Ethanol exposure produces alterations in GABAergic signaling that are associated with dependence and withdrawal. Previously, we demonstrated that ethanol-induced protein kinase Cγ (PKCγ) signaling selectively contributes to changes in GABAA α1 synaptic receptor activity and surface expression. Here, we demonstrate that protein kinase A (PKA) exerts opposing effects on GABAA receptor adaptations during brief ethanol exposure. Cerebral cortical neurons from day 0-1 rat pups were tested after 18 days in culture. Receptor trafficking was assessed by western blot analysis and functional changes were measured using whole cell patch clamp recordings of evoked and mIPSC responses. One-hour ethanol exposure increased membrane-associated PKC and PKA, but steady-state GABAA α1 subunit levels were maintained. Activation of PKA by Sp-cAMP alone increased GABAA α1 subunit surface expression and zolpidem potentiation of GABA responses, while co-exposure of ethanol with the PKA inhibitor Rp-cAMP decreased α1 subunit expression and zolpidem responses. Exposure to the PKC inhibitor calphostin-C with ethanol mimicked the effect of direct PKA activation. The effects of PKA modulation on mIPSC decay τ were consistent with its effects on GABA currents evoked in the presence of zolpidem. Overall, the results suggest that PKA acts in opposition to PKC on α1-containing GABAA receptors, mediating the GABAergic effects of ethanol exposure, and may provide an important target for the treatment of alcohol dependence/withdrawal.
- Received November 19, 2012.
- Revision received February 12, 2013.
- Accepted February 12, 2013.
- The American Society for Pharmacology and Experimental Therapeutics