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Cawthon CR, Blonde GD, Spector AC. Lingual Taste Nerve Transection Alters Food Selection, Relative Macronutrient Intake, and Meal Patterns in Rats Consuming a Cafeteria Diet without Changing Total Energy Intake. eNeuro 2024; 11:ENEURO.0393-23.2024. [PMID: 38346902 PMCID: PMC10921256 DOI: 10.1523/eneuro.0393-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 01/19/2024] [Accepted: 02/02/2024] [Indexed: 02/20/2024] Open
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.
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Affiliation(s)
- Carolina R Cawthon
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, Florida 32306
| | - Ginger D Blonde
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, Florida 32306
| | - Alan C Spector
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, Florida 32306
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Sakamoto K, Matsumura S, Okafuji Y, Eguchi A, Lee S, Adachi SI, Fujitani M, Tsuzuki S, Inoue K, Fushiki T. Mechanisms Involved in Guiding the Preference for Fat Emulsion Differ Depending on the Concentration. J Nutr Sci Vitaminol (Tokyo) 2016; 61:247-54. [PMID: 26226962 DOI: 10.3177/jnsv.61.247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
High-fat foods tend to be palatable and can cause addiction in mice via a reinforcing effect. However, mice showed preference for low fat concentrations that do not elicit a reinforcing effect in a two-bottle choice test with water as the alternative. This behavior indicates the possibility that the mechanism underlying fat palatability may differ depending on the dietary fat content. To address this issue, we examined the influences of the opioid system and olfactory and gustatory transductions on the intake and reinforcing effects of various concentrations of a dietary fat emulsion (Intralipid). We found that the intake and reinforcing effects of fat emulsion were reduced by the administration of an opioid receptor antagonist (naltrexone). Furthermore, the action of naltrexone was only observed at higher concentrations of fat emulsion. The intake and the reinforcing effects of fat emulsion were also reduced by olfactory and glossopharyngeal nerve transections (designated ONX and GLX, respectively). In contrast to naltrexone, the effects of ONX and GLX were mainly observed at lower concentrations of fat emulsion. These results imply that the opioid system seems to have a greater role in determining the palatability of high-fat foods unlike the contribution of olfactory and glossopharyngeal nerves.
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Affiliation(s)
- Kazuhiro Sakamoto
- Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University
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Spector AC. Behavioral analyses of taste function and ingestion in rodent models. Physiol Behav 2015; 152:516-26. [PMID: 25892670 PMCID: PMC4608852 DOI: 10.1016/j.physbeh.2015.04.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/09/2015] [Indexed: 12/31/2022]
Abstract
In 1975, at the start of my junior year in college, I took a course on experimental methods in psychology from Dr. James C. Smith, when he was a Visiting Professor at Penn State University. That experience set me on the professional path of studying the neural bases of taste function and ingestion on which I remain to this day. Along the way, I did my graduate work at Florida State University under the tutelage of Jim, I did my postdoctoral training at the University of Pennsylvania under the supervision of Harvey Grill, and I also worked closely with Ralph Norgren, who was at the Penn State Medical College. This article briefly summarizes some of the lessons I learned from my mentors and highlights a few key research findings arising from my privilege of working with gifted students and postdocs. After close to 40 years of being a student of the gustatory system and ingestive behavior, it is still with the greatest conviction that I believe rigorous analysis of behavior is indispensable to any effort seeking to understand brain function.
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Affiliation(s)
- Alan C Spector
- Department of Psychology, Florida State University, Tallahassee, FL, USA; Program in Neuroscience, Florida State University, Tallahassee, FL, USA.
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Abstract
Fat is a vital macronutrient, and its intake is closely monitored by an array of molecular sensors distributed throughout the alimentary canal. In the mouth, dietary fat constituents such as mono- and diunsaturated fatty acids give rise to taste signals that stimulate food intake, in part by enhancing the production of lipid-derived endocannabinoid messengers in the gut. As fat-containing chyme enters the small intestine, it causes the formation of anorexic lipid mediators, such as oleoylethanolamide, which promote satiety. These anatomically and functionally distinct responses may contribute to the homeostatic control and, possibly, the pathological dysregulation of food intake.
