Beneficial effects of chlorogenic acid on alcohol-induced damage in PC12 cells

As one of the most commonly abused psychotropic substances, ethanol exposure has deleterious effects on the central nervous system (CNS). The most detrimental results of ethanol exposure during development are the loss of neurons in brain regions such as the hippocampus and neocortex, which may be related to the apoptosis and necrosis mediated by oxidative stress. Recent studies indicated that a number of natural drugs from plants play an important role in protection of nerve cells from damage. Among these, it has been reported that chlorogenic acid (CA) has neuroprotective effects against oxidative stress. Thus, it may play some beneficial effects on ethanol-induced neurotoxicity. However, the effects of CA on ethanol-induced nerve damage remain unclear. In order to investigate the protective effects of CA on alcohol-induced apoptosis in rat pheochromocytoma PC12 cells, in the present study, cell viability and the optimal dosage of CA were first quantified by MTT assay. Then, the cell apoptosis and cell cycle were respectively investigated by Hoechst 33258 staining and flow cytometer (FCM). To further clarify the possible mechanism, followed with the test of mitochondria transmembrane potential with Rhodamine 123 (Rho 123) staining, the expression of Bcl-2, Capase-3 and growth associated protein-43 (GAP-43) were analyzed by immunofluorescence assay separately. The results showed that treatment with 500 mM alcohol decreased the cell viability and then significantly induced apoptosis in PC12 cells. However, when pretreated with different concentrations of CA (1, 5, 10, 50 μM), cell viability increased in different degree. Comparatively, CA with the concentration of 10 μM most effectively promoted the proliferation of damaged cells, increased the distribution ratio of the cells at the G2/M and S phases, and enhanced mitochondria transmembrane potential. This appears to be in agreement with up-regulation of the expression of Bcl-2 and GAP-43, and down-regulation of the expression of Capsae-3. Taken together, CA can increase cell viability and promote cell differentiation by preventing alcohol-induced cell from apoptosis. The mechanism may be related to the enhancement of the expression of GAP-43 and the inhibition of mitochondrial apoptotic pathway including promotion of mitochondria transmembrane potential, up-regulation of the expression of Bcl-2, and down-regulation of the expression of Capsae-3.