Effects of subarachnoid injection of TSA on RTX-induced neuropathic pain and its mechanism

CHEN Wenjia; MENG Xiaowen; WANG Lina; ZHAN Ying; JI Fuhai; YANG Jianping

doi:10.3969/j.issn.1002-266X.2017.29.004

Abstract：Objective To study the effects of subarachnoid injection of trichostatin A (TSA) on resiniferatoxin (RTX)-induced neuropathic pain in rats and its mechanism.Methods Twenty-four male SD rats were randomly divided into four groups (n=6): Vehicle group, RTX group, RTX+DMSO group, and RTX+TSA group.The models of neuropathic pain were established in the remaining three groups except Vehicle group.Subarachnoid catheterization was performed in the RTX+DMSO group and RTX+TSA group one week prior to modeling.Before the establishment of the models, the rats were sacrificed with von Frey filaments to detect the basal value of the pain, and the mechanical pain threshold was measured on the 1st, 3rd, 5th, and 7th days after modeling.Vehicle group was treated with a single peritoneal RTX solvent 1.5 mL;rats in the RTX group received intraperitoneal injection of RTX (210 μg/kg);from 60 min before RTX injection, 5% DMSO (10 μL) was injected into rats of the RTX+DMSO group intrathecally once a day for 7 days;from 60 min before RTX injection, TSA (0.5 μg/kg) with solvent of 5% DMSO was injected into rats of the RTX+TSA group intrathecally once a day.The expression of BDNF mRNA in the spinal cord (SC) and dorsal root ganglion (DRG) was measured by qRT-PCR at 2 h after last time of TSA injection.Results Compared with the Vehicle group, the RTX group, RTX+DMSO group, and RTX+TSA group displayed a significantly decrease in mechanical allodynia on the 3th, 5th, and 7th days (P<0.05).Compared with the RTX group and RTX+DMSO group, the RTX+TSA group had significantly higher mechanical pain threshold on 5th and 7th days (all P<0.05).There was no statistically significant difference between the RTX group and RTX+DMSO group (P>0.05).Compared with the Vehicle group, the expression of BDNF mRNA was down-regulated in the spinal cord and DRG in the RTX group and RTX+DMSO group (P<0.05).Compared with the RTX group and RTX+DMSO group, the expression of BDNF mRNA in the spinal cord was up-regulated in the RTX+TSA group (P<0.05).There was no statistically significant difference between the RTX+DMSO group and RTX group (P>0.05).Conclusion The subarachnoid injection of TSA can relieve RTX-induced neuropathic pain by up-regulating the expression of brain-derived neurotrophic factor (BDNF).