Changes in Neurosecretory Material, Water Intake, and Urine Output in X-Irradiated Rats

Abstract

Neuroendocrine mechanisms are known to be involved in the regulation of water intake and urine output (1). It is generally held that the hypothalamo-hypophyseal system is the seat of such a regulatory mechanism. Scharrer showed that the supraoptic nucleus of the hypothalamus possesses secretory activity (2). The secretions from the neurons of the supraoptic nucleus migrate along the neural tracts into the neurohypophysis. Bargmann was able to stain this selectively by the Gomori chrome hematoxylin method and showed that it appeared as a granular material (3). Aldehyde fuchsin has also been shown to be selective for this secretion (4). The decrease in staining intensity of this granular material under conditions of water deprivation (5) and its depletion in diabetes insipidus (6) suggest that it is the antidiuretic hormone (ADH) or its associated carrier. Several investigators (7-10) have measured water intake and urine output in rodents after exposure of the whole body to X-irradiation. Their results have shown that increased water intake and polyuria often occur and preferentially on the first or second and fifth or sixth days after irradiation (7-10). However, polydipsia and polyuria do not occur in some animals (10). The reason for the absence of these phenomena in some irradiated animals is not known. Hypophysectomy or adrenalectomy prior to irradiation abolished the postirradiation polydipsia (10) and polyuria (8) often seen in some animals after irradiation. Williams et al. (11) abolished postirradiation polyuria and polydipsia by injections of oily pitressin tannate. Significant decreases in the serum content of antidiuretic substances after irradiation have been reported (12). In a study of posterior pituitary