Separation of water and ambient temperature effects on polydipsia

The separate contributions to schedule-induced polydipsia in rats of water temperature and ambient temperature were examined by varying each while the other was held constant. Water intake varied directly with water temperature between 5° and 30°C, and decreased at 35°C and 40°C relative to 30°C. Ambient temperature did not influence water intake when water temperature was held constant. These observations favor an orolingual locus for the effect of temperature on water intake, and rule out the participation of skin temperature receptors.