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Weiner SP, Carr KD. Behavioral tests of the insulin-cholinergic-dopamine link in nucleus accumbens and inhibition by high fat-high sugar diet in male and female rats. Physiol Behav 2024; 284:114647. [PMID: 39067780 PMCID: PMC11323239 DOI: 10.1016/j.physbeh.2024.114647] [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: 05/13/2024] [Revised: 07/20/2024] [Accepted: 07/23/2024] [Indexed: 07/30/2024]
Abstract
It was previously shown in striatal slices obtained from male rats that insulin excites cholinergic interneurons and increases dopamine (DA) release via α4β2 nicotinic receptors on DA terminals. The effect of insulin on DA release was blocked either by maintaining rats on a high sugar-high fat (HS-HF) diet that induced hyperinsulinemia and nucleus accumbens (NAc) insulin receptor insensitivity, or applying the α4β2 antagonist DHβE. In vivo, NAc shell insulin inactivation decreased a glucose lick microstructure parameter indicative of hedonic impact in male and female rats, and prevented flavor-nutrient learning, tested only in males. The HS-HF diet decreased hedonic impact in males but not females, and prevented flavor-nutrient learning, tested only in males. The present study extends testing to more fully assess the translation of brain slice results to the behaving rat. Insulin inactivation by antibody microinjection in NAc shell was found to decrease the number of lick bursts emitted and average lick burst size, measures of incentive motivation and hedonic impact respectively, for a wide range of glucose concentrations in male and female rats. In contrast, the HS-HF diet decreased these lick parameters in males but not females. Follow-up two-bottle choice tests for 10 % versus 40 % glucose showed decreased intake of both concentrations by males but increased intake of 40 % glucose by females. In a further set of experiments, it was predicted that α4β2 receptor blockade would induce the same behavioral effects as insulin inactivation. In females, DHβE microinjection in NAc shell decreased both lick parameters for glucose as predicted, but in males only the number of lick bursts emitted was decreased. DHβE also decreased the number of lick bursts emitted for saccharin by females but not males. Finally, DHβE microinjection in NAc shell decreased flavor-nutrient learning in both sexes. The few discrepancies seen with regard to the hypothesized insulin-nicotinic-dopaminergic regulation of behavioral responses to nutritive sweetener, and its inhibition by HS-HF diet, are discussed with reference to sex differences in DA dynamics, female resistance to diet-induced metabolic morbidities, and extra-striatal cholinergic inputs to NAc.
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Affiliation(s)
- Sydney P Weiner
- Departments of Psychiatry, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA
| | - Kenneth D Carr
- Departments of Psychiatry, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA; Departments of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, 435 East 30th Street, New York, NY 10016, USA.
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2
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Tufvesson-Alm M, Zhang Q, Aranäs C, Blid Sköldheden S, Edvardsson CE, Jerlhag E. Decoding the influence of central LEAP2 on food intake and its effect on accumbal dopamine release. Prog Neurobiol 2024; 236:102615. [PMID: 38641041 DOI: 10.1016/j.pneurobio.2024.102615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/03/2024] [Accepted: 04/16/2024] [Indexed: 04/21/2024]
Abstract
The gut-brain peptide ghrelin and its receptor are established as a regulator of hunger and reward-processing. However, the recently recognized ghrelin receptor inverse agonist, liver-expressed antimicrobial peptide 2 (LEAP2), is less characterized. The present study aimed to elucidate LEAP2s central effect on reward-related behaviors through feeding and its mechanism. LEAP2 was administrated centrally in mice and effectively reduced feeding and intake of palatable foods. Strikingly, LEAP2s effect on feeding was correlated to the preference of the palatable food. Further, LEAP2 reduced the rewarding memory of high preference foods, and attenuated the accumbal dopamine release associated with palatable food exposure and eating. Interestingly, LEAP2 was widely expressed in the brain, and particularly in reward-related brain areas such as the laterodorsal tegmental area (LDTg). This expression was markedly altered when allowed free access to palatable foods. Accordingly, infusion of LEAP2 into LDTg was sufficient to transiently reduce acute palatable food intake. Taken together, the present results show that central LEAP2 has a profound effect on dopaminergic reward signaling associated with food and affects several aspects of feeding. The present study highlights LEAP2s effect on reward, which may have applications for obesity and other reward-related psychiatric and neurological disorders.
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Affiliation(s)
- Maximilian Tufvesson-Alm
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden
| | - Qian Zhang
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden
| | - Cajsa Aranäs
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden
| | - Sebastian Blid Sköldheden
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden
| | - Christian E Edvardsson
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 13A, Gothenburg SE-405 30, Sweden.
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3
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Ayman J, Palotai M, Dochnal R, Bagosi Z. Ghrelin Amplifies the Nicotine-Induced Release of Dopamine in the Bed Nucleus of Stria Terminalis (BNST). Biomedicines 2023; 11:2456. [PMID: 37760897 PMCID: PMC10525377 DOI: 10.3390/biomedicines11092456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/02/2023] [Accepted: 09/03/2023] [Indexed: 09/29/2023] Open
Abstract
Ghrelin is an orexigenic neuropeptide that is known for stimulating the release of growth hormone (GH) and appetite. In addition, ghrelin has been implicated in addiction to drugs such as nicotine. Nicotine is the principal psychoactive component in tobacco and is responsible for the reward sensation produced by smoking. In our previous in vitro superfusion studies, it was demonstrated that ghrelin and nicotine stimulate equally the dopamine release in the rat amygdala, and ghrelin amplifies the nicotine-induced dopamine release in the rat striatum. However, less attention was paid to the actions of ghrelin and nicotine in the bed nucleus of the stria terminalis (BNST). Therefore, in the present study, nicotine and ghrelin were superfused to the BNST of male Wistar rats, and the dopamine release from the BNST was measured in vitro. In order to determine which receptors mediate these effects, mecamylamine, a non-selective nicotinic acetylcholine receptor (nAchR) antagonist, and GHRP-6, a selective growth hormone secretagogue receptor (GHS-R1A) antagonist, were also superfused to the rat BNST. Nicotine significantly increased the release of dopamine, and this effect was significantly inhibited by mecamylamine. Ghrelin increased dopamine release even more significantly than nicotine did, and this effect was significantly inhibited by GHRP-6. Moreover, when administered together, ghrelin significantly amplified the nicotine-induced release of dopamine in the BNST, and this additive effect was reversed partly by mecamylamine and partly by GHRP-6. Therefore, the present study provides a new base of evidence for the involvement of ghrelin in dopamine signaling implicated in nicotine addiction.
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Affiliation(s)
- Jázmin Ayman
- Department of Obstetrics and Gynecology, Albert Szent-Györgyi School of Medicine, University of Szeged, H-6701 Szeged, Hungary;
| | - Miklós Palotai
- Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
| | - Roberta Dochnal
- Department of Pediatrics and Pediatric Health Center, Albert Szent-Györgyi School of Medicine, University of Szeged, H-6701 Szeged, Hungary;
| | - Zsolt Bagosi
- Department of Pathophysiology, Albert Szent-Györgyi School of Medicine, University of Szeged, H-6725 Szeged, Hungary
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4
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Jin R, Sun S, Hu Y, Zhang H, Sun X. Neuropeptides Modulate Feeding via the Dopamine Reward Pathway. Neurochem Res 2023:10.1007/s11064-023-03954-4. [PMID: 37233918 DOI: 10.1007/s11064-023-03954-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 05/13/2023] [Accepted: 05/16/2023] [Indexed: 05/27/2023]
Abstract
Dopamine (DA) is a catecholamine neurotransmitter widely distributed in the central nervous system. It participates in various physiological functions, such as feeding, anxiety, fear, sleeping and arousal. The regulation of feeding is exceptionally complex, involving energy homeostasis and reward motivation. The reward system comprises the ventral tegmental area (VTA), nucleus accumbens (NAc), hypothalamus, and limbic system. This paper illustrates the detailed mechanisms of eight typical orexigenic and anorexic neuropeptides that regulate food intake through the reward system. According to recent literature, neuropeptides released from the hypothalamus and other brain regions regulate reward feeding predominantly through dopaminergic neurons projecting from the VTA to the NAc. In addition, their effect on the dopaminergic system is mediated by the prefrontal cortex, paraventricular thalamus, laterodorsal tegmental area, amygdala, and complex neural circuits. Research on neuropeptides involved in reward feeding can help identify more targets to treat diseases with metabolic disorders, such as obesity.
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Affiliation(s)
- Ruijie Jin
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, Shandong, China
- Department of Clinical Medicine, Medical College, Qingdao University, Qingdao, China
| | - Shanbin Sun
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, Shandong, China
- Department of Clinical Medicine, Medical College, Qingdao University, Qingdao, China
| | - Yang Hu
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, Shandong, China
- Department of Clinical Medicine, Medical College, Qingdao University, Qingdao, China
| | - Hongfei Zhang
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, Shandong, China
- Department of Clinical Medicine, Medical College, Qingdao University, Qingdao, China
| | - Xiangrong Sun
- Department of Physiology and Pathophysiology, School of Basic Medicine, Qingdao University, Qingdao, Shandong, China.
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5
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Geisler CE, Hayes MR. Metabolic Hormone Action in the VTA: Reward-Directed Behavior and Mechanistic Insights. Physiol Behav 2023; 268:114236. [PMID: 37178855 DOI: 10.1016/j.physbeh.2023.114236] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/10/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023]
Abstract
Dysfunctional signaling in midbrain reward circuits perpetuates diseases characterized by compulsive overconsumption of rewarding substances such as substance abuse, binge eating disorder, and obesity. Ventral tegmental area (VTA) dopaminergic activity serves as an index for how rewarding stimuli are perceived and triggers behaviors necessary to obtain future rewards. The evolutionary linking of reward with seeking and consuming palatable foods ensured an organism's survival, and hormone systems that regulate appetite concomitantly developed to regulate motivated behaviors. Today, these same mechanisms serve to regulate reward-directed behavior around food, drugs, alcohol, and social interactions. Understanding how hormonal regulation of VTA dopaminergic output alters motivated behaviors is essential to leveraging therapeutics that target these hormone systems to treat addiction and disordered eating. This review will outline our current understanding of the mechanisms underlying VTA action of the metabolic hormones ghrelin, glucagon-like peptide-1, amylin, leptin, and insulin to regulate behavior around food and drugs of abuse, highlighting commonalities and differences in how these five hormones ultimately modulate VTA dopamine signaling.
