Release of atrial natriuretic factor from intact and hypophysectomized rat hypothalamic expiants

Alterations in brain levels of atrial and C-type natriuretic peptides after chronic moderate ethanol consumption in spontaneously hypertensive rats

Atrial (ANP) and C-type (CNP) natriuretic peptides have been found in brain regions associated with fluid homeostasis and blood pressure. Since chronic moderate ethanol consumption has been shown to prevent the age-dependent increase in blood pressure in experimental animals, the objective of the present studies was to investigate the effect of ethanol (20% (v/v) for 8 months) on the total content and concentration of ANP and CNP in the brain of spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Ethanol increased the content and concentration of both ANP and CNP in the hypothalamus, pons and medulla of SHR rats. In contrast, in the WKY rats ethanol had no effect on the levels of ANP in any of the brain regions studies, but enhanced the concentration of CNP in the hypothalamus and medulla. Thus, ethanol induced changes in the content of natriuretic peptides in distinct brain regions associated with control of cardiovascular activity. Such changes may be partially responsible for the effect of chronic moderate ethanol consumption on blood pressure.

Binding sites for atrial natriuretic peptide (ANP) on cultured pituicytes: lack of effect of ANP on release of neurohypophysial hormones in vitro

Receptors for atrial natriuretic peptide (ANP) are known to be present in the posterior pituitary gland and this is a possible site of action of ANP to modulate neurohypophysial hormone release. Pituicytes cultured from adult rat neurohypophyses are shown to possess high affinity binding sites for ANP, suggesting that in vivo a population of neurohypophysial ANP receptors are present on these astrocytic glial cells. alpha-rANP (1-100 nM) did not modulate the basal or electrically stimulated release of oxytocin or vasopressin from the isolated neurohypophysis in vitro. The physiological significance of the glial ANP binding sites thus remains unknown.