THE SIGNIFICANCE OF THE ANTIDIURETIC HORMONE IN THE RELEASE MECHANISM OF CORTICOTROPIN

Abstract

In posterior lobectomized rats the antidiurctic response to hemorrhage, histamine injection and a painful stimulus is markedly depressed. Exposure of such animals to “systemic” stress such as hemorrhage under ether anesthesia, histamine and nicotine injection elicits an increase in plasma free corticosterone levels similar to that found in sham operated controls. The increment in plasma free corticosterone following “neurogenic” stress such as strange environment, sound and pain is significantly reduced. A distinct adrenal hypertrophy is found in posterior lobectomized rats. However, the sensitivit of these adrenals is similar to that of sham operated controls. Treatment of posterior lobectomized rats with 1 unit of Pitrcssin tannate for 5 consecutive days decreases water intake to that of intact controls, induces the accumulation of neurosecretory material in the infundibular stem, normalizes adrenal weight and simultaneously restores pituitary response to neurogenic stimuli in posterior lobectomized rats. In dehydrated intact rats, in which the posterior lobe was completely depleted of neurosecretory material the effect of strange environment and of sound on plasma free corticosterone levels is also markedly diminished, whereas the effect of hemorrhage under ether anesthesia and the injection of nicotine equals that of control rats. It is suggested that the antidiuretic hormone is involved in the corticotropic effect of neurogenic stimuli.