Stimuli Rats From the Gut

Among the internal factors, as with drinking, are stimuli from the gut. The activity cycle is paralleled by one in the muscles of the stomach. Powelson used an operation in which the stomach of a rat is shifted to a position between the skin and the abdominal wall; here its movements can be both seen and automatically recorded. Gastric peristalsis reached a peak at the time of greatest locomotor activity; sometimes the peristalsis began before peristalsis movements, but more often the rat started to move around before peristalsis began.

Overt activity, at least of adult, therefore does not depend on gastric movements; moreover, the activity cycle persists even if the stomach has been surgically removed or the nerves to the stomach have been cut. Feeding, too, persists after these operations. There is, however, still the possibility that impulses from the stomach and intestines play some part in inducing feeding behavior, the findings show only that the stomach does not play a necessary part.

There is indeed, good evidence that impulses from the gut influence eating, but its end rather than its begining. Rats was allowed to feed for only two hours in each twenty four, during which the effect of various previous treatments were studied. Some received a mixture of kaolin and water, others, kaolin and glucose solution isotonic with body fluids. The mixture depressed eating to similar extent. The rats were evidently responding to increased volume of the stomach contents by ceasing to eat.

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