Heroin-induced suppression of saccharin intake in water-deprived and water-replete rats.
Rats suppress intake of a saccharin conditioned stimulus (CS) when paired with an aversive unconditioned stimulus such as lithium chloride. This phenomenon is referred to as a conditioned taste aversion (CTA). Rats also suppress intake of a saccharin CS when paired with a rewarding sucrose solution and when paired with a drug of abuse. Although the suppressive effects of drugs of abuse have long been interpreted as CTAs, evidence suggests that rats may suppress intake of the saccharin CS following taste-drug pairings because they are anticipating the rewarding rather than the aversive properties of the drug. Oddly, however, while all other drugs of abuse tested suppress intake of a gustatory CS, the highly reinforcing drug, heroin, is reportedly ineffective. The present study reexamined this issue in both water-deprived and water-replete rats using procedures that sustain both morphine- and cocaine-induced suppression of CS intake. The results showed that heroin greatly reduced CS intake following saccharin-heroin pairings and that this effect was less variable when assessed in water-replete subjects. When taken with other reports, these data suggest that rats suppress intake of a saccharin CS in anticipation of the availability of all drugs of abuse tested.
Grigson
P S
PS
Penn State College of Medicine, Department of Behavioral Science, Hershey, PA 17033, USA.
Twining
R C
RC
Carelli
R M
RM
D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004327:Drinking Behavior / Q000187:drug effects*; D004435:Eating / Q000187:drug effects; D003932:Heroin / Q000494:pharmacology*; D008297:Male; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D012439:Saccharin; D013649:Taste / Q000187:drug effects; D014868:Water Deprivation
D009294:Narcotics; D003932:Heroin; D012439:Saccharin