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Affiliation(s)
- Caroline E Geisler
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Matthew R Hayes
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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6
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Reich N, Hölscher C. Beyond Appetite: Acylated Ghrelin As A Learning, Memory and Fear Behavior-modulating Hormone. Neurosci Biobehav Rev 2022; 143:104952. [DOI: 10.1016/j.neubiorev.2022.104952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 04/27/2022] [Accepted: 11/05/2022] [Indexed: 11/10/2022]
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7
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Zhao P, Wang H, Li A, Sun Q, Jiang T, Li X, Gong H. The Mesoscopic Connectome of the Cholinergic Pontomesencephalic Tegmentum. Front Neuroanat 2022; 16:843303. [PMID: 35655583 PMCID: PMC9152021 DOI: 10.3389/fnana.2022.843303] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 03/29/2022] [Indexed: 11/25/2022] Open
Abstract
The pontomesencephalic tegmentum, comprising the pedunculopontine nucleus and laterodorsal tegmental nucleus, is involved in various functions via complex connections; however, the organizational structure of these circuits in the whole brain is not entirely clear. Here, combining viral tracing with fluorescent micro-optical sectional tomography, we comprehensively investigated the input and output circuits of two cholinergic subregions in a continuous whole-brain dataset. We found that these nuclei receive abundant input with similar spatial distributions but with different quantitative measures and acquire similar neuromodulatory afferents from the ascending reticular activation system. Meanwhile, these cholinergic nuclei project to similar targeting areas throughout multiple brain regions and have different spatial preferences in 3D. Moreover, some cholinergic connections are unidirectional, including projections from the pedunculopontine nucleus and laterodorsal tegmental nucleus to the ventral posterior complex of the thalamus, and have different impacts on locomotion and anxiety. These results reveal the integrated cholinergic connectome of the midbrain, thus improving the present understanding of the organizational structure of the pontine-tegmental cholinergic system from its anatomical structure to its functional modulation.
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Affiliation(s)
- Peilin Zhao
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, China
| | - Huading Wang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, China
| | - Anan Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, China
- HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, China
| | - Qingtao Sun
- HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, China
| | - Tao Jiang
- HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, China
| | - Xiangning Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, China
- HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, China
- *Correspondence: Xiangning Li,
| | - Hui Gong
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, MoE Key Laboratory for Biomedical Photonics, Huazhong University of Science and Technology, Wuhan, China
- HUST-Suzhou Institute for Brainsmatics, Jiangsu Industrial Technology Research Institute (JITRI), Suzhou, China
- Hui Gong,
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8
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Gupta S, Mukhopadhyay S, Mitra A. Therapeutic potential of GHSR-1A antagonism in alcohol dependence, a review. Life Sci 2022; 291:120316. [PMID: 35016882 DOI: 10.1016/j.lfs.2022.120316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 01/05/2022] [Accepted: 01/05/2022] [Indexed: 11/28/2022]
Abstract
Growth hormone secretagogue receptor type 1A (GHSR-1A) is a functional receptor of orexigenic peptide ghrelin and is highly expressed in mesolimbic dopaminergic systems that regulate incentive value of artificial reward in substance abuse. Interestingly, GHSR-1A has also shown ligand-independent constitutive activity. Alcohol use disorder (AUD) is one of the growing concerns worldwide as it involves complex neuro-psycho-endocrinological interactions. Positive correlation of acylated ghrelin and alcohol-induced human brain response in the right and left ventral striatum are evident. In the last decade, the beneficial effects of ghrelin receptor (GHSR-1A) antagonism to suppress artificial reward circuitries and induce self-control for alcohol consumption have drawn significant attention from researchers. In this updated review, we summarize the available recent preclinical, clinical, and experimental data to discuss functional, molecular actions of central ghrelin-GHSR-1A signaling in different craving levels for alcohol as well as to promote "GHSR-1A antagonism" as one of the potential therapies in early abstinence.
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Affiliation(s)
- Shreyasi Gupta
- Department of Zoology, Triveni Devi Bhalotia College, Raniganj, Paschim Bardhaman 713 347, West Bengal, India
| | - Sanchari Mukhopadhyay
- Department of Psychiatry, National Institute of Mental Health and Neurosciences, Hombegowda Nagar, Bengaluru 560029, India
| | - Arkadeep Mitra
- Department of Zoology, City College, 102/1, Raja Rammohan Sarani, Kolkata 700 009, West Bengal, India.
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9
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Rodrigues VST, Moura EG, Peixoto TC, Soares PN, Lopes BP, Oliveira E, Manhães AC, Atella GC, Kluck GEG, Cabral SS, Trindade PL, Daleprane JB, Lisboa PC. Changes in gut-brain axis parameters in adult rats of both sexes with different feeding pattern that were early nicotine-exposed. Food Chem Toxicol 2021; 158:112656. [PMID: 34740714 DOI: 10.1016/j.fct.2021.112656] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 01/09/2023]
Abstract
Nicotine is an endocrine disruptor and imprinting factor during breastfeeding that can cause food intake imbalance in the adulthood. As nicotine affects the intestinal microbiota, altering the composition of the bacterial communities and short-chain fatty acids (SCFAs) synthesis in a sex-dependent manner, we hypothesized that nicotine could program the gut-brain axis, consequently modifying the eating pattern of adult male and female rats in a model of maternal nicotine exposure (MNE) during breastfeeding. Lactating Wistar rat dams received minipumps that release 6 mg/kg/day of nicotine (MNE group) or saline for 14 days. The progeny received standard diet from weaning until euthanasia (26 weeks of age). We measured: in vivo electrical activity of the vagus nerve; c-Fos expression in the nucleus tractus solitarius, gastrointestinal peptides receptors, intestinal brain-derived neurotrophic factor (BDNF), SCFAs and microbiota. MNE females showed hyperphagia despite normal adiposity, while MNE males had unchanged food intake, despite obesity. Adult MNE offspring showed decreased Bacteroidetes and increased Firmicutes, Actinobacteria and Proteobacteria. MNE females had lower fecal acetate while MNE males showed higher vagus nerve activity. In summary nicotine exposure through the milk induces long-term intestinal dysbiosis, which may affect eating patterns of adult offspring in a sex-dependent manner.
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Affiliation(s)
- V S T Rodrigues
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - E G Moura
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - T C Peixoto
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - P N Soares
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - B P Lopes
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - E Oliveira
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - A C Manhães
- Neurophysiology Laboratory, Biology Institute, State University of Rio de Janeiro, RJ, Brazil
| | - G C Atella
- Laboratory of Lipids and Lipoprotein Biochemistry, Biochemistry Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | - G E G Kluck
- Laboratory of Lipids and Lipoprotein Biochemistry, Biochemistry Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | - S S Cabral
- Laboratory of Lipids and Lipoprotein Biochemistry, Biochemistry Institute, Federal University of Rio de Janeiro, RJ, Brazil
| | - P L Trindade
- Laboratory for Studies of Interactions Between Nutrition and Genetics, Nutrition Institute, Rio de Janeiro State University, RJ, Brazil
| | - J B Daleprane
- Laboratory for Studies of Interactions Between Nutrition and Genetics, Nutrition Institute, Rio de Janeiro State University, RJ, Brazil
| | - P C Lisboa
- Laboratory of Endocrine Physiology, Biology Institute, State University of Rio de Janeiro, RJ, Brazil.
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Micioni Di Bonaventura E, Botticelli L, Del Bello F, Giorgioni G, Piergentili A, Quaglia W, Cifani C, Micioni Di Bonaventura MV. Assessing the role of ghrelin and the enzyme ghrelin O-acyltransferase (GOAT) system in food reward, food motivation, and binge eating behavior. Pharmacol Res 2021; 172:105847. [PMID: 34438062 DOI: 10.1016/j.phrs.2021.105847] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 02/06/2023]
Abstract
The peripheral peptide hormone ghrelin is a powerful stimulator of food intake, which leads to body weight gain and adiposity in both rodents and humans. The hormone, thus, increases the vulnerability to obesity and binge eating behavior. Several studies have revealed that ghrelin's functions are due to its interaction with the growth hormone secretagogue receptor type 1a (GHSR1a) in the hypothalamic area; besides, ghrelin also promotes the reinforcing properties of hedonic food, acting at extra-hypothalamic sites and interacting with dopaminergic, cannabinoid, opioid, and orexin signaling. The hormone is primarily present in two forms in the plasma and the enzyme ghrelin O-acyltransferase (GOAT) allows the acylation reaction which causes the transformation of des-acyl-ghrelin (DAG) to the active form acyl-ghrelin (AG). DAG has been demonstrated to show antagonist properties; it is metabolically active, and counteracts the effects of AG on glucose metabolism and lipolysis, and reduces food consumption, body weight, and hedonic feeding response. Both peptides seem to influence the hypothalamic-pituitary-adrenal (HPA) axis and the corticosterone/cortisol level that drive the urge to eat under stressful conditions. These findings suggest that DAG and inhibition of GOAT may be targets for obesity and bingeing-related eating disorders and that AG/DAG ratio may be an important potential biomarker to assess the risk of developing maladaptive eating behaviors.
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Affiliation(s)
| | - Luca Botticelli
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 9, 62032 Camerino, Italy
| | - Fabio Del Bello
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Gianfabio Giorgioni
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Alessandro Piergentili
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Wilma Quaglia
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 9, 62032 Camerino, Italy.
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11
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Fan K, Li Q, Pan D, Liu H, Li P, Hai R, Du C. Effects of amylin on food intake and body weight via sympathetic innervation of the interscapular brown adipose tissue. Nutr Neurosci 2020; 25:343-355. [PMID: 32338170 DOI: 10.1080/1028415x.2020.1752998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Objective: Amylin acts on the lateral dorsal tegmental nucleus (LDT), resulting in anorexic and weight-loss effects and activates thermogenesis in the interscapular brown adipose tissue (IBAT). In addition, it induces neuronal nitric oxide synthase (nNOS) and choline acetyltransferase (ChAT)-mediated feeding. However, the influence of the intact sympathetic nervous system (SNS) in mediating amylin's effects has not been fully characterised. We investigated whether extracellular signal-regulated kinase (ERK), nNOS, and ChAT activities in the LDT are responsible for amylin's anorexigenic effects and whether this requires an intact SNS.Methods: C57BL/6J mice [wild-type (WT), sham, and sympathetic denervation of IBAT] were used. Food consumption, body weight, and distribution of pERK, nNOS, and ChAT positive neurons in the brain were examined following acute and chronic amylin administration.Results: Food intake was significantly decreased in WT and sham animals following acute amylin injection, but not in the denervated mice. Chronic amylin reduced body weight and serum glucose levels after 6 weeks, but increased insulin levels; no changes were observed in the denervated mice. Acute amylin increased the expression of nNOS, ChAT, and uncoupling protein-1 in the IBAT of WT and sham mice, while no changes were observed in the denervated mice and pERK from the above effect.Conclusions: Intact SNS of IBAT influences amylin-induced suppression of food intake and body weight, thus affecting nNOS and ChAT signalling in the LDT and locus coeruleus.
