Sexual Dimorphism in the Cardiovascular Actions of Vasopressin

Abstract

Vasopressin is synthesized in the magnocellular neurosecretory neurons of the hypothalamic paraventricular and supraoptic nuclei. The hormone is transported along the axons of these neurons to the posterior pituitary gland, where it is stored until it is released into the circulation in response to an appropriate stimulus. The primary physiological stimuli for this release are an increase in plasma osmolality, sensed by osmoreceptors in the brain, and reductions in arterial blood pressure or blood volume, sensed by the arterial baroreceptors and cardiac receptors. Afferents from these cardiovascular receptors ascend to centers in the medulla involved in cardiovascular regulation. Pathways from these centers project to the paraventricular and supraoptic nuclei. The neural control of vasopressin release has been reviewed recently (e.g., Bisset and Chowdrey 1988; Renaud and Bourque 1991). Estrogen and androgen receptors are found in centers in the brain involved in the control of vasopressin secretion and in cardiovascular regulation (Stumpf and Sar 1977; Heritage et al. 1980), suggesting that the gonadal steroid hormones can act centrally to modulate these functions.