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Affiliation(s)
| | - Daniele Piomelli
- Departments of Anatomy and Neurobiology
- Department of Pharmacology, and
- Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, California, USA
- Drug Discovery and Development, Istituto Italiano di Tecnologia, Genoa, Italy
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Massen JJM, Dusch K, Eldakar OT, Gallup AC. A thermal window for yawning in humans: yawning as a brain cooling mechanism. Physiol Behav 2014; 130:145-8. [PMID: 24721675 DOI: 10.1016/j.physbeh.2014.03.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 02/24/2014] [Accepted: 03/31/2014] [Indexed: 12/23/2022]
Abstract
The thermoregulatory theory of yawning posits that yawns function to cool the brain in part due to counter-current heat exchange with the deep inhalation of ambient air. Consequently, yawning should be constrained to an optimal thermal zone or range of temperature, i.e., a thermal window, in which we should expect a lower frequency at extreme temperatures. Previous research shows that yawn frequency diminishes as ambient temperatures rise and approach body temperature, but a lower bound to the thermal window has not been demonstrated. To test this, a total of 120 pedestrians were sampled for susceptibly to self-reported yawn contagion during distinct temperature ranges and seasons (winter: 1.4°C, n=60; summer: 19.4°C, n=60). As predicted, the proportion of pedestrians reporting yawning was significantly lower during winter than in summer (18.3% vs. 41.7%), with temperature being the only significant predictor of these differences across seasons. The underlying mechanism for yawning in humans, both spontaneous and contagious, appears to be involved in brain thermoregulation.
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Affiliation(s)
- Jorg J M Massen
- Department of Cognitive Biology, University of Vienna, Vienna, Austria.
| | - Kim Dusch
- Department of Education, University of Vienna, Vienna, Austria
| | - Omar Tonsi Eldakar
- Farquhar College of Arts and Sciences, Nova Southeastern University, Ft. Lauderdale, USA
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DiPatrizio NV. Is fat taste ready for primetime? Physiol Behav 2014; 136:145-54. [PMID: 24631296 DOI: 10.1016/j.physbeh.2014.03.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/26/2014] [Accepted: 03/05/2014] [Indexed: 12/11/2022]
Abstract
Mounting evidence suggests that gustation is important for the orosensory detection of dietary fats, and might contribute to preferences that humans, rodents, and possibly other mammals exhibit for fat-rich foods. In contrast to sweet, sour, salty, bitter, and umami, fat is not widely recognized as a primary taste quality. Recent investigations, however, provide a wealth of information that is helping to elucidate the specific molecular, cellular, and neural mechanisms required for fat detection in mammals. The latest evidence supporting a fat taste will be explored in this review, with a particular focus on recent studies that suggest a surprising role for gut-brain endocannabinoid signaling in controlling intake and preference for fats based on their proposed taste properties.
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Affiliation(s)
- Nicholas V DiPatrizio
- Department of Anatomy and Neurobiology, University of California, Irvine, School of Medicine, United States.
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Foo H, Norgren R. Concentration and state dependent reductions in corn oil intakes after glossopharyngeal nerve transections in rats. Physiol Behav 2014; 128:166-71. [PMID: 24534178 DOI: 10.1016/j.physbeh.2014.02.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 01/25/2014] [Accepted: 02/04/2014] [Indexed: 11/19/2022]
Abstract
Previous studies indicate a role for the glossopharyngeal nerve (GL) in the detection of dietary fats. The present experiments examined the effects of bilateral glossopharyngeal nerve transections (GLx) on the intake of low (4.8%), moderate (16%), and full-fat (100%) corn oil in non-deprived, food-deprived, and water-deprived rats. The rats had access to oils, 0.3 M sucrose, and water in a gustometer that measured number of licks and latency to the first lick during brief access trials. The behavioral measures were used as indices of the amount consumed and the motivation to ingest, respectively. After baseline intakes had stabilized, the rats received GLx or sham transections (Sham) and were then re-tested. Pre and post-surgery responses were compared to determine the impact of GLx on intake and the motivation to ingest. In non-deprived rats, GLx reduced the intake of 4.8% and 16% oils and decreased the motivation to ingest these oils. In food-deprived rats, GLx prevented increases in the ingestion of 4.8% and 16% oils and in the motivation to ingest these oils. In water-deprived rats, GLx reduced the intake of 100% oil and produced a general decrease in the motivation to consume low, moderate, and full-fat emulsions. These results indicate that GL is partially involved in corn oil intake and suggest an interactive effect of oil concentration with homeostatic state.
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Affiliation(s)
- H Foo
- Department of Neural & Behavioral Sciences, College of Medicine, Pennsylvania State University, United States.