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Affiliation(s)
- Kuikui Fan
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China
| | - Qiang Li
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China
| | - Deng Pan
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China
| | - Haodong Liu
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China
| | - Penghui Li
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China
| | - Rihan Hai
- Vocational and Technical College, Inner Mongolia Agricultural University, Baotou, People's Republic of China
| | - Chenguang Du
- Inner Mongolia Key Laboratory of Basic Veterinary Science, Hohhot, People's Republic of China.,College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot, People's Republic of China.,Vocational and Technical College, Inner Mongolia Agricultural University, Baotou, People's Republic of China
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12
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Modeling drug exposure in rodents using e-cigarettes and other electronic nicotine delivery systems. J Neurosci Methods 2019; 330:108458. [PMID: 31614162 DOI: 10.1016/j.jneumeth.2019.108458] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 10/05/2019] [Accepted: 10/06/2019] [Indexed: 12/25/2022]
Abstract
Smoking tobacco products is the leading cause of preventable death worldwide. Coordinated efforts have successfully reduced tobacco cigarette smoking in the United States; however, electronic cigarettes (e-cigarette) and other electronic nicotine delivery systems (ENDS) recently have replaced traditional cigarettes for many users. While the clinical risks associated with long-term ENDS use remain unclear, advancements in preclinical rodent models will enhance our understanding of their overall health effects. This review examines the peripheral and central effects of ENDS-mediated exposure to nicotine and other drugs of abuse in rodents and evaluates current techniques for implementing ENDS in preclinical research.
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Nazari-Serenjeh F, Darbandi N, Majidpour S, Moradi P. Ghrelin modulates morphine-nicotine interaction in avoidance memory: Involvement of CA1 nicotinic receptors. Brain Res 2019; 1720:146315. [DOI: 10.1016/j.brainres.2019.146315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 11/29/2022]
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14
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Löfgren M, Holmberg E, Bäckström T, Egecioglu E, Dickson SL. The additive effect of allopregnanolone on ghrelin's orexigenic effect in rats. Neuropeptides 2019; 76:101937. [PMID: 31253440 DOI: 10.1016/j.npep.2019.101937] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 06/08/2019] [Accepted: 06/12/2019] [Indexed: 11/20/2022]
Abstract
The progesterone metabolite, allopregnanolone (AlloP), is a GABAA receptor modulating steroid and is known to have orexigenic and pro-obesity effects. The neurobiological mechanisms underpinning these effects are most likely due to enhanced GABAergic signaling in the lateral arcuate nucleus (ARC) and medial paraventricular nucleus (PVN) of the hypothalamus. Inspired by the finding that GABAergic signaling is also important for the orexigenic effects of the circulating hormone, ghrelin, we sought to determine the extent to which AlloP (one of the most potent endogenous GABAA-receptor modulators) operates alongside ghrelin to enhance food intake. Male rats with ad libitum access to standard chow were injected intravenously with AlloP and/or ghrelin, alone or in combination. The intake of the standard chow was greater after AlloP 1 mg/kg together with ghrelin 30 μg/kg than with 30 μg/kg ghrelin alone. Food intake was also increased for the combined treatment of AlloP 0.5 mg/kg + ghrelin 10 μg/kg, AlloP 1 mg/kg + ghrelin 10 μg/kg, and AlloP 0.5 mg/kg + ghrelin 30 μg/kg. There was no significant difference in food intake between the two ghrelin doses or between the two doses of AlloP and the vehicle. In electrophysiological studies, physiologically relevant concentrations of AlloP prolonged the current decay time of spontaneous inhibitory post-synaptic current of dissociated cells of the ARC and PVN. We conclude that AlloP enhances the hyperphagic effect of ghrelin, findings of potential relevance for the hyperphagia associated with the luteal phase of the reproductive cycle.
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Affiliation(s)
- Magnus Löfgren
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden.
| | - Ellinor Holmberg
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden
| | - Torbjörn Bäckström
- Department of Clinical Sciences, Obstetrics and Gynaecology, Umeå University Hospital, SE-Building QA, 3rd floor, 901 85 Umeå, Sweden
| | - Emil Egecioglu
- Department of Experimental Medical Science, Appetite Regulation Unit, Faculty of Medicine, Lund University, 221 84 Lund, Sweden
| | - Suzanne L Dickson
- Institute for Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, P.O. Box 434, SE-405 30 Gothenburg, Sweden
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15
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Jerlhag E. Gut-brain axis and addictive disorders: A review with focus on alcohol and drugs of abuse. Pharmacol Ther 2018; 196:1-14. [PMID: 30439457 DOI: 10.1016/j.pharmthera.2018.11.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Due to the limited efficacy of existing medications for addictive disorders including alcohol use disorder (AUD), the need for additional medications is substantial. Potential new medications for addiction can be identified through investigation of the neurochemical substrates mediating the ability of drugs of abuse such as alcohol to activate the mesolimbic dopamine system. Interestingly, recent studies implicate neuropeptides of the gut-brain axis as modulators of reward and addiction processes. The present review therefore summarizes the current studies investigating the ability of the gut-brain peptides ghrelin, glucagon-like peptide-1 (GLP-1), amylin and neuromedin U (NMU) to modulate alcohol- and drug-related behaviors in rodents and humans. Extensive literature demonstrates that ghrelin, the only known orexigenic neuropeptide to date, enhances reward as well as the intake of alcohol, and other drugs of abuse, while ghrelin receptor antagonism has the opposite effects. On the other hand, the anorexigenic peptides GLP-1, amylin and NMU independently inhibits reward from alcohol and drugs of abuse in rodents. Collectively, these rodent and human studies imply that central ghrelin, GLP-1, amylin and NMU signaling may contribute to addiction processes. Therefore, the need for randomized clinical trials investigating the effects of agents targeting these aforementioned systems on drug/alcohol use is substantial.
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Affiliation(s)
- Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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16
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Sztainert T, Hay R, Wohl MJA, Abizaid A. Hungry to gamble? Ghrelin as a predictor of persistent gambling in the face of loss. Biol Psychol 2018; 139:115-123. [PMID: 30392826 DOI: 10.1016/j.biopsycho.2018.10.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 10/18/2018] [Accepted: 10/18/2018] [Indexed: 01/08/2023]
Abstract
Ghrelin, a peptide hormone associated with appetite, is also linked to increased reward seeking behaviors, including food, sex, and drug seeking behaviors through the stimulation of the mesolimbic dopaminergic system. Moreover, plasma ghrelin concentrations are increased by cues that predict rewards, suggesting that cues could facilitate cravings and ultimately relapse. In this project we examined the effects of an overnight fast, a manipulation known to increase ghrelin concentrations, on gambling behaviors. We also examined if cues associated with gambling would also increase ghrelin and, if so, we examined if these increases were associated with gambling behavior. One hundred and one (37 females) participants were asked to fast overnight or after breakfast and then asked to complete food and gambling craving questionnaires. Participants were then presented with gambling cues (a casino like environment in the lab) or a control cue (a cubicle with a computer). After the cue, subjects filled gambling craving questionnaires, and were allowed to gamble. Following 25 practice spins, the slot machines were fixed so that all subsequent spins were losses, and the number of spins in spite of losses were quantified. Blood samples were collected throughout the experiment. Results showed that the gambling cues significantly increased ghrelin concentrations particularly in fasted individuals, and that ghrelin concentrations 20 min after the cue were the best predictor for gambling persistence in the face of continued loss (p < 0.05). Our results suggest that cues that predict the opportunity to gamble have an acute effect on ghrelin concentrations that is facilitated by fasting, and that ghrelin concentrations are a significant predictor of gambling persistence.
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Affiliation(s)
| | - Rebecca Hay
- Carleton University Department of Neuroscience, Canada
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17
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Hu T, Yang Z, Li MD. Pharmacological Effects and Regulatory Mechanisms of Tobacco Smoking Effects on Food Intake and Weight Control. J Neuroimmune Pharmacol 2018; 13:453-466. [PMID: 30054897 DOI: 10.1007/s11481-018-9800-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/16/2018] [Indexed: 12/26/2022]
Abstract
Beyond promoting smoking initiation and preventing smokers from quitting, nicotine can reduce food intake and body weight and thus is viewed as desirable by some smokers, especially many women. During the last several decades, the molecular mechanisms underlying the inverse correlation between smoking and body weight have been investigated extensively in both animals and humans. Nicotine's weight effects appear to result especially from the drug's stimulation of α3β4 nicotine acetylcholine receptors (nAChRs), which are located on pro-opiomelanocortin (POMC) neurons in the arcuate nucleus (ARC), leading to activation of the melanocortin circuit, which is associated with body weight. Further, α7- and α4β2-containing nAChRs have been implicated in weight control by nicotine. This review summarizes current understanding of the regulatory effects of nicotine on food intake and body weight according to the findings from pharmacological, molecular genetic, electrophysiological, and feeding studies on these appetite-regulating molecules, such as α3β4, α7, and α4β2 nAChRs; neuropeptide Y (NPY); POMC; melanocortin 4 receptor (MC4R); agouti-related peptide (AgRP); leptin, ghrelin, and protein YY (PYY).
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Affiliation(s)
- Tongyuan Hu
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhongli Yang
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China.
| | - Ming D Li
- State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, China. .,Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, China. .,Institute of Neuroimmune Pharmacology, Seton Hall University, South Orange, NJ, USA.
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18
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Waguespack HF, Málková L, Forcelli PA, Turchi J. Effects of systemic cholinergic antagonism on reinforcer devaluation in macaques. Neurosci Lett 2018; 678:62-67. [PMID: 29729357 DOI: 10.1016/j.neulet.2018.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/27/2018] [Accepted: 05/01/2018] [Indexed: 11/16/2022]
Abstract
The capacity to adjust actions based on new information is a vital cognitive function. An animal's ability to adapt behavioral responses according to changes in reward value can be measured using a reinforcer devaluation task, wherein the desirability of a given object is reduced by decreasing the value of the associated food reinforcement. Elements of the neural circuits serving this ability have been studied in both rodents and nonhuman primates. Specifically, the basolateral amygdala, orbitofrontal cortex, nucleus accumbens, and mediodorsal thalamus have each been shown to play a critical role in the process of value updating, required for adaptive goal selection. As these regions receive dense cholinergic input, we investigated whether systemic injections of non-selective nicotinic or muscarinic acetylcholine receptor antagonists, mecamylamine and scopolamine, respectively, would impair performance on a reinforcer devaluation task. Here we demonstrate that in the presence of either a nicotinic or muscarinic antagonist, animals are able to shift their behavioral responses in an appropriate manner, suggesting that disruption of cholinergic neuromodulation is not sufficient to disrupt value updating, and subsequent goal selection, in rhesus macaques.
