Role of gliocytes in the spinal cord in development of inflammatory pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the role of gliocytes in the spinal cord in the development of inflammatory pain (IP) in rats. Methods Adult male SD rats weighing 180-220 g were used in this experiment. A catheter was implanted in the subarachnoid space according to the method described by Yang. Animals with abnormal motor function of the hindlimb after intrathecal (IT) catheter implantation were excluded. IP was induced by subcutaneous (sc) injection of complete Freund's adjuvant (CFA) 50 μl at the lateral side of the ankle joint of the right hindpaw. Sixty-five rats were randomly divided into 5 groups ( n = 13 each): group I IP control normal saline (NS) 50μl was injected sc instead of CFA; group II IP; group IE PC (IT) + IP control fluorinated citric acid (FC, a gliocyte metabolism inhibitor) 1 nmol/10μl was injected IT at 15 min before NS 50 μl sc injection; group IV NS (IT) + IP and group V FC (IT) + IP. The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured 2 d before induction of IP (T_0, baseline) .before and at 2, 4, 6, 8, 10, 12, 24 and 26 h (T_(1-9)) after sc NS or CFA injection. Five enimals in each group were killed at T_5 (8 h after sc NS/CFA injection) and the lumbar segment (L_(4,5)) was removed for determination of glial fibrillary acidic protein ( CFAP) and OX-42 expression by immuno-histochemistry. Results In group Ⅱ and Ⅳ sc CFA significantly decreased MWT and TWL. Mechanical and thermal hyperalgegia induced by sc CFA was significantly suppressed by intrathecal FC in group V . IP significantly increased GFAP and OX-42 expression in the spinal cord. Intrathecal FC significantly attenuated IP-induced up-regulation of GFAP and OX-42 expression in the spinal cord. Conclusion The activation of gliocytes in the spinal cord is involved in the development of CFA-induced hyperalgesia in rats.