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Stark R. The olfactory bulb: A neuroendocrine spotlight on feeding and metabolism. J Neuroendocrinol 2024; 36:e13382. [PMID: 38468186 DOI: 10.1111/jne.13382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/22/2024] [Accepted: 02/25/2024] [Indexed: 03/13/2024]
Abstract
Olfaction is the most ancient sense and is needed for food-seeking, danger protection, mating and survival. It is often the first sensory modality to perceive changes in the external environment, before sight, taste or sound. Odour molecules activate olfactory sensory neurons that reside on the olfactory epithelium in the nasal cavity, which transmits this odour-specific information to the olfactory bulb (OB), where it is relayed to higher brain regions involved in olfactory perception and behaviour. Besides odour processing, recent studies suggest that the OB extends its function into the regulation of food intake and energy balance. Furthermore, numerous hormone receptors associated with appetite and metabolism are expressed within the OB, suggesting a neuroendocrine role outside the hypothalamus. Olfactory cues are important to promote food preparatory behaviours and consumption, such as enhancing appetite and salivation. In addition, altered metabolism or energy state (fasting, satiety and overnutrition) can change olfactory processing and perception. Similarly, various animal models and human pathologies indicate a strong link between olfactory impairment and metabolic dysfunction. Therefore, understanding the nature of this reciprocal relationship is critical to understand how olfactory or metabolic disorders arise. This present review elaborates on the connection between olfaction, feeding behaviour and metabolism and will shed light on the neuroendocrine role of the OB as an interface between the external and internal environments. Elucidating the specific mechanisms by which olfactory signals are integrated and translated into metabolic responses holds promise for the development of targeted therapeutic strategies and interventions aimed at modulating appetite and promoting metabolic health.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
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Vetrivelan R, Kong D, Ferrari LL, Arrigoni E, Madara JC, Bandaru SS, Lowell BB, Lu J, Saper CB. Melanin-concentrating hormone neurons specifically promote rapid eye movement sleep in mice. Neuroscience 2016; 336:102-113. [PMID: 27595887 DOI: 10.1016/j.neuroscience.2016.08.046] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/25/2016] [Accepted: 08/27/2016] [Indexed: 12/30/2022]
Abstract
Currently available evidence indicates that neurons containing melanin-concentrating hormone (MCH) in the lateral hypothalamus are critical modulators of sleep-wakefulness, but their precise role in this function is not clear. Studies employing optogenetic stimulation of MCH neurons have yielded inconsistent results, presumably due to differences in the optogenetic stimulation protocols, which do not approximate normal patterns of cell firing. In order to resolve this discrepancy, we (1) selectively activated the MCH neurons using a chemogenetic approach (Cre-dependent hM3Dq expression) and (2) selectively destroyed MCH neurons using a genetically targeted diphtheria toxin deletion method, and studied the changes in sleep-wake in mice. Our results indicate that selective activation of MCH neurons causes specific increases in rapid eye movement (REM) sleep without altering wake or non-REM (NREM) sleep. On the other hand, selective deletions of MCH neurons altered the diurnal rhythm of wake and REM sleep without altering their total amounts. These results indicate that activation of MCH neurons primarily drives REM sleep and their presence may be necessary for normal expression of diurnal variation of REM sleep and wake.
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Affiliation(s)
- Ramalingam Vetrivelan
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States.
| | - Dong Kong
- Department of Neuroscience, Tufts University School of Medicine, Programs of Neuroscience and Cellular, Molecular and Development Biology, Tufts Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, United States
| | - Loris L Ferrari
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States
| | - Elda Arrigoni
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, United States
| | - Sathyajit S Bandaru
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, United States
| | - Jun Lu
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States
| | - Clifford B Saper
- Department of Neurology, Beth Israel Deaconess Medical Center and Division of Sleep Medicine, Harvard Medical School, Boston, MA 02215, United States.