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Affiliation(s)
- Hannah F Waguespack
- Department of Pharmacology & Physiology, Georgetown University, New Research Bldg., 3970 Reservoir Rd. NW, Washington, DC 20007, USA.
| | - Ludise Málková
- Department of Pharmacology & Physiology, Georgetown University, New Research Bldg., 3970 Reservoir Rd. NW, Washington, DC 20007, USA.
| | - Patrick A Forcelli
- Department of Pharmacology & Physiology, Georgetown University, New Research Bldg., 3970 Reservoir Rd. NW, Washington, DC 20007, USA.
| | - Janita Turchi
- Laboratory of Neuropsychology, NIMH, NIH, Bethesda, MD 20892, USA.
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19
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Reiner DJ, Leon RM, McGrath LE, Koch-Laskowski K, Hahn JD, Kanoski SE, Mietlicki-Baase EG, Hayes MR. Glucagon-Like Peptide-1 Receptor Signaling in the Lateral Dorsal Tegmental Nucleus Regulates Energy Balance. Neuropsychopharmacology 2018; 43:627-637. [PMID: 28920591 PMCID: PMC5770766 DOI: 10.1038/npp.2017.225] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/12/2017] [Accepted: 09/13/2017] [Indexed: 01/05/2023]
Abstract
The neurobiological substrates that mediate the anorectic effects of both endogenous glucagon-like peptide-1 (GLP-1) and exogenous GLP-1 receptor (GLP-1R) agonists are an active area of investigation. As the lateral dorsal tegmental nucleus (LDTg) expresses the GLP-1R and represents a potential neuroanatomical hub connecting the nucleus tractus solitarius (NTS), the major central source of GLP-1, with the other nuclei in the midbrain and forebrain, we tested the hypothesis that GLP-1R signaling in the LDTg controls food intake. Direct activation of LDTg GLP-1R suppresses food intake through a reduction in average meal size and independent of nausea/malaise. Immunohistochemical data show that GLP-1-producing neurons in the NTS project to the LDTg, providing anatomical evidence of endogenous central GLP-1 in the LDTg. Pharmacological blockade of LDTg GLP-1Rs with exendin-(9-39) dose-dependently increases food intake and attenuates the hypophagic effects of gastric distension. As GLP-1 mimetics are administered systemically in humans, we evaluated whether peripherally administered GLP-1R agonists access the LDTg to affect feeding. Immunohistochemical data show that a systemically administered fluorescent GLP-1R agonist accesses the LDTg and is juxtaposed with neurons. Additionally, blockade of LDTg GLP-1Rs attenuates the hypophagic effects of a systemic GLP-1R agonist. Together, these data indicate that LDTg GLP-1R signaling controls energy balance and underscores the role of the LDTg in integrating energy balance-relevant signals to modulate feeding.
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Affiliation(s)
- David J Reiner
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA
| | - Rosa M Leon
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA
| | - Lauren E McGrath
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA
| | - Kieran Koch-Laskowski
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA
| | - Joel D Hahn
- Neurobiology Section, University of Southern California, Los Angeles, CA, USA
| | - Scott E Kanoski
- Human and Evolutionary Biology Section, University of Southern California, Los Angeles, CA, USA
| | - Elizabeth G Mietlicki-Baase
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA
| | - Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Department of Biological Sciences, University of Pennsylvania, Center for Neurobiology and Behavior, Philadelphia, PA, USA,Department of Psychiatry, University of Pennsylvania, Center for Neurobiology and Behavior, 125 S. 31st St, Philadelphia, PA 19104, USA, Tel: +1 215 573 6070, Fax: +1 215 573 2041, E-mail:
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20
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Kalafateli AL, Vallöf D, Jörnulf JW, Heilig M, Jerlhag E. A cannabinoid receptor antagonist attenuates ghrelin-induced activation of the mesolimbic dopamine system in mice. Physiol Behav 2017; 184:211-219. [PMID: 29221808 DOI: 10.1016/j.physbeh.2017.12.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 12/04/2017] [Accepted: 12/05/2017] [Indexed: 01/26/2023]
Abstract
Ghrelin has been attributed various physiological processes including food intake and reward regulation, through activation of the mesolimbic dopamine system. Reward modulation involves the mesolimbic dopamine system, consisting of the ventral tegmental area (VTA) dopamine neurons targeting nucleus accumbens (NAc), a system that ghrelin activates through VTA-dependent mechanisms. In the first study, we found that systemic intraperitoneal (ip) administration of rimonabant attenuated intracerebroventricular (icv) ghrelin's ability to cause locomotor stimulation and NAc dopamine release in mice. Ghrelin-induced (icv) chow intake was not altered by rimonabant administration (ip). Finally, we showed that bilateral VTA administration of rimonabant blocks the ability of intra-VTA administered ghrelin to increase locomotor activity, but does not affect food intake in mice. Collectively, these data indicate clear dissociation between regulation of food intake and activation of the mesolimbic dopamine system.
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Affiliation(s)
- Aimilia Lydia Kalafateli
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Daniel Vallöf
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Julia Winsa Jörnulf
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Markus Heilig
- Center for Social and Affective Neuroscience, Division of Neuro and Inflammation Sciences, Linköping University, Linköping, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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21
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Reiner DJ, Mietlicki-Baase EG, Olivos DR, McGrath LE, Zimmer DJ, Koch-Laskowski K, Krawczyk J, Turner CA, Noble EE, Hahn JD, Schmidt HD, Kanoski SE, Hayes MR. Amylin Acts in the Lateral Dorsal Tegmental Nucleus to Regulate Energy Balance Through Gamma-Aminobutyric Acid Signaling. Biol Psychiatry 2017; 82:828-838. [PMID: 28237459 PMCID: PMC5503810 DOI: 10.1016/j.biopsych.2016.12.028] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 12/13/2016] [Accepted: 12/28/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND The pancreatic- and brain-derived hormone amylin promotes negative energy balance and is receiving increasing attention as a promising obesity therapeutic. However, the neurobiological substrates mediating amylin's effects are not fully characterized. We postulated that amylin acts in the lateral dorsal tegmental nucleus (LDTg), an understudied neural processing hub for reward and homeostatic feeding signals. METHODS We used immunohistochemical and quantitative polymerase chain reaction analyses to examine expression of the amylin receptor complex in rat LDTg tissue. Behavioral experiments were performed to examine the mechanisms underlying the hypophagic effects of amylin receptor activation in the LDTg. RESULTS Immunohistochemical and quantitative polymerase chain reaction analyses show expression of the amylin receptor complex in the LDTg. Activation of LDTg amylin receptors by the agonist salmon calcitonin dose-dependently reduces body weight, food intake, and motivated feeding behaviors. Acute pharmacological studies and longer-term adeno-associated viral knockdown experiments indicate that LDTg amylin receptor signaling is physiologically and potentially preclinically relevant for energy balance control. Finally, immunohistochemical data indicate that LDTg amylin receptors are expressed on gamma-aminobutyric acidergic neurons, and behavioral results suggest that local gamma-aminobutyric acid receptor signaling mediates the hypophagia after LDTg amylin receptor activation. CONCLUSIONS These findings identify the LDTg as a novel nucleus with therapeutic potential in mediating amylin's effects on energy balance through gamma-aminobutyric acid receptor signaling.
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Affiliation(s)
- David J Reiner
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Elizabeth G Mietlicki-Baase
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Diana R Olivos
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Lauren E McGrath
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Derek J Zimmer
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Kieran Koch-Laskowski
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Joanna Krawczyk
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Christopher A Turner
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania; Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Emily E Noble
- Department of Biological Sciences, Human and Evolutionary Biology Section, Los Angeles, California
| | - Joel D Hahn
- Neurobiology Section, University of Southern California, Los Angeles, California
| | - Heath D Schmidt
- Department of Biobehavioral Health Sciences, School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Scott E Kanoski
- Department of Biological Sciences, Human and Evolutionary Biology Section, Los Angeles, California
| | - Matthew R Hayes
- Translational Neuroscience Program, Department of Psychiatry, Perelman School of Medicine, Philadelphia, Pennsylvania.
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22
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The GHR-R antagonist JMV 2959 neither induces malaise nor alters the malaise property of LiCl in the adult male rat. Physiol Behav 2017; 183:46-48. [PMID: 29056353 DOI: 10.1016/j.physbeh.2017.10.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 10/18/2022]
Abstract
The orexigenic peptide ghrelin (GHR) interacts with ghrelin receptors (GHR-Rs) to modulate brain reinforcement and feeding circuits. Pharmacological inactivation of GHR-Rs via administration of the drug JMV 2959 attenuates the rewarding/reinforcing effects of several drugs of abuse including alcohol, morphine, amphetamine and nicotine. One view of these results is that inactivation of GHR-Rs taps into brain reinforcement/feeding circuits acted upon by drugs of abuse. An alternate explanation is that JMV 2959 may induce malaise, which in turn may limit reinforcement as well as food ingestion. This is a variable of interest given that nicotine alone can induce malaise which may be enhanced by JMV 2959. In the present study, we assessed the capacity of JMV 2959 to produce malaise using a conditioned taste aversion (CTA) task. Adult male rats were allowed to consume a 0.1% sodium saccharin solution and then injected IP with either vehicle, 0.4mg/kg nicotine, 3mg/kg JMV 2959, a combination of 0.4mg/kg nicotine and 3mg/kg JMV 2959, or 32mg/kg lithium chloride (a positive control known to support induction of CTA). Lithium chloride produced a robust avoidance of the saccharin solution in subsequent 2 bottle (water and saccharin) tests, whereas JMV 2959 alone did not induce CTA. The combination of JMV 2959 and nicotine induced a moderate degree of CTA that was similar to that produced by nicotine alone. These results suggest that JMV 2959 is unlikely to limit either reinforcement or food ingestion via induction of malaise.
