Adaptation of the adrenal medulla: sustained increase in choline acetyltransferase by psychosocial stimulation.

Sustained increases were produced in adrenal choline acetyltransferase of individually caged mice by placing them into groups for 10 or 15 minutes daily for 7 to 10 days. They were left undisturbed in their individual cages for the remainder of each day. As in previous experiments of similar design, adrenal catecholamines and adrenal weight were also increased, although body weight was not affected.