Quantitative reverse transcription-polymerase chain reaction of GABAA α1, β1 and γ2S subunits in epileptic rats following photothrombotic infarction of neocortex

Abstract Photothrombotic brain infarction can result in altered expression of cortical GABA A receptors and in epileptic seizures. We sought to determine whether infarct size and/or epileptic seizures resulted in a differential expression of cortical GABA A receptor subunit mRNA in adult rats. A reverse transcription-polymerase chain reaction (RT-PCR) was used with internal standards for GABA A receptor subunits to quantify α 1 , β 1 , and γ 2S subunit mRNA expression in cortex ipsilateral and contralateral to left cerebral infarcts in small or large infarct/nonepileptic cohorts, a large infarct/epileptic cohort, and a young adult control cohort. Unilateral hemispheric subunit mRNA was pooled for each cohort, quantified, and expressed as mean values±S.E.M. In general, the magnitude of mRNA expression (pg/1 μg total RNA) was different for the individual subunits: γ 2S (10 4 ), α 1 (10 2 ), and β 1 (10 1 ). Hemispheric subunit mRNA expression for the different cohorts was compared by ANOVA testing, which noted significant differences for the α 1 ( P 1 ( P 1 cohorts indicated that mRNA expression for the large infarct/epilepsy cohort (624.2±6.8 pg) was greater than all other cohorts ( P 1 cohorts, there was decreased mRNA expression in the large infarct/nonepileptic cohort (9.2±0.8 pg; P P t -tests compared subunit mRNA expression within individual animal cohorts (ipsilateral vs. contralateral) and indicated decreased mRNA expression ipsilaterally for the β 1 subunit in the small infarct cohort (14.2±2.6 vs. 22.9±3.0 pg; P =0.0102) and the large infarct/epilepsy cohort (10.5±2.3 vs. 18.0±3.6 pg; P =0.0462). These findings suggest that large photothrombotic infarcts of the neocortex can result in a long-lasting differential expression of GABA A receptor subunit mRNAs in ipsilateral cortex variably associated with the epileptic state.