rat dorsal root ganglion cells. Neurosci Lett 694:215–219 [DOI] [PubMed] [Google Scholar] - Parkitny L, McAuley JH, Di Pietro F et al (2013) Inflammation in complex regional pain syndrome: a systematic review and meta-analysis. Neurology 80:106–117 [DOI] [PMC free article] [PubMed] [Google Scholar] - Petcu M, Dias JP, Ongali B et al (2008) Role of kinin B 1 and B 2 receptors in a rat model of neuropathic pain. Int Immunopharmacol 8:188–196 [DOI] [PubMed] [Google Scholar] - Qadri F, Bader M (2017) Kinin B1 receptors as a therapeutic target for inflammation. Expert Opin Ther Targets 22:31–44 [DOI] [PubMed] [Google Scholar] - Quintão N, Rocha L, Silva G et al (2019) The kinin B1 and B2 receptors and TNFR1/p55 axis on neuropathic pain in the mouse brachial plexus. Inflammopharmacology 27:573–586 [DOI] [PubMed] [Google Scholar] - Quintão NLM, Passos GF, Medeiros R et al (2008) Neuropathic pain-like behavior after brachial plexus avulsion in mice: the relevance of kinin B1 and B2 receptors. J Neurosci 28:2856–2863 [DOI] [PMC free article] [PubMed] [Google Scholar] - Reimer M, Rempe T, Diedrichs C et al (2016) Sensitization of the nociceptive system in complex regional pain syndrome. PLoS ONE 11:1–25 [DOI] [PMC free article] [PubMed] [Google Scholar] - Rupniak N, Boyce S, Webb J et al (1997) Effects of the bradykinin B1 receptor antagonist des-Arg9[Leu8]bradykinin and genetic disruption of the B2 receptor on nociception in rats and mice. Pain 71:89–97 [DOI] [PubMed] [Google Scholar] - Sabsovich I, Guo T, Wei T et al (2008) TNF signaling contributes to the development of nociceptive sensitization in a tibia fracture model of complex regional pain syndrome type I. Pain 137:507–519 [DOI] [PMC free article] [PubMed] [Google Scholar] - Sandroni P, Benrud-larson LM, Mcclelland RL, Low PA (2003) Complex regional pain syndrome type I: incidence and prevalence in Olmsted county, a population-based study. Pain 103:199–207 [DOI] [PubMed] [Google Scholar] - Schinkel C, Scherens A, Koller M et al (2009) Systemic inflammatory mediators in post-traumatic complex regional pain syndrome (CRPS I)—longitudinal investigations and differences to control groups. Eur J Med Res 14:130–135 [DOI] [PMC free article] [PubMed] [Google Scholar] - Schuelert N, Just S, Corradini L et al (2015) The bradykinin B1 receptor antagonist BI113823 reverses inflammatory hyperalgesia by desensitization of peripheral and spinal neurons. Eur J Pain (United Kingdom) 19:132–142 [DOI] [PubMed] [Google Scholar] - Sharma JN, Buchanan WW (1994) Pathogenic responses of bradykinin system in chronic inflammatory rheumatoid disease. Exp Toxicol Pathol 46:421–433 [DOI] [PubMed] [Google Scholar] - Shughrue PJ, Ky B, Austin CP (2003) Localization of B1 bradykinin receptor mRNA in the primate brain and spinal cord: an in situ hybridization study. J Comp Neurol 465:372–384 [DOI] [PubMed] [Google Scholar] - Soley da BS, Morais RL, Pesquero MB et al (2016) Kinin receptors in skin wound healing. J Dermatol Sci 82:95–105 [DOI] [PubMed] [Google Scholar] - Steranka L, Manning D, DeHaas C et al (1988) Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions. Proc Natl Acad Sci 85:3245–3249 [DOI] [PMC free article] [PubMed] [Google Scholar] - Tang C, Li J, Tai W et al (2017) Sex differences in complex regional pain syndrome type-I. J Pain Res 10:1811–1819 [DOI] [PMC free article] [PubMed] [Google Scholar] - Wang D, Couture R, Hong Y (2014) Activated microglia in the spinal cord underlies diabetic neuropathic pain. Eur J Pharmacol 728:59–66 [DOI] [PubMed] [Google Scholar] - Wang H, Kohno T, Amaya F et al (2005) Bradykinin produces pain hypersensitivity by potentiating spinal cord glutamatergic synaptic transmission. J Neurosci 25:7986–7992 [DOI] [PMC free article] [PubMed] [Google Scholar] - Wasner G, Schattschneider J, Binder A et al (2003) Review complex regional pain syndrome ± diagnostic, mechanisms, CNS involvement and therapy. Spinal Cord 41:61–75 [DOI] [PubMed] [Google Scholar] - Woolf CJ (2011) Central sensitization: implications for the diagnosis and treatment of pain. Pain 152:S2–S15. 10.1016/j.pain.2010.09.030 [DOI] [PMC free article] [PubMed] [Google Scholar] - Yoshino O, Kobayashi M, Andoh T et al (2018) Bradykinin system is involved in endometriosis-related pain through endothelin-1 production. Eur J Pain 22:501–510 [DOI] [PubMed] [Google Scholar] - Yu S, Ouyang A (2009) TRPA1 in bradykinin-induced mechanical hypersensitivity of vagal C fibers in guinea pig esophagus. Am J Physiol 296:G255–G265 [DOI] [PubMed] [Google Scholar]