A clinical and mechanistic study of topical bingpian-induced analgesia / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE Bingpian is an almost pure chemical with a chemical composition of (+)-borneol and has been historically used as a topical analgesic in traditional Chinese medicine for millen-nia. However, the clinical efficacy of topical bingpian lacks stringent evidence-based clinical studies and the underlying molecular mechanisms are unclear.This study verified the analgesic efficacy of topi-cal bingpian in humans, and elucidated the underling mechanisms in animal models of pain. METH-ODS The analgesic efficacy of topical bingpian was examined in a randomized,double-blind,placebo-controlled clinical study at the Shanghai Changzheng Hospital. Capsaicin, formalin, CFA or thermal caused pain/hyperalgesia were established in different mouse models,and bingpian-induced analgesia and the underlying mechanisms were studied in these models.The molecular targets of bingpian were examined by calcium imaging, patch-clamp recording and enzymatic activity assay in mouse sensory neurons or transfected HEK 293 cells. RESULTS (1)Topical application of bingpian leads to significantly greater pain relief than placebo does in a randomized, double-blind, placebo-controlled clinical study involving 122 patients with postoperative pain.(2)TRPM8 channel is the most sensitive molecular target of bingpian and mediates topical bingpian-induced analgesia in mice. (3)A downstream glutamatergic mechanism in the spinal cord contributes to topical bingpian-induced analgesia. (4)Bingpian shows mechanistic differences and advantages as a topical analgesic when compared with menthol.