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Yen E, Maron JL. Aberrant Feeding and Growth in Neonates With Prenatal Opioid Exposure: Evidence of Neuromodulation and Behavioral Changes. Front Pediatr 2021; 9:805763. [PMID: 35127598 PMCID: PMC8814597 DOI: 10.3389/fped.2021.805763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 12/28/2021] [Indexed: 11/13/2022] Open
Abstract
Opioid use disorder (OUD) among pregnant women over the last decade has led to more than a fivefold increase in the number of neonates born with withdrawal signs known as Neonatal Abstinence Syndrome (NAS) or Neonatal Opioid Withdrawal Syndrome (NOWS). The impact of prenatal opioid exposure on these neonates remains a public health and research priority due to both its short and long-term effects on offspring. Among the adverse long-term effects associated with OUD is a metabolic syndrome with accompanying cardiovascular comorbidities. The susceptibility to metabolic diseases may begin as early as conception. Neonates born in a setting of prenatal opioid exposure are known to have aberrant early growth, e.g., lower birth weight and smaller head size, and dysregulated feeding behavior that ranges from feeding difficulty to hyperphagia which may predispose these neonates to metabolic syndrome in adulthood. However, studies on this topic are lacking. In this article, we describe the reported association between OUD and metabolic syndrome in adults, animal data linking opioid receptors with the development of diet-induced obesity, the inflammatory modulation of opioids and finally, neonatal salivary transcriptomic data from our laboratory that highlighted the sex-specific impact of opioids on the hypothalamic and reward receptors that regulate feeding behavior in opioid-exposed neonates. There is a great need for future research linking opioids with epigenetic and gene expression changes, as well as neuromodulatory effects in the developing brain, that may underlie the dysregulated feeding, growth, and long-term metabolic and cardiovascular risks for these neonates.
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Affiliation(s)
- Elizabeth Yen
- Mother Infant Research Institute, Tufts Medical Center, Boston, MA, United States.,Department of Pediatrics, Tufts University School of Medicine, Boston, MA, United States
| | - Jill L Maron
- Department of Pediatrics, Women & Infants Hospital of Rhode Island, Providence, RI, United States.,Warren Alpert Medical School of Brown University, Providence, RI, United States
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2
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Mumolo MG, Rettura F, Melissari S, Costa F, Ricchiuti A, Ceccarelli L, de Bortoli N, Marchi S, Bellini M. Is Gluten the Only Culprit for Non-Celiac Gluten/Wheat Sensitivity? Nutrients 2020; 12:E3785. [PMID: 33321805 PMCID: PMC7762999 DOI: 10.3390/nu12123785] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/05/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022] Open
Abstract
The gluten-free diet (GFD) has gained increasing popularity in recent years, supported by marketing campaigns, media messages and social networks. Nevertheless, real knowledge of gluten and GF-related implications for health is still poor among the general population. The GFD has also been suggested for non-celiac gluten/wheat sensitivity (NCG/WS), a clinical entity characterized by intestinal and extraintestinal symptoms induced by gluten ingestion in the absence of celiac disease (CD) or wheat allergy (WA). NCG/WS should be regarded as an "umbrella term" including a variety of different conditions where gluten is likely not the only factor responsible for triggering symptoms. Other compounds aside from gluten may be involved in the pathogenesis of NCG/WS. These include fructans, which are part of fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs), amylase trypsin inhibitors (ATIs), wheat germ agglutinin (WGA) and glyphosate. The GFD might be an appropriate dietary approach for patients with self-reported gluten/wheat-dependent symptoms. A low-FODMAP diet (LFD) should be the first dietary option for patients referring symptoms more related to FODMAPs than gluten/wheat and the second-line treatment for those with self-reported gluten/wheat-related symptoms not responding to the GFD. A personalized approach, regular follow-up and the help of a skilled dietician are mandatory.
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Affiliation(s)
| | - Francesco Rettura
- Gastrointestinal Unit, Department of Translational Sciences and New Technologies in Medicine and Surgery, University of Pisa, 56124 Pisa, Italy; (M.G.M.); (S.M.); (F.C.); (A.R.); (L.C.); (N.d.B.); (S.M.); (M.B.)
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Butler MJ, Eckel LA. Eating as a motivated behavior: modulatory effect of high fat diets on energy homeostasis, reward processing and neuroinflammation. Integr Zool 2019; 13:673-686. [PMID: 29851251 DOI: 10.1111/1749-4877.12340] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Eating is a basic motivated behavior that provides fuel for the body and supports brain function. To ensure survival, the brain's feeding circuits are tuned to monitor peripheral energy balance and promote food-seeking behavior when energy stores are low. The brain's bias toward a positive energy state, which is necessary to ensure adequate nutrition during times of food scarcity, is evolutionarily conserved across mammalian species and is likely to drive overeating in the presence of a palatable, energy-dense diet. Animal models of diet-induced overeating have played a vital role in investigating how the drive to consume palatable food may override the homeostatic processes that serve to maintain energy balance. These animal models have provided valuable insights into the neurobiological mechanisms underlying homeostatic and non-homeostatic eating, motivation and food reward, and the development of obesity and related comorbidities. Here, we provide a brief review of this literature and discuss how diet-induced inflammation in the central nervous system impacts the neural control of food intake and regulation of body weight. The connection between diet and the immune system provides an exciting new direction for the study of ingestive behavior and the pathophysiology of obesity.
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Affiliation(s)
- Michael J Butler
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida, USA
| | - Lisa A Eckel
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida, USA
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Yousefvand S, Hamidi F, Zendehdel M, Parham A. Interaction of neuropeptide Y receptors (NPY1, NPY2 and NPY5) with somatostatin on somatostatin-induced feeding behaviour in neonatal chicken. Br Poult Sci 2018; 60:71-78. [DOI: 10.1080/00071668.2018.1547359] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- S. Yousefvand
- Department of Basic Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - F. Hamidi
- Department of Basic Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
| | - M. Zendehdel
- Department of Basic Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
| | - A. Parham
- Department of Basic Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
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Novelle MG, Diéguez C. Food Addiction and Binge Eating: Lessons Learned from Animal Models. Nutrients 2018; 10:E71. [PMID: 29324652 PMCID: PMC5793299 DOI: 10.3390/nu10010071] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/26/2017] [Accepted: 01/09/2018] [Indexed: 01/10/2023] Open
Abstract
The feeding process is required for basic life, influenced by environment cues and tightly regulated according to demands of the internal milieu by regulatory brain circuits. Although eating behaviour cannot be considered "addictive" under normal circumstances, people can become "addicted" to this behaviour, similarly to how some people are addicted to drugs. The symptoms, cravings and causes of "eating addiction" are remarkably similar to those experienced by drug addicts, and both drug-seeking behaviour as eating addiction share the same neural pathways. However, while the drug addiction process has been highly characterised, eating addiction is a nascent field. In fact, there is still a great controversy over the concept of "food addiction". This review aims to summarize the most relevant animal models of "eating addictive behaviour", emphasising binge eating disorder, that could help us to understand the neurobiological mechanisms hidden under this behaviour, and to improve the psychotherapy and pharmacological treatment in patients suffering from these pathologies.
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Affiliation(s)
- Marta G Novelle
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 15786 Santiago de Compostela, Spain.
| | - Carlos Diéguez
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria (IDIS), CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 15786 Santiago de Compostela, Spain.
