Fatty acid taste quality information via GPR120 in the anterior tongue of mice

Abstract

Aim: To elucidate whether fatty acid taste has a quality that does not overlap with other primary qualities, we investigated potential neuron types coding fatty acid information and how GPR120 is involved. Methods: Single fibre recordings in the chorda tympani (CT) nerve and behavioural response measurements using a conditioned taste aversion paradigm were performed in GPR120-knockout (KO) and wild-type (WT) mice. Results: Single fibres can be classified into fatty acid (F)-, S-, M-, electrolyte (E)-, Q-, and N-type groups according to the maximal response among oleic acid, sucrose, monopotassium glutamate (MPG), HCl, quinine hydrochloride, and NaCl respectively. Among fibres, 4.0% in GPR120-KO and 17.9% in WT mice showed a maximal response to oleic acid (F-type). Furthermore, half or more of S-and M-type fibres showed responses to fatty acids in both mouse strains, although the thresholds in KO mice were significantly higher and impulse frequencies lower than those in WT mice. GPR120-KO mice conditioned to avoid linoleic acid showed generalized stimulus avoidances for MPG, indicating qualitative similarity between linoleic acid and MPG. The KO mice showed a higher generalization threshold for linoleic acid than that of WT mice. Conclusion: Fatty acid taste is suggested to have a unique quality owing to the discovery of F-type fibres, with GPR120 involved in neural information pathways for a unique quality and palatable taste qualities in the mouse CT nerve. GPR120 plays roles in distinguishing fatty acid taste from other primary tastes and the detection of low linoleic acid concentrations. K E Y W O R D Sfat taste, fatty acid, GPR120, single fibre, taste, taste nerve

Taste Sensor: Electronic Tongue with Lipid Membranes

“…Over the past 20 years, many researchers have provided evidence of free fatty acid receptors 9 and the roles of G protein-coupled receptor 120 (GPR120), GPR40, and the cluster of differentiation 36 (CD36) in the fat taste. 10,11 In addition to the five basic tastes, the fat taste may be recognized as the sixth basic taste in the near future.…”

New evidence for fat as a primary taste quality

“…Although first described in 1909, a fifth basic taste modality, umami, was finally recognized in 2002, when a receptor was identified in human and rodent taste buds. 1 Although recording from single gustatory nerve fibres in mice is a challenging technique, they convincingly demonstrate for the first time that specific nerve fibres, so-called "F-type fibres", are dedicated to the transmission of fatty acid signals from taste buds to the brain in mice. While sweet, umami and low concentrations of salt are attractive to humans, and bitter, sour and high concentrations of salt are generally avoided, an acquired attraction to bitter and sour can develop in life (eg coffee, beer, lemon, sour candies).…”

“…Further, they investigated the role of GPR120, a G protein-coupled receptor expressed in mouse and human taste buds, in lingual fat perception. 1 Although recording from single gustatory nerve fibres in mice is a challenging technique, they convincingly demonstrate for the first time that specific nerve fibres, so-called "F-type fibres", are dedicated to the transmission of fatty acid signals from taste buds to the brain in mice. Activation of F-type fibres upon lingual stimulation with lipids is significantly diminished, albeit not abolished, in GPR120 knockout mice, suggesting GPR120 mediates at least a portion of this response.…”

“…1 The sense of taste helps the body discriminate between beneficial versus toxic and spoiled food to ensure survival by covering daily nutrient needs and preventing poisoning. 1 The sense of taste helps the body discriminate between beneficial versus toxic and spoiled food to ensure survival by covering daily nutrient needs and preventing poisoning.…”

“…In the current issue of Acta Physiologica, Yasumatsu et al addressed whether oral perception of dietary lipids constitutes a discrete basic taste modality. 1 The sense of taste helps the body discriminate between beneficial versus toxic and spoiled food to ensure survival by covering daily nutrient needs and preventing poisoning. Taste not only informs the body of whether food can be ingested, but also prepares the body for processing the incoming food.…”