| | - R Norgren
- Department of Neural & Behavioral Sciences, College of Medicine, Pennsylvania State University, United States
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Running CA, Mattes RD, Tucker RM. Fat taste in humans: Sources of within- and between-subject variability. Prog Lipid Res 2013; 52:438-45. [DOI: 10.1016/j.plipres.2013.04.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Revised: 04/26/2013] [Accepted: 04/27/2013] [Indexed: 01/14/2023]
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DiPatrizio NV, Joslin A, Jung KM, Piomelli D. Endocannabinoid signaling in the gut mediates preference for dietary unsaturated fats. FASEB J 2013; 27:2513-20. [PMID: 23463697 DOI: 10.1096/fj.13-227587] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dietary fat exerts a potent stimulatory effect on feeding. This effect is mediated, at least in part, by a cephalic mechanism that involves recruitment of the vagus nerve and subsequent activation of endocannabinoid signaling in the gut. Here, we used a sham-feeding protocol in rats to identify fatty-acid constituents of dietary fat that might be responsible for triggering small-intestinal endocannabinoid signaling. Sham feeding rats with a corn oil emulsion increased endocannabinoid levels in jejunum, relative to animals that received either mineral oil (which contains no fatty acids) or no oil. Sham-feeding emulsions containing oleic acid (18:1) or linoleic acid (18:2) caused, on average, a nearly 2-fold accumulation of jejunal endocannabinoids, whereas emulsions containing stearic acid (18:0) or linolenic acid (18:3) had no such effect. In a 2-bottle-choice sham-feeding test, rats displayed strong preference for emulsions containing 18:2, which was blocked by pretreatment with the peripherally restricted CB1 cannabinoid receptor antagonists, AM6546 and URB447. Our results suggest that oral exposure to the monoenoic and dienoic fatty acid component of dietary fat selectively initiates endocannabinoid mobilization in the gut, and that this local signaling event is essential for fat preference.
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Affiliation(s)
- Nicholas V DiPatrizio
- Department of Anatomy and Neurobiology, University of California-Irvine School of Medicine, Irvine, CA 92697-1275, USA
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Dotson CD, Colbert CL, Garcea M, Smith JC, Spector AC. The consequences of gustatory deafferentation on body mass and feeding patterns in the rat. Am J Physiol Regul Integr Comp Physiol 2012; 303:R611-23. [PMID: 22785426 DOI: 10.1152/ajpregu.00633.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The contribution of orosensory signals, especially taste, on body mass, and feeding and drinking patterns in the rat was examined. Gustatory deafferentation was produced by bilateral transection of the chorda tympani, glossopharyngeal, and greater superficial petrosal nerves. Total calories consumed from sweetened-milk diet and oil-chow mash by the nerve-transected rats significantly decreased relative to sham-operated controls, mostly attributable to decreases in bout number, but not size. Nevertheless, caloric intake steadily increased over the postsurgical observation period, but body mass remained below both presurgical baseline and control levels and did not significantly increase over this time. After the sweetened-milk diet/oil-chow mash phase, rats received a series of sucrose preference tests. Interestingly, the nerve-transected rats preferred sucrose, and intake did not differ from controls, likely due to the stimulus sharing some nontaste chemosensory properties with the sweetened-milk diet. The neurotomized rats initiated a greater number of sucrose-licking bouts that were smaller in size and slower in licking rate, compared with control rats, and, unlike in control rats, the latter two bout parameters did not vary across concentration. Thus, in the absence of gustatory neural input, body mass is more stable compared with the progressive trajectory of weight gain seen in intact rats, and caloric intake initially decreases but recovers. The consequences of gustatory neurotomy on processes that determine meal initiation (bout number) and meal termination (bout size) are not fixed and appear to be influenced by presurgical experience with food stimuli coupled with its nongustatory chemosensory properties.
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Affiliation(s)
- Cedrick D Dotson
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, USA.
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Mattes RD. Accumulating evidence supports a taste component for free fatty acids in humans. Physiol Behav 2011; 104:624-31. [PMID: 21557960 PMCID: PMC3139746 DOI: 10.1016/j.physbeh.2011.05.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 04/13/2011] [Accepted: 05/03/2011] [Indexed: 01/22/2023]
Abstract
The requisite criteria for what constitutes a taste primary have not been established. Recent advances in understanding of the mechanisms and functions of taste have prompted suggestions for an expanded list of unique taste sensations, including fat, or more specifically, free fatty acids (FFA). A set of criteria are proposed here and the data related to FFA are reviewed on each point. It is concluded that the data are moderate to strong that there are: A) adaptive advantages to FFA detection in the oral cavity; B) adequate concentrations of FFA to serve as taste stimuli; C) multiple complimentary putative FFA receptors on taste cells; D) signals generated by FFA that are conveyed by gustatory nerves; E) sensations generated by FFA that can be detected and scaled by psychophysical methods in humans when non-gustatory cues are masked; and F) physiological responses to oral fat/FFA exposure. On no point is there strong evidence challenging these observations. The reviewed findings are suggestive, albeit not definitive, that there is a taste component for FFA.
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Affiliation(s)
- Richard D Mattes
- Department of Foods and Nutrition, Purdue University, 700 W State Street, West Lafayette, IN 47907-2059, USA.
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