Adolescent Alcohol Exposure Alters GABAA Receptor Subunit Expression in Adult Hippocampus. (November 2014)

• Record Type: Journal Article
• Authors: Centanni, Samuel W.; Teppen, Tara; Risher, Mary‐Louise; Fleming, Rebekah L.; Moss, Julia L.; Acheson, Shawn K.; Mulholland, Patrick J.; Pandey, Subhash C.; Chandler, L. Judson; Swartzwelder, H. S.
• Is Part Of: Alcoholism. Volume 38:Number 11(2014:Nov.)
• Page Start: 2800
• Page End: 2808
• Publication Date: 2014-11
• Subjects: Alcoholism -- Periodicals; Alcoholism -- Periodicals; Alcoolisme; Electronic journals; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.861005
• DOI: 10.1111/acer.12562
• Languages: English
• ISSNs: 0145-6008

Abstract

<abstract abstract-type="main" id="acer12562-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="acer12562-sec-0001" sec-type="section"> <title>Background</title> <p>The long‐term consequences of adolescent alcohol abuse that persist into adulthood are poorly understood and have not been widely investigated. We have shown that intermittent exposure to alcohol during adolescence decreased the amplitude of GABA<sub>A</sub> receptor (GABA<sub>A</sub>R)‐mediated tonic currents in hippocampal dentate granule cells in adulthood. The aim of this study was to investigate the enduring effects of chronic intermittent alcohol exposure during adolescence or adulthood on the expression of hippocampal GABA<sub>A</sub>Rs.</p> </sec> <sec id="acer12562-sec-0002" sec-type="section"> <title>Methods</title> <p>We used a previously characterized tissue fractionation method to isolate detergent resistant membranes and soluble fractions, followed by Western blots to measure GABA<sub>A</sub>R protein expression. We also measured mRNA levels of GABA<sub>A</sub>R subunits using quantitative real‐time polymerase chain reaction.</p> </sec> <sec id="acer12562-sec-0003" sec-type="section"> <title>Results</title> <p>Although the protein levels of <italic>α</italic>1‐, <italic>α</italic>4‐, and <italic>δ</italic>‐GABA<sub>A</sub>R subunits remained stable between postnatal day (PD) 30 (early adolescence) and PD71 (adulthood), the <italic>α</italic>5‐GABA<sub>A</sub>R subunit was reduced across that period. In rats that were subjected to adolescent intermittent ethanol (AIE) exposure between PD30 and PD46, there was a significant reduction in the protein levels of the <italic>δ</italic>‐GABA<sub>A</sub>R, in the absence of any changes in mRNA levels, at 48 hours and 26 days after the last ethanol (EtOH) exposure. Protein levels of the <italic>α</italic>4‐GABA<sub>A</sub>R subunit were significantly reduced, but mRNA levels were increased, 26 days (but not 48 hours) after the last AIE exposure. Protein levels of <italic>α</italic>5‐GABA<sub>A</sub>R were not changed by AIE, but mRNA levels were reduced at 48 hours but normalized 26 days after AIE. In contrast to the effects of AIE, chronic intermittent ethanol (CIE) exposure during adulthood had no effect on expression of any of the GABA<sub>A</sub>R subunits examined.</p> </sec> <sec id="acer12562-sec-0004" sec-type="section"> <title>Conclusions</title> <p>AIE produced both short‐ and long‐term alterations of GABA<sub>A</sub>R subunits mRNA and protein expression in the hippocampus, whereas CIE produced no long‐lasting effects on those measures. The observed reduction of protein levels of the <italic>δ</italic>‐GABA<sub>A</sub>R, specifically, is consistent with previously reported altered hippocampal GABA<sub>A</sub>R‐mediated electrophysiological responses after AIE. The absence of effects of CIE underscores the emerging view of adolescence as a time of distinctive vulnerability to the enduring effects of repeated EtOH exposure.</p> </sec> </abstract>