The effect of different dose of butorphanol with epidural injections on neurological function for rats

Abstract

Objective To observe the effect of epidural injection with different dose of butorphanol on the rats' neurological function.Methods A PE-530 catheter was inserted into the epidural space of all the SpragueDawley rats (male, weighting 180 ～210 g) at L1-2 level.After three days, a total of 32 rats without any motor dysfunction were randomly divided into 4 groups as follows saline(NS) group (group C, n= 8 )and butorphanol injection (B) group( B1∶ n=8;B2∶ n=8;B3∶ n=8).Rats in group C were epidurally injected NS 30 μl each ,and rats in group B1, B2 and B3 were respectively epidurally injected Butorphanol 60 μg/30μl, 120 μg/30 μl,240 μg/30 μl (all diluted with NS) ,and 1 time per day for5 days.The neurological function of rats was recorded before injection (T0) and 6h after injection on day 1 ～4(T1 ～T 4) and 6h,24h and 72h after injection on day 5 (T5 ～T7) by BBB (BASSO,BEATTIE and BRESNAHAN ) Score and the inclined plane test .Results Compared with group C ,the BBB score and the inclined plane test of group B1 showed no significant difference throughout the experimental period(P＞ 0.05 ).There was also no significant difference at T0 ～ T3 of group B2 and group B3 compared with group C (P ＞ 0.05 ), while at T4, the BBB score ( ( 18.50 ± 2.00 ) points, ( 16.38 ± 2.33 ) points) and the inclined plane test( (58.75 ± 5.17 )°, (59.38 ± 3.20) ° ) of the two groups were both obviously decreased when compared with group C( (21.00 ±0.00) points, (65.00 ±3.78)°, P＜0.05) ,and the same significant differences appeared at T5,T6 and T7 (P ＜ 0.05 ).Conclusion Repeated epidural injection of butorphanol 60 μg have no effect on neurological function of rats,while repeated epidural injection of butorphanol 120 μg and 240 μg could impaire the neurological function. Key words: Butorphanol; Epidural; BBB score; The inclined plane test