Naltrexone fails to block the acquisition or expression of a flavor preference conditioned by intragastric carbohydrate infusions.
The effects of naltrexone on the expression and acquisition of flavor preferences conditioned by the postingestive actions of carbohydrates were investigated. Food-restricted rats (Experiment 1) were given one-bottle training with one flavored saccharin solution (CS+) paired with intragastric (IG) infusions of 16% sucrose, and another flavored saccharin solution (CS-) paired with water infusions. In two-bottle tests CS+ was preferred to CS-, and naltrexone (1.0-5.0 mg/kg) reduced total intake but not CS+ preference. In Experiment 2 food-restricted rats that received naltrexone (0.1 or 1.0 mg/kg; NTX group) throughout one-bottle training consumed less CS+ and CS- than did saline-treated control rats. Yet, the NTX and control groups displayed similar CS+ preferences during two-bottle tests when treated with saline or naltrexone (0.1-5.0 mg/kg). In Experiment 3, rats were trained to accept more CS+ than CS- in one-bottle tests. Naltrexone (0.1-2.5 mg/kg) reduced the one-bottle intakes of both solutions, and the rats continued to consume more CS+ than CS-. We conclude that the opioid system modulates the consumption of flavored solutions, but is not critically involved in the acquisition or expression of flavor preferences conditioned by IG carbohydrate.
Azzara
A V
AV
Experimental Doctoral Subprogram, Department of Psychology, Brooklyn Colleges, City University of New York, Brooklyn, New York, NY 11210, USA.
Bodnar
R J
RJ
Delamater
A R
AR
Sclafani
A
A
D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D004750:Enteral Nutrition; D005518:Food Preferences / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004040:Dietary Carbohydrates; D009292:Narcotic Antagonists; D009271:Naltrexone