Lingual Taste Nerve Transection Alters Food Selection, Relative Macronutrient Intake, and Meal Patterns in Rats Consuming a Cafeteria Diet without Changing Total Energy Intake

Abstract

The control of ingestive behavior is complex and involves input from many different sources, including the gustatory system. Signals transmitted via the taste nerves trigger responses that promote or discourage ingestion. The lingual taste nerves innervate 70% of taste buds, yet their role in the control of food selection and intake remarkably remains relatively underinvestigated. Here we used our custom five-item Food Choice Monitor to compare postsurgical behavioral responses to chow and a five-choice cafeteria diet (CAF) between male rats that had sham surgery (SHAM) or histologically verified transection of the chorda tympani and glossopharyngeal nerves (2NX). Compared with SHAM rats, 2NX rats ate significantly more of the high-fat CAF foods. The altered food choices led to dramatically increased fat intake and substantially reduced carbohydrate intake by 2NX vs SHAM rats. Furthermore, whether offered chow or CAF, 2NX rats ate fewer, larger meals each day. Eating rates implied that, compared with SHAM, 2NX rats were equally motivated to consume CAF but less motivated to eat chow. Even with these differences, energy intake and weight gain trajectories remained similar between SHAM and 2NX rats. Although some rats experienced CAF before surgery, contrary to our expectations, the effects of prior CAF experience on postsurgical eating were minimal. In conclusion, although total energy intake was unaffected, our results clearly indicate that information from one or both lingual taste nerves has a critical role in food selection, regulation of macronutrient intake, and meal termination but not long-term energy balance.