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Feeding-modulatory effects of mu-opioids in the medial prefrontal cortex: a review of recent findings and comparison to opioid actions in the nucleus accumbens. Psychopharmacology (Berl) 2017; 234:1439-1449. [PMID: 28054099 PMCID: PMC5420483 DOI: 10.1007/s00213-016-4522-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/20/2016] [Indexed: 12/20/2022]
Abstract
RATIONALE Whereas reward-modulatory opioid actions have been intensively studied in subcortical sites such as the nucleus accumbens (Acb), the role of cortical opioid transmission has received comparatively little attention. OBJECTIVES The objective of this study is to describe recent findings on the motivational actions of opioids in the prefrontal cortex (PFC), emphasizing studies of food motivation and ingestion. PFC-based opioid effects will be compared/contrasted to those elicited from the Acb, to glean possible common functional principles. Finally, the motivational effects of opioids will be placed within a network context involving the PFC, Acb, and hypothalamus. RESULTS Mu-opioid receptor (μ-OR) stimulation in both the Acb and PFC induces eating and enhances food-seeking instrumental behaviors; μ-OR signaling also enhances taste reactivity within a highly circumscribed zone of medial Acb shell. In both the Acb and PFC, opioid-sensitive zones are aligned topographically with the sectors that project to feeding-modulatory zones of the hypothalamus and intact glutamate transmission in the lateral/perifornical (LH-PeF) hypothalamic areas is required for both Acb- and PFC-driven feeding. Conversely, opioid-mediated feeding responses elicited from the PFC are negatively modulated by AMPA signaling in the Acb shell. CONCLUSIONS Opioid signaling in the PFC engages functionally opposed PFC➔hypothalamus and PFC➔Acb circuits, which, respectively, drive and limit non-homeostatic feeding, producing a disorganized and "fragmented" pattern of impulsive food-seeking behaviors and hyperactivity. In addition, opioids act directly in the Acb to facilitate food motivation and taste hedonics. Further study of this cortico-striato-hypothalamic circuit, and incorporation of additional opioid-responsive telencephalic structures, could yield insights with translational relevance for eating disorders and obesity.
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Bojanowska E, Ciosek J. Can We Selectively Reduce Appetite for Energy-Dense Foods? An Overview of Pharmacological Strategies for Modification of Food Preference Behavior. Curr Neuropharmacol 2016; 14:118-42. [PMID: 26549651 PMCID: PMC4825944 DOI: 10.2174/1570159x14666151109103147] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 09/19/2015] [Accepted: 10/31/2015] [Indexed: 12/11/2022] Open
Abstract
Excessive intake of food, especially palatable and energy-dense carbohydrates and fats, is
largely responsible for the growing incidence of obesity worldwide. Although there are a number of
candidate antiobesity drugs, only a few of them have been proven able to inhibit appetite for palatable
foods without the concurrent reduction in regular food consumption. In this review, we discuss the
interrelationships between homeostatic and hedonic food intake control mechanisms in promoting
overeating with palatable foods and assess the potential usefulness of systemically administered pharmaceuticals that
impinge on the endogenous cannabinoid, opioid, aminergic, cholinergic, and peptidergic systems in the modification of
food preference behavior. Also, certain dietary supplements with the potency to reduce specifically palatable food intake
are presented. Based on human and animal studies, we indicate the most promising therapies and agents that influence the
effectiveness of appetite-modifying drugs. It should be stressed, however, that most of the data included in our review
come from preclinical studies; therefore, further investigations aimed at confirming the effectiveness and safety of the
aforementioned medications in the treatment of obese humans are necessary.
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Affiliation(s)
- Ewa Bojanowska
- Department of Behavioral Pathophysiology, Institute of General and Experimental Pathology, Medical University of Lodz, 60 Narutowicza Street, 90-136 Lodz, Poland.
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Nicola SM. Reassessing wanting and liking in the study of mesolimbic influence on food intake. Am J Physiol Regul Integr Comp Physiol 2016; 311:R811-R840. [PMID: 27534877 PMCID: PMC5130579 DOI: 10.1152/ajpregu.00234.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/09/2016] [Indexed: 01/12/2023]
Abstract
Humans and animals such as rats and mice tend to overconsume calorie-dense foods, a phenomenon that likely contributes to obesity. One often-advanced explanation for why we preferentially consume sweet and fatty foods is that they are more "rewarding" than low-calorie foods. "Reward" has been subdivided into three interdependent psychological processes: hedonia (liking a food), reinforcement (formation of associations among stimuli, actions, and/or the food), and motivation (wanting the food). Research into these processes has focused on the mesolimbic system, which comprises both dopamine neurons in the ventral tegmental area and neurons in their major projection target, the nucleus accumbens. The mesolimbic system and closely connected structures are commonly referred to as the brain's "reward circuit." Implicit in this title is the assumption that "rewarding" experiences are generally the result of activity in this circuit. In this review, I argue that food intake and the preference for calorie-dense foods can be explained without reference to subjective emotions. Furthermore, the contribution of mesolimbic dopamine to food intake and preference may not be a general one of promoting or coordinating behaviors that result in the most reward or caloric intake but may instead be limited to the facilitation of a specific form of neural computation that results in conditioned approach behavior. Studies on the neural mechanisms of caloric intake regulation must address how sensory information about calorie intake affects not just the mesolimbic system but also many other forms of computation that govern other types of food-seeking and food-oriented behaviors.
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Affiliation(s)
- Saleem M Nicola
- Departments of Neuroscience and Psychiatry, Albert Einstein College of Medicine, Bronx, New York
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Kanarek RB, D'anci KE. Diet and Lighting Conditions Modify the Effects of the Kappa Opioid Agonist U50,488H on Feeding Behavior in Rats. Nutr Neurosci 2016. [DOI: 10.1080/1028415x.2000.11747321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Cole J, Ross A, Bodnar R. Dietary History Affects the Potency of Chronic Opioid Receptor Subtype Antagonist Effects upon Body Weight in Rats. Nutr Neurosci 2016; 1:405-17. [DOI: 10.1080/1028415x.1998.11747251] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Bressan P, Kramer P. Bread and Other Edible Agents of Mental Disease. Front Hum Neurosci 2016; 10:130. [PMID: 27065833 PMCID: PMC4809873 DOI: 10.3389/fnhum.2016.00130] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/10/2016] [Indexed: 12/16/2022] Open
Abstract
Perhaps because gastroenterology, immunology, toxicology, and the nutrition and agricultural sciences are outside of their competence and responsibility, psychologists and psychiatrists typically fail to appreciate the impact that food can have on their patients' condition. Here we attempt to help correct this situation by reviewing, in non-technical, plain English, how cereal grains-the world's most abundant food source-can affect human behavior and mental health. We present the implications for the psychological sciences of the findings that, in all of us, bread (1) makes the gut more permeable and can thus encourage the migration of food particles to sites where they are not expected, prompting the immune system to attack both these particles and brain-relevant substances that resemble them, and (2) releases opioid-like compounds, capable of causing mental derangement if they make it to the brain. A grain-free diet, although difficult to maintain (especially for those that need it the most), could improve the mental health of many and be a complete cure for others.
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Affiliation(s)
- Paola Bressan
- Department of General Psychology, University of PaduaPadova, Italy
| | - Peter Kramer
- Department of General Psychology, University of PaduaPadova, Italy
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Alvarado-Bañuelos M, Barrios De Tomasi E, Juárez J. Changes in the incentive value of food after naltrexone treatment depend on a differential preference for a palatable food in male rats. Nutr Neurosci 2016; 20:416-423. [DOI: 10.1080/1028415x.2016.1162389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Mariana Alvarado-Bañuelos
- Laboratorio de Farmacología y Conducta, Instituto de Neurociencias, CUCBA, Universidad de Guadalajara, Guadalajara, Jalisco CP 44130, México
| | - Eliana Barrios De Tomasi
- Laboratorio de Farmacología y Conducta, Instituto de Neurociencias, CUCBA, Universidad de Guadalajara, Guadalajara, Jalisco CP 44130, México
| | - Jorge Juárez
- Laboratorio de Farmacología y Conducta, Instituto de Neurociencias, CUCBA, Universidad de Guadalajara, Guadalajara, Jalisco CP 44130, México
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Burghardt PR, Rothberg AE, Dykhuis KE, Burant CF, Zubieta JK. Endogenous Opioid Mechanisms Are Implicated in Obesity and Weight Loss in Humans. J Clin Endocrinol Metab 2015; 100:3193-201. [PMID: 26108093 PMCID: PMC4524998 DOI: 10.1210/jc.2015-1783] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Successful long-term weight loss is challenging. Brain endogenous opioid systems regulate associated processes; however, their role in the maintenance of weight loss has not been adequately explored in humans. OBJECTIVE In a preliminary study, the objective was to assess central μ-opioid receptor (MOR) system involvement in eating behaviors and their relationship to long-term maintenance of weight loss. DESIGN This was a case-control study with follow-up of the treatment group at 1 year after intervention. SETTING The study was conducted at a tertiary care university medical center. PARTICIPANTS Lean healthy (n = 7) and chronically obese (n = 7) men matched for age and ethnicity participated in the study. INTERVENTIONS MOR availability measures were acquired with positron emission tomography and [(11)C]carfentanil. Lean healthy men were scanned twice under both fasted and fed conditions. Obese men were placed on a very low-calorie diet to achieve 15% weight loss from baseline weight and underwent two positron emission tomography scans before and two after weight loss, incorporating both fasted and fed states. MAIN OUTCOME MEASURES Brain MOR availability and activation were measured by reductions in MOR availability (nondisplaceable binding potential) from the fed compared with the fasted-state scans. RESULTS Baseline MOR nondisplaceable binding potential was reduced in obese compared with the lean and partially recovered obese after weight loss in regions that regulate homeostatic, hedonic, and emotional responses to feeding. Reductions in negative affect and feeding-induced MOR system activation in the right temporal pole were highly correlated in leans but not in obese men. A trend for an association between MOR activation in the right temporal pole before weight loss and weight regain 1 year was found. CONCLUSIONS Although these preliminary studies have a small sample size, these results suggest that obesity and diet-induced weight loss impact central MOR binding and endogenous opioid system function. MOR system activation in response to an acute meal may be related to the risk of weight regain.
