Separate lateral hypothalamic pathways for extracellular and intracellular thirst.

Small lesions of the midlateral zone of the lateral hypothalamus in rats attentuated water intake elicted by the central microinjection angiotensin or by the peripheral injection of isoproterenol or renin without attenuating drinking to peripherally administered hypertonic saline. Lesions placed further lateral in the hypothalamus, which destroyed the medial aspects of the internal capsule and globus pallidus, produced a marked decrease in water intake induced by hypertonic saline. Abaltion of the ventromedial nucleus of the hypothalamus increased drinking elicited by angiotension, isoproterenol, or renin. These results suggest that extracellular and intracellular thirst stimuli are mediated by separate neural pathways at the level of the lateral hypothalamus.