Effect of tetrahydropalmatine on expression of Cav1. 2 in dorsal root ganglion neurons in mice with sciatic nerve chronic constriction injury / 中国药理学通报

ABSTRACT

Aim To investigate the analgesic effect of tetrahydropalmatine on Cav1 . 2 expression in the dorsal root ganglion ( DRG) of mice with sciatic nerve chronic constriction injury ( CCI ) -induced neuropathic pain. Methods Forty male C57 BL/6 mice were randomly divided into 5 groups ( n =5 ) sham group ( group S) , CCI group ( group C ) and L-THP group ( group L) . Steady mice models of neuropathic pain were es-tablished by inducing CCI of sciatic nerve. According to development of neuropathic pain in mice, L group was divided into induction period, induction with ma-intenance period and long-term low-dose group. The mice were intraperitoneally administered with 45 mg · kg-1 tetrahydropalmatine in induction ( day 0~5 ) , in-duction with maintenance ( day 0~5 , 14~19 ) period of neuropathic pain state. From the instant after opera-tion, 15 mg · kg-1 tetrahydropalmatine was injected into the long-term low-dose group once per day for 19 days. Then, the behavior changes of mice were moni-tored. Moreover, the threshold of mechanical and ther-mal stimuli was tested. In addition, the expression of Cav1 . 2 protein was detected by Western blot and im-munohistochemical staining. Results The lowest ex-pression of Cav1 . 2 was observed in group C and the highest expression level of Cav1 . 2 was found in group S. Cav1. 2 expression was significantly up-regulated in induction period group, induction with maintenance period group and long-term low-dose group ( P0. 05 ) in long-term low-dose group. Conclusions High dose of tet-rahydropalmatine in induction period group, induction with maintenance period group and low-dose among the whole experiment process obviously relieves the neuro-pathic pain induced by nerve injury. The analgesic effect of tetrahydropalmatine on neuropathic pain may be due to the increased expression of Cav1 . 2 protein in DRG neurons.