Differential Expression of GABA_A/Benzodiazepine Receptor Subunit mRNAs and Ligand Binding Sites in Mouse Cerebellar Neurons Following In Vivo Ethanol Administration: An Autoradiographic Analysis

Abstract

The y-aminobutyric acid A (GABAA )/benzodiazepine (BZ) receptor is a pentamer composed of subunits belonging to several classes (a,_6, 01-1, y,_4, b, and p, and P2 ) . In situ hybridization, radioligand autoradiography, and immunocytochemistry were used to examine GABA A /BZ receptor cr, , a6, 13 2, 03, and y2 subunit expression in murine Purkinje, granule, and deep cerebellar neurons after in vivo ethanol exposure . Chronic ethanol treatment resulted in decreased a, subunit mRNA expression in each cell type, whereas the expression of a 6 and y 2 subunit mRNA levels increased ; no changes were observed in the expression of ß2 and 03 subunit mRNA . GABA and BZ agonist binding and antibody staining paralleled the changes in mRNA levels . Acute ethanol injection resulted in increased expression of a, and 133 mRNAs, whereas levels of a 6 ,ß2 , and y2 mRNAs remained stable .Our results indicate that, in cerebellar neurons, the expression of specific GABA A /BZ receptor subunit mRNAs, polypeptides, and binding sites is independently regulated by in vivo administration of alcohol . The observed changes were not restricted to any one cerebellar cell type, because subunit expression in Purkinje, granule, and deep cerebellar cells was similarly affected .

Effects of Concurrent Access to Multiple Ethanol Concentrations and Repeated Deprivations on Alcohol Intake of Alcohol‐Preferring Rats

“…The effects of repeated cycles of alcohol drinking and deprivation to increase further the magnitude and duration of the ADE could be a result of increased alterations occurring at the molecular level or changes affecting a larger proportion of neurons. For example, chronic alcohol drinking could produce alterations in the expression of different subunits for the ␥-aminobutyric acid-A (GABA A ; Mhatre and Ticku, 1992;Wu et al, 1995) and N-methyl-Daspartate (NMDA; Follesa and Ticku, 1996;Trevisan et al, 1994) receptors, alter the activity of the mesolimbic dopamine system (Smith and Weiss, 1999), or both of these. These changes could be increased further with repeated episodes of excessive alcohol drinking.…”

Regulation of GABAA Receptor Subunit Expression by Pharmacological Agents

“…␣6 Subunit. Cerebellar ␣6 mRNA expression was up-regulated by CE in rat (Mhatre and Ticku, 1992;Morrow et al, 1992) and mouse (Wu et al, 1995) cerebellum (Table 14). Withdrawal from CE resulted in a drastic increase in ␣6 mRNA expression in the study by Mhatre and Ticku (1992), but not in that of Petrie et al (2001).…”

“…In the cerebellum, CE treatment down-regulated ␣1 mRNA expression in male Sprague-Dawley rats (Mhatre and Ticku, 1992;Morrow et al, 1992) and in female C57BL/6 mice (Wu et al, 1995). After 1-day wdr-CE, ␣1 mRNA down-regulation was still present (Mhatre and Ticku, 1992).…”

“…The up-regulation persisted for at least 7 days after wdr-CIE (Marutha Ravindran and Ticku, 2006;Ravindran and Ticku, 2006) but not wdr-CE (Marutha Ravindran and Ticku, 2006;Ravindran and Ticku, 2006;Sheela Rani and Ticku, 2006). Cerebellar ␤2 polypeptide was upregulated by CE in rats in vivo (Marutha Ravindran et al, 2007), whereas it had no effect on cerebellar ␤2 mRNA in mice (Wu et al, 1995). After 2-day wdr-CE (Marutha Ravindran et al, 2007) and 2-day wdr-CIE (Petrie et al, 2001), the expressions of cerebellar ␤2 mRNA and polypeptide, respectively, were not different from control values.…”

The regulation of neuronal gene expression by alcohol

“…Advances in our understanding of the mechanisms of neuronal excitability and synaptic transmission have shown that ethanol interacts with a variety of neurotransmitter systems, including glutamate (Lovinger et al, 1989; Valenzuela and Cardoso, 1999; Woodward, 2000; Crowder et al, 2002), dopamine (Gessa et al, 1985, Imperato and Di Chiara, 1986; Brodie et al, 1990, Budygin et al, 2001), adenosine (Dar et al, 1983; Dunwiddle, 1996), and γ-aminobutyric acid [GABA] (Wu et al, 1995; Charlton et al, 1997; Cagetti et al, 2003; Sanna et al, 2003; Follesa et al, 2004a; Follesa et al, 2004b; reviewed in: Kumar et al 2009). Actions on all of these systems may converge to produce the varied behavioral effects of acute alcohol ingestion.…”