Comparison between some digestive processes after eating and gastric loading in rats.

Physiological and biochemical differences were found between normal and intragastric feeding in the rat. Milk ingested orally remained in the stomach significantly longer than milk ingested via a chronic intragastric fistula. Milk samples were removed from the stomach at intervals of 5, 20 and 45 min after ingestion and it was found that milk which had been ingested via intragastric fistula underwent substantially less lipolysis than did milk which had been ingested orally. These results are discussed in relation to the aversive and rewarding effects obtained by injections of edible nutrients into the stomachs of rats.