Ethanol, but not the anxiolytic drugs buspirone and diazepam, produces a conditioned place preference in rats exposed to conditioned fear stress

The present study was designed to investigate the role of an anxiolytic eff ect in the development of a drug-associated place preference in rats expose d to conditioned fear stress, using the conditioned place-preference paradi gm. The administration of a low dose of ethanol (300 mg/kg, IP) and the anx iolytic drugs, buspirone (1 and 2 mg/kg, IP) and diazepam (1.25 and 2.5 mg/ kg, IP), did not produce a place preference in rats that were not exposed t o conditioned fear stress. In rats that were exposed to conditioned fear st ress, ethanol produced a significant place preference, while buspirone and diazepam failed to produce a place preference. In addition, ethanol, buspir one, and diazepam produced no place preference in rats treated with an anxi ogenic dose of pentylenetetrazole (20 mg/kg, IP). A significant decrease in locomotor activity was observed in rats exposed to conditioned fear stress . Ethanol, but not buspirone and diazepam, significantly recovered or incre ased locomotor activity in rats exposed to conditioned fear stress. Further , the locomotor-stimulating effect of ethanol was markedly enhanced by repe ated exposure to conditioned fear stress. These results suggest that the st imulating effect may be strongly related to the development of the rewardin g effect of a low dose of ethanol under psychological stress, and that the conditioned place preference paradigm with conditioned fear stress may be u seful for studying the rewarding mechanism of ethanol with regard to the in teraction between ethanol and psychological stress. (C) 2000 Elsevier Scien ce Inc.