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23
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Stojakovic A, Espinosa EP, Farhad OT, Lutfy K. Effects of nicotine on homeostatic and hedonic components of food intake. J Endocrinol 2017; 235:R13-R31. [PMID: 28814527 PMCID: PMC5578410 DOI: 10.1530/joe-17-0166] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 07/17/2017] [Indexed: 12/30/2022]
Abstract
Chronic tobacco use leads to nicotine addiction that is characterized by exaggerated urges to use the drug despite the accompanying negative health and socioeconomic burdens. Interestingly, nicotine users are found to be leaner than the general population. Review of the existing literature revealed that nicotine affects energy homeostasis and food consumption via altering the activity of neurons containing orexigenic and anorexigenic peptides in the brain. Hypothalamus is one of the critical brain areas that regulates energy balance via the action of these neuropeptides. The equilibrium between these two groups of peptides can be shifted by nicotine leading to decreased food intake and weight loss. The aim of this article is to review the existing literature on the effect of nicotine on food intake and energy homeostasis and report on the changes that nicotine brings about in the level of these peptides and their receptors that may explain changes in food intake and body weight induced by nicotine. Furthermore, we review the effect of nicotine on the hedonic aspect of food intake. Finally, we discuss the involvement of different subtypes of nicotinic acetylcholine receptors in the regulatory action of nicotine on food intake and energy homeostasis.
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Affiliation(s)
- Andrea Stojakovic
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
- Mitochondrial Neurobiology and Therapeutics LaboratoryMayo Clinic, Rochester, Minnesota, USA
| | - Enma P Espinosa
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
- Faculty of MedicineSchool of Clinica Biochemistry, Pontifical Catholic University of Ecuador (PUCE), Quito, Ecuador
| | - Osman T Farhad
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
| | - Kabirullah Lutfy
- Department of Pharmaceutical SciencesCollege of Pharmacy, Western University of Health Sciences, Pomona, California, USA
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24
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Sominsky L, Hodgson DM, McLaughlin EA, Smith R, Wall HM, Spencer SJ. Linking Stress and Infertility: A Novel Role for Ghrelin. Endocr Rev 2017; 38:432-467. [PMID: 28938425 DOI: 10.1210/er.2016-1133] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 07/24/2017] [Indexed: 12/23/2022]
Abstract
Infertility affects a remarkable one in four couples in developing countries. Psychological stress is a ubiquitous facet of life, and although stress affects us all at some point, prolonged or unmanageable stress may become harmful for some individuals, negatively impacting on their health, including fertility. For instance, women who struggle to conceive are twice as likely to suffer from emotional distress than fertile women. Assisted reproductive technology treatments place an additional physical, emotional, and financial burden of stress, particularly on women, who are often exposed to invasive techniques associated with treatment. Stress-reduction interventions can reduce negative affect and in some cases to improve in vitro fertilization outcomes. Although it has been well-established that stress negatively affects fertility in animal models, human research remains inconsistent due to individual differences and methodological flaws. Attempts to isolate single causal links between stress and infertility have not yet been successful due to their multifaceted etiologies. In this review, we will discuss the current literature in the field of stress-induced reproductive dysfunction based on animal and human models, and introduce a recently unexplored link between stress and infertility, the gut-derived hormone, ghrelin. We also present evidence from recent seminal studies demonstrating that ghrelin has a principal role in the stress response and reward processing, as well as in regulating reproductive function, and that these roles are tightly interlinked. Collectively, these data support the hypothesis that stress may negatively impact upon fertility at least in part by stimulating a dysregulation in ghrelin signaling.
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Affiliation(s)
- Luba Sominsky
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
| | - Deborah M Hodgson
- School of Psychology, Faculty of Science and IT, The University of Newcastle, New South Wales 2308, Australia
| | - Eileen A McLaughlin
- School of Biological Sciences, Faculty of Science, The University of Auckland, Auckland 1010, New Zealand.,School of Environmental & Life Sciences, Faculty of Science and IT, The University of Newcastle, New South Wales 2308, Australia
| | - Roger Smith
- Mothers and Babies Research Centre, Hunter Medical Research Institute, Lookout Road, New Lambton Heights, New South Wales 2305, Australia.,Priority Research Centre in Reproductive Science, The University of Newcastle, New South Wales 2308, Australia
| | - Hannah M Wall
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
| | - Sarah J Spencer
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia
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25
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Sasagawa T, Horii-Hayashi N, Okuda A, Hashimoto T, Azuma C, Nishi M. Long-term effects of maternal separation coupled with social isolation on reward seeking and changes in dopamine D1 receptor expression in the nucleus accumbens via DNA methylation in mice. Neurosci Lett 2017; 641:33-39. [DOI: 10.1016/j.neulet.2017.01.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/26/2016] [Accepted: 01/11/2017] [Indexed: 01/10/2023]
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Abstract
Obesity is a global epidemic that contributes to a number of health complications including cardiovascular disease, type 2 diabetes, cancer and neuropsychiatric disorders. Pharmacotherapeutic strategies to treat obesity are urgently needed. Research over the past two decades has increased substantially our knowledge of central and peripheral mechanisms underlying homeostatic energy balance. Homeostatic mechanisms involve multiple components including neuronal circuits, some originating in hypothalamus and brain stem, as well as peripherally-derived satiety, hunger and adiposity signals that modulate neural activity and regulate eating behavior. Dysregulation of one or more of these homeostatic components results in obesity. Coincident with obesity, reward mechanisms that regulate hedonic aspects of food intake override the homeostatic regulation of eating. In addition to functional interactions between homeostatic and reward systems in the regulation of food intake, homeostatic signals have the ability to alter vulnerability to drug abuse. Regarding the treatment of obesity, pharmacological monotherapies primarily focus on a single protein target. FDA-approved monotherapy options include phentermine (Adipex-P®), orlistat (Xenical®), lorcaserin (Belviq®) and liraglutide (Saxenda®). However, monotherapies have limited efficacy, in part due to the recruitment of alternate and counter-regulatory pathways. Consequently, a multi-target approach may provide greater benefit. Recently, two combination products have been approved by the FDA to treat obesity, including phentermine/topiramate (Qsymia®) and naltrexone/bupropion (Contrave®). The current review provides an overview of homeostatic and reward mechanisms that regulate energy balance, potential therapeutic targets for obesity and current treatment options, including some candidate therapeutics in clinical development. Finally, challenges in anti-obesity drug development are discussed.
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Affiliation(s)
- Vidya Narayanaswami
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, 40536, USA
| | - Linda P Dwoskin
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, 40536, USA.
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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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Edwards A, Abizaid A. Driving the need to feed: Insight into the collaborative interaction between ghrelin and endocannabinoid systems in modulating brain reward systems. Neurosci Biobehav Rev 2016; 66:33-53. [PMID: 27136126 DOI: 10.1016/j.neubiorev.2016.03.032] [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: 08/28/2015] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 01/29/2023]
Abstract
Independent stimulation of either the ghrelin or endocannabinoid system promotes food intake and increases adiposity. Given the similar distribution of their receptors in feeding associated brain regions and organs involved in metabolism, it is not surprising that evidence of their interaction and its importance in modulating energy balance has emerged. This review documents the relationship between ghrelin and endocannabinoid systems within the periphery and hypothalamus (HYP) before presenting evidence suggesting that these two systems likewise work collaboratively within the ventral tegmental area (VTA) to modulate non-homeostatic feeding. Mechanisms, consistent with current evidence and local infrastructure within the VTA, will be proposed.
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Affiliation(s)
- Alexander Edwards
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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Suchankova P, Nilsson S, Pahlen B, Santtila P, Sandnabba K, Johansson A, Jern P, Engel JA, Jerlhag E. Genetic variation of the growth hormone secretagogue receptor gene is associated with alcohol use disorders identification test scores and smoking. Addict Biol 2016; 21:481-8. [PMID: 26059200 PMCID: PMC5033010 DOI: 10.1111/adb.12277] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The multifaceted gut‐brain peptide ghrelin and its receptor (GHSR‐1a) are implicated in mechanisms regulating not only the energy balance but also the reward circuitry. In our pre‐clinical models, we have shown that ghrelin increases whereas GHSR‐1a antagonists decrease alcohol consumption and the motivation to consume alcohol in rodents. Moreover, ghrelin signaling is required for the rewarding properties of addictive drugs including alcohol and nicotine in rodents. Given the hereditary component underlying addictive behaviors and disorders, we sought to investigate whether single nucleotide polymorphisms (SNPs) located in the pre‐proghrelin gene (GHRL) and GHSR‐1a gene (GHSR) are associated with alcohol use, measured by the alcohol use disorders identification test (AUDIT) and smoking. Two SNPs located in GHRL, rs4684677 (Gln90Leu) and rs696217 (Leu72Met), and one in GHSR, rs2948694, were genotyped in a subset (n = 4161) of a Finnish population‐based cohort, the Genetics of Sexuality and Aggression project. The effect of these SNPs on AUDIT scores and smoking was investigated using linear and logistic regressions, respectively. We found that the minor allele of the rs2948694 SNP was nominally associated with higher AUDIT scores (P = 0.0204, recessive model) and smoking (P = 0.0002, dominant model). Furthermore, post hoc analyses showed that this risk allele was also associated with increased likelihood of having high level of alcohol problems as determined by AUDIT scores ≥ 16 (P = 0.0043, recessive model). These convergent findings lend further support for the hypothesized involvement of ghrelin signaling in addictive disorders.
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Affiliation(s)
- Petra Suchankova
- Department of Pharmacology Institute of Neuroscience and Physiology The Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Staffan Nilsson
- Department of Mathematical Statistics Institute of Mathematical Sciences Chalmers University of Technology Gothenburg Sweden
| | - Bettina Pahlen
- Department of Psychology and Logopedics Abo Akademi University Turku Finland
| | - Pekka Santtila
- Department of Psychology and Logopedics Abo Akademi University Turku Finland
| | - Kenneth Sandnabba
- Department of Psychology and Logopedics Abo Akademi University Turku Finland
| | - Ada Johansson
- Department of Pharmacology Institute of Neuroscience and Physiology The Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
- Department of Psychology and Logopedics Abo Akademi University Turku Finland
| | - Patrick Jern
- Department of Psychology and Logopedics Abo Akademi University Turku Finland
- Department of Behavioral Sciences and Philosophy University of Turku Turku Finland
| | - Jörgen A. Engel
- Department of Pharmacology Institute of Neuroscience and Physiology The Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology Institute of Neuroscience and Physiology The Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
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Prieto-Garcia L, Egecioglu E, Studer E, Westberg L, Jerlhag E. Ghrelin and GHS-R1A signaling within the ventral and laterodorsal tegmental area regulate sexual behavior in sexually naïve male mice. Psychoneuroendocrinology 2015; 62:392-402. [PMID: 26398679 DOI: 10.1016/j.psyneuen.2015.09.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/18/2015] [Accepted: 09/08/2015] [Indexed: 01/01/2023]
Abstract
In addition to food intake and energy balance regulation, ghrelin mediate the rewarding and motivational properties of palatable food as well as addictive drugs. The ability of ghrelin to regulate reinforcement involves the cholinergic-dopaminergic reward link, which encompasses a cholinergic projection from the laterodorsal tegmental area (LDTg) to the ventral tegmental area (VTA) together with mesolimbic dopaminergic projections from the VTA to the nucleus accumbens (NAc). Recently, systemic ghrelin was shown to regulate sexual behavior and motivation in male mice via dopamine neurotransmission. The present study therefore elucidates the role of ghrelin and ghrelin receptor (GHS-R1A) antagonist treatment within NAc, VTA or LDTg for sexual behavior in sexually naïve male mice. Local administration of the GHSR-1A antagonist, JMV2959, into the VTA or LDTg was found to reduce the preference for female mice, the number of mounts and the duration of mounting as well as to prolong the latency to mount. This was further substantiated by the findings that ghrelin administration into the VTA or LDTg increased the number of mounts and the duration of mounting and decreased the latency to mount. Moreover, ghrelin administered into the LDTg increased the preference for female mice. Accumbal administration of ghrelin increased whereas GHS-R1A antagonist decreased the intake of palatable food, but did not alter sexual behavior. In males exposed to sexual interaction, systemic administration of ghrelin increases whereas JMV2959 decreases the turnover of dopamine in the VTA. These data suggest that ghrelin signaling within the tegmental areas is required for sexual behavior in sexually naïve male mice.
