Leptin enhances the tolerance of rat brain astrocytes to isehemia and hypoxia in vitro

Objective To investigate the effect of leptin on the tolerance of cultured rat brain astrocytes to ischemia and hypoxia.Methods The brain astrocytes isolated from neonatal SD rats,after purification and identification,were incubated in serum-and glucose-flee medium in the presence of 5%CO2+95%N2 for 90 min to induce isehemic and hypoxic injury. RT-PCR was performed to detect the expressions of the leptin receptors Ob-Ra and Ob-Rb in the cells, and colorimetry was used to measure the content of malonaldehyde(MDA) and lactate dehydrogenase(LDH) activity in the cell supematant.The expression level ofglial fibrillary acidicprotein(GFAP)in the cells was detected with fluorescence immunocytochemistry.Results Ischemic and hypoxic exposure of the cells induced obvious cell necrosis.Compared with the cells without the exposure,significantly decreased Ob-Rb expression(0.52±0.01 vs 1.32±0.01,P 0.05). Compared with the exposed cells,the leptin-treated cells showed a significant reduction in MDA levels(3.94±0.36 vs 3.19±0.25,P<0.05) with significantly increased GFAP expression(0.057±0.006 vs 0.109±0.008, P<0.05)after the exposure, and the cells maintained basically intact cell morphology.Conclusion With neuroprotective effects against ischemic neuronal injuries,leptin canimprove the tolerance of rat brain astrocytes to ischemia and hypoxia. Key words: Leptin; Astrocyte; Hypoxia-lschemia, Brain