RESUMO
Objective To evaluate the effect of intrathecal ropivacaine on spinal histone deacetylase 1 (HDAC1) and HDAC2 expression in the rats with neuropathic pain (NP).Methods Thirty adult male Sprague-Dawley rats, weighing 220-250 g, in which intrathecal catheters were successfully placed, were randomly divided into 3 groups (n=10 each) using a random number table: sham operation group (group S), group NP, and NP + ropivacaine group (group R).NP was induced by chronic constriction injury (CCI) in anesthetized rats.Sciatic nerve was exposed and 4 loose ligatures were placed on the left sciatic nerve at 1 mm intervals with 4-0 chromic catgut.Starting from 7th day after CCI, 0.25％ ropivacaine 20 μl was injected intrathecally in group R, while the equal volume of normal saline was given instead of ropivacaine in S and CCI groups once a day for 7 consecutive days.At 1 day before CCI (T0) ,and 3, 7, 10, 14, 17 and 21 days after CCI (T1-6) , the mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.After the pain threshold was measured at T4,3 rats from each group were sacrificed, and their lumbar enlargements were harvested for determination of the expression of HDAC1 and HDAC2 by Western blot.Results Compared with group S, the MWT was significantly decreased, and the TWL was shortened at T2-6, and the expression of HDAC 1 and HDAC2 was up-regulated at T4 in NP and R groups (P＜0.05).Compared with group NP, the MWT was significantly increased at T4, and the TWL was prolonged at T3.4, and the expression of HDAC1 and HDAC2 was downregulated at T4 in group R (P＜0.05).Conclusion The mechanism by which intrathecal ropivacaine alleviates NP may be related to inhibited up-regulation of spinal HDACI and HDAC2 expression in rats.