The Rat's Preference for Sucrose, Polycose and their Mixtures

Abstract

In one-bottle tests (30 min/day) food-deprived rats consumed significantly more 2% Polycose than 2% sucrose, and yet in two-bottle choice tests they did not consistently prefer Polycose to sucrose. A previously proposed explanation for this effect is that rats habituate, or develop oral satiety, to the flavor of sucrose more rapidly than to Polycose, and sucrose satiety generalizes to Polycose. This idea was not supported by the results of sequential 15-min one-bottle tests: the intake of 2% sucrose did not suppress subsequent Polycose intake. Instead, the failure of rats to consistently prefer Polycose to sucrose was attributed to the development of a drinking pattern that allowed the rats to mix the two solutions in their mouths. When the drinking spouts were nearby, the rats consumed similar amounts of sucrose and Polycose, but when the spouts were far apart, they consumed more Polycose than sucrose. That rats prefer the combined flavor of sucrose and Polycose to either flavor alone was confirmed in subsequent tests. Rats strongly preferred a 1% sucrose + 1% Polycose mixture to a plain 2% sucrose or 2% Polycose solution. They also preferred sucrose-Polycose mixtures to plain solutions at concentrations ranging up to 32%. The potency of the sucrose-Polycose mixture is presumably related to the activation of separate "sweet" and "polysaccharide" taste channels in the rat.