Vasopressin in vascular regulation and water homeostasis in the brain.

It is well known that vasopressin participates in the regulation of the cardiovascular system, water electrolyte balance and many functions of the central nervous system. Receptors for vasopressin are widely distributed throughout the brain. They are present in neurons, in astrocytes and their perivascular processes, in endothelial and smooth muscle cells of blood vessels and in choroid plexus. Such a location suggests that vasopressin may participate in the regulation of vascular resistance in cerebral circulation and water homeostasis in the brain. Present review of the data published on this subject suggests that endogenous vasopressin is involved in brain pathology rather than in physiological regulations. Numerous studies have shown increased release of vasopressin and expression of vasopressin receptors in the brain following ischemia, trauma or subarachnoid hemorrhage in patients and in animal models of these diseases. Moreover, it has been demonstrated that antagonists of vasopressin V(1a) receptors are able to alleviate brain edema and spastic changes in blood vessels after subarachnoid hemorrhage. Vasopressin is also implicated in brain edema and in impairment of cerebral vasculature in hypo-osmotic states. The discussed results suggest that vasopressin V(1a) receptors antagonists may be a useful tool for the treatment of some states associated with cerebrovascular pathology.