Abstract
γ-aminobutyric acid type-A receptors associate with auxiliary proteins such as Shisa7 and have allosteric binding sites for benzodiazepines, barbiturates, and alcohols. In this study, Shisa7 was knocked down to assess its involvement in the discriminative-stimulus effects of drugs from each class and in the positive reinforcing effects of alcohol. Twelve male Long-Evans rats were trained to respond in a drug-discrimination procedure with 6 trained to discriminate ethanol (1 g/kg) from saline and 6 trained to discriminate alprazolam (1.8 mg/kg) from cyclodextrin. Following training, cumulative dose-effect curves for ethanol, alprazolam, and pentobarbital were established before and after Shisa7 knockdown was achieved using an intravenous dicer substrate small-interfering ribonucleic acid. A separate group of 6 rats was also trained to consume ethanol orally to assess ethanol intake before and after Shisa7 knockdown. In general, before Shisa7 knockdown, alprazolam and pentobarbital partially substituted for ethanol in ethanol-trained subjects up to doses that decreased response rate, whereas pentobarbital, but not ethanol, partially substituted for alprazolam in alprazolam-trained subjects. After Shisa7 knockdown, the dose-effect curve for ethanol-lever responding in ethanol-trained subjects was shifted downward, the curve for alprazolam-lever responding in alprazolam-trained subjects was shifted rightward, and the curve for pentobarbital was shifted rightward in both ethanol- and alprazolam-trained subjects. Shisa7 knockdown did not affect response rates. In rats orally consuming ethanol, both ethanol intake and dose were significantly decreased after Shisa7 knockdown compared with the dicer substrate small-interfering ribonucleic acid control. These findings demonstrate that reducing Shisa7 levels attenuated the discriminative-stimulus effects of 3 positive allosteric modulators of γ-aminobutyric acid type-A receptors and decreased ethanol's reinforcing effects. SIGNIFICANCE STATEMENT: This study demonstrates that Shisa7, an auxiliary protein associated with γ-aminobutyric acid type-A receptor, plays a crucial role in mediating the discriminative-stimulus effects of ethanol, alprazolam, and pentobarbital, as well as the reinforcing effects of ethanol. By demonstrating that Shisa7 knockdown attenuates the behavioral effects of these drugs, the findings provide new insights into the molecular mechanisms underlying γ-aminobutyric acid type-A receptor-mediated drug effects and potentially identify Shisa7 as a key modulatory mechanism through which these drugs produce their effects.