lithium-chloride and sucrose-octaacetate

The diverse chemical structures of stimuli that are bitter to humans suggest a need for multiple bitter receptors. Reactions of golden hamsters (Mesocricetus auratus) to 1 mM quinine hydrochloride, 3 mM denatonium benzoate, 180 mM magnesium sulfate, 30-100 mM caffeine, and 1-1.5 mM sucrose octaacetate (SOA) were studied to address whether there are multiple sensations elicited by bitter stimuli. Methods included behavioral generalization of LiCl-induced conditioned taste aversions (CTAs), intake preference tests, and electrophysiological recordings from the chorda tympani (CT) nerve. The five compounds, all bitter to humans, were all innately aversive to hamsters. CTA for the ionic quinine.HCl, denatonium benzoate, and MgSO(4) mutually cross-generalized and these ionic compounds were effective CT stimuli. Yet, the hamsters were much less sensitive to denatonium than humans, requiring a 100,000 times higher concentration for detection. CTA for nonionic caffeine and SOA did not cross-generalize to quinine or the other two ionic stimuli and these nonionic compounds were not effective CT stimuli. SOA and caffeine may elicit aversive reflexes or systemic reactions rather than taste sensations in the animals. Thus, the three ionic and two nonionic compounds form separate aversive stimulus classes in hamsters, neither of which appears to be a close homologue of the human bitter taste.

Topics: Animals; Avoidance Learning; Caffeine; Cricetinae; Generalization, Psychological; Humans; Ions; Lithium Chloride; Male; Mesocricetus; Quaternary Ammonium Compounds; Quinine; Species Specificity; Structure-Activity Relationship; Sucrose; Taste; Taste Buds; Taste Threshold

Rats ate less food than normal on cyclic-ratio schedules following cholecystokinin and lithium chloride injections. Nevertheless, they defended this lower eating rate in the same way as under control conditions. The pattern of effects produced by cholecystokinin and lithium chloride resembled those following diet adulteration with citric acid and sucrose octa acetate and differed from the effects produced by increases in body weight. Cholecystokinin and lithium chloride injections also produced similar changes in the free-feeding patterns of non-deprived rats: Both meal size and intermeal intervals decreased in manner similar to the effects of citric acid and sucrose octa acetate adulteration. Interpreted in terms of a static regulatory model, these results suggest that cholecystokinin and lithium chloride suppress feeding by degrading the palatability of food, not by promoting satiety, discomfort, or illness.

Topics: Animals; Chlorides; Citrates; Citric Acid; Conditioning, Operant; Feeding Behavior; Female; Food Preferences; Lithium; Lithium Chloride; Male; Rats; Reaction Time; Satiation; Satiety Response; Sincalide; Sucrose; Taste