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Melatonin impedes Tet1‐dependent mGluR5 promoter demethylation to relieve pain
Author(s) -
Hsieh MingChun,
Ho YuCheng,
Lai ChengYuan,
Chou Dylan,
Wang HsuehHsiao,
Chen GinDen,
Lin TzerBin,
Peng HsienYu
Publication year - 2017
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/jpi.12436
Subject(s) - melatonin , allodynia , nociception , hyperalgesia , chemistry , pharmacology , biology , medicine , endocrinology , receptor
Melatonin ( N ‐acetyl‐5‐methoxytryptamine)/ MT 2 receptor‐dependent epigenetic modification represents a novel pathway in the treatment of neuropathic pain. Because spinal ten‐eleven translocation methylcytosine dioxygenase 1 (Tet1)‐dependent epigenetic demethylation has recently been linked to pain hypersensitivity, we hypothesized that melatonin/ MT 2‐dependent analgesia involves spinal Tet1‐dependent demethylation. Here, we showed that spinal Tet1 gene transfer by intrathecal delivery of Tet1‐encoding vectors to naïve rats produced profound and long‐lasting nociceptive hypersensitivity. In addition, enhanced Tet1 expression, Tet1‐metabotropic glutamate receptor subtype 5 (mGluR5) promoter coupling, demethylation at the mGluR5 promoter, and mGluR5 expression in dorsal horn neurons were observed. Rats subjected to spinal nerve ligation and intraplantar complete Freund's adjuvant injection displayed tactile allodynia and behavioral hyperalgesia associated with similar changes in the dorsal horn. Notably, intrathecal melatonin injection reversed the protein expression, protein‐promoter coupling, promoter demethylation, and pain hypersensitivity induced by Tet1 gene transfer, spinal nerve ligation, and intraplantar complete Freund's adjuvant injection. All the effects caused by melatonin were blocked by pretreatment with a MT 2 receptor‐selective antagonist. In conclusion, melatonin relieves pain by impeding Tet1‐dependent demethylation of mGluR5 in dorsal horn neurons through the MT 2 receptor. Our findings link melatonin/ MT 2 signaling to Tet1‐dependent epigenetic demethylation of nociceptive genes for the first time and suggest melatonin as a promising therapy for the treatment of pain.