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Kraft TT, Yakubov Y, Huang D, Fitzgerald G, Natanova E, Sclafani A, Bodnar RJ. Dopamine D1 and opioid receptor antagonists differentially reduce the acquisition and expression of fructose-conditioned flavor preferences in BALB/c and SWR mice. Physiol Behav 2015. [PMID: 26220464 DOI: 10.1016/j.physbeh.2015.07.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Sugar appetite is influenced by unlearned and learned preferences in rodents. The present study examined whether dopamine (DA) D1 (SCH23390: SCH) and opioid (naltrexone: NTX) receptor antagonists differentially altered the expression and acquisition of fructose-conditioned flavor preferences (CFPs) in BALB/c and SWR mice. In expression experiments, food-restricted mice alternately (10 sessions, 1h) consumed a flavored (e.g., cherry) 8% fructose+0.2% saccharin solution (CS+) and a differently-flavored (e.g., grape) 0.2% saccharin solution (CS-). Two-bottle CS choice tests (1h) occurred 0.5h following vehicle: SCH (200 or 800 nmol/kg) or NTX (1 or 5mg/kg). SCH, but not NTX significantly reduced CS+ preference in both strains. In acquisition experiments, 0.5h prior to 10 acquisition training sessions, vehicle, SCH (50 nmol/kg), NTX (1 mg/kg) or Limited Control vehicle treatments were administered, followed by two-bottle CS choice tests without injections. SCH and NTX reduced training intakes in both strains. BALB/c mice displayed hastened extinction of the fructose-CFP following training with SCH, but not NTX. SCH eliminated fructose-CFP acquisition in SWR mice, whereas NTX hastened extinction of the CFP. These results are compared to previous drug findings obtained with sucrose-CFPs in SWR and BALB/c mice, and are discussed in terms of differential effects of these sugars on oral and post-oral conditioning.
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Affiliation(s)
- Tamar T Kraft
- Behavioral and Cognitive Neuroscience Cluster of the Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, USA
| | - Yakov Yakubov
- Department of Psychology, Queens College, City University of New York, New York, NY, USA
| | - Donald Huang
- Department of Psychology, Queens College, City University of New York, New York, NY, USA
| | - Gregory Fitzgerald
- Department of Psychology, Queens College, City University of New York, New York, NY, USA
| | - Elona Natanova
- Department of Psychology, Queens College, City University of New York, New York, NY, USA
| | - Anthony Sclafani
- Behavioral and Cognitive Neuroscience Cluster of the Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, USA; Department of Psychology, Brooklyn College, City University of New York, New York, NY, USA
| | - Richard J Bodnar
- Behavioral and Cognitive Neuroscience Cluster of the Psychology Doctoral Program, The Graduate Center, City University of New York, New York, NY, USA; Department of Psychology, Queens College, City University of New York, New York, NY, USA.
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Keramati M, Gutkin B. Homeostatic reinforcement learning for integrating reward collection and physiological stability. eLife 2014; 3. [PMID: 25457346 PMCID: PMC4270100 DOI: 10.7554/elife.04811] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 11/03/2014] [Indexed: 01/26/2023] Open
Abstract
Efficient regulation of internal homeostasis and defending it against perturbations requires adaptive behavioral strategies. However, the computational principles mediating the interaction between homeostatic and associative learning processes remain undefined. Here we use a definition of primary rewards, as outcomes fulfilling physiological needs, to build a normative theory showing how learning motivated behaviors may be modulated by internal states. Within this framework, we mathematically prove that seeking rewards is equivalent to the fundamental objective of physiological stability, defining the notion of physiological rationality of behavior. We further suggest a formal basis for temporal discounting of rewards by showing that discounting motivates animals to follow the shortest path in the space of physiological variables toward the desired setpoint. We also explain how animals learn to act predictively to preclude prospective homeostatic challenges, and several other behavioral patterns. Finally, we suggest a computational role for interaction between hypothalamus and the brain reward system. DOI:http://dx.doi.org/10.7554/eLife.04811.001 Our survival depends on our ability to maintain internal states, such as body temperature and blood sugar levels, within narrowly defined ranges, despite being subject to constantly changing external forces. This process, which is known as homeostasis, requires humans and other animals to carry out specific behaviors—such as seeking out warmth or food—to compensate for changes in their environment. Animals must also learn to prevent the potential impact of changes that can be anticipated. A network that includes different regions of the brain allows animals to perform the behaviors that are needed to maintain homeostasis. However, this network is distinct from the network that supports the learning of new behaviors in general. These two systems must, therefore, interact so that animals can learn novel strategies to support their physiological stability, but it is not clear how animals do this. Keramati and Gutkin have now devised a mathematical model that explains the nature of this interaction, and that can account for many behaviors seen among animals, even those that might otherwise appear irrational. There are two assumptions at the heart of the model. First, it is assumed that animals are capable of guessing the impact of the outcome of their behaviors on their internal state. Second, it is assumed that animals find a behavior rewarding if they believe that the predicted impact of its outcome will reduce the difference between a particular internal state and its ideal value. For example, a form of behavior for a human might be going to the kitchen, and an outcome might be eating chocolate. Based on these two assumptions, the model shows that animals stabilize their internal state around its ideal value by simply learning to perform behaviors that lead to rewarding outcomes (such as going into the kitchen and eating chocolate). Their theory also explains the physiological importance of a type of behavior known as ‘delay discounting’. Animals displaying this form of behavior regard a positive outcome as less rewarding the longer they have to wait for it. The model proves mathematically that delay discounting is a logical way to optimize homeostasis. In addition to making a number of predictions that could be tested in experiments, Keramati and Gutkin argue that their model can account for the failure of homeostasis to limit food consumption whenever foods loaded with salt, sugar or fat are freely available. DOI:http://dx.doi.org/10.7554/eLife.04811.002
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Affiliation(s)
- Mehdi Keramati
- Group for Neural Theory, INSERM U960, Departément des Etudes Cognitives, Ecole Normale Supérieure, PSL Research University, Paris, France
| | - Boris Gutkin
- Group for Neural Theory, INSERM U960, Departément des Etudes Cognitives, Ecole Normale Supérieure, PSL Research University, Paris, France
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Katsuura Y, Taha SA. Mu opioid receptor antagonism in the nucleus accumbens shell blocks consumption of a preferred sucrose solution in an anticipatory contrast paradigm. Neuroscience 2014; 261:144-52. [PMID: 24342569 PMCID: PMC3956648 DOI: 10.1016/j.neuroscience.2013.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 11/27/2013] [Accepted: 12/03/2013] [Indexed: 01/09/2023]
Abstract
Binge eating, a central feature of multiple eating disorders, is characterized by excessive consumption occurring during discrete, often brief, intervals. Highly palatable foods play an important role in these binge episodes - foods chosen during bingeing are typically higher in fat or sugar than those normally consumed. Multiple lines of evidence suggest a central role for signaling by endogenous opioids in promoting palatability-driven eating. This role extends to binge-like feeding studied in animal models, which is reduced by administration of opioid antagonists. However, the neural circuits and specific opioid receptors mediating these effects are not fully understood. In the present experiments, we tested the hypothesis that endogenous opioid signaling in the nucleus accumbens promotes consumption in a model of binge eating. We used an anticipatory contrast paradigm in which separate groups of rats were presented sequentially with 4% sucrose and then either 20% or 0% sucrose solutions. In rats presented with 4% and then 20% sucrose, daily training in this paradigm produced robust intake of 20% sucrose, preceded by learned hypophagia during access to 4% sucrose. We tested the effects of site-specific infusions of naltrexone (a nonspecific opioid receptor antagonist: 0, 1, 10, and 50μg/side in the nucleus accumbens core and shell), naltrindole (a delta opioid receptor antagonist: 0, 0.5, 5, and 10μg/side in the nucleus accumbens shell) and beta-funaltrexamine (a mu opioid receptor antagonist: 0 and 2.5μg/side in the nucleus accumbens shell) on consumption in this contrast paradigm. Our results show that signaling through the mu opioid receptor in the nucleus accumbens shell is dynamically modulated during formation of learned food preferences, and promotes binge-like consumption of palatable foods based on these learned preferences.
