Ethanol and PTZ effects on siRNA-mediated GABAB1 receptor: down regulation of intracellular signaling pathway in prenatal rat cortical and hippocampal neurons.

GABA(B) receptors (R) are widely expressed and distributed in the nervous system, and have been implicated in variety of neurodegenerative and pathophysiological disorders. However, the exact molecular mechanism regarding responsibility of GABA(B1)R in downstream signaling pathway is not well understood. The present study was undertaken to explore the downstream signaling and role of GABA(B1)R upon acute ethanol and pentylenetetrazol (PTZ) exposure for (20 min) in cortical and hippocampal neuronal cell cultures by using GABA(B1)R RNA interference (i) (30 nM, 48 h) at gestational days 17.5. The results showed that GABA(B1)R and protein kinase A-alpha (PKA) showed decreased expression upon ethanol and PTZ exposure in cortical and hippocampal neurons during transfected and nontransfected conditions, whereas these effects could lead to significant changes in phosphorylation of cAMP-response element binding protein (p-CREB) expression where GABA(B1)R was knocked down. Furthermore, intracellular Ca(+2) concentrations were also reduced in some groups after transfection with GABA(B1)R RNAi. These results showed a critical role of GABA(B1)R upon ethanol and PTZ exposure by modulating downstream signaling pathway. Finally, these findings suggested that inhibition of GABA(B1)R results in the modulation of PKA, p-CREB pathway may play a role in long-term changes in the nervous system, and may be an underlying cause of ethanol's effects. (c) 2009 Wiley-Liss, Inc.