Baclofen alters ethanol-stimulated activity but not conditioned place preference or taste aversion in mice

The present experiments examined the effects of the GABA, receptor agonist, baclofen, on the acquisition of ethanol-induced conditioned place preferen ce (CPP) and conditioned taste aversion (CTA) in male DBA/2J mice. Mice in the CPP experiment received four pairings of ethanol (2 g/kg) with a distin ctive floor stimulus for a 5-min conditioning session (CS+ sessions). On in tervening days (CS- sessions), mice received saline injections paired with a different floor type. On CS+ days, mice also received one of four doses o f baclofen (0.0, 2.5, 5.0, or 7.5 mg/kg) 15 min before an injection of etha nol. For the preference test, all mice received saline injections, and were placed on a half-grid and half-hole floor for a 60-min session. Baclofen d ose dependently reduced ethanol-stimulated activity, but did not alter the magnitude of ethanol-induced CPP at any dose. For the CTA experiment, mice were adapted to a 2-h per day water restriction regimen followed by five co nditioning trials every 48 h. During conditioning trials, subjects received an injection of saline or baclofen (2.0 and 6.0 mg/kg) 15 min before injec tion of 2 g/kg ethanol or saline following 1-h access to a saccharin soluti on. Baclofen did not alter the magnitude of ethanol-induced CTA at any dose . In addition, baclofen alone did not produce a CTA. Overall, these studies show that activation of GABA(B) receptors with baclofen reduces ethanol-in duced locomotor activation, but does not alter ethanol's rewarding or avers ive effects in the CPP and CTA paradigms in DBA/2J mice. (C) 1999 Elsevier Science Inc.