A Farther Study of Polydipsia Evoked by Hypo‐thalamic Stimulation in the Gloat

Abstract

Summary. 1. Microinjections of 0.003 to 0.01 ml of 2 to 3 % sodium chloride solution into a fairly limited part of the hypothalamus of the goat produced drinking of from 2 to 8 liters of water on one or more occasions in 8 experiments in 16 goats. 2. Drinking commenced 30 to 60 seconds after the injection and continued for 2 to 5 minutes. 3. The polydipsic effect of the injections was not always re‐peatable. 4. Electrical stimulation of the hypothalamus in 7 experiments produced drinking from 5 different points of stimulation. 5. In contrast to the injection experiments, polydipsia could be produced at will by electrical stimulation of a discrete region of the hypothalamus lying between Columna fornicis descendens and Tractus Vicq d'Azyr. 6. Drinking caused by electrical stimulation commenced 10 to 30 seconds from the onset of stimulation and stopped 2 to 3 seconds after the current was discontinued. 7. Tremendous overhydration could be induced in this way followed by marked hemodilution and polyuria. 8. When tested in one experiment, the stimulation at the same point, where polydipsia was evoked, produced a marked antidiure‐sis of neurohypophyseal type.