Immunohistochemical Study of Spinal Motor Neurons Following Sciatic Nerve Repair in Adult Rat

Introduction: Epineural suture and autologous graft are two routinetechniques in peripheral nerve surgery. However, their efficiency can behighly limited depending on the type of lesion and the gap between twonerve stumps and because of deficient proper nerve donors. So muchinterest has been focused on the development of alternative instruments forbridging the nerve gaps. In the present study, we have used chargedpolyvinelidene fluoride (PVDF) tube filled with nerve growth factor (NGF) andcollagen gel as a substitute for nerve autograft and compared the resultswith other current surgical techniques. We studied the changes of spinalmotoneurons to evaluate the effect of repairing techniques.Material and Methods: In this study, 30 male Wistar rats weighing 200-250g were divided randomly in five groups: axotomy, epineural suture, autograft,nerve guidance channel, and sham operation. In all experimental groups, theleft sciatic nerve was transected at mid-thigh level. The nerve was notrepaired in axotomy group. In epineural suture group, it was sutured end-toend.In autograft group, a 10 mm piece of nerve was rotated 180° andsutured again in the nerve gap. Finally, in nerve guidance channel group, apiece of PVDF tube containing NGF7s (100 ng/ml) and collagen gel (1.28mg/ml) was replaced in the gap. After one week, one month, and twomonths, L4-6 segments of spinal cord were removed and 5 μm paraffinsections were prepared for bax immunohistochemical study. In all groupscontralateral spinal cord was used as the control. The proportion of Baxpositiveapoptotic motoneurons was studied in all groups to evaluate theefficiency of different repairing techniques.Results: Mean percentage of Bax-positive neurons to the total number ofmotor neurons in left side was analyzed. One way ANOVA showedsignificant difference after two months. LSD post hoc test showed that meanpercentage of Bax-positive neurons in axotomized group was significantlyhigher compared to other surgical groups (p