The dorsal striatum expressing adenylyl cyclase-5 controls behavioral sensitivity of the righting reflex to high-dose ethanol

Abstract

High-dose ethanol inflicts sedation and loss of righting reflex (LORR). Recently, it was reported that AC5 knockout (AC5−/−) mice consumed more ethanol and showed reduced sensitivity to high-dose ethanol compared to wild-type mice. As an extension of the previous study, in the present study we examined the signaling mechanism regulating altered behavioral sensitivity of LORR in AC5−/− mice. AC5−/− mice had enhanced phosphorylation of the NR2B subunit of NMDA receptors in the dorsal striatum and a partial reduction of MK801 (NMDA receptor antagonist)/ethanol-induced LORR. AC5−/− mice showed increased levels of phospho-CaMKIIα, phospho-CREB, and BDNF in the dorsal striatum. CaMKIIα+/− or BDNF+/− mice displayed enhanced LORR, a behavioral phenotype opposite to that displayed by AC5−/− mice. Consistently with these results, stereotaxic infusion of KN62 (CaMKII inhibitor), siRNA-CaMKIIα, or siRNA-BDNF, within the dorsal striatum was sufficient to prolong LORR. These results suggest that neural mechanism is important for regulating behavioral sensitivity of LORR and that the signaling pathway(s) interplayed by AC5, CaMKIIα and BDNF within the dorsal striatum is important for regulating the duration of ethanol-induced LORR.