Effect of pretreatment with botulinum toxin A on NK-1 receptor internalization in spinal dorsal horn in a rat model of incisional pain / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of pretreatment with botulinum toxin A injected intrath?ecally or locally at the incision site on the neurokinin?1 ( NK?1) receptor internalization in the spinal dorsal horn in a rat model of incisional pain. Methods Male Sprague?Dawley rats, weighing 280-300 g, aged 6-8 weeks, were used in the study. The experiment was performed in two parts. ExperimentⅠ Twenty?seven rats with no sign of nerve injury at day 7 after successful catheterization were selected and divided into 3 groups (n=9 each) using a random number table control group (C1 group), incisional pain group (IP1 group) and intrathecal botulinum toxin A group (BoNT∕A1 group). At 24 h before operation, botulinum tox?in A 0.5 U ( in 10μl of normal saline) was injected intrathecally in group BoNT∕A1, and normal saline 10μl was injected intrathecally in group IP1. ExperimentⅡ Twenty?seven rats were selected and divided into 3 groups (n=9 each) using a random number table control group (group C2), incisional pain group (IP2 group) and locally injected botulinum toxin A at the incision site group (BoNT∕A2 group). At 24 h before op?eration, botulinum toxin A 2 U ( in 0.4 ml of normal saline) was injected subcutaneously at the incision site and into the plantar surface, and normal saline 0.4 ml was injected subcutaneously at the incision site and into the plantar surface in group IP2. Six rats in each group were selected, and the cumulative pain score (CPS) was recorded, and the mechanical paw withdrawal threshold ( MWT) in the right hindpaw was measured be?fore administration, before operation, and at 3 h and 1, 3, 5 and 7 days after operation. At 3 h after opera?tion, 3 rats in each group were selected and sacrificed, and the lumbar segment ( L4,5 ) of the spinal cord was removed for determination of the expression of NK?1 receptors in the spinal dorsal horn by immunofluores?cence. Results ExperimentⅠ Compared with group C1, the CPS was significantly increased at 3 h and 1, 3, 5 and 7 days after operation, the MWT was significantly decreased at 3 h and 1 and 3 days after opera?tion, and the expression of NK?1 receptors in the spinal dorsal horn was significantly up?regulated in group IP1, and the CPS was significantly increased at 3 h and 1, 3 and 5 days after operation, the MWT was sig?nificantly decreased at 3 h after operation ( P0.05). Compared with group IP1, the CPS was significantly decreased, and the MWT was significantly increased at 3 h and 1, 3, and 5 days after oper?ation, and the expression of NK?1 receptors in the spinal dorsal horn was significantly down?regulated in group BoNT∕A1 (P0.05) . Compared with group IP2, the CPS was significantly decreased at 3 h and 1, 3, and 5 days after operation, the MWT was signifi?cantly increased at 3 h and 1 and 3 days after operation, and the expression of NK?1 receptors in the spinal dorsal horn was significantly down?regulated in group BoNT∕A2 (P<0.05). Conclusion Pretreatment with botulinum toxin A injected intrathecally or locally at the incision site can inhibit the internalization of NK?1 re?ceptors in the spinal dorsal horn in a rat model of incisional pain.