FLUID INTAKE AND BEHAVIORAL-CHANGES IN RATS ASSOCIATED WITH THE DISTENSION OF THE SMALL AND LARGE-INTESTINE

Effects of volumetric distension of the small and the large intestine on rats' behavior were compared. Rats were stimulated by a rubber ball oon inserted into chronic isolated intestinal loops prepared from the lower duodenum-upper jejunum and from the upper colon In the same anim al. Thresholds of 3 reaction classes (weak, strong, and painful) were not different from each other in the 2 loops. Distension decreased flu id intake in an intensity-dependent way, with weak and painful stimuli being less effective in the large intestine and strong stimuli less e ffective in the small bowel. Behavioral indexes supported intake data, satiety indexes were similar to each other and changed in time, where as aversivity indexes differed in the 2 loops and as a function of int ensity but not time. The author suggests that mild discomfort is a phy siological satiety factor whereas strong and painful stimuli signal da nger and induce aversivity.