Anthocyanins Protect Against Ethanol-Induced Neuronal Apoptosis via GABA(B1) Receptors Intracellular Signaling in Prenatal Rat Hippocampal Neurons

Abstract

Here, we investigated the possible involvement of gamma-aminobutyric acid B1 receptor (GABA(B1)R) in mediating the protective effects of black soybean anthocyanins against ethanol-induced apoptosis in prenatal hippocampal neurons because GABARs are known to play an important role in the development of central nervous system. Treatments were performed on primary cultures of prenatal rat hippocampal neurons transfected with or without GABA(B1)R small interfering RNA (siRNA). The results showed that, when ethanol treatment was followed by anthocyanins treatment, cellular levels of proapoptotic proteins such as Bax, activated caspase-3, and cleaved poly (ADP-ribose) polymerase 1 (PARP-1) were decreased, and the cellular level of the antiapoptotic protein Bcl-2 was increased compared to treatment with ethanol alone. Furthermore, the effects of ethanol on cellular levels of GABA(B1)R and its downstream signaling molecules such as protein kinase A, calcium/calmodulin-dependent protein kinase II (CaMKII), and phosphorylated cAMP response element binding protein were diminished or reversed by anthocyanins treatment. The ability of anthocyanins to reverse the effects of ethanol on cellular levels of Bax, Bcl-2, active caspase-3, cleaved PARP-1, GABA(B1)R, and CaMKII were abrogated in cells transfected with GABA(B1)R siRNA. In a GABA(B1)R-dependent manner, anthocyanins also inhibited the ability of ethanol to elevate intracellular free Ca2+ level and increase the proportion of cells with low mitochondrial membrane potential in the population. Cell apoptosis assay and morphological studies also confirmed the neuroprotective effect of anthocyanins against ethanol via GABA(B1)R. Our data suggest that GABA(B1)R plays an important role in the neuroprotective effects of anthocyanins against ethanol.