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

Objective:To explore dose-effect relationship on intraperitoneal injection of progesterone to sciatic nerve regeneration.Methods:30adult health SD rats(male and female half) were randomly divided into six groups (A, B, C, D, E, F group) and castrated to establish SD rat models without progesterone. Two weeks later right sciatic nerve was removed5mm, and the defect was bridged with a silicon tube which was sutured with10-0nylon under a microscope to establish a sciatic nerve defect model. Then group A (control group) was intraperitoneally injected with saline0.2ml every day; group B, C, D, E, F was intraperitoneally injected with different doses of progestin every day, respectively (group B2mg/kg, group C4mg/kg, group D6mg,/kg group E8mg/kg, group F16mg/kg). Then functional tests according to the sciatic nerve function index (SFI) have been completed at postoperative12weeks.12weeks later, both calf muscles were harvested and weighed to evaluate the degree of re-dominating target tissue. Regenerative sciatic nerves were harvested for histological examination including counting the number of myelinated nerve fibers and measuring thickness of myelin sheath. Then GDNF protein immunohistochemical had been completed to observe GDNF expression in new sciatic nerve. Finally statistical analysis had been done by SPSS15.0statistical package, a P value<0.05has been considerated significantly.Results:The increase degrees of all group’s SFI were different after12weeks. Group B, C, D, E, F were obviously superior to group A (P<0.05). Group E, F were better than group B, C, D(P<0.05). Group D was better than group C, group C was better than group B, the differences were significant (P<0.05). There were no significant differences between group E and group F (P>0.05. The degrees of gastrocnemius muscle atrophy among of all groups showed different at postoperative12weeks. Compared with the group A, the wet weight recovery rates of gastrocnemius muscle of group B, C, D, E, F were obviously improved(P <0.05). Group E, F were better than group B, C, D(P<0.05). Group D was better than group C, and group C was better than group B (P<0.05). There were no significant differences between group E and group F (P>0.05). Compared with the group A, the number of regenerative nerve fiber and thickness of myelin sheath of groupB, C, D, E, F increased significantly after12weeks (P<0.05). Group E, F were better than group B, C, D(P<0.05). Group D was better than group C, and group C was better than groupB(P<0.05). There were no significant differences between group E and group F (P>0.05) The GDNF expressions of regenerative sciatic nerve of each group decreased significantly at postoperative12weeks. Compared with the group A, the gray value of GNDF positive cells of group B, C, D, E, F decreased more significantly, there were significant differences(P<0.05) between any two groups in group B, C, D, E, F but between group E and group F (P>0.05). Small amount of milky white floc had been observed in peritoneum and mesentery of group E’s rats while large amount of milky white floc had been observed in peritoneum and mesentery of group F’s rats.Conclusion:Intraperitoneal injection of progestin can promote sciatic nerve regeneration of SD rats and its best dose is8mg/kg.