The effect of epidural injections with different dose of butorphanol on the rats' serum myelin basic protein and spinal cord morphology

Abstract

Objective To observe the effect of epidural injection with different dose of tartrate-butorphanol(butorphanol)on the rats' serum myelin basic protein(MBP)and spinal cord morphology.Methods A PE-530 catheter was inserted into the epidural space of each Sprague-Dawley rat(male,weighting 180 g-210 g)at L1-2 level,and three days later,a total of 32 rats without any motor dysfunction were divided into 4 groups by random number table method as follow:saline group(group NS,n=8)and butorphanol group(B1,n=8;B2,n=8;B3,n=8).Rats in group NS were epidurally injected NS 30 μl each,and rats in group B1,B2 and B3 were respectively epidurally injected butorphanol 60,120 μg and 240 μg(all diluted to 30 μl with NS)1 time per day 5 d,the serum MBP of rats were measured before injection(T0),6(T1),24(T2)and 72 h(T3)after the last injection.At T3,the lumbar enlargement of the spinal cord was taken for detecting the morphology and apoptosis with optical microscope and electron microscope.Results There was no significant difference between each group in content of the serum MBP(P＜0.05).In group B2(21.2±2.6)and B3(25.3±3.1),compared with group NS(39.2±3.4)and B1(35.1±2.7),the number of nissl body in the neurons were decrease(P＜0.05).In group B2(36.3±7.2)and B3(48.2±8.5),compared with group NS(10.6±1.6)and B1(13.4±2.1),the expression of the Bcl-2 decreased obviously(P＜0.05).In group B2(37.9 ±7.6)and B3(45.2 ±8.3),compared with group NS(8.6 ±2.5)and B1(10.2 ±3.1),the expression of the Bax increased obviously(P＜0.05).In group B2(15.7±2.6)and B3(18.8±3.2),compared with group NS(6.1 ±2.5)and B1(9.7±2.9),the number of apoptosis neurons increased obviously(P＜0.05).In the electron microscope,the structure of myelins was destroyed,but not demyelinated.Conclusion Repeated epidural injection of butorphanol 60 pg has no influence on spinal cord morphology of rats,while injection of 120 μg and 240 μg can impair the spinal cord morphology. Key words: Butorphanol ; Epidural ; Myelin basic protein ; Morphology ;