VASOPRESSIN CONTENT AND NEUROSECRETORY MATERIAL IN THE HYPOTHALAMO-NEUROHYPOPHYSEAL SYSTEM OF RATS UNDER DIFFERENT STATES OF WATER METABOLISM

Abstract

ABSTRACT Rats were subjected to different degrees of dehydration and overhydration and the vasopressin content of the hypothalamo-neurohypophyseal system was examined. Histological preparations of neurohypophyseal tissue were used to estimate changes in neurosecretory material. As expected, dehydration caused a depletion of the hormone in the system. It was also found that overhydration caused an accumulation of hormone in the neural lobe, but no increase in the hypothalamic nuclei. The amount of stainable material seemed to vary in parallel with the changes in hormone content. On the basis of the marked accumulation of hormone in the neural lobe during acute overhydration, an estimate of the rate of production of vasopressin was attempted. It was found to be much higher than the rate of secretion. This might indicate the existence of a considerable hormone breakdown in the neurohypophysis.