Levo-Tetrahydropalmatine Retards the Growth of Ectopic Endometrial Implants and Alleviates Generalized Hyperalgesia in Experimentally Induced Endometriosis in Rats

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Levo-tetrahydropalmatine treatment reduced ectopic endometrial lesion size and improved thermal hyperalgesia in rats by altering pain-mediating molecules.

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The study evaluated the analgesic and anti-lesion efficacy of levo-tetrahydropalmatine (l-THP), alone or combined with valproic acid (VPA), in 55 adult female rats with surgically induced endometriosis, assessing pain-related behavior using hot-plate response latency before surgery and after 3 weeks of treatment. Compared with untreated rats, animals receiving l-THP (with or without VPA) showed significantly reduced ectopic lesion size and improved thermal nociceptive responses, along with decreased immunoreactivity for markers of central sensitization and related signaling pathways in dorsal root ganglia and ectopic/eutopic endometrium. The authors report a mechanistic caveat that outcomes are based on biomarker immunoreactivity in selected tissues and timepoints rather than directly demonstrating causal pathways. This paper is centrally about endometriosis — it tests l-THP (±VPA) for effects on ectopic implant growth and generalized hyperalgesia in an experimentally induced rat model.

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Abstract

One primary goal of medical treatment of endometriosis is to alleviate pain and there is a pressing need for new therapeutics for endometriosis with better efficacy and side-effect profiles. Levo-tetrahydropalmatine (l-THP) has been used as a sedative or analgesic for chronic pains in China since 1970s. In this study, we sought to evaluate the efficacy of l-THP, with or without valproic acid (VPA), in a rat model of endometriosis. We surgically induced endometriosis in 55 adult female rats. Two weeks after, all rats were further divided into 5 groups randomly: untreated, low- and high-dose of l-THP, VPA, and l-THP + VPA. Response latency in hotplate test was measured before the surgery, before and after 3-week treatment of respective drugs. All rats were then sacrificed for analysis. The average lesion size and the immunoreactivity to N-methyl-D-asparate receptor 1 (NMDAR1), acid-sensing ion channel 3 (ASIC3), calcitonin gene-related peptide (CGRP), c-Fos, tyrosine kinase receptor A (TrkA), and histone deacetylase 2 (HDAC2) in dorsal root ganglia (DRG), to phorphorylated p65, HDAC2, TrkA, and CGRP in ectopic endometrium and to phorphorylated p65 and CGRP in eutopic endometrium were evaluated. We found that rats receiving l-THP, with or without VPA, had significantly reduced lesion size and exhibited significantly improved response to noxious thermal stimulus. The treatment also significantly lowered immunoreactivity to all mediators involved in central sensitization and to HDAC2 in DRG, to TrkA and CGRP in ectopic endometrium, and to CGRP in eutopic endometrium. In summary, l-THP reduces lesion growth and generalized hyperalgesia. Thus, l-THP may be a promising therapeutics for endometriosis.
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Abstract

One primary goal of medical treatment of endometriosis is to alleviate pain and there is a pressing need for new therapeutics for endometriosis with better efficacy and side-effect profiles. Levo-tetrahydropalmatine (l-THP) has been used as a sedative or analgesic for chronic pains in China since 1970s. In this study, we sought to evaluate the efficacy of l-THP, with or without valproic acid (VPA), in a rat model of endometriosis. We surgically induced endometriosis in 55 adult female rats. Two weeks after, all rats were further divided into 5 groups randomly: untreated, low- and high-dose of l-THP, VPA, and l-THP + VPA. Response latency in hotplate test was measured before the surgery, before and after 3-week treatment of respective drugs. All rats were then sacrificed for analysis. The average lesion size and the immunoreactivity to N-methyl-d-asparate receptor 1 (NMDAR1), acid-sensing ion channel 3 (ASIC3), calcitonin gene-related peptide (CGRP), c-Fos, tyrosine kinase receptor A (TrkA), and histone deacetylase 2 (HDAC2) in dorsal root ganglia (DRG), to phorphorylated p65, HDAC2, TrkA, and CGRP in ectopic endometrium and to phorphorylated p65 and CGRP in eutopic endometrium were evaluated. We found that rats receiving l-THP, with or without VPA, had significantly reduced lesion size and exhibited significantly improved response to noxious thermal stimulus. The treatment also significantly lowered immunoreactivity to all mediators involved in central sensitization and to HDAC2 in DRG, to TrkA and CGRP in ectopic endometrium, and to CGRP in eutopic endometrium. In summary, l-THP reduces lesion growth and generalized hyperalgesia. Thus, l-THP may be a promising therapeutics for endometriosis. Similar content being viewed by others

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endometriosis

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Analgesics, Non-Narcotic Berberine Alkaloids Endometriosis Hyperalgesia Acid Sensing Ion Channels Analgesics, Non-Narcotic Analgesics, Non-Narcotic Animals Berberine Alkaloids Berberine Alkaloids Calcitonin Gene-Related Peptide Calcitonin Gene-Related Peptide Disease Models, Animal Endometriosis Endometriosis Endometriosis Endometrium Endometrium Endometrium Female

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