title: Ethanol Regulation of Synaptic GABAA α4 Receptors Is Prevented by Protein Kinase A Activation.
abstract: Ethanol alters GABAA receptor trafficking and function through activation of protein kinases, and these changes may underlie ethanol dependence and withdrawal. In this study, we used subsynaptic fraction techniques and patch-clamp electrophysiology to investigate the biochemical and functional effects of protein kinase A (PKA) and protein kinase C (PKC) activation by ethanol on synaptic GABAA α4 receptors, a key target of ethanol-induced changes. Rat cerebral cortical neurons were grown for 18 days in vitro and exposed to ethanol and/or kinase modulators for 4 hours, a paradigm that recapitulates GABAergic changes found after chronic ethanol exposure in vivo. PKA activation by forskolin or rolipram during ethanol exposure prevented increases in P2 fraction α4 subunit abundance, whereas inhibiting PKA had no effect. Similarly, in the synaptic fraction, activation of PKA by rolipram in the presence of ethanol prevented the increase in synaptic α4 subunit abundance, whereas inhibiting PKA in the presence of ethanol was ineffective. Conversely, PKC inhibition in the presence of ethanol prevented the ethanol-induced increases in synaptic α4 subunit abundance. Finally, we found that either activating PKA or inhibiting PKC in the presence of ethanol prevented the ethanol-induced decrease in GABA miniature inhibitory postsynaptic current decay τ1, whereas inhibiting PKA had no effect. We conclude that PKA and PKC have opposing effects in the regulation of synaptic α4 receptors, with PKA activation negatively modulating, and PKC activation positively modulating, synaptic α4 subunit abundance and function. These results suggest potential targets for restoring normal GABAergic functioning in the treatment of alcohol use disorders.
authors: Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
authors: Stephen L
authors: SL
authors: Carlson
authors: Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina.
authors: John Peyton
authors: JP
authors: Bohnsack
authors: Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina morrow@med.unc.edu.
authors: A Leslie
authors: AL
authors: Morrow
mesh_terms: D000818:Animals; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D008297:Male; D009473:Neuronal Plasticity / Q000187:drug effects; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011493:Protein Kinase C / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000096:biosynthesis* / Q000187:drug effects; D020889:Rolipram / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D002492:Central Nervous System Depressants; D020536:Enzyme Activators; C546262:Gabra4 protein, rat; D047428:Protein Kinase Inhibitors; D011963:Receptors, GABA-A; D005576:Colforsin; D000431:Ethanol; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D020889:Rolipram