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MESH Headings
- Animals
- Anticipation, Psychological/drug effects
- Anticipation, Psychological/physiology
- Food Preferences/drug effects
- Food Preferences/physiology
- Learning/drug effects
- Learning/physiology
- Male
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiology
- Random Allocation
- Rats
- Rats, Long-Evans
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/metabolism
- Sucrose
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Affiliation(s)
- Y Katsuura
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, USA
| | - S A Taha
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT, USA.
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17
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Goebel-Stengel M, Stengel A, Wang L, Taché Y. Orexigenic response to tail pinch: role of brain NPY(1) and corticotropin releasing factor receptors. Am J Physiol Regul Integr Comp Physiol 2014; 306:R164-74. [PMID: 24338440 PMCID: PMC3921301 DOI: 10.1152/ajpregu.00335.2013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 12/10/2013] [Indexed: 12/30/2022]
Abstract
Tail pinch stimulates food intake in rats. We investigated brain mechanisms of this response and the influence of repeated exposure. Sprague-Dawley rats received acute (5 min) or repeated (5 min/day for 14 days) tail pinch using a padded clip. Acute tail pinch increased 5-min food intake compared with control (0.92 ± 0.2 vs. 0.03 ± 0.01 g, P < 0.01). This response was inhibited by 76% by intracerebroventricular injection of BIBP-3226, a neuropeptide Y1 (NPY1) receptor antagonist, increased by 48% by astressin-B, a corticotropin-releasing factor (CRF) receptor antagonist, and not modified by S-406-028, a somatostatin subtype 2 antagonist. After the 5-min tail pinch without food, blood glucose rose by 21% (P < 0.01) while changes in plasma acyl ghrelin (+41%) and adrenocorticotropic hormone (+37%) were not significant. Two tail pinches (45 min apart) activate pontine and hindbrain catecholaminergic and hypothalamic paraventricular CRF neurons. After 14 days of repeated tail pinch, the 5-min orexigenic response was not significantly different from days 2 to 11 but reduced by 50% thereafter (P < 0.001). Simultaneously, the 5-min fecal pellet output increased during the last 5 days compared with the first 5 days (+58%, P < 0.05). At day 14, the body weight gain was reduced by 22%, with a 99% inhibition of fat gain and a 25% reduction in lean mass (P < 0.05). The orexigenic response to acute 5-min tail pinch is likely to involve the activation of brain NPY1 signaling, whereas that of CRF tends to dampen the acute response and may contribute to increased defecation and decreased body weight gain induced by repeated tail pinch.
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Affiliation(s)
- Miriam Goebel-Stengel
- CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division, Department of Medicine, at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California
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18
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Gugusheff JR, Ong ZY, Muhlhausler BS. A maternal “junk‐food” diet reduces sensitivity to the opioid antagonist naloxone in offspring postweaning. FASEB J 2012; 27:1275-84. [DOI: 10.1096/fj.12-217653] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jessica R. Gugusheff
- FOODplus Research CentreSchool of Agriculture, Food, and WineThe University of AdelaideAdelaideSouth AustraliaAustralia
| | - Zhi Yi Ong
- FOODplus Research CentreSchool of Agriculture, Food, and WineThe University of AdelaideAdelaideSouth AustraliaAustralia
- Sansom Institute for Health ResearchSchool of Pharmacy and Medical ScienceUniversity of South AustraliaAdelaideSouth AustraliaAustralia
| | - Beverly S. Muhlhausler
- FOODplus Research CentreSchool of Agriculture, Food, and WineThe University of AdelaideAdelaideSouth AustraliaAustralia
- Sansom Institute for Health ResearchSchool of Pharmacy and Medical ScienceUniversity of South AustraliaAdelaideSouth AustraliaAustralia
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19
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Inhibition of opioid transmission at the μ-opioid receptor prevents both food seeking and binge-like eating. Neuropsychopharmacology 2012; 37:2643-52. [PMID: 22805601 PMCID: PMC3473330 DOI: 10.1038/npp.2012.128] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Endogenous opioids, and in particular μ-opioid receptors, have been linked to hedonic and rewarding mechanisms engaged during palatable food intake. The aim of this study was to investigate the effects of GSK1521498, a novel μ-opioid receptor antagonist, on food-seeking behavior and on binge-like eating of a highly preferred chocolate diet. Food seeking was measured in rats trained to respond for chocolate under a second-order schedule of reinforcement, in which prolonged periods of food-seeking behavior were maintained by contingent presentation of a reward-associated conditioned reinforcer. After reaching a stable baseline in both procedures, animals were treated with GSK1521498 (0.1, 1, and 3 mg/kg; IP) or naltrexone (NTX, 0.1, 1, and 3 mg/kg; SC). The binge eating model was characterized by four temporally contiguous phases: 1-h chow access, 2-h food deprivation, 10-min chow access, and 10-min access to either chocolate-flavoured food or standard chow. During training the rats developed binge-like hyperphagia of palatable food and anticipatory chow hypophagia (anticipatory negative contrast). Both compounds reduced binge-like palatable food hyperphagia. However, GSK1521498 reduced the impact of high hedonic value on ingestion more specifically than NTX, abolishing anticipatory chow hypophagia. GSK1521498 also dose-dependently reduced food seeking both before and after food ingestion, whereas NTX reduced food seeking only after food ingestion. Thus, while both drugs affected the hedonic value of the preferred food, GSK1521498 also directly decreased incentive motivation for chocolate. Selective μ-opioid receptor antagonism by GSK1521498 may have utility as a treatment for reducing maladaptive, palatability-driven eating behavior by reducing the motivational properties of stimuli that elicit the binge eating commonly associated with obesity.
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20
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Lowe MR, Levine AS. Eating Motives and the Controversy over Dieting: Eating Less Than Needed versus Less Than Wanted. ACTA ACUST UNITED AC 2012; 13:797-806. [PMID: 15919830 DOI: 10.1038/oby.2005.90] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anti-dieting sentiment has grown in recent years. Critics of restrained eating suggest that it evokes counter-regulatory responses that render it ineffective or even iatrogenic. However, restrained eaters are not in negative energy balance and overweight individuals show reduced eating problems when losing weight by dieting. A distinction is often drawn between physiological and psychological hunger, and neuroscience research has shown that there is a neurophysiological reality underlying this distinction. The brain has a homeostatic system (activated by energy deficits) and a hedonic system (activated by the presence of palatable food). The omnipresence of highly palatable food in the environment may chronically activate the hedonic appetite system, producing a need to actively restrain eating not just to lose weight but to avoid gaining it. Just as restricting energy intake below homeostatic needs produces physiological deprivation, restricting intake of palatable foods may produce "perceived deprivation" despite a state of energy balance. In summary, the motivation to eat more than one needs appears to be every bit as real, and perhaps every bit as powerful, as the motivation to eat when energy deprived.
