Sex differences in salt preference and taste reactivity in rats.

Previous studies have shown that female rats consume significantly more sodium chloride (NaCl) than do age-matched males. The gustatory contribution to this sex difference was examined in the following experiments. In Experiment 1, female rats demonstrated a higher two-bottle preference for NaCl ranging from 0.03 M to 1.0 M than did age-matched males. Next, to determine if the animal's sex modified gustatory sensitivity for NaCl, taste reactivity responses elicited by intraoral infusions (0.8 ml) of NaCl (0.03 M, 0.15 M, 0.3 M, and 1.0 M) were measured in age-matched male and female Sprague-Dawley rats. Intraoral infusions of NaCl were administered in ascending concentration order on successive days. During the intraoral infusion, the animal's oral motor taste reactivity responses were videotaped and subsequently analyzed to determine the number of ingestive and aversive responses. Intraoral infusions of 0.15 M and 0.3 M NaCl elicited reliably more ingestive responses and 1.0 M NaCl more aversive responses in females than in males. Because differences in taste reactivity were not found for all those concentrations for which female rats showed a higher preference than did males, changes in gustatory sensitivity contributes to, but does not appear to fully account for the female rats' preference for NaCl.