Progesterone Regulates The Expression Of COX-2 And Caspase-3 Via NF-κB Signaling Pathway In Hippocampal Neurons After Traumatic Brain Injury In Rats

Objective:To investigate the effect of nuclear factor-κB (NF-κB) on the regulation of cyclooxygenase-2 (COX-2) and Caspase-3 in hippocampal neurons after traumatic brain injury (TBI) in rats, explore the neuroprotective effect and the possible mechanism of progesterone (PROG) in hippocampal neurons after TBI.Methods:90 Male Spraque-Dawley rats were randomly divided into 3 groups: sham-operated group (n=30), TBI group (n=30) and PROG-treated group (n=30). The rat model of TBI was duplicated with the improved Feeney,s method.①TBI-1: The injections in the TBI-1 group were given at 1h after the injury by subcutaneous injection of 0.9% sodium chloride (16 mg/kg body weight). The rats were killed at 6h after injury.②TBI-2: The injections in the TBI-2 group were given at 1h, 6h after the injury by subcutaneous injection of 0.9% sodium chloride (16 mg/kg body weight). The rats were killed at 24h after injury.③TBI-3: The injections in the TBI-3 group were given at 1h, 6h after the injury by subcutaneous injection of 0.9% sodium chloride (16 mg/kg body weight) and the subsequent injections were given every day after the injury for 2 consecutive days.④PROG-1: The injections in the PROG-treated group were given at 1h after the injury by subcutaneous injection of PROG (16 mg/kg body weight). The rats were killed at 6h after injury.⑤PROG-2: The injections in the PROG-treated group were given at 1h, 6h after the injury by subcutaneous injection of PROG (16 mg/kg body weight). The rats were killed at 24h after injury.⑥PROG-3: The injections in the PROG-treated group were given at 1h, 6h after the injury by subcutaneous injection of PROG (16 mg/kg body weight) and the subsequent injections were given every day after the injury for 2 consecutive days. The rats were killed at 72h after injury.⑦sham-operated: Rats in the sham-operated was given 0.9% sodium chloride injection instead of PROG. The rats were killed respectively at 6h, 24h, 72h after injury. Pathological changes were observed with HE and Nissl`s staining in hippocampal neurons. Immunohistochemistry and Western blot for NF-κB, COX-2, PGE2 and Caspase-3 was used to observe the changes of immune positive cell number and protein level in hippocampal neurons and changes after treated with PROG. Computer Image Analysis System was used to explain the number of immunoreactive cells and the expression levels of protein. All data use statistical analysis software of SPSS13.0 for statistical analysis and the statistial significance level was set at P<0.05.Results: Compared with in sham-operated group, the number of NF-κB (13.5±2.2) immune positive neurons increased in hippocampal at 6h after TBI. The number of COX-2 (16.3±1.9), PGE2 (15.0±2.6), Caspase-3 (11.7±3.3) immune positive neurons than in sham-operated group was not increased obviously in hippocampus at 6h after TBI. Compared with in sham-operated group, the number of NF-κB (24.0±2.5) immune positive neurons significantly increased in hippocampal at 24h after TBI. Compared with in sham-operated group, the number of COX-2 (35.9±2.7), PGE2 (34.4±2.9) immune positive neurons was increased obviously, the number of Caspase-3 (25.1±2.7) immune positive neurons was not increased obviously in hippocampus at 24h after TBI. Compared with in sham-operated group, the number of NF-κB (12.8±2.3), COX-2 (22.8±2.7), PGE2 (22.4±2.3) immune positive neurons increased in hippocampal at 72h after TBI. Compared with in sham-operated group, the number of Caspase-3 (33.8±3.8) immune positive neurons significantly increased in hippocampal at 72h after TBI. In treatment with PROG group, compared with the TBI group, the number of NF-κB(7.9±1.7 vs 13.5±2.2)immune positive neurons was reduced obviously in hippocampal at 6h after TBI, the number of NF-κB (14.2±1.8 vs 24.0±2.5), COX-2 (16.6±2.7 vs 35.9±2.7), PGE2 (16.5±2.0 vs 34.4±2.9) immune positive neurons significantly reduced in hippocampal at 24h after TBI. The number of Caspase-3 (16.9±1.4) immune positive neurons significantly reduced in hippocampal at 72h after TBI.Conclusion: NF-κB signaling pathway may play an important role regulate COX-2 and Caspase-3 in hippocampual neurons after TBI in rats. PROG may influence the expression of NF-κB and protect the hippocampal neurons.