The curative effect of intrathecal injection of pregabalin on postherpetic neuralgia in rats and its effect on the expression of COX2 in spinal cord

BI Hou-hui; ZHANG Xing

doi:10.13820/j.cnki.gdyx.20176154

Abstract：Objective To investigate the effects of intrathecal injection of pregabalin on the behavioral effects of the postherpetic neuralgia (PHN) model and the expression of COX2 in the spinal cord. Methods Using SPSS19.0 random digital generator, 32 SPF class SD rats were divided into 4 groups (n=8): blank control group (Group C), PHN group (Group PHN), intrathecal injection control group (Group PHN-NS) and intrathecal injection drug group (Group PHN-pr). Except for Group C, the other 3 groups received intraperitoneal injection of resintoxin (0.2 μg/g) to replicate the PHN model. After the pain threshold of the PHN model was stable, intrathecal administration of Pregabalin (600 μg/24 h) was applied in Group PHN-pr, while saline was used as placebo in Group PHN-NS. The pain of the rats was monitored for 21 consecutive days. The levels of IL-6 and TNF-α were detected by ELISA in the spinal cord homogenate, and the expression of COX2 was detected by immunohistochemical staining and western blot. Results Compared with Group C, the mechanical pain threshold of the PHN model was stable on Day 7 (P＞0.05). Compared with Group PHN, the mechanical pain threshold was significantly increased in Group PHN-pr (P＜0.05), but there was no significant difference between the Group PHN-NS and PHN-pr on Day 22 (P＞0.05). Compared with Group C, the relative expression of COX2 protein of spinal cord, and spinal cord homogenate IL-6 and TNF-α concentrations were significantly increased in Group PHN (P＜0.05). Compared with Group PHN, the relative expression of COX2 protein in spinal cord, IL-6 and TNF-α concentrations in spinal cord homogenate were significantly reduced in Group PHN-pr (P＜0.05), but there was no significant difference between Group PHN and PHN-NS (P＞0.05). Conclusion Intrathecal injection of Pregabalin could down-regulate the expression of COX2 in the spinal cord of PHN model rats, reduce the infiltration of myelitis inflammatory factor and achieve better analgesic effect.