| Peripheral nerve injury is one of the usual diseases of surgical system, a vital factor that influence it's result is the velocity of nerve regeneration. As an unit, neurons, axons and distal effect organs are connect with each other. Besides the injury to peripherial nerves, both the neurons and the distal effect organs degenerating or dying in different extent, and all this changes will influence the final result. The reasonable method is choose a drug that not only protecting the neurons and promoting the regeneration of axons but also preventing the atrophy of skeletal muscles. Research in neuroendocrine field indicates androgen, as the neurotrophic substance has an effect on the growth, differentiation and regeneration of nerve cells. But there is no report on androgen for the regeneration of sciatic nerves. This experiment is designed to administrate TP(Testosterone Propionate) to the sciatic nerve injured rats and observe It's result in the aspect ofmorphological and functional as well as research on it's effect and mechanism. So that provides experimental evidence for clinical purpose.Method: 60 male wistar rats were randomly divided into two groups: Test group (TP-treated group) and control group(physiological saline-treated group). The left sciatic nerve was transected and sutured epineurium immediately. TP groups were injected with O.lmg TP(50mg/ml) intramuscularly two times per week, control group received the saline as control. After operation, each group was randomly further divided into two groups which according to the observing periods for 4 and 12 weeks respectively. Denervated changes of rat and morphologic changes of regenerated nerve were observed and recovery rate of sciatic function index (SFI%) was measured to observe the function restoration of damaged hind limbs. Recovery rate of the complex muscular action potential (CMAP%) and motor nerve conduction velocities (MNCV%) were measured with Nerve-Electrophysiological instrument. Specimens in the distal ends of regenerated nerves were sectioned histologically and stained with hematoxylineosin, Loyez-hematoxylin and toluidine blue to observe the histomorphologic changes under light microscope. Then, quantitative analysis of recovery rate of myelinated fiber populations were performed. Electron microscope was used to observe the ultrastnicture changes. The recover}' rate of wet weightof gastrocnemius muscle measured to observe the effect of TP on atrophy of skeletal muscles.Result: 1. General morphology: At 12 weeks the sciatic nerve of TP group is thicker than that of control group . 2. The recovery rate of SFI showed that: 39.89+5.93% in TP group and 22.11+10.17% in control group at 4 weeks; 74.69+10.94% in TPgroup and 60.81+7.70% in control group at 12 weeks. The difference between two groups were all significant statistically(P<0.05).3.Resultof Nerve-electrophysiology: at 4 weeks MNCV% and CMAP% of TP group are 26.74+6.54% and 28.58+4.49%, that of control group are 19.71+4.34% and 18.95+5.51%, there were difference statistically between two groups (P<0.05). At 12 weeks, MNCV% and CMAP% of TP group are 54.31+12.89% and 71.24+4.05%, that of control group are 40.23+10.00% and 62.95+4.89%, there were difference statistically between two groups (P<0.05). 4. The observation of light microscope and electronmicroscope: at 4 weeks, the regenerated fibers in TP group were denser and more regular than that in control group. At 12 weeks, the fibers in TP group were more regular and homogeneous and the myelin sheaths were thicker than that in control group. The observation was further confirmed under electron microscopy. 5. Quantitative analysis of the recovery rate of myelinated fiber population: at 4 weeks, in TP group:51.67+9.32%, in control group : 34.04+10.86%; at 12 weeks, in TP group:84.03+3.84%, in control group: 75.13+6.58%. The difference between two groups were all significant statistically (P<0.05). 6. The recovery rate of wet weight of gastrocnemius muscle: at 4 weeks, in TP group : 80.08+5.23%, in control group : 71...
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