With the use of the Horsley–Clarke stereotaxic instrument, bilateral electrolytic lesions were placed in the lateral hypothalamic areas of female Sprague–Dawley rats. Changes in food and water intake and body weight were correlated with the histological localization of the lesions. Rats with large lesions in the frontal plane of the middle of the tuber cinereum died within a week of the operation. Food and water administered by stomach tube did not prevent weight loss and death.Two rats developed adipsia which lasted 13 and 16 days respectively; 10 ml. of tap water per day by stomach tube resulted in increases in food intake and body weight during the period of adipsia. These rats had lesions in the lateral hypothalamic areas in the frontal plane of the middle of the tuber cinereum, but these were small and relatively asymmetrical.Another rat refused water from the time of operation until sacrifice (55 days). Administration of 20 ml. per day of tap water caused an increase in food intake and body weight, and a general improvement. Whenever intake of water was not imposed by stomach tube, however, the food intake dropped and body weight was lost. This animal failed to drink spontaneously. The lesions in this animal were more symmetrical, slightly more dorsal, and about 0.75 mm. more posterior than those which produced temporary adipsia. In the rat, an area essential to the regulation of voluntary consumption of water appears to be located in the lateral hypothalamic areas at about the plane of the posterior ventromedial nuclei and the anterior border of the premammillary nuclei.
