The Protective Effects Of Methylprednisolone By Subarachnoid Injection On Motor Endplate Degeneration After Spinal Cord Injury At Rats

Objectives:To research the protective effects of methylprednisol one on pretibial muscle motor endplate degeneration after spinal cor d injury in rats, and to further discuss the possible mechanism of protective effect.Methods:Ninety healthy Sprague-Dawley rats, weighted150-250g, were randomly divided into three groups completely: group A (n=30), group B (n=30),was made into spinal cord injury by methods of Allen and treated by local subarachnoid infusion methylpredniso lone, and group C (n=30), was given The same injure, but got tr eatment of physiological saline. The rats of A、B、C group were assigned randomly to A1、A2、A3、A4、A5、B1、B2、B3、B4、B5group and C1、C2、C3、C4、C5group at24hours、1weeks、2weeks、4weeks、8weeks after SCI, respectively. Each subgroup h as6rats.All the rats of B、C group were received the modeling of spinal cord contusion by the improved Allen’s method. The rats o f B group were received injection from local subarachnoid infusion methylprednisolone after SCI,and the rats of C group were receiv ed normal saline.The rats of A group were got with vertebral plate open and subarachnoid catheter,but did not damage the spinal co rd.Each rat The BBB score was graded by the methods of BBB, and the pretibial muscle accepted HE staining for pathology observa tion, CGRP and AchE immunohistochemical staining for positive ex pression and sliver staining for observe motor endplate.Results:1.BBB score: The score of all subgroup in A group is21point s.B3(2w)>C3(2w), B4(4w)>C4(4w), B5(8w)>C5(8w)(P<0.05); C5(8w)>C4(4w)>C3(2w)>C2(1w)>C1(24h)(P<0.05)。2. HE staining:Myocyte had the hyperchromatic nuclei,muscle fi bers were full and arranged orderly in the A group. The changes o f pathologic inflammation in the B1and B2group were less than th ose in C1and C2group; compared with group B3, the inflammatory response and Neuron atrophy of group C3was significantly more serious; muscle recovery of group B4were better than C4, and the cicatrix tissue formation of group C5were more than group B5si gnificantly.3. CGRP OD of anterior tibial muscle: B3>C3, B4>C4, B5> C5,(P<0.05); During the one week after surgery,the mean optica1density of C group was decreased obviously than that of A grou p, since then actually increased.4.AchE OD of anterior tibial muscle:B3>C3, B4>C4(P<0.05); C4>C3>C2(P<0.05). At the second week after surgery, the mean optical density of C group was decreased obviously than that of A group, and in the fourth week reached a bottom, since then actual ly increased.5. The Bielschowsky sliver staining:The nerve terminals and neuromuscular junction in the sham operation group tibialis anterior muscle. The disintegration of motor end plate in C2、C3group was more serious than those in C2and C3group respectively, as w as the decrease of number; the motor endplate degeneration gradual ly accelerated in C4group, conversely, the motor endplate and nu mber was gradually getting better in B4group; the motor endplat e in B5group got a better recovering and regeneration than that of C5.Conclusion:1. Methylprednisolone by local subarachnoid infusion can preven t motor endplate degeneration anddenervated muscles atrophy, promo te the refreshment of athletic function2. Through preventing the decline of CGRP、AchE, and enha ncing CGRP、AchE expression, reducing inflammatory reaction, a melioratting muscles atrophy,Methylprednisolone can reduce the de generation of neuromuscular junction and promote that recovery afte r SCI.