Schedule-induced cocaine drinking: choice between cocaine and vehicle.
Rats were exposed to daily 3-hr schedule-induced polydipsia sessions (fixed-time 1-min food-pellet delivery) with two drinking fluids available: cocaine solution and water. Fluid position was alternated daily. Polydipsia occurred mostly from a preferred-side spout (position preference) until cocaine solution concentration was increased to between 0.52 and 1.04 mg/ml and animals drank mostly water. Within a lower concentration range (0.28-0.6 mg/ml) maximum session cocaine intakes ranged from 54.3 to 120.1 mg/kg. Postsession serum cocaine levels were about 200 ng/ml. At individually chosen cocaine solution concentrations, the addition of saccharin to the solution did not increase cocaine intake, but a compound solution (saccharin plus glucose) did. With progressive dilution of the compound vehicle, an almost complete preference for cocaine solution was maintained. But with a return to water as the vehicle, animals reverted to a position preference after a few sessions, although one maintained a clear cocaine preference. Schedule-induced polydipsia produced chronic, oral self-administration of cocaine resulting in pharmacologically significant intakes and serum levels.
Falk
J L
JL
Department of Psychology, Busch, Rutgers University, New Brunswick, NJ 08903.
vigorito
M
M
Tang
M
M
Lau
C E
CE
D000818:Animals; D002755:Choice Behavior / Q000187:drug effects*; D003042:Cocaine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004327:Drinking Behavior / Q000187:drug effects*; D004334:Drug Administration Schedule; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D003042:Cocaine