Effects of Tribulus terrestris L. saponion on apoptosis of cortical neurons induced by hypoxia-reoxygenation in rats

Abstract

To observe the effects of Tribulus terrestris L. saponion (TTLS) on apoptosis in cortical neurons induced by hypoxia-reoxygenation in rats. Primary culture of rat cortical neurons was performed in vitro. A model of apoptosis of cortical neurons was established by hypoxia and reoxygenation. Hypoxia for 3 h in neural cells was induced with mixture of 95% N(2) and 5% CO(2), and then reoxygenation in neural cells was induced with mixture of 95% O(2) and 5% CO(2) for 12 h. Different concentrations of TTLS were administered to traditional Chinese herbal medicine-treated group separately during hypoxia and reoxygenation. The apoptosis rate was analyzed quantitatively by flow cytometry with Annexin V-FITC and propidium iodide staining. Mitochondria membrane potential was observed by a confocal laser-scanning microscope with JC-1 fluorescence. Caspase-3/7 activity in cytoplasm was measured by fluorescent plate reader. Bax protein expression was observed by immunohistochemical technique. The percentage of apoptosis was significantly increased, mitochondria membrane potential was obviously decreased, fluorescence of caspase-3/7 activity was increased, and Bax protein was abundantly expressed followed by 3 h of hypoxia and 12 h of reoxygenation (P<0.01). TTLS could inhibit the depression of membrane potential induced by hypoxia and reoxygenation, decrease the activity of caspase-3/7, reduce the expression of Bax protein, and inhibit the apoptosis of the cortical neurons. Hypoxia and reoxygenation can induce apoptosis of rat cortical neurons. TTLS can decrease the apoptosis induced by hypoxia and reoxygenation. The mechanism might be related to stabilization of mitochondria membrane potential, inhibition of caspase activity and reduction of Bax protein expression.