Ethanol state dependence involving a lever press response requirement in rats

Previous studies have found that the timely completion of an FR10 schedule of food-rewarded lever pressing in rats demonstrates state dependence in dr ug-to-saline state changes with benzodiazepines and NMDA antagonists, but n ot with ethanol. We report here that, using sweetened condensed milk rather than food pellets as a reward, ethanol nonetheless produces a symmetrical state dependence with the lever press response requirement at doses that al so impair acquisition. Extensive parametric studies are needed to unravel t he apparently subtle conditions that govern the occurrence and features of the state dependence produced by various CNS compounds. (C) 1999 Lippincott Williams & Wilkins.