Behaviorally conditioned anorexia: role of gastric emptying and prostaglandins.

The reduction of food intake in response to bacteria is posited to be a favourable host reaction. This report attempted to examine whether gastric emptying is involved in the known conditionability of this response. Additionally, this study investigated the role of prostaglandins in the conditioned anorexic response. To investigate this phenomenon, lipopolysaccharide (LPS) (100 micrograms/kg) was used as the unconditioned stimulus, and paired with a novel 1% saccharin solution (conditioned stimulus). Upon conditioned stimulus (CS) representation, experimental animals displayed a marked reduction in food consumption (experiment 1) and emptying of gastric contents (experiment 2). Additionally, treatment with indomethacin upon CS reexposition blocked both the conditioned anorexia and suppression of gastric emptying. These results indicate that conditioned anorexia is possibly the result of a conditioned inhibition of gastric emptying, and this process is mediated by conditioned alterations in PG levels.