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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Integr. Neurosci. | doi: 10.3389/fnint.2019.00035

Taste Responses in the Nucleus of the Solitary Tract of Awake Obese Rats are Blunted Compared with those in Lean Rats

 Patricia M. Di Lorenzo1*, Michael S. Weiss1, Andras Hajnal2 and Krzysztof Czaja3
  • 1Binghamton University, United States
  • 2College of Medicine, Pennsylvania State University, United States
  • 3University of Georgia, United States

Taste perception changes with obesity but the underlying neural changes remain poorly understood. To address this issue, we recorded taste responses from single cells in the nucleus tractus solitarius (NTS, the first synapse in the central gustatory circuit) in awake, diet-induced obese [(DIO; ≥ 8wks on a high-energy diet (45%fat, 17% sugar; HED)] and lean rats. Rats were implanted with a bundle of microelectrodes in the NTS and allowed to recover. Water-deprived rats were allowed to freely lick various tastants in an experimental chamber. Taste stimuli included an array of sapid stimuli dissolved in artificial saliva (AS). Each taste trial consisted of five consecutive licks followed by five AS licks presented on a VR5 schedule. Results showed that taste responses in NTS cells in DIO rats (n=49) were smaller in magnitude, shorter in duration and longer in latency that those in lean rats (n=74). However, there were proportionately more taste-responsive cells in DIO than in lean rats. Lick coherence in DIO rats was significantly lower than in lean rats, both in taste-responsive and lick-related cells (n=172 in lean; n=65 in DIO). Analyses of temporal coding showed that taste cells in DIO rats conveyed less information about taste quality than cells in lean rats. Collectively, results suggest that a HED produces blunted, but more prevalent, responses to taste in the NTS and a weakened association of taste responses with ingestive behavior. These neural adaptations may represent both negative effects and compensatory mechanisms of a HED that may underlie deficits in taste-related behavior associated with obesity.

Keywords: high fat diet, Obesity, Taste, Nucleus of the solitary tract (NTS), Electrophysiology, gustatory, rat

Received: 21 May 2019; Accepted: 11 Jul 2019.

Edited by:

Ivan E. De Araujo, Icahn School of Medicine at Mount Sinai, United States

Reviewed by:

Ranier Gutierrez, Center for Research and Advanced Studies (CINVESTAV), Mexico
Shashank Tandon, The University of Utah, United States  

Copyright: © 2019 Di Lorenzo, Weiss, Hajnal and Czaja. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Patricia M. Di Lorenzo, Binghamton University, Binghamton, United States, diloren@binghamton.edu