Phenolic alkaloids from Menispermum dauricum inhibits apoptosis of cerebral ischemia in rats

Abstract

Stroke was a debilitating disease for which limited therapeutic approaches are available currently. Thus, there was an urgent need for developing novel therapies for stroke. Cell apoptosis played an important role in embryonic development, maturity of the immune system, and other respects. Cells received apoptotic signals, activated the cells’ protein, started the gene regulation mechanisms, and caused the suicide death. Recently many research showed that neuron apoptosis took part in ischemic cell damage and was the important form of neurons loss caused by ischemia. After ischemia, necrosis or apoptosis was observed in cells because of inflammation, calcium overload, oxygen free radical, damage of mitochondria and DNA. Phenolic alkaloids from Menispermum dauricum (PAMD) have gained growing appreciation for its beneficial biological effects through its anti-inflammatory property. There was a close relationship between apoptosis and inflammatory reaction during cerebral ischemia. In this study we investigated the protective effect of PAMD on apoptosis and the potential molecular mechanisms in cerebral ischemia rats. Cerebral ischemia in male Sprague–Dawley rats was induced by middle cerebral artery occlusion (MCAO) and PAMD was pre-administered intragastrically once daily for five consecutive days before surgery. The effect of the PAMD on the ethology and pathomorphology of the rats with MCAO were observed before and after treatment. Neurological deficit scores and morphological characteristics were measured after cerebral ischemia. The expression of caspase-3 was determined by immunohistochemistry at 24, 48, and 72 h after cerebral ischemia. RT-qPCR was used to analyze the levels of caspase-3 mRNA of middle and high dosage groups at 72 h after cerebral ischemia. Neurons apoptosis rate was measured by flow cytometry. The result showed that, compared with MCAO groups, PAMD noticeably improved neurological deficit at 24, 48, and 72 h after ischemic insult. Consistent with these results, our data also indicated that PAMD significantly downregulated the expression of caspase-3 protein and caspase-3 mRNA (P < 0.01, P < 0.05), decreased the neuron apoptosis rate (P < 0.05). The results provided a neuroprotective effect of PAMD on cerebral ischemia and this effect was exerted by inducing the bcl-2 expression and suppressing the bax upregulation, then inhibiting the expression of caspase-3 protein and caspase-3 mRNA, and terminating the cascade reaction of caspases.