Behavioral and Physiological Rhythms and the Development of Gastric Erosions in the Rat

Abstract

Rats immobilized at the peak as compared to the trough in the 24 hr. activity cycle are more susceptible to gastric erosions. In a series of experiments designed to delineate some of the factors which may have contributed to this phenomenon, it was found that the 24 hr. rhythm in plasma corticosterone levels is not correlated with activity and is not related to the development of erosions under 6 hr. immobilization; plasma pepsinogen levels show a 24 hr. rhythm which is synchronized with activity, but the magnitude of the daily fluctuations arenotsufficienttoaccountfor the altered erosion susceptibility; and the increased susceptibility shown by animals immobilized during a period of maximum activity obtains even when one eliminates animals protected by the presence of food in the stomach.