Demand for food and cocaine in Fischer and Lewis rats.

Fischer and Lewis rat strains often serve as animal vulnerability models for drug abuse and addiction. When these strains respond for drugs of abuse, several measures, including total drug intake, response rate and progressive-ratio breakpoints, have been reported to be strain-dependent, a result suggesting genetic differences in drug reactivity and vulnerability. The present study extends these strain comparisons to a previously untested measure--demand analysis.

Schedule-induced polydipsia alters cocaine- but not ethanol-induced suppression of saccharin consumption.

Under traditional water-deprived conditions, both LiCl and morphine produce comparable suppression of saccharin consumption after repeated pairings. However, under conditions of spaced food deliveries (i.e.