Water Restriction and Fluid Temperature Alter Preference for Water and Sucrose Solutions

The role of diet temperature in ingestive behavior is poorly understood. We examined the importance of stimulus temperature and water-restriction state on the preference for and intake of water and sucrose. Using custom-designed equipment that allows us to monitor and maintain solution temperatures during testing (+/- 0.1 degrees C), we conducted a series of 2-bottle preference tests (10 degrees C water vs. sucrose 10-40 degrees C) and brief access tests (10-40 degrees C water and sucrose). Water-restricted rats preferred cold water over any sucrose concentration (0.0-1.0 M) if the sucrose was 30 or 40 degrees C, whereas the same rats preferred sucrose at all concentrations and temperatures when unrestricted suggesting that the water-restriction state interacts with temperature preference. In a series of brief-access tests using a Davis Rig (MS-180), rats reduced licking to cold sucrose compared with 20 degrees C sucrose, suggesting that unlike water, cold temperature reduced the palatability of sucrose.