Effects of Paeoniflorin on Apoptosis and Bcl-2/Bax Protein Expression in Hippocampal Neurons Induced by Lead Acetate

OBJECTIVE To investigate the effect of paeoniflorin(PF) on hippocampal neuron apoptosis and Bcl-2/Bax protein expression induced by lead acetate. METHODS Hippocampal neurons of fetal rats were isolated and cultured, and the purity was identified by immunofluorescence staining. MTT assay was used to determine the hippocampal neuron cell viability so as to determine the optimal modeling concentration and time of lead acetate, while screening the suitable dose PF intervention on hippocampal neuron apoptosis. Based on the MTT assay results, the hippocampal neuronal cells were divided into blank, model and 20, 40 and 80 μmol·L<>sup-1 PF groups for intervention, followed by lead acetate staining 24 h, and cytochrome C(Cyt-C) content, mitochondrial membrane potential and intracellular Ca²⁺ concentration were detected. Cell apoptosis was assessed by flow cytometry, and the protein expression levels of cleaved caspase-3, cleaved-caspase-3, caspase-8, cleaved-caspase-8, caspase-9, cleaved-caspase-9, Bax and Bcl-2 in hippocampal neuronal cells were determined by Western blotting. RESULTS The identification result of cell immunofluorescence staining showed that the isolated and cultured cells were hippocampal neuronal cells with high purity. The results of MTT assay showed that lead acetate at the optimal concentration and time of 25 μmol·L<>sup-1 for 24 h. PF at the dose of 20, 40 and 80 μmol·L<>sup-1 could significantly improve the cell activity of hippocampal neurons in a dose-dependent manner. Compared with the blank group, the Cyt-C content, apoptosis rate, intracellular Ca²⁺ concentration in the model group were significantly increased(P<0.01), and the mitochondrial membrane potential was significantly decreased(P<0.01). Compared with the model group, 40 μmol·L<>sup-1 PF and 80 μmol·L<>sup-1 PF group decreased Cyt-C content, apoptosis rate, intracellular Ca²⁺ concentration(P<0.05 or P<0.01), increased mitochondrial membrane potential(P<0.01), and 20 μmol·L<>sup-1 PF group significantly increased mitochondrial membrane potential(P<0.05). Moreover, PF at a certain dose could downregulate the protein expression of cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9 and Bax, and upregulate the protein expression of Bcl-2. CONCLUSION PF can inhibit hippocampal neuron apoptosis induced by lead acetate and may exert neuroprotective effects by regulating Bcl-2/Bax protein expression.