Behavioral neuroscience
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Behavioral neuroscience · Jun 1983
Self-administered intravenous infusion of hypertonic solutions and sodium appetite of sheep.
The effects of self-administered iv infusion of hypertonic NaCl, mannitol, glucose, urea, or isotonic NaCl on Na appetite were studied. Sodium-depleted sheep were trained to bar press in order to replace Na deficits of 300-500 mmol. During basal conditions, each delivery to a drinking cup was 15 ml of .6 M NaHCO3 (9 mmol). ⋯ Isotonic NaCl had no effect on the ingestion of NaHCO3 solution, plasma, or CSF composition. In regard to the "turn-off" of Na appetite by systemic infusion, these data are consistent with the theory of neural cells within the blood-brain barrier responsive to changes of Na concentration or osmolality in their environment. In contrast, water intake was stimulated by hypertonic NaCl or mannitol but not by urea or glucose, results suggestive that the sensors involved in thirst (e.g., osmoreceptors) are in an area of the brain lacking the blood-brain barrier.