Anteroventral third ventricle site of action for angiotensin induced thirst.

The central site of action for angiotensin induced thirst was investigated in rats. Subfornical organ lesions resulted in a temporary abolition of drinking induced by lateral preoptic or lateral ventricle microinjections of angiotensin but drinking to anteroventral third ventricle microinjections of angiotensin (or carbachol) was unaffected. Drinking to elevated systemic levels of angiotensin was attenuated but not abolished by subfornical organ lesions. When spread of injected angiotensin via cerebrospinal fluid circulation was controlled by placing plugs at selected locations in the ventricles, drinking was elicited only when intracranial microinjections of angiotensin gained access to anteroventral third ventricle. It was concluded that subfornical organ is not the exclusive dipsogenic receptor for angiotensin, rather angiotensin exerts at least part of its dipsogenic effect by spread through the ventricular system to receptors in the vicinity of the anteroventral third ventricle.