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Affiliation(s)
- Luna Prieto-Garcia
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Emil Egecioglu
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Studer
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Lars Westberg
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Institute of Neuroscience and Physiology, Department of Pharmacology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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31
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Muscarinic and nicotinic cholinergic receptor antagonists differentially mediate acquisition of fructose-conditioned flavor preference and quinine-conditioned flavor avoidance in rats. Neurobiol Learn Mem 2015; 123:239-49. [DOI: 10.1016/j.nlm.2015.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/16/2015] [Accepted: 07/02/2015] [Indexed: 01/06/2023]
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Ghrelin's Role in the Hypothalamic-Pituitary-Adrenal Axis Stress Response: Implications for Mood Disorders. Biol Psychiatry 2015; 78:19-27. [PMID: 25534754 DOI: 10.1016/j.biopsych.2014.10.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 09/26/2014] [Accepted: 10/15/2014] [Indexed: 12/24/2022]
Abstract
Ghrelin is a stomach hormone normally associated with feeding behavior and energy homeostasis. Recent studies highlight that ghrelin targets the brain to regulate a diverse number of functions, including learning, memory, motivation, stress responses, anxiety, and mood. In this review, we discuss recent animal and human studies showing that ghrelin regulates the hypothalamic-pituitary-adrenal axis and affects anxiety and mood disorders, such as depression and fear. We address the neural sites of action through which ghrelin regulates the hypothalamic-pituitary-adrenal axis and associated stress-induced behaviors, including the centrally projecting Edinger-Westphal nucleus, the hippocampus, amygdala, locus coeruleus, and the ventral tegmental area. Stressors modulate many behaviors associated with motivation, fear, anxiety, depression, and appetite; therefore, we assess the potential role for ghrelin as a stress feedback signal that regulates these associated behaviors. Finally, we briefly discuss important areas for future research that will help us move closer to potential ghrelin-based therapies to treat stress responses and related disorders.
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Kroemer NB, Wuttig F, Bidlingmaier M, Zimmermann US, Smolka MN. Nicotine enhances modulation of food-cue reactivity by leptin and ghrelin in the ventromedial prefrontal cortex. Addict Biol 2015; 20:832-44. [PMID: 25060944 DOI: 10.1111/adb.12167] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Endocrine signals such as ghrelin and leptin are known to modulate the mesocorticolimbic dopaminergic system and, consequently, show associations with food and drug reward. In animal models, nicotine was demonstrated to reduce body weight by attenuating food intake and effects of leptin and ghrelin are partly modulated by nicotinic acetylcholine receptors which hint at potential interactions. However, the neuropharmacological modulation of endocrine signals by nicotine in healthy humans remains to be tested experimentally. We used functional magnetic resonance imaging to investigate food-cue reactivity after an overnight fast and following a caloric load (oral glucose tolerance test, OGTT) in 26 healthy normal-weight never-smokers. Moreover, we administered either nicotine (2 mg) or placebo gums using a randomized cross-over design and assessed blood plasma levels of ghrelin and leptin. During fasting, nicotine administration decreased correlations with ghrelin levels in the mesocorticolimbic system whereas correlations with leptin were increased. After the OGTT, nicotine increased the modulatory effects of ghrelin and leptin on food-cue reactivity, particularly in the ventromedial prefrontal cortex (vmPFC) and the amygdala. Critically, this led to an indirect modulation of the behavioral 'appetizer effect' (i.e. cue-induced increases in subjective appetite) by homeostatic feedback signals via food-cue reactivity in vmPFC. We conclude that nicotine enhances the effect of ghrelin and leptin in the valuation and relevance network which might, in turn, reduce appetite. This highlights that amplifying the impact of homeostatic signals such as ghrelin and leptin in normal-weight individuals might hint at a mechanism contributing to nicotine's anorexic potential.
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Affiliation(s)
- Nils B. Kroemer
- Department of Psychiatry and Neuroimaging Center; Technische Universität Dresden; Germany
| | - Franziska Wuttig
- Department of Psychiatry and Neuroimaging Center; Technische Universität Dresden; Germany
| | - Martin Bidlingmaier
- Endocrine Research Unit; Medizinische Klinik und Poliklinik IV; Ludwig-Maximilians Universität; Germany
| | - Ulrich S. Zimmermann
- Department of Psychiatry and Neuroimaging Center; Technische Universität Dresden; Germany
| | - Michael N. Smolka
- Department of Psychiatry and Neuroimaging Center; Technische Universität Dresden; Germany
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34
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Perello M, Dickson SL. Ghrelin signalling on food reward: a salient link between the gut and the mesolimbic system. J Neuroendocrinol 2015; 27:424-34. [PMID: 25377898 PMCID: PMC5033008 DOI: 10.1111/jne.12236] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 10/29/2014] [Accepted: 11/02/2014] [Indexed: 12/12/2022]
Abstract
'Hunger is the best spice' is an old and wise saying that acknowledges the fact that almost any food tastes better when we are hungry. The neurobiological underpinnings of this lore include activation of the brain's reward system and the stimulation of this system by the hunger-promoting hormone ghrelin. Ghrelin is produced largely from the stomach and levels are higher preprandially. The ghrelin receptor is expressed in many brain areas important for feeding control, including not only the hypothalamic nuclei involved in energy balance regulation, but also reward-linked areas such as the ventral tegmental area. By targeting the mesoaccumbal dopamine neurones of the ventral tegmental area, ghrelin recruits pathways important for food reward-related behaviours that show overlap with but are also distinct from those important for food intake. We review a variety of studies that support the notion that ghrelin signalling at the level of the mesolimbic system is one of the key molecular substrates that provides a physiological signal connecting gut and reward pathways.
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Affiliation(s)
- M. Perello
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology [Argentine Research Council (CONICET) and Scientific Research CommissionProvince of Buenos Aires (CIC‐PBA)]La PlataBuenos AiresArgentina
| | - S. L. Dickson
- Department of Physiology/EndocrinologyThe Sahlgrenska Academy at the University of GothenburgGothenburgSweden
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35
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Liu S, Borgland S. Regulation of the mesolimbic dopamine circuit by feeding peptides. Neuroscience 2015; 289:19-42. [DOI: 10.1016/j.neuroscience.2014.12.046] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 12/27/2014] [Accepted: 12/31/2014] [Indexed: 12/30/2022]
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36
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Hauberg K, Kohlmeier KA. The appetite-inducing peptide, ghrelin, induces intracellular store-mediated rises in calcium in addiction and arousal-related laterodorsal tegmental neurons in mouse brain slices. Peptides 2015; 65:34-45. [PMID: 25645492 DOI: 10.1016/j.peptides.2015.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/21/2015] [Accepted: 01/21/2015] [Indexed: 12/16/2022]
Abstract
Ghrelin, a gut and brain peptide, has recently been shown to be involved in motivated behavior and regulation of the sleep and wakefulness cycle. The laterodorsal tegmental nucleus (LDT) is involved in appetitive behavior and control of the arousal state of an organism, and accordingly, behavioral actions of ghrelin could be mediated by direct cellular actions within this nucleus. Consistent with this interpretation, postsynaptically mediated depolarizing membrane actions of ghrelin on LDT neurons have been reported. Direct actions were ascribed solely to closure of a potassium conductance however this peptide has been shown in other cell types to lead to rises in calcium via release of calcium from intracellular stores. To determine whether ghrelin induced intracellular calcium rises in mouse LDT neurons, we conducted calcium imaging studies in LDT brain slices loaded with the calcium binding dye, Fura-2AM. Ghrelin elicited TTX-insensitive changes in dF/F indicative of rises in calcium, and a portion of these rises were independent of membrane depolarization, as they persisted in conditions of high extracellular potassium solutions and were found to involve SERCA-pump mediated intracellular calcium stores. Involvement of the ghrelin receptor (GHR-S) in these actions was confirmed. Taken together with other studies, our data suggest that ghrelin has multiple cellular actions on LDT cells. Ghrelin's induction of calcium via intracellular release in the LDT could play a role in behavioral actions of this peptide as the LDT governs processes involved in stimulation of motivated behavior and control of cortical arousal.
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Affiliation(s)
- Katrine Hauberg
- Department of Drug Design and Pharmacology, Faculty of Health Sciences, Universitetsparken 2, University of Copenhagen, Copenhagen 2100, Denmark
| | - Kristi A Kohlmeier
- Department of Drug Design and Pharmacology, Faculty of Health Sciences, Universitetsparken 2, University of Copenhagen, Copenhagen 2100, Denmark.
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37
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Zhang XL, Albers KM, Gold MS. Inflammation-induced increase in nicotinic acetylcholine receptor current in cutaneous nociceptive DRG neurons from the adult rat. Neuroscience 2015; 284:483-499. [PMID: 25453771 PMCID: PMC4268410 DOI: 10.1016/j.neuroscience.2014.10.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/02/2014] [Accepted: 10/09/2014] [Indexed: 12/29/2022]
Abstract
The goals of the present study were to determine (1) the properties of the nicotinic acetylcholine receptor (nAChR) currents in rat cutaneous dorsal root ganglion (DRG) neurons; (2) the impact of nAChR activation on the excitability of cutaneous DRG neurons; and (3) the impact of inflammation on the density and distribution of nAChR currents among cutaneous DRG neurons. Whole-cell patch-clamp techniques were used to study retrogradely labeled DRG neurons from naïve and complete Freund's adjuvant inflamed rats. Nicotine-evoked currents were detectable in ∼70% of the cutaneous DRG neurons, where only one of two current types, fast or slow currents based on rates of activation and inactivation, was present in each neuron. The biophysical and pharmacological properties of the fast current were consistent with nAChRs containing an α7 subunit while those of the slow current were consistent with nAChRs containing α3/β4 subunits. The majority of small diameter neurons with fast current were IB4- while the majority of small diameter neurons with slow current were IB4+. Preincubation with nicotine (1 μM) produced a transient (1 min) depolarization and increase in the excitability of neurons with fast current and a decrease in the amplitude of capsaicin-evoked current in neurons with slow current. Inflammation increased the current density of both slow and fast currents in small diameter neurons and increased the percentage of neurons with the fast current. With the relatively selective distribution of nAChR currents in putative nociceptive cutaneous DRG neurons, our results suggest that the role of these receptors in inflammatory hyperalgesia is likely to be complex and dependent on the concentration and timing of acetylcholine release in the periphery.