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Affiliation(s)
- Michael R Lowe
- Department of Psychology, Drexel University, Mail Stop 626, 245 North Fifteenth Street, Philadelphia, PA 19102, USA.
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21
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Cognitive and neuronal systems underlying obesity. Physiol Behav 2012; 106:337-44. [PMID: 22266286 DOI: 10.1016/j.physbeh.2012.01.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 12/30/2011] [Accepted: 01/08/2012] [Indexed: 01/31/2023]
Abstract
Since the late 1970s obesity prevalence and per capita food intake in the USA have increased dramatically. Understanding the mechanisms underlying the hyperphagia that drives obesity requires focus on the cognitive processes and neuronal systems controlling feeding that occurs in the absence of metabolic need (i.e., "non-homeostatic" intake). Given that a portion of the increased caloric intake per capita since the late 1970s is attributed to increased meal and snack frequency, and given the increased pervasiveness of environmental cues associated with energy dense, yet nutritionally depleted foods, there's a need to examine the mechanisms through which food-related cues stimulate excessive energy intake. Here, learning and memory principles and their underlying neuronal substrates are discussed with regard to stimulus-driven food intake and excessive energy consumption. Particular focus is given to the hippocampus, a brain structure that utilizes interoceptive cues relevant to energy status (e.g., neurohormonal signals such as leptin) to modulate stimulus-driven food procurement and consumption. This type of hippocampal-dependent modulatory control of feeding behavior is compromised by consumption of foods common to Western diets, including saturated fats and simple carbohydrates. The development of more effective treatments for obesity will benefit from a more complete understanding of the complex interaction between dietary, environmental, cognitive, and neurophysiological mechanisms contributing to excessive food intake.
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22
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Figlewicz DP, Sipols AJ. Energy regulatory signals and food reward. Pharmacol Biochem Behav 2010; 97:15-24. [PMID: 20230849 PMCID: PMC2897918 DOI: 10.1016/j.pbb.2010.03.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 02/26/2010] [Accepted: 03/09/2010] [Indexed: 12/23/2022]
Abstract
The hormones insulin, leptin, and ghrelin have been demonstrated to act in the central nervous system (CNS) as regulators of energy homeostasis, acting at medial hypothalamic sites. Here, we summarize research demonstrating that, in addition to direct homeostatic actions at the hypothalamus, CNS circuitry that subserves reward and is also a direct and indirect target for the action of these endocrine regulators of energy homeostasis. Specifically, insulin and leptin can decrease food reward behaviors and modulate the function of neurotransmitter systems and neural circuitry that mediate food reward, the midbrain dopamine (DA) and opioidergic pathways. Ghrelin can increase food reward behaviors, and support midbrain DA neuronal function. We summarize discussion of behavioral, systems, and cellular evidence in support of the contributions of reward circuitry to the homeostatic roles of these hormones in the CNS. The understanding of neuroendocrine modulation of food reward, as well as food reward modulation by diet and obesity, may point to new directions for therapeutic approaches to overeating or eating disorders.
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Affiliation(s)
- Dianne P Figlewicz
- Metabolism/Endocrinology, VA Puget Sound Health Care System, Seattle Division, Seattle, WA 98108, USA.
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23
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Stengel A, Coskun T, Goebel M, Wang L, Craft L, Alsina-Fernandez J, Rivier J, Taché Y. Central injection of the stable somatostatin analog ODT8-SST induces a somatostatin2 receptor-mediated orexigenic effect: role of neuropeptide Y and opioid signaling pathways in rats. Endocrinology 2010; 151:4224-35. [PMID: 20610566 PMCID: PMC2940496 DOI: 10.1210/en.2010-0195] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Somatostatin and octreotide injected into the brain have been reported to modulate food intake. However, little is known regarding the underlying mechanisms. The stable oligosomatostatin analog, des-AA(1,2,4,5,12,13)-[DTrp(8)]-somatostatin (ODT8-SST), like somatostatin, binds to all five somatostatin receptors (sst(1-5)). We characterized the effects of ODT8-SST injected intracerebroventricularly (i.c.v.) on food consumption and related mechanisms of action in freely fed rats. ODT8-SST (0.3 and 1 microg per rat, i.c.v.) injected during the light or dark phase induced an early onset (within 1 h) and long-lasting (4 h) increase in food intake in nonfasted rats. By contrast, i.p. injection (0.3-3 mg/kg) or i.c.v. injection of selective sst(1) or sst(4) agonists (1 microg per rat) had no effect. The 2 h food intake response during the light phase was blocked by i.c.v. injection of a sst(2) antagonist, the neuropeptide Y (NPY) Y(1) receptor antagonist, BIBP-3226, and ip injection of the mu-opioid receptor antagonist, naloxone, and not associated with changes in plasma ghrelin levels. ODT8-SST (1 microg per rat, i.c.v.) stimulated gastric emptying of a solid meal which was also blocked by naloxone. The increased food intake was accompanied by a sustained increase in respiratory quotient, energy expenditure, and drinking as well as mu-opioid receptor-independent grooming behavior and hyperthermia, while ambulatory movements were not altered after ODT8-SST (1 microg per rat, i.c.v.). These data show that ODT8-SST acts primarily through brain sst(2) receptors to induce a long-lasting orexigenic effect that involves the activation of Y(1) and opiate-receptors, accompanied by enhanced gastric transit and energy expenditure suggesting a modulation of NPYergic and opioidergic orexigenic systems by brain sst(2) receptors.
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MESH Headings
- Animals
- Anti-Anxiety Agents/administration & dosage
- Anti-Anxiety Agents/pharmacology
- Arginine/administration & dosage
- Arginine/analogs & derivatives
- Arginine/pharmacology
- Body Temperature/drug effects
- Eating/drug effects
- Eating/physiology
- Energy Metabolism/drug effects
- Gastric Emptying/drug effects
- Grooming/drug effects
- Injections, Intraperitoneal
- Injections, Intraventricular
- Male
- Mice
- Mice, Inbred C57BL
- Naloxone/administration & dosage
- Naloxone/pharmacology
- Peptide Fragments/administration & dosage
- Peptide Fragments/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Neuropeptide Y/antagonists & inhibitors
- Receptors, Neuropeptide Y/physiology
- Receptors, Opioid, mu/antagonists & inhibitors
- Receptors, Opioid, mu/physiology
- Receptors, Somatostatin/agonists
- Receptors, Somatostatin/antagonists & inhibitors
- Receptors, Somatostatin/physiology
- Somatostatin/administration & dosage
- Somatostatin/analogs & derivatives
- Somatostatin/pharmacology
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, Center for Ulcer Research and Education, Digestive Diseases Division, University of California Los Angeles, and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA
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24
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Bonacchi KB, Ackroff K, Touzani K, Bodnar RJ, Sclafani A. Opioid mediation of starch and sugar preference in the rat. Pharmacol Biochem Behav 2010; 96:507-14. [PMID: 20655942 DOI: 10.1016/j.pbb.2010.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 07/07/2010] [Accepted: 07/17/2010] [Indexed: 01/07/2023]
Abstract
In our prior studies, administration of the opioid receptor antagonist naltrexone did not block conditioned preferences for a flavor paired with a preferred sugar solution over a flavor paired with saccharin. This may be because both training solutions were sweet, and their attractiveness was reduced by naltrexone. The present study compared the effects of naltrexone on preferences for flavors paired with sugar or starch drinks that have distinctive tastes to rats. Experiment 1 assessed naltrexone's effect on the preference for unflavored 8% cornstarch and 8% sucrose aqueous solutions/suspensions. The food-restricted rats displayed a significant sucrose preference which increased following systemic treatment with naltrexone (1 or 3mg/kg) even though total intake of both solutions declined. In Experiment 2, rats were trained to drink flavored (cherry or grape) starch and sucrose solutions in separate one-bottle sessions. In a two-bottle choice test with both flavors presented in a sucrose-starch mixture, the rats significantly preferred the starch-paired flavor. Naltrexone treatment blocked the expression of this starch-conditioned preference. In Experiment 3, rats were treated with saline or naltrexone throughout one-bottle training with flavored sucrose and starch solutions. In a subsequent choice test, both the saline and naltrexone groups displayed significant preferences for the starch-paired flavor, indicating that opioid antagonism failed to alter the acquisition of this conditioned preference. In summary, novel outcomes of this study included the increased rather than the predicted decrease in sucrose preference produced by naltrexone. Also, starch unexpectedly conditioned the stronger flavor preference, although this can be explained by the differential post-oral reinforcing actions of starch and sucrose, and naltrexone blocked the expression, but not the acquisition, of this preference. These findings suggest that the reward value of starch in liquid form is more dependent upon opioid signaling than is that of sugar.
