Effects of acute and chronic administration of delta 9-tetrahy-drocannabinol or cocaine on ethanol intake in a rat model.
The acute and chronic administration of delta 9-tetrahydrocannabinol (delta 9-THC) or cocaine were studied in rats trained to obtain all of their daily food by lever pressing during four equally-spaced 30-min periods with water and 5% or 7.5% ethanol solutions freely available. With 5% ethanol available, rats consumed almost all of their daily fluid intake as ethanol, while with 7.5% ethanol available, rats consumed water and ethanol solution in approximately equal amounts. Rats consumed more food pellets with 7.5% ethanol available than with 5% ethanol available. Acute administration of delta 9-THC produced a dose-dependent decrease of 5% ethanol intake and food pellets consumed with a small increase in water intake, especially after the higher doses. Acute administration of delta 9-THC also depressed food intake when 7.5% ethanol was available, but decreases in ethanol solution intake were small. Chronic administration of delta 9-THC initially decreased ethanol intake, but tolerance occurred to this effect, so that during chronic delta 9-THC administration ethanol intake not only recovered, but increased above control levels. When the chronic administration of delta 9-THC was discontinued, ethanol intake was increased for 1 (5% ethanol) to 3 (7.5% ethanol) weeks. Animals with initially high, or initially low, but not with initially moderate ethanol intake, accounted for the increased ethanol intake during chronic delta 9-THC administration and withdrawal. Acute cocaine administration, at doses up to 30 mg/kg, had little effect on eating and drinking; however, during chronic cocaine administration, ethanol intake gradually increased, an increase which was sustained during cocaine withdrawal. The increased ethanol drinking was confined to the first 6-h period after cocaine administration. These data suggest that the chronic administration and withdrawal of other drugs can increase ethanol intake in this rat model.
McMillan
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Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock 72295.
Snodgrass
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D000428:Alcohol Drinking / Q000523:psychology*; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects; D003042:Cocaine / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D013759:Dronabinol / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D051381:Rats; D013375:Substance Withdrawal Syndrome / Q000523:psychology
D013759:Dronabinol; D003042:Cocaine