Temperature effects on thirst: Cutaneous or oral receptors?

Abstract

Water intake of rats was not greatly different as a function of the ambient temperature in which the water was consumed provided that the temperature of the water was maintained at 25°C. If water temperature was allowed to follow ambient temperature, then less water was consumed in cool environments. Thirst is modulated by receptors in or around the mouth and not in the skin.It is well-known that water intake varies directly with ambient temperature (Budgell, 1970;Hamilton, 1963), presumably as a consequence of afferent information from temperature receptors in the skin (Fitzsimons, 1972). There is now considerable evidence to show that water intake also varies directly with water temperature (Gold, Kapatos, Prowse, Quackenbush, & Oxford, 1973; Gold & Prowse, 1974; Kapatos & Gold, 1972). Unless independently controlled, the temperature of drinking water tends to follow variations in ambient temperature. Could the effect on water intake attributed to ambient temperature be due to the temperature of drinking water? If so, the appropriate receptor system mediating the modulation of water intake would be located in or around the mouth and not in the skin. This notion was tested in three experiments in which water temperature was controlled independently of ambient temperature. METHOD Animals and ApparatusSix adult female rats of the Sprague-Dawley strain with body weights of 211-263 g were kept in a colony room maintained at 23± 2°C and given access to water for 20 min each day in a Model 1316 Lehigh Valley test apparatus located in a 3 x 2.5 x 2.5 m temperature-controlled room . Purina Chow pellets were available ad lib except during each daily drinking test. Water temperature was controlled by circulating water from a constanttemperature bath to copper tubing wrapped around the metal spout of a drinking tube, the aperture of which was 4 mm outside a 1.8 x 3.2 em slot in the wall of the animal enclosure. The maximal variation in the temperature of drinking water during a test, as measured by a thermistor inside the drinking tube near the tip, was ± 1°C. Water intake was determined by reading the level of a calibrated buret to the nearest 0.1 mI. Pre-and posttest rectal temperature was measured with a Yellow Springs Instrument Co. Model 46 Telethermometer and small-animal probe inserted 6 ern. Two weeks of daily tests were given with neutral (25°C) water and ambient temperatures to assure stable intakes before the first experiment commenced. ProcedureIn the first experiment, the animals were given daily access to water of 25°C for 20 min at ambient temperatures which varied between 5°and 40°C in 5°C steps. One temperature was in effect each day. An ascending series of temperatures was given first, followed by a descending series so that each subject received two tests at each temperature. The second experiment provided water that was either controlled at 25°C or free to vary with ambient temperatures of 5°, 15°, 25°, or 35°C. Random presentations of the various combinations of ambient and water temperature were gi...

Influence of Beverage Temperature on Palatability and Fluid Ingestion During Endurance Exercise: A Systematic Review

“…Early rodent-based research showed that saliva production was increased in rats with cold (0 °C) versus warm (22 and 37 °C) beverage ingestion (Pangborn, Chrisp, & Bertolero, 1970). Furthermore, fluid consumption in rats was not different when ambient (skin) temperature was cold (5 °C) or warm (40 °C), but when both mouth and skin temperature were altered together, cold-fluid consumption was reduced (Carlisle, 1977). These findings were interpreted as evidence for an orolingualreceptor mechanism that influences fluid consumption by feedback from temperature-sensitive receptors in the mouth rather than skin.…”

The role of fluid temperature and form on endurance performance in the heat

“…The association between drink temperature and drinking behavior has been reported extensively. Water temperature appears to have an immediate satiating effect on thirst, which suggests the involvement of an orolingual receptor mechanism (Carlisle, ). Taken together with previous studies (Pangborn et al., ; Boulze et al., ; Brunstrom & Macrae, ), Brunstrom () suggested that the ingestion of cold water is (a) likely to be labeled as “thirst‐quenching;” (b) likely to be chosen and ingested in greater quantities when individuals are thirsty; and (c) is most sensitive to hedonic shifts caused by mouth dryness.…”