Angiotensin/aldosterone synergy governs the salt appetite of the pigeon

Sodium-replete pigeons drink excess 3% NaCl following concurrent treatment with both i.m. deoxycorticosterone acetate and pulse i.c.v. (p.i.c.v.) angiotensin II. This is not just a consequence of the water intake induced by p.i.c.v. angiotensin II, since the tachykinin eledoisin, given at equidipsogenic dose, does not evoke intake of salt. On the other hand, salt intake is not aroused in the sodium replete pigeon by continuous i.c.v. (c.i.c.v.) infusion of hyperosmotic mannitol (0.7 M) and c.i.c.v. infusions of hyperosmotic NaCl (0.3 M) or mannitol have no effect on the salt intake of the sodium deplete pigeon, or have effects that are unrelated to brain sodium. The salt appetite of the pigeon, like that of the rat, is evoked by an angiotensin and aldosterone synergy, and the angiotensin/aldosterone mechanism may be the general vertebrate theme of this behavior.