The effects of diazepam and zolpidem on cocaine- and amphetamine-induced place preference

Drugs such as benzodiazepines which enhance the effects of inhibitory neuro transmitter gamma-amino butyric acid (GABA), are known to modulate the meso corticolimbic dopaminergic system, which is considered to mediate the rewar ding effects of psychostimulants. The effects of diazepam, a benzodiazepine that binds unspecifically to omega 1- (omega 1-) and omega 2-receptors, an d zolpidem, a nonbenzodiazepine drug that binds preferentially to omega 1-r eceptors, on cocaine- and amphetamine-induced place preference were evaluat ed in Wistar rats. In tests using the counterbalanced method, neither diaze pam (0.2, 1, and 5 mg/kg) nor zolpidem (2.5, 5, and 10 mg/kg) alone induced place preference or place aversion. Diazepam pretreatment prevented both c ocaine- and amphetamine-induced (15 and 9 mg/kg, respectively) place prefer ence; however, at doses that were earlier shown to cause sedation and amnes ia, zolpidem failed to prevent either cocaine- or amphetamine-induced place preference. These results suggest that diazepam interferes with the reward ing properties of the psychostimulants, whereas zolpidem is less effective in this respect, possibly due to differential distribution of omega 1- and omega 2-receptors in the brain. (C) 1998 Elsevier Science Inc.