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Affiliation(s)
- Kristine B Bonacchi
- Department of Psychology, Queens College, City University of New York, Flushing, NY 11210, USA
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25
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Abstract
The hormones insulin, leptin, and ghrelin have been demonstrated to act in the central nervous system (CNS) as regulators of energy homeostasis, acting at medial hypothalamic sites. Here, we summarize research demonstrating that, in addition to direct homeostatic actions at the hypothalamus, CNS circuitry that subserves reward and is also a direct and indirect target for the action of these endocrine regulators of energy homeostasis. Specifically, insulin and leptin can decrease food reward behaviors and modulate the function of neurotransmitter systems and neural circuitry that mediate food reward, the midbrain dopamine (DA) and opioidergic pathways. Ghrelin can increase food reward behaviors, and support midbrain DA neuronal function. We summarize discussion of behavioral, systems, and cellular evidence in support of the contributions of reward circuitry to the homeostatic roles of these hormones in the CNS. The understanding of neuroendocrine modulation of food reward, as well as food reward modulation by diet and obesity, may point to new directions for therapeutic approaches to overeating or eating disorders.
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26
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Taha SA. Preference or fat? Revisiting opioid effects on food intake. Physiol Behav 2010; 100:429-37. [PMID: 20211638 DOI: 10.1016/j.physbeh.2010.02.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 02/16/2010] [Accepted: 02/28/2010] [Indexed: 10/19/2022]
Abstract
It is well established that opioid signaling in the central nervous system constitutes a powerful stimulus for food intake. The role of opioids in determining food preference, however, is less well defined. Opioids have been proposed to promote intake of preferred foods, or, alternatively, to preferentially increase consumption of fat. In the present manuscript, I comprehensively review results from previous studies investigating this issue. Data from these studies suggests a mechanism for opioid action that may reconcile the previously proposed hypotheses: opioid effects on food intake do appear to be largely specific for fat consumption, but individual animals' sensitivity to this effect may be dependent on baseline food preferences. In addition, I highlight the possibility that the selectivity of endogenous opioid effects may importantly differ from that of exogenous agonists in the degree to which baseline preferences, rather than macronutrient intake, are altered. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.
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Affiliation(s)
- Sharif A Taha
- University of Utah School of Medicine, 420 Chipeta Way, Suite 1700, Salt Lake City, UT 84108, United States.
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27
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Gosnell BA, Mitra A, Avant RA, Anker JJ, Carroll ME, Levine AS. Operant responding for sucrose by rats bred for high or low saccharin consumption. Physiol Behav 2010; 99:529-33. [PMID: 20096717 DOI: 10.1016/j.physbeh.2010.01.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 12/21/2009] [Accepted: 01/11/2010] [Indexed: 11/28/2022]
Abstract
The use of rats differing in the intake of sweet substances has highlighted some interesting parallels between taste preferences and drug self-administration. For example, rats selectively bred to consume high (HiS) or low (LoS) amounts of a 0.1% saccharin solution (when compared to water consumption), show corresponding differences across several measures of cocaine self-administration (HiS>LoS). In this study, we measured whether the two strains also differ when response requirements are imposed for obtaining a sucrose reinforcer. Male HiS and LoS rats were measured for operant responding for sucrose pellets under fixed-ratio (FR) schedules of 1, 3, 5 and 10 and under a progressive-ratio (PR) schedule, during which the response requirement for each successive pellet increased exponentially. The effect of systemic naltrexone (0.3, 1 and 3mg/kg) on PR responding for sucrose pellets was also tested. Under all FR and PR schedules, the number of pellets obtained by the LoS rats were significantly lower than those obtained by the HiS rats. Although the LoS weighed more than the HiS rats, this difference does not appear to explain differences in operant behavior. No strain differences in the effect of naltrexone were observed; the 3mg/kg dose reduced the number of pellets obtained in both strains. Measures of locomotor activity taken prior to operant trials suggest that the differences in responding were not due to differences in general activity levels. These studies provide further characterization of the HiS and LoS rat lines by demonstrating that motivation to consume sucrose is greater in HiS than in LoS rats.
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Affiliation(s)
- Blake A Gosnell
- Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave., St. Paul, MN 55108, USA.
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28
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From taste hedonics to motivational drive: central μ-opioid receptors and binge-eating behaviour. Int J Neuropsychopharmacol 2009; 12:995-1008. [PMID: 19433009 DOI: 10.1017/s146114570900039x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Endogenous opioids and μ-opioid receptors (MORs) have long been implicated in the mechanism of appetite control and, in particular, hedonic processes associated with food evaluation, consumption and orosensory reward processes. In animal models of binge eating, selective MOR antagonists suppress food consumption. In humans, non-selective opioid receptor antagonists reduce hedonic taste preferences and food intake, particularly for palatable foods, and cause short-term weight loss. These effects have been linked to direct stimulation of MORs and modulation of dopamine release within the reward circuitry including the nucleus accumbens. These findings suggest that reduction of MOR-mediated hedonic and motivation processes driving consumption of highly palatable foods may be a promising therapeutic approach and provide a strong rationale for developing safer and more selective MOR antagonists or inverse agonists for disorders of 'appetitive motivation' including obesity and binge-eating disorder.
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29
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Bello NT, Guarda AS, Terrillion CE, Redgrave GW, Coughlin JW, Moran TH. Repeated binge access to a palatable food alters feeding behavior, hormone profile, and hindbrain c-Fos responses to a test meal in adult male rats. Am J Physiol Regul Integr Comp Physiol 2009; 297:R622-31. [PMID: 19535681 DOI: 10.1152/ajpregu.00087.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Repetitive cycles of palatable food access and chronic calorie restriction alter feeding behaviors and forebrain neural systems. The purpose of this study was to determine the behavioral, endocrine, and meal-related hindbrain neural activation in adult male Sprague-Dawley rats exposed to a binge-access feeding schedule. The binge-access schedule consisted of repeated twice-per-week episodes of acute calorie restriction (to one-third of the previous day's intake) followed by 2 h of concurrent access to high-calorie palatable food (sweetened fat: 90% vegetable shortening-10% sucrose) and chow. The binge-access rats consumed more calories during the "binge" period than rats with continuous access to sweetened fat (continuous-access group) or subjected to repeated acute calorie restriction only (chow-restricted group). The binge-access group also exhibited a approximately 25% increase in sweetened fat intake from week 1 to week 6. Persistence of the binge phenotype in the binge-access animals was demonstrated 2 wk, but not 4 wk, after ad libitum chow. The binge-access and chow-restricted groups maintained a similar normal body composition and hormonal profiles, whereas the continuous-access animals developed an obese phenotype. Terminal ghrelin levels were significantly higher in the binge-access group than in the continuous-access group. Consumption of a standardized meal resulted in more c-Fos-positive cells along the anterior-posterior nucleus of the solitary tract regions in the binge-access group than in naive controls. These results suggest that repeated cycles of acute calorie restriction followed by palatable food produce physiological alterations that may facilitate overconsumption of a highly palatable food during limited-access periods.
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Affiliation(s)
- Nicholas T Bello
- Dept. of Psychiatry and Behavioral Sciences, Johns Hopkins Univ. School of Medicine, Ross 618, 720 Rutland Ave., Baltimore, MD 21205, USA.
