ANGIOTENSIN AS NEUROMODULATOR NEUROTRANSMITTER IN CENTRAL CONTROL OF BODY-FLUID AND ELECTROLYTE HOMEOSTASIS

Stimulation of central angiotensin receptors promotes, among others, d rinking behaviour, stimulation of natriuresis and increased release of vasopressin. Angiotensin (ANG II)-containing pathways in the lamina t erminalis and the hypothalamic paraventricular (PVN) and supraoptic (S ON) nuclei, brain areas involved in the regulation of body fluid homeo stasis, have been described. All these areas express predominantly AT1 receptors. The drinking response and the vasopressin release to centr ally administered ANG II are mediated by AT1 receptors, while AT2 rece ptors exert inhibitory effects. Evidence for the involvement of the ca techolaminergic and angiotensinergic pathways in the PVN and SON in me diating the ANG II-induced release of vasopressin is presented. ANG II is released in the PVN upon local osmotic stimulation and water depri vation. Finally, we present evidence that activation angiotensinergic receptors, water deprivation, or hypertonicity transcription of immedi ate-early genes and expression of the respective proteins in the lamin a terminalis and in the PVN and SON. The summarized data implicate ANG II as a neuromodulator/neurotransmitter in central control of body fl uid and electrolyte homeostasis.