The role of taste in dietary self-selection in rats

In order to study the role of taste in dietary self-selection, rats were subjected to two degrees of gustatory deafferentation. The chorda tympani was sectioned alone or in combination with the glossopharyngeal nerve and the pharyngeal branch of the vagus. The animals chose from two diets, only one of which contained protein. After surgery, deficits were observed in body weight, food and water intake, and diet selection, proportional to the extent of deafferentation. Some 76% of the animals increased protein and decreased carbohydrate intake, but all rats continued to select a nutritionally balanced diet (Experiment 1). When subjected to a nutritional challenge of intragastric protein or carbohydrate supplementation, the rats compensated for calories and nutrients by selectively adjusting oral intake (Experiment 2). In saccharin preference tests, the preference as well as the total consumption of the test solutions was reduced (Experiment 3). The findings are contrasted to the effects of oral somatosensory deafferentation and are interpreted as a change in preference within the limits of metabolic requirements. The different roles/mechanisms of the two sensory systems in regard to dietary self-selection are discussed.