The Time-Effect Relationship Study On Intraperitoneal Injection Of Progesterone To Sciatic Nerve Regeneration

Objective:To explore the time-effect relationship on intraperitoneal injection of progesterone to sciatic nerve regenerationMethods:30adult health SD rats(male and female half) were randomly divided into6groups (Group A, B, C, D, E and F, every group included5rats), and castrated to establish models without progesterone. The right sciatic nerve was removed5mm, and the defect was bridged with a number8silicon tube to establish a sciatic nerve defect model two weeks after castration. Then the experimental group A, B, C, D and E were given8mg/kg progesterone intraperitoneal injection everyday, and the treatment time was4,6,8,10,12weeks respectively. The control group was given0.2ml saline solution injection everyday. After12weeks, the functional tests according to the sciatic nerve function index (SFI) have been completed, both gastrocnemius were harvested and weighed to get their wet weight recovery rates. Regenerative sciatic nerves were harvested for histological examination including counting the number of myelinated nerve fibers and measuring thickness of myelin sheath. Then glial cell line-derived neurotrophic factor (GDNF) protein immunohistochemical had been completed to observe GDNF expression in new sciatic nerve. SPSS16.0statistical package had been used for statistical analysis, a P value<0.05has been considerated significantly.Results:(1)SFI:Each group’s SFI was different after12weeks. GroupA, B, C, D and E were obviously superior to group F (P<0.05). Group D and group E were better than group A, B, C(P<0.05). Group C was better than group B, group B was better than group A, the differences were significant (P<0.05). There were no significant differences between group D and group E (P>0.05)(2)Gastrocnemius wet weight recovery rate:The degrees of gastrocnemius muscle atrophy among of all groups showed different at postoperative12weeks. Compared with the group F, the wet weight recovery rates of gastrocnemius muscle of groupA, B, C, D, E were obviously improved(P<0.05). The differences of pairwise comparisions in every experimental group apart from between group D and group E were significant (P<0.05).(3) Histological examination:Compared with group F, the number of regenerative nerve fiber and thickness of myelin sheath of groupA, B, C, D, E increased significantly12weeks later (P<0.05). The differences of pairwise comparisions in every experimental group apart from between group D and group E were significant (P<0.05).(4) GDNF gray values of the sciatic nerve distal:gray value decreased sharply in experimental groups with the time extending. Every research group was compared with group F, there were significant differences (P <0.05). The differences of pairwise comparisions in every experimental group apart from between group D and group E were significant (P<0.05).(5) Floe ivory on the enterocoelia omentum was observed in group C、 D、E, and the amount increased with the time extending.Conclusion:Intraperitoneal injection of progestin can promote sciatic nerve regeneration, the best treatment time is10weeks.