Differential Effects of Continuous versus Intermittent Dietary Fat Intake on Markers of Serotonin Signaling in the Circumvallate Papillae of the Tongue

Abstract

Taste is a primary sensory modality that guides organisms in their determination of food preferences. Previous studies suggest that orosensory fat sensing may contribute to the intake and preference of dietary fat leading to the development of obesity. CD36 is the proposed fat taste receptor on the circumvallate papillae (CV) of the tongue and mediates fat sensing. Fat signaling via CD36 on the CV involves the regulation of serotonin (5‐HT) in taste receptor cells and activation of gustatory afferent nerves. The aim of these experiments was to investigate the effects of dietary fat intake on 5‐HT signaling in the CV using two feeding paradigms: continuous access to high fat diet (HFD) vs. limited access to dietary fat. We hypothesized that consumption of dietary fat, in specific patterns, contributes to the decreased sensitivity (i.e. hyposensitivity) of fat sensing through 5‐HT signaling dysregulation. The first experiment investigated the effects of continuous access to either a HFD or a low fat diet (LFD) for 1, 3 or 14 days on 5‐HT signaling in the CV. The second experiment investigated the effects of limited daily and intermittent access to dietary fat on 5‐HT signaling in the CV. Body weight and kilocalorie intake were assessed. In the CV, expression levels of CD36, 5‐HT1A, SERT, TPH1, and TPH2 mRNA were determined by Real Time PCR. Continuous HFD consumption for 14 days increased CD36, 5‐HT1A and SERT mRNA expression on the CV, suggesting reduced lingual fat sensing via decreased gustatory signaling from taste receptor cells. Limited, daily access to dietary fat increased CD36 and TPH1 mRNA expression on the CV suggesting enhanced lingual fat sensing compared to chow fed controls. Limited, intermittent access to dietary led to an escalation of fat intake without significant alterations in lingual expression of 5‐HT signaling. These data suggest that different patterns of fat consumption differentially affect 5‐HT signaling in the CV and that continuous access to HFD may lead to decreased orosensory fat perception by altering 5‐HT signaling in taste receptors cells.Support or Funding InformationLSUHSC to SDPThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.