Quantitation of Changes in the Content of Neurohypophyseal Peptides in Hypothalamic Nuclei after Adrenalectomy

Abstract

In adrenal insufficiency there is an increase in the content of vasopressin in the external zone of the median eminence as determined by immunohistology. We studied rats after bilateral adrenalectomy and obtained punched samples of the supraoptic, the paraventricular, and the suprachiasmatic nuclei, and from the median eminence and the posterior pituitary. Vasopressin, neurophysin and oxytocin were all decreased in content in the posterior pituitary but in the suprachiasmatic nucleus and in the median eminence there was a significant increase in the content of vasopressin. The increased levels of vasopressin in the median eminence are interpreted as representative of the content in axons and demonstrate a large increase of transport of vasopressin. In the SON and PVN there was no increase in the content of vasopressin during this state of augmented synthesis and transport, indicating that vasopressin moves rapidly from the site of synthesis into the transport system. The increased content of vasopressin in the suprachiasmatic nucleus shows that vasopressin at this level also varies with changes in adrenal function. Levels of oxytocin throughout the neurohypophysis did not change in parallel with vasopressin demonstrating relatively selective responses of the neurohypophyseal hormones.