Vasopressin and Neurophysin: High Concentrations in Monkey Hypophyseal Portal Blood

Abstract

Vasopressin and its binding protein, neurophysin, were measured by radioimmunoassay in the hypophyseal portal blood of monkeys after cannulation of individual long portal veins. Mean vasopressin concentrations (13,800 picograms per milliliter) in portal blood were more than 300 times as high as those in the systemic circulation (42 picograms per milliliter). Neurophysin concentration was approximately 25 times as high in portal as in systemic blood. By immunoperoxidase techniques, high concentrations of neurophysin were demonstrated around portal capillaries of the median eminence. These studies indicate direct secretion of vasopressin and neurophysin into the portal circulation; the quantities secreted during stress may be sufficient to exert significant effects on secretion of anterior pituitary hormone.

Hypertriglyceridemia in Infants and Children with Hypernatremia

“…Four patients from the study group had normal serum triglycerides (M±SD = 1.1±0.1 mmol/l). With treatment, serum sodium was normalized in all patients followed by One explanation is the enhanced hepatic triglyceride formation, as a direct action of hypernatremia; (30) or indirectly, through hormonal mediators released in response to hyperosmolar state, (31) stress (32,33) or lesions of ventromedial hypothalamus (VMH).…”

“…(34, 35) Hypertriglyceridemia has been attributed, both in human (19) and laboratory animals, (31,36,37) to the destructive lesions of (VMH). An alteration in dietary habits as well as hypothyroidism, secondary to VMH destruction, was suggested as additional contributory factors.…”

Elevation of Plasma Neurophysin in Women on Oral Contraceptives

“…The possibility that neurophysins are an integral link in the negative feedback of estrogen on anterior pituitary function might be considered. Anatomic studies have localized neurophysins in the external layer of the median eminence, which is the contact zone for neurosecretion of hypothalamic releasing factors into anterior pituitary blood (9), and recent studies have detected neurophysin in blood from the long portal veins of monkeys (15). In the median eminence, neurophysin is present in tanycytes (9), specialized ependymal cells of the infundibular recess with processes that reach from the third ventricle to the anterior portal blood system (16).…”

Different effects of metoclopramide and domperidone on arginine‐ vasopressin secretion in man.

“…The dopaminergic system seems to be involved at various levels in the control of AVP secretion. Central dopaminergic neurons terminate in the supraoptic nucleus, in the median eminence and in the neuropituitary (Fuxe & Hokfelt, 1969;Cuello & Iversen 1973;Parry & Livett, 1973;Zimmerman et al, 1973;Passo et al, 1981). The majority of these systems, constituted by cell bodies and proximal parts of axons, lie inside the BBB, while nerve terminals are located in the median eminence and neuropituitary and thus lie outside the BBB (Loizou, 1970;Davson, 1972;Rapaport, 1976).…”