Responses to basic taste qualities in rats selectively bred for high versus low saccharin intake.

Rats selectively bred for relatively high (HiS) and relatively low (LoS) saccharin intake were offered sweet (sucrose), bitter (quinine, sucrose octaacetate), salty (sodium chloride), starchy (Polycose((R))), and sour (citric acid) solutions at several concentrations; sucrose/quinine, and sucrose/citric acid mixtures were also tested. Compared to HiS rats, LoS rats displayed weaker preferences for and lower consumption of sweet, salty, and starchy solutions. HiS and LoS rats did not differ in responses to simple bitter or sour solutions or to adulteration of sucrose with citric acid. However, quinine adulteration reduced sucrose preference more among LoS rats. Thus, selection on a saccharin intake phenotype has yielded line differences on all hedonically positive tastants and, probably as a consequence of that difference, greater finickiness specifically towards bittersweet solutions in the low saccharin-consuming line. Additional work can clarify the psychobiological mechanisms for the phenotypic difference and, potentially, the reasons for its relationship to measures of emotionality.