Consummatory responses to taste stimuli in rats selected for high and low rates of self-stimulation

The factors mediating self-stimulation are often considered to coincide with those initiating and maintaining avid intake of sweet-tasting substances. The availability of two populations of albino rats (LC1 and LC2), each genetically selected for high- and low-self-stimulators, provided an opportunity to test this hypothesis. Consummatory responses of these 4 lines were investigated using a 24-hr two-bottle test. Seven concentrations of sodium saccharin, as well as 8 concentrations of quinine hydrochloride, were each presented against water in a double-blind setting. Lateral hypothalamic self-stimulation rates were then determined. It was found that the population (LC2) exhibiting the largest separation of high and low self-stimulation rates, also was separated most by saccharin solution intakes: The genetically high ICSS responders consumed the most-while the genetically low ICSS responders of that population drank the least-saccharin solution across concentrations. In contrast, the effect of genetic line on quinine intake was minimal. Sex was a relevant variable with the females consuming relatively more saccharin solution and bar pressing at higher rates for self-stimulation, than males in each population. On the other hand, there was a tendency for the females of each line to be less rejecting of quinine solutions than males.