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Sung H, Vesela I, Driks H, Ferrario CR, Mistretta CM, Bradley RM, Dus M. High-sucrose diet exposure is associated with selective and reversible alterations in the rat peripheral taste system. Curr Biol 2022; 32:4103-4113.e4. [PMID: 35977546 PMCID: PMC9561051 DOI: 10.1016/j.cub.2022.07.063] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/03/2022] [Accepted: 07/21/2022] [Indexed: 12/14/2022]
Abstract
Elevated sugar consumption is associated with an increased risk for metabolic diseases. Whereas evidence from humans, rodents, and insects suggests that dietary sucrose modifies sweet taste sensation, understanding of peripheral nerve or taste bud alterations is sparse. To address this, male rats were given access to 30% liquid sucrose for 4 weeks (sucrose rats). Neurophysiological responses of the chorda tympani (CT) nerve to lingual stimulation with sugars, other taste qualities, touch, and cold were then compared with controls (access to water only). Morphological and immunohistochemical analyses of fungiform papillae and taste buds were also conducted. Sucrose rats had substantially decreased CT responses to 0.15-2.0 M sucrose compared with controls. In contrast, effects were not observed for glucose, fructose, maltose, Na saccharin, NaCl, organic acid, or umami, touch, or cold stimuli. Whereas taste bud number, size, and innervation volume were unaffected, the number of PLCβ2+ taste bud cells in the fungiform papilla was reduced in sucrose rats. Notably, the replacement of sucrose with water resulted in a complete recovery of all phenotypes over 4 weeks. The work reveals the selective and modality-specific effects of sucrose consumption on peripheral taste nerve responses and taste bud cells, with implications for nutrition and metabolic disease risk. VIDEO ABSTRACT.
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Affiliation(s)
- Hayeon Sung
- Department of Molecular, Cellular, and Developmental Biology, The College of Literature, Arts, and Science, The University of Michigan, Ann Arbor, MI, USA
| | - Iva Vesela
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA
| | - Hannah Driks
- Department of Molecular, Cellular, and Developmental Biology, The College of Literature, Arts, and Science, The University of Michigan, Ann Arbor, MI, USA
| | - Carrie R Ferrario
- Department of Pharmacology, The University of Michigan Medical School, Ann Arbor, MI, USA; Department of Psychology (Biopsychology), College of Literature, Arts, and Science, The University of Michigan, Ann Arbor, MI, USA
| | - Charlotte M Mistretta
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA
| | - Robert M Bradley
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, The University of Michigan, Ann Arbor, MI, USA; Department of Molecular and Integrative Physiology, The University of Michigan Medical School, Ann Arbor, MI, USA.
| | - Monica Dus
- Department of Molecular, Cellular, and Developmental Biology, The College of Literature, Arts, and Science, The University of Michigan, Ann Arbor, MI, USA.
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The Neural Code for Taste in the Nucleus of the Solitary Tract of Rats with Obesity Following Roux-En-Y Gastric Bypass Surgery. Nutrients 2022; 14:nu14194129. [PMID: 36235781 PMCID: PMC9570596 DOI: 10.3390/nu14194129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 11/07/2022] Open
Abstract
Previous work has shown that taste responses in the nucleus tractus solitarius (NTS; the first central relay for gustation) are blunted in rats with diet-induced obesity (DIO). Here, we studied whether these effects could be reversed by Roux-en-Y gastric bypass (RYGB) surgery, an effective treatment for obesity. Rats were fed a high energy diet (60% kcal fat; HED) both before and after undergoing RYGB. Electrophysiological responses from NTS cells in unrestrained rats were recorded as they licked tastants from a lick spout. Sweet, salty, and umami tastes, as well as their naturalistic counterparts, were presented. Results were compared with those of lean rats from a previous study. As with DIO rats, NTS cells in RYGB rats were more narrowly tuned, showed weaker responses, and less lick coherence than those in lean rats. Both DIO and RYGB rats licked at a slower rate than lean rats and paused more often during a lick bout. However, unlike DIO rats, the proportion of taste cells in RYGB rats was similar to that in lean rats. Our data show that, despite being maintained on a HED after surgery, RYGB can induce a partial recovery of the deficits seen in the NTS of DIO rats.
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Kovacs P, Hajnal A. Short-term high-fat diet consumption increases body weight and body adiposity and alters brain stem taste information processing in rats. Chem Senses 2022; 47:6673811. [PMID: 35997757 DOI: 10.1093/chemse/bjac020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Diet-induced obesity is known to develop whether exposed to a high-energy diet (HED) or a high-fat diet (HFD). However, it is still not clear whether the elevated energy content or the macronutrient imbalance is the key factor in early disease progression. Therefore, this study compared the short-term effects of 2 widely used rodent obesogenic diets, an HFD with 60 kcal% fat content and a carbohydrate-based HED, on the body weight, body fat content, glucose tolerance, and neuronal taste responses in rats. We found that only HFD induced an early significant body weight increase compared with the control normal diet (ND) group, starting on week 4, and resulting in a significantly elevated body adiposity compared with both the ND and HED groups. Oral glucose tolerance test revealed no difference across groups. Subsequently, we also found that HFD resulted in a significant body weight gain even under energy-restricted (isocaloric to ND) conditions. In vivo electrophysiological recordings revealed that only the ad libitum HFD and not the isocaloric-HFD altered the brain stem gustatory neural responses to oral taste stimulation. In conclusion, this study showed that increased fat intake might result in significant body weight gain even under isocaloric and metabolically healthy conditions and demonstrated changes in central taste processing in an early stage of dietary obesity. A better understanding of these initial physiological changes may offer new drug targets for preventing obesity.
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Affiliation(s)
- Peter Kovacs
- Department of Neural and Behavioral Sciences, College of Medicine, The Pennsylvania State University, Hershey, PA 17033, USA
| | - Andras Hajnal
- Department of Neural and Behavioral Sciences, College of Medicine, The Pennsylvania State University, Hershey, PA 17033, USA
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