Localization of central nervous system structures mediating extracellular thirst in the female rat.
Water intake elicited by microinjection of the hormone angiotensin-II into the preoptic region of cyclic female rats was significantly less on days of vaginal oestrus than at dioestrus or metoestrus, whereas the drinking of 2.7% NaCl solution, to which rats also had access, did not vary with the cycle. Administration of the same dose of angiotensin-II to the subfornical organ and the lateral cerebral ventricles induced drinking at all stages of the oestrous cycle, but the volumes of water or 2.7% NaCl ingested did not vary with the cycle. Water intake after subcutaneous injection of isoprenaline, a beta-adrenergic agonist which causes increased angiotensin biosynthesis, varied cyclically with the stage of the oestrous cycle. On the other hand, water and 2.7% NaCl intakes induced by intraperitoneal injection of hypertonic NaCl (a cellular stimulus of thirst) or by 24-h water deprivation (which dehydrates both the extracellular and cellular body fluid compartments) did not differ significantly at the various stages of the oestrous cycle. The finding that fluctuations in angiotensin- and isoprenaline-induced water intake parallel the changes in spontaneous 24-h drinking suggests that the preoptic region may play an important role in the maintenance of extracellular fluid balance in synchrony with the oestrous cycle.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000502:physiology*; D002552:Cerebral Ventricles / Q000187:drug effects; D004326:Drinking / Q000187:drug effects; D004971:Estrus; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D011247:Pregnancy; D011301:Preoptic Area / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic; D013356:Subfornical Organ / Q000187:drug effects; D013894:Thirst / Q000502:physiology*
D012462:Saline Solution, Hypertonic; D000804:Angiotensin II; D007545:Isoproterenol