Dose-effect Relationship Research On Regional Injection Of Progesterone To Sciatic Nerve Regeneration

OBJECTIVE:To explore the dose-effect relationship of regional injection of progesterone to sciatic nerve regenerationMETHODS:30SD rats(male and female half) were randomly divided into6groups (Group A, B, C, D, E and F), and castrated to establish models without progesterone inside body. Two weeks after castration, their right sciatic nerves were removed5mm, and the defects were bridged with T shape silicone tubes to establish sciatic nerve defect models. Then Group A(control group)was regionally injected with saline0.2ml every day, Group B, C, D, E and F was regionally injected with different doses of progesterone every day,respectively(Group B2mg/kg, Group C4mg/kg, Group D6mg/kg,Group E8mg/kg, Group F16mg/kg). Functiongal recovery of right hind limbs were evaluated according to the sciatic nerve function index (SFI) at postoperative4,8,12weeks respectively.12weeks later, both gastrocnemius muscle were harvested and weighed to evaluate the degree of re-dominating target tissue. Then new born sciatic nerves were harvested for histological examination including counting the number of myelinated nerve fibers and measuring thickness of myelin sheath. Moreover, glial cell line-derived neurotrophic factor (GDNF) immunohistochemical protein had been completed to observe GDNF expression in new sciatic nerves.Finally, statistical analysis had been done by SPSS17.0statistical software, a P value<0.05has been considerate significantly.RESULTS:1) The SFI of each group after treatment increased gradually. Compared with A, the SFIs of Group B, C, D, E and F increased more significantly (P<0.05). of which group C showed a better result than that of group B, D, Eand F (P<0.05); Group B displayed a better outcome than group D, E, F (P<0.05),, there were no significance of the SFIs between group D, Eand F(P>0.05).2) The gastrocnemius muscle of each group was of atrophy in varied degree12weeks later. Compared with Group A, the wet weigh of gastrocnemius muscle of group B, C, D, E and F recovered more obviously (P<0.05), within which Group C displayed a better result than that of Group B, D, E and F (P<0.05), Group B demonstrated a better consequence than group D, E, F (P<0.05). No significance was found between group D, E and F (P>0.05).3) Compared with group A, the number of neurofibra myelinata and the thickness of myelin of the newborn sciatic nerves of groupB, C, D, E and F increased more significantly(P<0.05), of which group C showed a better result than that of group B, D, E and F (P<0.05), Group B displayed a better result than group D, E, F (P<0.05). No significance was found between group D, E and F (P>0.05).4) The milky substance was seen in all surroundings of T tube in rats, the quantity increased as the dosage of progesterone increased.CONCLUSION:Regional injection of progesterone can promote sciatic nerve regeneration, the best dose is4mg/kg.