Obesity is a major contributor to serious health problems. The incidence of obesity within the US has soared during the last 30-40 years, with a contributing cause being the increased consumption of high-fat foods. Diets high in fat can result in overeating (hyperphagia), which promotes obesity in susceptible individuals. There is evidence in both humans and rats that hyperphagia is related to reduce sensitivity to the satiating effect of dietary fat, due to reduced engagement of brainstem satiety circuits. The proposed research will further elucidate the functional organization of these circuits, highlightin a potentially critical role for hindbrain noradrenergic neurons that co-express prolactin-releasing peptide (PrRP). The proposed work is consistent with the NIH Strategic Plan for Obesity Research by its focus on physiological neural mechanisms that regulate food intake and body weight. Animal models can provide critical insights into physiological and behavioral factors that predispose humans to become obese. Further, PrRP neurons are located within human caudal brainstem in a distribution similar to that in rodent species. Thus, experimental outcomes will have translational implications for understanding how dietary fat promotes overeating in humans who are susceptible to diet-induced hyperphagia, while others exposed to the same diet remain relatively resistant. We propose that behavioral satiety is generated, at least in part, by recruitment of PrRP-positive neurons in the caudal visceral portion of the nucleus of the solitary tract, and that these neurons are polysynaptically linked to brainstem oral ingestive control motor neurons. PrRP neurons receive direct visceral sensory input from gastrointestinal vagal afferents, and central PrRP signaling is implicated in the homeostatic control of food intake in rats and mice. The proposed research will use adult male rats to challenge the overarching hypothesis that satiety signals recruit brainstem PrRP signaling pathways that limit meal size. In addition, we will test the hypothesis that a high-fat diet attenuates this natural PrRP-mediated satiety process in individual rats that develop hyperphagia, but not in resistant rats. We propose that increased consummatory responses to high fat diet are due, at least in part, to attenuated satiety signal-induced recruitment of brainstem PrRP neurons that act to limit food intake. Outbred Sprague-Dawley rats are an ideal experimental model for the proposed research, because approximately 50% develop behavioral hyperphagia (i.e., increased meal size and daily food intake) that promotes increased body weight gain during high fat diet exposure, whereas the remainder are resistant, and do not increase their daily intake or BW more than they do on normal control diet.

Public Health Relevance

The proposed research will use laboratory rats to examine how satiety signals from the gastrointestinal tract act on brainstem neural circuits that control meal size. We will test the hypothesis that maintenance of rats on a high-fat diet attenuates this natural satiety process in the subset of rats that overeat and gain more body weight than rats that are resistant and remain lean. Results in rats will have translational relevance for understanding the neural underpinnings of overeating and obesity in humans.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
7R01DK100685-04
Application #
9462292
Study Section
Integrative Physiology of Obesity and Diabetes Study Section (IPOD)
Program Officer
Stoeckel, Luke
Project Start
2017-05-01
Project End
2019-06-30
Budget Start
2017-07-11
Budget End
2018-06-30
Support Year
4
Fiscal Year
2017
Total Cost
Indirect Cost
Name
Florida State University
Department
Psychology
Type
Schools of Arts and Sciences
DUNS #
790877419
City
Tallahassee
State
FL
Country
United States
Zip Code
32306
Hogue, Ian B; Card, J Patrick; Rinaman, Linda et al. (2018) Characterization of the neuroinvasive profile of a pseudorabies virus recombinant expressing the mTurquoise2 reporter in single and multiple injection experiments. J Neurosci Methods 308:228-239
Card, J Patrick; Johnson, Aaron L; Llewellyn-Smith, Ida J et al. (2018) GLP-1 neurons form a local synaptic circuit within the rodent nucleus of the solitary tract. J Comp Neurol 526:2149-2164
Maniscalco, J W; Rinaman, L (2018) Vagal Interoceptive Modulation of Motivated Behavior. Physiology (Bethesda) 33:151-167
Maniscalco, James W; Rinaman, Linda (2017) Interoceptive modulation of neuroendocrine, emotional, and hypophagic responses to stress. Physiol Behav 176:195-206
Alhadeff, Amber L; Holland, Ruby A; Zheng, Huiyuan et al. (2017) Excitatory Hindbrain-Forebrain Communication Is Required for Cisplatin-Induced Anorexia and Weight Loss. J Neurosci 37:362-370
Foster, Jane A; Rinaman, Linda; Cryan, John F (2017) Stress & the gut-brain axis: Regulation by the microbiome. Neurobiol Stress 7:124-136
Zheng, Huiyuan; Rinaman, Linda (2016) Simplified CLARITY for visualizing immunofluorescence labeling in the developing rat brain. Brain Struct Funct 221:2375-83
Kreisler, Alison D; Rinaman, Linda (2016) Hindbrain glucagon-like peptide-1 neurons track intake volume and contribute to injection stress-induced hypophagia in meal-entrained rats. Am J Physiol Regul Integr Comp Physiol 310:R906-16
Kojima, Sayuri; Catavero, Christina; Rinaman, Linda (2016) Maternal high-fat diet increases independent feeding in pre-weanling rat pups. Physiol Behav 157:237-45
Zheng, H; Stornetta, R L; Agassandian, K et al. (2015) Glutamatergic phenotype of glucagon-like peptide 1 neurons in the caudal nucleus of the solitary tract in rats. Brain Struct Funct 220:3011-22

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