Intragastric calcium infusions support flavor preference learning by calcium-deprived rats

We investigated whether rats can associate the flavor of ingested solutions with the postingestive delivery of calcium. In one series of experiments using the "electronic esophagus" preparation, calcium-deprived rats received pairs of daily one-bottle training trials in which they received intragastric infusions whenever they ingested an arbitrary flavor of Kool Aid. Rats later preferred the flavor associated with infusions of 50 mM CaCl(2) or 50 mM calcium lactate (CaLa), but not with water, 10, 100 or 250 mM CaCl(2) or 100 mM sodium lactate (NaLa). In another experiment, rats had simultaneous access to two arbitrary flavors, ingestion of one of which produced intragastric infusion of 50 mM CaCl(2), 75 mM NaCl or water. Only the rats given 50 mM CaCl(2) developed a preference for the flavor associated with the infusion. The preference for calcium infusions was not as large as that seen for orally ingested calcium. Nevertheless, these results show that 50 mM calcium infusions are rewarding to calcium-deprived rats. They thus suggest that rats can associate flavor ingestion with the postingestive benefits of consuming calcium.