ETHANOL AND FOOD PELLET SELF-ADMINISTRATION BY BABOONS

During daily 23-h sessions, baboons had concurrent access to food pell ets and an oral ethanol/dextrose solution. The effect of increasing th e fixed-ratio or ''cost'' for pellets on pellet and fluid intake was e xamined when baboons had access to 2%, 4%, or 8% (w/v) ethanol. Increa sing the response requirement for a pellet decreased pellet intake. Th e rate of decrease in pellet intake with increasing pellet cost was un affected by the availability of ethanol solutions, which were either s elf-administered or given in investigator-planned doses. Increasing th e response cost for pellets significantly increased self-administratio n of 4% ethanol. The effect of increasing the cost for fluid on fluid and pellet intake was examined when baboons had access to vehicle, 4% or 8% (w/v) ethanol. Although the total daily number of fluid deliveri es was significantly greater when 4% ethanol was available, compared t o vehicle, increasing the cost for a fluid delivery to 32 responses an d above decreased intake of all three fluids similarly. Increasing the cost of ethanol did not affect food intake. (C) 1998 Elsevier Science Inc.