VOLUNTARY ACTIVITY OF THE RAT AFTER DESTRUCTION OF THE ADRENAL MEDULLA

Abstract

The voluntary activity of rats in revolving drums is invariably reduced to a low level by complete bilateral adrenalcctomy. Since loss of the adrenal cortex is followed by a state'' of profound muscular asthenia and by eventual death of the untreated animal, the accompanying loss of activity is not surprising or particularly relevant in determining the physiologic conditions of this trait of behavior. It has been demonstrated by Ingle, Halcs, and Haslerud that the capacity for muscular work is not diminished by loss of adrenal medullary tissue, but the effect of medullary deficiency on activity has not been studied. The autogenous transplant of the whole adrenal gland affords a convenient means of studying the problem since the cortical portion alone survives in the new locus. Normal levels of activity were established for 34 [female] rats by the revolving drum technic. On the basis of the preliminary records the animals were divided into 2 groups. Both adrenal glands for each of the exp. animals were excised and transplanted to the surface of the corresponding ovary. The control group of animals was not operated on. After a temporary depression in activity, the exptl. animals whose glands had been transplanted returned to their preoperative level, and 28 days after operation equalled the activity of their respective controls. Histologic examination of the adrenal glands and physiologic tests for the presence of eplnephrine demonstrated that the medulla of the transplanted glands had degenerated to a state in which it did not function whereas the cortical portion had survived.