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30
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Olszewski PK, Shaw TJ, Grace MK, Höglund CE, Fredriksson R, Schiöth HB, Levine AS. Complexity of neural mechanisms underlying overconsumption of sugar in scheduled feeding: involvement of opioids, orexin, oxytocin and NPY. Peptides 2009; 30:226-33. [PMID: 19022308 PMCID: PMC2657876 DOI: 10.1016/j.peptides.2008.10.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 10/19/2008] [Accepted: 10/20/2008] [Indexed: 11/23/2022]
Abstract
A regular daily meal regimen, as opposed to ad libitum consumption, enforces eating at a predefined time and within a short timeframe. Hence, it is important to study food intake regulation in animal feeding models that somewhat reflect this pattern. We investigated the effect of scheduled feeding on the intake of a palatable, high-sugar diet in rats and attempted to define central mechanisms - especially those related to opioid signaling--responsible for overeating sweet foods under such conditions. We found that scheduled access to food, even as challenging as 20 min per day, does not prevent overconsumption of a high-sucrose diet compared to a standard one. An opioid receptor antagonist, naloxone, at 0.3-1 mg/kg b. wt., decreased the intake of the sweet diet, whereas higher doses were required to reduce bland food consumption. Real-time PCR analysis revealed that expression of hypothalamic and brainstem genes encoding opioid peptides and receptors did not differ in sucrose versus regular diet-fed rats, which suggests that scheduled intake of sweet food produces only a transient change in the opioid tone. Intake of sugar was also associated with upregulation of orexin and oxytocin genes in the hypothalamus and NPY in the brainstem. We conclude that scheduled consumption of sugar diets is associated with activity of a complex network of neuroregulators involving opioids, orexin, oxytocin and NPY.
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Affiliation(s)
- Pawel K. Olszewski
- Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Uppsala SE 75124, Sweden
- Minnesota Obesity Center, Department of Food Science and Nutrition, Saint Paul, MN 55108, USA
| | - Timothy J. Shaw
- Minnesota Obesity Center, Department of Food Science and Nutrition, Saint Paul, MN 55108, USA
- Bethel University, Arden Hills, MN 55112, USA
| | - Martha K. Grace
- Minnesota Obesity Center, Department of Food Science and Nutrition, Saint Paul, MN 55108, USA
| | - Catherine E. Höglund
- Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Uppsala SE 75124, Sweden
| | - Robert Fredriksson
- Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Uppsala SE 75124, Sweden
| | - Helgi B. Schiöth
- Department of Neuroscience, Functional Pharmacology, Uppsala University, BMC, Uppsala SE 75124, Sweden
| | - Allen S. Levine
- Minnesota Obesity Center, Department of Food Science and Nutrition, Saint Paul, MN 55108, USA
- Department of Food Science and Nutrition, Saint Paul, MN 55108, USA
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Beckman TR, Shi Q, Levine AS, Billington CJ. Amygdalar opioids modulate hypothalamic melanocortin-induced anorexia. Physiol Behav 2008; 96:568-73. [PMID: 19136019 DOI: 10.1016/j.physbeh.2008.12.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 11/18/2008] [Accepted: 12/10/2008] [Indexed: 11/17/2022]
Abstract
We wanted to assess the possibility that opioid activity in the central amygdala (CeA) could modulate the feeding inhibition of melanocortin stimulation of the paraventricular hypothalamus (PVN). The melanocortin system is important in both the acute regulation of satiety and feeding behavior and in the integration of long-term appetite signals. Melanotan II (MTII) is a synthetic MC3R and MC4R agonist which reduces food intake when given intracerebroventricularly (ICV) and into the PVN. Tyr-D-Ala-Gly-(me) Phe-Gly-ol (DAMGO), a micro-opioid receptor agonist, increases food intake, while opioid antagonists, like naltrexone (NTX), inhibit food intake after injection into many brain sites involved in appetite regulation, including the CeA. In food-deprived male Sprague-Dawley rats, co-injected intra-PVN MTII partially blocked the orexigenic effect of co-injected intra-CeA DAMGO. Intra-CeA NTX co-injected with intra-PVN MTII reduced food intake significantly more than either alone. NTX administered intra-CeA reduced c-Fos-immunoreactivity (IR) in nucleus accumbens neurons significantly compared to the intra-PVN MTII treated animals, animals co-injected intra-PVN with MTII and intra-CeA with NTX animals, and control animals. Intra-PVN MTII induced c-Fos-IR in significantly more PVN neurons than observed in control animals. Intra-CeA NTX co-injected with intra-PVN MTII induced c-Fos-IR significantly in PVN neurons relative to control and intra-CeA NTX animals. Such data support the significance of opioid action within the CeA as a modulator of the feeding regulation action of melanocortins within the PVN, occurring within the context of a larger appetitive network.
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MESH Headings
- Amygdala/drug effects
- Amygdala/metabolism
- Analgesics, Opioid/metabolism
- Animals
- Appetite Regulation/drug effects
- Appetite Regulation/physiology
- Drug Interactions
- Eating/drug effects
- Eating/physiology
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Food Deprivation
- Hormones/pharmacology
- Male
- Melanocortins/metabolism
- Naltrexone/pharmacology
- Neural Pathways/physiology
- Neurotransmitter Agents/pharmacology
- Paraventricular Hypothalamic Nucleus/drug effects
- Paraventricular Hypothalamic Nucleus/metabolism
- Peptides, Cyclic/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Melanocortin, Type 3/drug effects
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/drug effects
- Receptor, Melanocortin, Type 4/metabolism
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/metabolism
- alpha-MSH/analogs & derivatives
- alpha-MSH/pharmacology
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Affiliation(s)
- Tiffany R Beckman
- Department of Medicine, University of Minnesota, Minneapolis, MN 55455, United States.
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Sahr AE, Sindelar DK, Alexander-Chacko JT, Eastwood BJ, Mitch CH, Statnick MA. Activation of mesolimbic dopamine neurons during novel and daily limited access to palatable food is blocked by the opioid antagonist LY255582. Am J Physiol Regul Integr Comp Physiol 2008; 295:R463-71. [DOI: 10.1152/ajpregu.00390.2007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An analog of the trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine series (LY255582) exhibits high in vitro binding affinity and antagonist potency for the μ-, δ-, and κ-opioid receptors. In vivo, LY255582 exhibits potent effects in reducing food intake and body weight in several rodent models of obesity. In the present study, we evaluated the effects of LY255582 to prevent the consumption of a highly palatable (HP) diet (a high-fat/high-carbohydrate diet) both when the food was novel and following daily limited access to the HP diet. Additionally, we examined the effects of consumption of the HP diet and of LY255582 treatment on mesolimbic dopamine (DA) signaling by in vivo microdialysis. Consumption of the HP diet increased extracellular DA levels within the nucleus accumbens (NAc) shell. Increased DA in the NAc shell was not related to the quantity of the HP diet consumed, and the DA response did not habituate following daily scheduled access to the HP diet. Interestingly, treatment with LY255582 inhibited consumption of the HP diet and the HP diet-associated increase in NAc shell DA levels. Moreover, the increased HP diet consumption observed following daily limited access to the HP diet was completely prevented by LY255582 treatment. LY255582 may be a useful tool in understanding the neural mechanisms involved in the reinforcement mechanisms regulating food intake.
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33
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Naleid AM, Grace MK, Chimukangara M, Billington CJ, Levine AS. Paraventricular opioids alter intake of high-fat but not high-sucrose diet depending on diet preference in a binge model of feeding. Am J Physiol Regul Integr Comp Physiol 2007; 293:R99-105. [PMID: 17428895 DOI: 10.1152/ajpregu.00675.2006] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous work from our laboratory indicates that when rats are given a choice between a high-fat and a high-sucrose diet, opioid blockade with naltrexone (NTX) in a reward-related site (central amygdala) inhibits intake of the preferred diet only, whereas NTX injected into a homeostasis-related site, such as the hypothalamic paraventricular nucleus (PVN), inhibits intake of both diets. However, other work suggests that opioids increase intake of fat specifically. The present study further investigates the role of PVN opioids in food choices made by calorically-replete animals. We used a binge model with chow-maintained rats given 3-h access to a choice of a high-fat or high-sucrose diet 3 days a week. We hypothesized that intra-PVN injection of the mu-opioid agonist, DAMGO (0, 0.025, 0.25, and 2.5 nmol) would enhance, and NTX (0, 10, 30, and 100 nmol) would inhibit intake of both diets to an equal extent. We found that when animals were divided into groups according to sucrose or fat preference, DAMGO increased fat intake in fat-consuming animals, while having no effect on intake of either diet in sucrose-consuming animals. NTX, however, inhibited fat intake in both groups. Intra-PVN NTX did not inhibit intake of sucrose when presented in the absence of a fat choice, but did so when injected peripherally. Furthermore, intra-PVN and systemic NTX inhibited intake of chow by 24-h-food-deprived animals. These results indicate a complex role for PVN opioids in food intake with preference, nutrient type, and energy state affecting the ability of these compounds to change behavior.
