Objective： TO determine the effect of berberine （Ber） on norepinephrine （NE）-induced apoptosis in neonatal rat cardiomyocytes. Methods： The cultured neonatal rat cardiomyocytes were treated with NE in the presence or absence of Ber. The activity of lactate dehydrogenase （LDH） in the culture medium was examined, and apoptosis of cardiomyocytes was assessed by Hoechst 33258, isothiocyanate （FITC）- conjugated annexin-V, and propidine iodide （PI） staining. In addition, the activities of caspases-2 and-3 were measured by a fluorescent assay kit. The level of secreted tumor necrosis factor oL （TNF-a） and production of intracellular reactive oxygen species （ROS） were also determined. Results： NE at a concentration of 50 p, mol/L induced an obvious increase in the activity of LDH in the culture medium （P〈0.05）, which was inhibited by coincubation with 0.5, 1.0, or 2.0 μ mol/L Ber （P〈0.05）. Ber also significantly attenuated NE- induced apoptosis in a dose-dependent manner （P〈0.01）. Moreover, Ber at a dose of 2 μ mol/L markedly decreased the ROS and TNF-a productions （P〈0.05） and inhibited the activation of caspases-2 and -3 in cardiomyocytes exposed to NE （P〈0.05）. Conclusion： The present study suggested that Ber could reduce NE-induced apoptosis in neonatal rat cardiomyocytes through inhibiting the ROS-TNF-a-caspase signaling pathway.
