Cold-induced stress in rats as a function of age.

Abstract

Three experiments were designed to measure the intensity of stress evoked in rats of different ages by immersion in cold water. Experiment 1 showed that survival time of rats immersed in 45[degree] F. water was longest for neonates, shortest for weanlings, and intermediate for adults. Experiment 2 measured colonic temperature and colonic temperature recovery time, and Experiment 3 measured behavioral recovery time in weanling and adult rats following removal from the stressor; initial colonic temperatures were lower and behavioral recovery times slower in weanling rats, whereas colonic temperature recovery times did not vary with age. Procedures for equating the severity of stress in rats of different ages were suggested.