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Affiliation(s)
- X-L Zhang
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - K M Albers
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15213, United States; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213, United States
| | - M S Gold
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213, United States; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213, United States.
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38
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Vadnie CA, Park JH, Abdel Gawad N, Ho AMC, Hinton DJ, Choi DS. Gut-brain peptides in corticostriatal-limbic circuitry and alcohol use disorders. Front Neurosci 2014; 8:288. [PMID: 25278825 PMCID: PMC4166902 DOI: 10.3389/fnins.2014.00288] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/26/2014] [Indexed: 12/22/2022] Open
Abstract
Peptides synthesized in endocrine cells in the gastrointestinal tract and neurons are traditionally considered regulators of metabolism, energy intake, and appetite. However, recent work has demonstrated that many of these peptides act on corticostriatal-limbic circuitry and, in turn, regulate addictive behaviors. Given that alcohol is a source of energy and an addictive substance, it is not surprising that increasing evidence supports a role for gut-brain peptides specifically in alcohol use disorders (AUD). In this review, we discuss the effects of several gut-brain peptides on alcohol-related behaviors and the potential mechanisms by which these gut-brain peptides may interfere with alcohol-induced changes in corticostriatal-limbic circuitry. This review provides a summary of current knowledge on gut-brain peptides focusing on five peptides: neurotensin, glucagon-like peptide 1, ghrelin, substance P, and neuropeptide Y. Our review will be helpful to develop novel therapeutic targets for AUD.
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Affiliation(s)
- Chelsea A Vadnie
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine Rochester, MN, USA ; Neurobiology of Disease Program, Mayo Clinic College of Medicine Rochester, MN, USA
| | - Jun Hyun Park
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine Rochester, MN, USA ; Department of Psychiatry, Sanggye Paik Hospital, College of Medicine, InJe University Seoul, South Korea
| | - Noha Abdel Gawad
- Department of Psychiatry and Psychology, Mayo Clinic College of Medicine Rochester, MN, USA
| | - Ada Man Choi Ho
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine Rochester, MN, USA ; Department of Psychiatry and Psychology, Mayo Clinic College of Medicine Rochester, MN, USA
| | - David J Hinton
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine Rochester, MN, USA ; Neurobiology of Disease Program, Mayo Clinic College of Medicine Rochester, MN, USA
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine Rochester, MN, USA ; Neurobiology of Disease Program, Mayo Clinic College of Medicine Rochester, MN, USA ; Department of Psychiatry and Psychology, Mayo Clinic College of Medicine Rochester, MN, USA
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Arias-Carrión O, Caraza-Santiago X, Salgado-Licona S, Salama M, Machado S, Nardi AE, Menéndez-González M, Murillo-Rodríguez E. Orquestic regulation of neurotransmitters on reward-seeking behavior. Int Arch Med 2014; 7:29. [PMID: 25061480 PMCID: PMC4108978 DOI: 10.1186/1755-7682-7-29] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/31/2014] [Indexed: 01/15/2023] Open
Abstract
The ventral tegmental area is strongly associated with the reward system. Dopamine is released in areas such as the nucleus accumbens and prefrontal cortex as a result of rewarding experiences such as food, sex, and neutral stimuli that become associated with them. Electrical stimulation of the ventral tegmental area or its output pathways can itself serve as a potent reward. Different drugs that increase dopamine levels are intrinsically rewarding. Although the dopaminergic system represent the cornerstone of the reward system, other neurotransmitters such as endogenous opioids, glutamate, γ-Aminobutyric acid, acetylcholine, serotonin, adenosine, endocannabinoids, orexins, galanin and histamine all affect this mesolimbic dopaminergic system. Consequently, genetic variations of neurotransmission are thought influence reward processing that in turn may affect distinctive social behavior and susceptibility to addiction. Here, we discuss current evidence on the orquestic regulation of different neurotranmitters on reward-seeking behavior and its potential effect on drug addiction.
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Affiliation(s)
- Oscar Arias-Carrión
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico ; Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Ajusco Medio, Mexico City, Mexico
| | - Xanic Caraza-Santiago
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico
| | - Sergio Salgado-Licona
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico
| | - Mohamed Salama
- Toxicology Department and Medical Experimental Research Center (MERC), Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Sergio Machado
- Panic and Respiration, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil ; Physical Activity Neuroscience Physical Activity Sciences Postgraduate Program, Salgado de Oliveira University, Niterói, Brazil
| | - Antonio Egidio Nardi
- Panic and Respiration, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Eric Murillo-Rodríguez
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud, Universidad Anáhuac Mayab, Mérida, Yucatán, Mexico
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Engel JA, Jerlhag E. Role of appetite-regulating peptides in the pathophysiology of addiction: implications for pharmacotherapy. CNS Drugs 2014; 28:875-86. [PMID: 24958205 PMCID: PMC4181507 DOI: 10.1007/s40263-014-0178-y] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Food intake and appetite are regulated by various circulating hormones including ghrelin and glucagon-like-peptide 1 (GLP-1). Ghrelin, mainly released from the stomach, increases food intake, induces appetite, enhances adiposity as well as releases growth hormone. Hypothalamic "ghrelin receptors" (GHS-R1A) have a critical role in food intake regulation, but GHS-R1A are also expressed in reward related areas. GLP-1 is produced in the intestinal mucosa as well as in the hindbrain in response to nutrient ingestion. This gut-brain hormone reduces food intake as well as regulates glucose homeostasis, foremost via GLP-1 receptors in hypothalamus and brain stem. However, GLP-1 receptors are expressed in areas intimately associated with reward regulation. Given that regulation of food and drug intake share common neurobiological substrates, the possibility that ghrelin and GLP-1 play an important role in reward regulation should be considered. Indeed, this leading article describes that the orexigenic peptide ghrelin activates the cholinergic-dopaminergic reward link, an important part of the reward systems in the brain associated with reinforcement and thereby increases the incentive salience for motivated behaviors via this system. We also review the role of ghrelin signaling for reward induced by alcohol and addictive drugs from a preclinical, clinical and human genetic perspective. In addition, the recent findings showing that GLP-1 controls reward induced by alcohol, amphetamine, cocaine and nicotine in rodents are overviewed herein. Finally, the role of several other appetite regulatory hormones for reward and addiction is briefly discussed. Collectively, these data suggest that ghrelin and GLP-1 receptors may be novel targets for development of pharmacological treatments of alcohol and drug dependence.
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Affiliation(s)
- Jörgen A. Engel
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, POB 431, 405 30 Gothenburg, Sweden
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Abstract
The prevalence of obesity continues to increase and has reached epidemic proportions. Accumulating data over the past few decades have given us key insights and broadened our understanding of the peripheral and central regulation of energy homeostasis. Despite this, the currently available pharmacological treatments, reducing body weight, remain limited due to poor efficacy and side effects. The gastric peptide ghrelin has been identified as the only orexigenic hormone from the periphery to act in the hypothalamus to stimulate food intake. Recently, a role for ghrelin and its receptor at the interface between homeostatic control of appetite and reward circuitries modulating the hedonic aspects of food has also emerged. Nonhomeostatic factors such as the rewarding and motivational value of food, which increase with food palatability and caloric content, can override homeostatic control of food intake. This nonhomeostatic decision to eat leads to overconsumption beyond nutritional needs and is being recognized as a key component in the underlying causes for the increase in obesity incidence worldwide. In addition, the hedonic feeding behavior has been linked to food addiction and an important role for ghrelin in the development of addiction has been suggested. Moreover, plasma ghrelin levels are responsive to conditions of stress, and recent evidence has implicated ghrelin in stress-induced food-reward behavior. The prominent role of the ghrelinergic system in the regulation of feeding gives rise to it as an effective target for the development of successful antiobesity pharmacotherapies that not only affect satiety but also selectively modulate the rewarding properties of food and reduce the desire to eat.
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Palotai M, Bagosi Z, Jászberényi M, Csabafi K, Dochnal R, Manczinger M, Telegdy G, Szabó G. Ghrelin amplifies the nicotine-induced dopamine release in the rat striatum. Neurochem Int 2013; 63:239-43. [DOI: 10.1016/j.neuint.2013.06.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 05/16/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
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Wellman PJ, Clifford PS, Rodriguez JA. Ghrelin and ghrelin receptor modulation of psychostimulant action. Front Neurosci 2013; 7:171. [PMID: 24093007 PMCID: PMC3782693 DOI: 10.3389/fnins.2013.00171] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/02/2013] [Indexed: 12/03/2022] Open
Abstract
Ghrelin (GHR) is an orexigenic gut peptide that modulates multiple homeostatic functions including gastric emptying, anxiety, stress, memory, feeding, and reinforcement. GHR is known to bind and activate growth-hormone secretagogue receptors (termed GHR-Rs). Of interest to our laboratory has been the assessment of the impact of GHR modulation of the locomotor activation and reward/reinforcement properties of psychostimulants such as cocaine and nicotine. Systemic GHR infusions augment cocaine stimulated locomotion and conditioned place preference (CPP) in rats, as does food restriction (FR) which elevates plasma ghrelin levels. Ghrelin enhancement of psychostimulant function may occur owing to a direct action on mesolimbic dopamine function or may reflect an indirect action of ghrelin on glucocorticoid pathways. Genomic or pharmacological ablation of GHR-Rs attenuates the acute locomotor-enhancing effects of nicotine, cocaine, amphetamine and alcohol and blunts the CPP induced by food, alcohol, amphetamine and cocaine in mice. The stimulant nicotine can induce CPP and like amphetamine and cocaine, repeated administration of nicotine induces locomotor sensitization in rats. Inactivation of ghrelin circuit function in rats by injection of a ghrelin receptor antagonist (e.g., JMV 2959) diminishes the development of nicotine-induced locomotor sensitization. These results suggest a key permissive role for GHR-R activity for the induction of locomotor sensitization to nicotine. Our finding that GHR-R null rats exhibit diminished patterns of responding for intracranial self-stimulation complements an emerging literature implicating central GHR circuits in drug reward/reinforcement. Finally, antagonism of GHR-Rs may represent a smoking cessation modality that not only blocks nicotine-induced reward but that also may limit weight gain after smoking cessation.
