Male hooded rats were trained to discriminate the taste of a sucrose solution from that of water by responding with a lever on one side of a food cup after 20 licks (500 microliter) a 0. M sucrose solution and responding with a lever on the alternating side after 20 licks of water for food reinforcement. All of the rats learned this discrimination reliably. The gustatory stimulus produced by sucrose was concentration dependent (EC50 = 1.3 X 10(-2) M). Saccharin (0.0002-0.002 M), dextrose (0.05-0.25 M), and glycine (0.002-0.2 M) produced a concentration-dependent generalization to the sucrose taste. The EC50 values were 1 X 10(-3), 2.7 X 10(-2), and 1.3 X 10(-1) M, respectively. Solutions of sodium chloride (0.15 M), citric acid (0.01 M), caffeine citrate (0.01 M), quinine hydrochloride (0.001 M), or l-amphetamine sulfate (0.05 M) did not produce sucrose-like taste. Generalization of sweet compounds and lack of generalization of other tastes to the sucrose taste suggest that the procedure of sucrose-water discrimination by the rat has potential in the detection and quantitation of the sweetening properties of new chemicals.
J. C. González HernándezAlfred Julius AyerMartínez Roca