Effect Of Sciatic Injection Injury On Enzymohistochemistry Of Skeletal Muscle In Rabbit's Legs

Objective:To establish rabbit animal model of sciatic nerve trunk injection injury; To reveal effect of sciatic injection injury on enzymohistochemistry of skeletal muscle in rabbit's legs; To explore the laws of enzymohistochemistry changes; and discuss the mechanism of skeletal muscle atrophy preliminarily.Method:45 adult healthy rabbit were used,2.50±0.50 kg; they were randomized into the normal group, penicillin injection group, a control group (normal saline was injected). Exposed sciatic nerve-trunk through surgery and injected penicillin or normal saline 0.5ml under the perilemma and made sciatic nerve injection injury model. Then VG staining method was adopted to observe the changes of collagen fibers in the rabbit's tibialis anterior and caput laterale musculi gastrocnemii before and after sciatic nerve penicillin and normal saline injection injury. NADH-TR staining method was used to study the histochemistry characteristics of the rabbit's leg muscle, compared the distribution and composition characteristics of the three types muscle fiber. Then the image analysis system was used to detect the change of composition of muscle fiber types, crosscut area and optical density. Muscle weight was weighed.Results:(1) After penicillin and normal saline injecting into sciatic nerve-trunk perilemma, the symptoms of hind traipse, limping and appearance thinning were observed. Movement of uninjured was at home. Muscle became thinner, their color has changed from ruddy to pale. (2) The weight of tibialis anterior muscle and the lateral head of the gastrocnemius muscle dropped; (3) Red collagen fibers, yellow muscle fibers and cytoplasm, and the black nuclei could be seen by VG staining in normal skeletal muscle; when penicillin injecting into sciatic nerve-trunk under-perilemma 2w, collagen fibers hyperplasia in tibialis anterior muscle and the lateral head of the gastrocnemius muscle has started. They reached the peak at 4w,and then the hyperplasia of collagen fibers had decreased at 8 w, reduced at 12 w significantly, but they were still more than the normal; An unexpected finding was that normal saline injection also caused collagen fiber hyperplasia, however, hyperplasia is less than penicillin injection visibly. (4) Three muscle fiber types were visible by NADH-TR enzymohistochemistry staining in tibialis anterior muscle and the lateral head of the gastrocnemius of rabbit, i.e. type I, type II A, type II B; Both penicillin and normal saline injecting into sciatic nerve trunk under-perilemma could cause obvious changes of composition ratio, crosscut area and optical density of muscle fiber in two muscles, which type II B was the most unstable one with a large fluctuation range; typeⅡA was the second, type I fiber change was small relatively; The changes of every observation indexes had outstanding differences amongst different time points, but follow the change rules:composition ratio and optical density value were 4w> 8w> 2w> 12w> the normal, muscle fiber crosscut area and muscle weight were the opposite just enough. Changes caused by penicillin injection are greater than normal saline injection. The injury caused by penicillin in caput laterale musculi gastrocnemii was much heavier than tibialis anterior.The damage caused by injecting normal saline did not make differences between two muscle.Conclusions:(1) Both penicillin and normal saline injecting into sciatic nerve trunk under-perilemma could cause collagen fiber hyperplasia, NADH-TR activation in skeletal muscle; (2) After sciatic nerve injection injury, collagen fiber hyperplasia and NADH-TR change had time compliance; (3) Collagen fiber hyperplasia and NADH-TR activation in skeletal muscle could lead to the muscle atrophy.