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Affiliation(s)
- Amy M Naleid
- Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave., St. Paul, MN 55108, USA
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Densmore VS, Morton NM, Mullins JJ, Seckl JR. 11 beta-hydroxysteroid dehydrogenase type 1 induction in the arcuate nucleus by high-fat feeding: A novel constraint to hyperphagia? Endocrinology 2006; 147:4486-95. [PMID: 16763061 DOI: 10.1210/en.2006-0106] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
11 beta-Hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) catalyzes regeneration of active intracellular glucocorticoids in fat, liver, and discrete brain regions. Although overexpression of 11 beta-HSD1 in adipose tissue causes hyperphagia and the metabolic syndrome, male 11 beta-HSD1 null (11 beta-HSD1-/-) mice resist metabolic disease on high-fat (HF) diet, but also show hyperphagia. This suggests 11 beta-HSD1 may influence the central actions of glucocorticoids on appetite and perhaps energy balance. We show that 11 beta-HSD1-/- mice express lower hypothalamic mRNA levels of the anorexigenic cocaine and amphetamine-regulated transcript and melanocortin-4 receptor, but higher levels of the orexigenic melanin-concentrating hormone mRNAs than controls (C57BL/6J) on a low-fat diet (11% fat). HF (58% fat) diet promoted transient ( approximately 8 wk) hyperphagia and decreased food efficiency in 11 beta-HSD1-/- mice and decreased melanocortin-4 receptor mRNA expression in control but not 11 beta-HSD1-/- mice. 11 beta-HSD1-/- mice showed a HF-mediated up-regulation of the orexigenic agouti-related peptide (AGRP) mRNA in the arcuate nucleus which paralleled the transient HF hyperphagia. Conversely, control mice showed a rapid (48 h) HF-mediated increase in arcuate 11 beta-HSD1 associated with subsequent down-regulation of AGRP. This regulatory pattern was unexpected because glucocorticoids increase AGRP, suggesting an alternate hyperphagic mechanism despite partial colocalization of 11 beta-HSD1 and AGRP in arcuate nucleus cells. One major alternate mechanism governing selective fat ingestion and the AGRP system is endogenous opioids. Treatment of HF-fed mice with the mu opioid agonist DAMGO recapitulated the HF-induced dissociation of arcuate AGRP expression between control and 11 beta-HSD1-/- mice, whereas the opioid antagonist naloxone given with HF induced a rise in arcuate AGRP and blocked HF-diet induction of 11 beta-HSD1. These data suggest that 11 beta-HSD1 in brain plays a role in the adaptive restraint of excess fat intake, in part by increasing inhibitory opioid tone on AGRP expression in the arcuate nucleus.
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Affiliation(s)
- Valerie S Densmore
- Endocrinology Unit, Queen's Medical Research Institute, Edinburgh EH16 4TJ, Scotland, United Kingdom
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35
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Statnick MA, Tinsley FC, Eastwood BJ, Suter TM, Mitch CH, Heiman ML. Peptides that regulate food intake: antagonism of opioid receptors reduces body fat in obese rats by decreasing food intake and stimulating lipid utilization. Am J Physiol Regul Integr Comp Physiol 2003; 284:R1399-408. [PMID: 12736177 DOI: 10.1152/ajpregu.00632.2002] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Agonists to opioid receptors induce a positive energy balance, whereas antagonists at these receptors reduce food intake and body weight in rodent models of obesity. An analog of 3,4-dimethyl-4-(3-hydroxyphenyl)piperidine, LY255582, is a potent non-morphinan antagonist for mu-, kappa-, and delta-receptors (K(i) of 0.4, 2.0, and 5.2 nM, respectively). In the present study, we examined the effects of oral LY255582 treatment on caloric intake, calorie expenditure, and body composition in dietary-induced obese rats. Acute oral treatment of LY255582 produced a dose-dependent decrease in energy intake and respiratory quotient (RQ), which correlated with the occupancy of central opioid receptors. Animals receiving chronic oral treatment with LY255582 for 14 days maintained a negative energy balance that was sustained by increased lipid use. Analysis of body composition revealed a reduction in fat mass accretion, with no change in lean body mass, in animals treated with LY255582. Therefore, chronic treatment with LY255582 reduces adipose tissue mass by reducing energy intake and stimulating lipid use.
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Affiliation(s)
- Michael A Statnick
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, Indiana 46285-0545, USA.
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36
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Glass MJ, Grace MK, Cleary JP, Billington CJ, Levine AS. Naloxone's effect on meal microstructure of sucrose and cornstarch diets. Am J Physiol Regul Integr Comp Physiol 2001; 281:R1605-12. [PMID: 11641133 DOI: 10.1152/ajpregu.2001.281.5.r1605] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The opioid receptor antagonist naloxone decreases consumption of high-sucrose diets but does not reduce cornstarch diet intake in energy-restricted rats. Sucrose-fed rats eat at a much higher rate, consuming more food than cornstarch-fed rats. We examined meal microstructure using an automated weighing system in food-restricted rats eating either a high-sucrose or high-cornstarch diet. Sucrose-fed rats exhibited a higher rate of eating during their first meal compared with cornstarch-fed rats (0.34 vs. 0.20 g/min, respectively). However, naloxone did not reduce eating rate in either group. Naloxone decreased the size of the first meal in both diet groups by shortening the length of the meal. Naloxone's anorectic effect was more potent in the sucrose-fed rats. These results indicate that naloxone's heightened anorectic effect on sucrose diet consumption is not "rate dependent." Naloxone's anorectic actions may be modulated by two conditions, the sensory properties of food and the energy state of the animal. Thus the elevated anorectic potency of naloxone in energy-restricted sucrose-fed rats may reflect actions on neural systems that mediate orosensory and/or postingestive signals.
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Affiliation(s)
- M J Glass
- Minnesota Obesity Center, Veterans Affairs Medical Center, Minneapolis 55417, USA
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37
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Glass MJ, Billington CJ, Levine AS. Naltrexone administered to central nucleus of amygdala or PVN: neural dissociation of diet and energy. Am J Physiol Regul Integr Comp Physiol 2000; 279:R86-92. [PMID: 10896868 DOI: 10.1152/ajpregu.2000.279.1.r86] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is evidence that opioids may affect food consumption through mechanisms as diverse as reward or energy metabolism. However, these hypotheses are derived from studies employing peripheral or, more rarely, intracerebroventricular administration of drugs. Opioid receptors have a wide distribution in the central nervous system and include a number of regions implicated in food intake such as the hypothalamic paraventricular nucleus (PVN) and the central nucleus of the amygdala (ACe). It is not known whether local opioid receptor blockade in either of these regions will produce similar effects on food intake. To examine this issue, a chronic cannula was aimed at either the PVN or ACe of rats that were fed a choice of a high-fat and high-carbohydrate diet, which allows for the measurement of both preference and total energy consumption. Naltrexone influenced preferred and nonpreferred food consumption, depending on the site of administration. Consumption of both preferred and nonpreferred diets was suppressed after PVN naltrexone administration, whereas only preferred diet intake was reduced after ACe injection of naltrexone. The present evidence indicates that direct stimulation of different brain regions with naltrexone may be associated with diverse effects on diet selection, which may be accounted for by manipulation of specific functional neural circuitry.
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Affiliation(s)
- M J Glass
- Minnesota Obesity Center, Departments of Psychiatry, Psychology, and Medicine, Veterans Affairs Medical Center and the University of Minnesota, Minneapolis, Minnesota, 55417, USA
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