Possible mechanism underlying analgesic effect of Tuina in rats may involve piezo mechanosensitive channels within dorsal root ganglia axon

Abstract OBJECTIVE To demonstrate the analgesic effect of Tuina mainly from mechanically sensitive ion channels in peripheral myelinated nerve fibers. METHODS A total of 40 healthy and pathogen-free adult male Sprague-Dawley rats were used in the study [weight: (220.0 ± 1.4) g, Shanghai Slac Laboratory Animal Co., Ltd., Shanghai, China; license No. Shanghai ICP 05033115]. The rats were housed in cages with free access to water and food in a temperature-controlled room [(22 ± 1) °C] and 12-h/12-h light-dark cycle. Thirty-two rats were randomly divided into five groups: naive, sham, chronic compression of dorsal root ganglion (CCD), Tuina (7 d) and Tuina (21 d). CCD rat model was established via unilateral DRG compression by “L” liked steel bar. Chinese Tuina treatment was accepted once per day. Behavior monitoring of paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were tested. The expression of Piezo1 and Piezo2 in myelinated nerve fiber were analyzed by immunohistochemistry and Western-blotting. RESULTS There was a high expression of Piezo2 and a low expression of Piezo1 in the naive and CCD groups. In contrast, the expression of Piezo2 was down regulated and Piezo1 was increased after a period of Tuina. There was significant difference ( P ≤ 0.05) between the groups. CONCLUSION Our findings suggest that Tuina therapy can increase the expression of Piezo2 and decrease the expression of Piezo1 in the test rats. The different changes in the expressions of Piezo1 and Piezo2 may play an important role in alleviating CCD-induced allodynia and hyperalgesia.