Nucleus accumbens AGS3 expression drives ethanol seeking through G betagamma.

Approximately 90% of alcoholics relapse within 4 years, in part because of an enhanced motivation to seek alcohol (EtOH). A novel G protein modulator (Gpsm1/AGS3) was up-regulated in the rat nucleus accumbens core (NAcore) but not in other limbic nuclei during abstinence from operant EtOH self-administration. Furthermore, NAcore AGS3 knockdown reduced EtOH seeking to pre-abstinence levels in a novel rat model of compulsive, human EtOH seeking. AGS3 can both inhibit G protein G i alpha-mediated signaling and stimulate G betagamma-mediated signaling. Accordingly, sequestration of G betagamma, but not G i alpha knockdown, significantly reduced EtOH seeking to pre-abstinence levels. Thus, AGS3 and G betagamma are hypothesized to gate the uncontrolled motivation to seek EtOH during abstinence. AGS3 up-regulation during abstinence may be a key determinant of the transition from social consumption to compulsion-like seeking during relapse.