Taste qualities of solutions preferred by hamsters

Abstract

Molecules of diverse chemical structure are sweet to humans and several lines of evidence (genetic, physiological, behavioral) suggest that there may be distinct sweet perceptual qualities. To address how many perceptual categories these molecules elicit in hamsters (Mesocricetus auratus), we studied patterns of generalization of conditioned taste aversions for seven sweeteners: 100 mM sucrose, 320 mM maltose, 32 mM D-phenylalanine, 3.2 mM sodium saccharin, 16 mM calcium cyclamate, 10 mM dulcin and 32 mM sodium m-nitrobenzene sulfonate. Each stimulus was preferred versus water in two-bottle intake tests and stimulated the chorda tympani nerve. For each of seven experimental groups the conditional stimulus (CS) was a sweetener and for the control group the CS was water. Apomorphine HCl was injected i.p. after a CS was sampled and, after recovery, test stimuli (TS) were presented for 1 h daily. The intake (ml) of each TS consumed by experimental animals was compared with mean TS intake by the control group. Learned aversions for 18/21 stimulus pairs cross-generalized, resulting in a single cluster of generalization patterns for the seven stimuli. Cross-generalization failures (maltose-cyclamate, maltose-sucrose cyclamate-NaNBS) may be the consequence of particular stimulus features (e.g. salience, cation taste), rather than the absence of a 'sucrose-like' quality. The results are consistent with a single hamster perceptual quality for a diverse set of chemical structures that are sweet to humans.