Effects of ovariectomy and administration of gonadotropin on the serum antidiuretic activity in the female rat.

Recently many studies have been reported on the antidiuretic substances (ADS) in serum. Birnie and his coworkers (1949) demonstrated ADS in rat serum and concluded that ADS was probably formed in the neurohypophysis. On the other hand, there is a general agreement that ADH is produced in the hypothalamus, transferred to the neurohypophysis and accumulated therein. As to the mechanism of the release of ADH into the blood stream, however, there are yet many diverse opinions. The release of ADH may be related to the activity of the pituicyte, the action of the osmoreceptor, or the autonomic nervous system. In the previous paper (1960) the present author showed that the amount of the neurosecrete in the neurohypophysis of female rats was remarkably increased by either ovariectomy or the administration of pregnant mare serum gonadotropin. Also the average volume of the pituicyte nucleus was found to increase by 10% of the control value after ovariectomy and to decrease by 59% after gonadotropin administration. The true function of the pituicyte being still a matter of speculation,it was suggested by Rennel and Dragar (1955) and Leveque and Small (1959) that the pituicyte might have an important function to release the posterior lobe hormone from the neurohypophysis into the blood stream. This paper deals with effects of ovariectomy and administration of pregnant mare serum gonadotropin on serum antidiuretic activity in female rats for the purpose of delineating the relationship among the neurosecrete, pituicyte in the hypophysis and ADS in the serum.