The Effection Of Minocycline To Apoptosis Of Hippocampal Neurons On Epilepsic Rats

Epilepsy is a common chronic disease in the nervous system. Due to the complexity of its pathogenesis and the diversity of its types, it is still a key issue to overcome the prophylaxis and treatment on epilepsy for the nerve scientists. Seizures can cause a variety of apoptosis-related gene expression and encephalo-neuron apoptosis, and this apoptosis in hippocampal is the most significant. This may be one of the reasons in leading to cognitive dysfunction and the later's affective disorder on patients of epilepsy. Some studies show that minocycline (Minocycline, MC),the second-generation semi-synthetic tetracycline derivative, has neuroprotective effects in central nervous system injury and neurodegenerative diseases on animal models. These reports also think that its beneficial effects are correlated with its reducing nerve inflammation and obstructing cell death. However, its research on epilepsy is still relatively small. So, this study was to investigate the protective effect of minocycline on apoptosis of hippocampal neurons in epilepsic rats and to provide some informations for the clinical treatment of epilepsy.96 adult SD male rats were used in this study, and they were random divided into 3 groups: normal saline control group (NS group), kainic acid group (KA group) and minocycline pretreatment plus kainic acid group (MC + KA group). Epilepsy was induced by intracerebroventricular injection of KA(2μg/kg) in KA group,and the NS groups injected equal capacity saline as control. MC + KA groups were intraperitoneally injected MC (45mg/kg) pretreatment at first, after 12h, these rats were induced epilepsy by intracerebroventricular injection of KA (2μg/kg), then they were intraperitoneally injected MC 90mg/kg again after 30min of KA treatment. After KA administration,seizure behavior was observed up to 2h or so;then we killed the rats at 2h, 8h,24h and 48h. The immunoreactivity of cytochrome C and caspase-3 in rat hippocampus were detected by immunohistochemical SABC staining; the level of caspase -3 mRNA were detected by semi-quantitative RT-PCR and the level of Bcl-2 and Bax protein expression were detected by Western Blot.These results showed, The rats in NS group had no abnormal behavior; The rats in KA group had epileptic seizures up toⅣ~Ⅴgrade, and it could last for 2h; The seizures of rats in MC+ KA group was significantly weaker than it in KA group,up toⅡ~Ⅲgrade. The immunohistochemistry showed that: Cytochrome C began to express at 2h after the KA-induced epilepsy, reached at a peal at 8h, then decreased at 24h, while the minocycline pretreatment significantly attenuated this effect. RT-PCR and immunohistochemistry showed that caspase-3 mRNA levels and caspase-3 immunoreactivity were no significant difference among three groups at 24h, while KA groups were significantly higher than NS control groups at 48h after KA-induced epilepsy(P<0.05), and minocycline pretreatment groups obviously antagonized KA-induced caspase-3 expression(P<0.05).Western Blot results showed that: the levels of Bcl-2 and Bax protein expression were negatively correlated in rats hippocampus. Compared to the NS control group, the protein expression of Bcl-2 was decreased while Bax increased in KA group;Compared to the KA group, the protein expression of Bcl-2 was increased while Bax decreased in MC+ KA group. Furthermore,Bcl-2/Bax value was lower at 48h point than at 24h point.The study suggest that seizure induced by KA can result in hippocampus neuronal apoptosis. While, MC pretreatment dose not only inhibit the KA-induced epileptic effecttion,but also reduce the generation of apoptosome in the way decreasing the amount of Cyt C which realeases from mitochondria to the cytoplasm. Meanwhile, the caspase-3 is inhibited to inhibit the generation of cell apoptosis; What is more, it can increase the ratio of Bcl-2/Bax to inhibit the apoptosis. These results suggest that MC can play a neuroprotective effect of anti-apoptosis in hippocampal neurons on epileptic rats induced by KA. This may have important implications on prevention and treatment of epilepsy and neuroprotection in clinical.