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Affiliation(s)
- Paul J Wellman
- Behavioral Neuroscience Program, Department of Psychology, Texas A&M University College Station, TX, USA
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Uchida A, Zigman JM, Perelló M. Ghrelin and eating behavior: evidence and insights from genetically-modified mouse models. Front Neurosci 2013; 7:121. [PMID: 23882175 PMCID: PMC3712270 DOI: 10.3389/fnins.2013.00121] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/25/2013] [Indexed: 01/08/2023] Open
Abstract
Ghrelin is an octanoylated peptide hormone, produced by endocrine cells of the stomach, which acts in the brain to increase food intake and body weight. Our understanding of the mechanisms underlying ghrelin's effects on eating behaviors has been greatly improved by the generation and study of several genetically manipulated mouse models. These models include mice overexpressing ghrelin and also mice with genetic deletion of ghrelin, the ghrelin receptor [the growth hormone secretagogue receptor (GHSR)] or the enzyme that post-translationally modifies ghrelin [ghrelin O-acyltransferase (GOAT)]. In addition, a GHSR-null mouse model in which GHSR transcription is globally blocked but can be cell-specifically reactivated in a Cre recombinase-mediated fashion has been generated. Here, we summarize findings obtained with these genetically manipulated mice, with the aim to highlight the significance of the ghrelin system in the regulation of both homeostatic and hedonic eating, including that occurring in the setting of chronic psychosocial stress.
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Affiliation(s)
- Aki Uchida
- Divisions of Hypothalamic Research and Endocrinology and Metabolism, Department of Medicine, The University of Texas Southwestern Medical Center Dallas, TX, USA ; Department of Psychiatry, The University of Texas Southwestern Medical Center Dallas, TX, USA
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Palotai M, Bagosi Z, Jászberényi M, Csabafi K, Dochnal R, Manczinger M, Telegdy G, Szabó G. Ghrelin and Nicotine Stimulate Equally the Dopamine Release in the Rat Amygdala. Neurochem Res 2013; 38:1989-95. [DOI: 10.1007/s11064-013-1105-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 06/26/2013] [Accepted: 06/28/2013] [Indexed: 11/29/2022]
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Suchankova P, Jerlhag E, Jayaram-Lindström N, Nilsson S, Toren K, Rosengren A, Engel JA, Franck J. Genetic variation of the ghrelin signalling system in individuals with amphetamine dependence. PLoS One 2013; 8:e61242. [PMID: 23579732 PMCID: PMC3620267 DOI: 10.1371/journal.pone.0061242] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 03/07/2013] [Indexed: 01/12/2023] Open
Abstract
The development of amphetamine dependence largely depends on the effects of amphetamine in the brain reward systems. Ghrelin, an orexigenic peptide, activates the reward systems and is required for reward induced by alcohol, nicotine, cocaine and amphetamine in mice. Human genetic studies have shown that polymorphisms in the pre-proghrelin (GHRL) as well as GHS-R1A (GHSR) genes are associated with high alcohol consumption, increased weight and smoking in males. Since the heritability factor underlying drug dependence is shared between different drugs of abuse, we here examine the association between single nucleotide polymorphisms (SNPs) and haplotypes in the GHRL and GHSR, and amphetamine dependence. GHRL and GHSR SNPs were genotyped in Swedish amphetamine dependent individuals (n = 104) and controls from the general population (n = 310). A case-control analysis was performed and SNPs and haplotypes were additionally tested for association against Addiction Severity Interview (ASI) composite score of drug use. The minor G-allele of the GHSR SNP rs2948694, was more common among amphetamine dependent individuals when compared to controls (pc = 0.02). A significant association between the GHRL SNP rs4684677 and ASI composite score of drug use was also reported (pc = 0.03). The haplotype analysis did not add to the information given by the individual polymorphisms. Although genetic variability of the ghrelin signalling system is not a diagnostic marker for amphetamine dependence and problem severity of drug use, the present results strengthen the notion that ghrelin and its receptor may be involved in the development of addictive behaviours and may thus serve as suitable targets for new treatments of such disorders.
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Affiliation(s)
- Petra Suchankova
- Department of Pharmacology, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- * E-mail:
| | - Nitya Jayaram-Lindström
- Department of Clinical Neuroscience, Division of Psychiatry at Karolinska Institutet, Stockholm, Sweden
| | - Staffan Nilsson
- Department of Mathematical Statistics, Institute of Mathematical Sciences at Chalmers University of Technology, Gothenburg, Sweden
| | - Kjell Toren
- Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Annika Rosengren
- Department of Molecular and Clinical Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Jörgen A. Engel
- Department of Pharmacology, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Johan Franck
- Department of Clinical Neuroscience, Division of Psychiatry at Karolinska Institutet, Stockholm, Sweden
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Jerlhag E, Janson AC, Waters S, Engel JA. Concomitant release of ventral tegmental acetylcholine and accumbal dopamine by ghrelin in rats. PLoS One 2012; 7:e49557. [PMID: 23166710 PMCID: PMC3498203 DOI: 10.1371/journal.pone.0049557] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/10/2012] [Indexed: 11/18/2022] Open
Abstract
Ghrelin, an orexigenic peptide, regulates energy balance specifically via hypothalamic circuits. Growing evidence suggest that ghrelin increases the incentive value of motivated behaviours via activation of the cholinergic-dopaminergic reward link. It encompasses the cholinergic afferent projection from the laterodorsal tegmental area (LDTg) to the dopaminergic cells of the ventral tegmental area (VTA) and the mesolimbic dopamine system projecting from the VTA to nucleus accumbens (N.Acc.). Ghrelin receptors (GHS-R1A) are expressed in these reward nodes and ghrelin administration into the LDTg increases accumbal dopamine, an effect involving nicotinic acetylcholine receptors in the VTA. The present series of experiments were undertaken directly to test this hypothesis. Here we show that ghrelin, administered peripherally or locally into the LDTg concomitantly increases ventral tegmental acetylcholine as well as accumbal dopamine release. A GHS-R1A antagonist blocks this synchronous neurotransmitter release induced by peripheral ghrelin. In addition, local perfusion of the unselective nicotinic antagonist mecamylamine into the VTA blocks the ability of ghrelin (administered into the LDTg) to increase N.Acc.-dopamine, but not VTA-acetylcholine. Collectively our data indicate that ghrelin activates the LDTg causing a release of acetylcholine in the VTA, which in turn activates local nicotinic acetylcholine receptors causing a release of accumbal dopamine. Given that a dysfunction in the cholinergic-dopaminergic reward system is involved in addictive behaviours, including compulsive overeating and alcohol use disorder, and that hyperghrelinemia is associated with such addictive behaviours, ghrelin-responsive circuits may serve as a novel pharmacological target for treatment of alcohol use disorder as well as binge eating.
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Affiliation(s)
- Elisabet Jerlhag
- Section for Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
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Alvarez-Crespo M, Skibicka KP, Farkas I, Molnár CS, Egecioglu E, Hrabovszky E, Liposits Z, Dickson SL. The amygdala as a neurobiological target for ghrelin in rats: neuroanatomical, electrophysiological and behavioral evidence. PLoS One 2012; 7:e46321. [PMID: 23071554 PMCID: PMC3468604 DOI: 10.1371/journal.pone.0046321] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 08/29/2012] [Indexed: 12/20/2022] Open
Abstract
Here, we sought to demonstrate that the orexigenic circulating hormone, ghrelin, is able to exert neurobiological effects (including those linked to feeding control) at the level of the amygdala, involving neuroanatomical, electrophysiological and behavioural studies. We found that ghrelin receptors (GHS-R) are densely expressed in several subnuclei of the amygdala, notably in ventrolateral (LaVL) and ventromedial (LaVM) parts of the lateral amygdaloid nucleus. Using whole-cell patch clamp electrophysiology to record from cells in the lateral amygdaloid nucleus, we found that ghrelin reduced the frequency of mEPSCs recorded from large pyramidal-like neurons, an effect that could be blocked by co-application of a ghrelin receptor antagonist. In ad libitum fed rats, intra-amygdala administration of ghrelin produced a large orexigenic response that lasted throughout the 4 hr of testing. Conversely, in hungry, fasted rats ghrelin receptor blockade in the amygdala significantly reduced food intake. Finally, we investigated a possible interaction between ghrelin's effects on feeding control and emotional reactivity exerted at the level of the amygdala. In rats allowed to feed during a 1-hour period between ghrelin injection and anxiety testing (elevated plus maze and open field), intra-amygdala ghrelin had no effect on anxiety-like behavior. By contrast, if the rats were not given access to food during this 1-hour period, a decrease in anxiety-like behavior was observed in both tests. Collectively, these data indicate that the amygdala is a valid target brain area for ghrelin where its neurobiological effects are important for food intake and for the suppression of emotional (anxiety-like) behaviors if food is not available.
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Affiliation(s)
- Mayte Alvarez-Crespo
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Karolina P. Skibicka
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Imre Farkas
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Csilla S. Molnár
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Emil Egecioglu
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Suzanne L. Dickson
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
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Perelló M, Zigman JM. The role of ghrelin in reward-based eating. Biol Psychiatry 2012; 72:347-53. [PMID: 22458951 PMCID: PMC3388148 DOI: 10.1016/j.biopsych.2012.02.016] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/03/2012] [Accepted: 02/17/2012] [Indexed: 01/18/2023]
Abstract
The peptide hormone ghrelin acts in the central nervous system as a potent orexigenic signal. Not only is ghrelin recognized as playing an important role in feeding circuits traditionally thought of as affecting body weight homeostasis, but also an accumulating number of scientific studies have identified ghrelin as being a key regulator of reward-based, hedonic eating behaviors. In the current article, we review ghrelin's orexigenic actions, the evidence linking ghrelin to food reward behavior, potential mechanisms by which ghrelin mediates reward-based eating behavior, and those studies suggesting an obligatory role for ghrelin in the changed eating behaviors induced by stress.
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Affiliation(s)
- Mario Perelló
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology (IMBICE-CONICET/CICPBA), Calle 526 s/n entre 10 y 11, La Plata, Buenos Aires, Argentina 1900
| | - Jeffrey M. Zigman
- Department of Internal Medicine (Divisions of Hypothalamic Research and of Endocrinology & Metabolism), The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9077,Department of Psychiatry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9077
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