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Palouzier-Paulignan B, Lacroix MC, Aimé P, Baly C, Caillol M, Congar P, Julliard AK, Tucker K, Fadool DA. Olfaction under metabolic influences. Chem Senses 2012; 37:769-97. [PMID: 22832483 PMCID: PMC3529618 DOI: 10.1093/chemse/bjs059] [Citation(s) in RCA: 222] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Recently published work and emerging research efforts have suggested that the olfactory system is intimately linked with the endocrine systems that regulate or modify energy balance. Although much attention has been focused on the parallels between taste transduction and neuroendocrine controls of digestion due to the novel discovery of taste receptors and molecular components shared by the tongue and gut, the equivalent body of knowledge that has accumulated for the olfactory system, has largely been overlooked. During regular cycles of food intake or disorders of endocrine function, olfaction is modulated in response to changing levels of various molecules, such as ghrelin, orexins, neuropeptide Y, insulin, leptin, and cholecystokinin. In view of the worldwide health concern regarding the rising incidence of diabetes, obesity, and related metabolic disorders, we present a comprehensive review that addresses the current knowledge of hormonal modulation of olfactory perception and how disruption of hormonal signaling in the olfactory system can affect energy homeostasis.
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Affiliation(s)
- Brigitte Palouzier-Paulignan
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
- Equal contribution
| | - Marie-Christine Lacroix
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
- Equal contribution
| | - Pascaline Aimé
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
| | - Christine Baly
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - Monique Caillol
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - Patrice Congar
- INRA, UR1197 Neurobiologie de l’Olfaction et Modélisation en ImagerieF-78350, Jouy-en-JosasFrance
- IFR 144NeuroSud Paris, 91190 Gif-Sur-YvetteFrance
| | - A. Karyn Julliard
- Centre de Recherche des Neurosciences de Lyon, Equipe Olfaction du Codage à la Mémoire, INSERM U 1028/CNRS 5292, Université de Lyon150 Ave. Tony Garnier, 69366, Lyon, Cedex 07,France
| | - Kristal Tucker
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of MedicinePittsburgh, PA 15261USAand
| | - Debra Ann Fadool
- Department of Biological Science, Programs in Neuroscience and Molecular Biophysics, The Florida State UniversityTallahassee, FL 32306-4295USA
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The melanin-concentrating hormone1 receptor antagonists, SNAP-7941 and GW3430, enhance social recognition and dialysate levels of acetylcholine in the frontal cortex of rats. Int J Neuropsychopharmacol 2008; 11:1105-22. [PMID: 18466669 DOI: 10.1017/s1461145708008894] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Melanin-concentrating hormone (MCH)1 receptors are widely expressed in limbic structures and cortex. Their inactivation is associated with anxiolytic and antidepressive properties but little information is available concerning cognition. This issue was addressed using the selective antagonists, SNAP-7941 and GW3430, in a social recognition paradigm in rats. The muscarinic blocker, scopolamine (1.25 mg/kg s.c.), reduced social recognition, an action dose-dependently blocked by SNAP-7941 and GW3430 (0.63-10.0 and 20.0-80.0 mg/kg i.p., respectively) which did not themselves display amnesic properties. Further, in a protocol where a spontaneous deficit was induced by a prolonged inter-session delay, SNAP-7941 and GW3430 dose-dependently enhanced social recognition. In dialysis studies, SNAP-7941 (0.63-40.0 mg/kg i.p.) and GW3430 (10.0-40.0 mg/kg i.p.) elevated extracellular levels of acetylcholine (ACh) in the frontal cortex (FCX) of freely moving rats. The SNAP-7941 effect was specific, as it did not increase levels of ACh in ventral and dorsal hippocampus: moreover, it did not modify levels of noradrenaline, dopamine, serotonin and glutamate in FCX. Active doses of SNAP-7941 and GW3430 corresponded to doses (2.5-40.0 and 10.0-80.0 mg/kg i.p., respectively) exerting anxiolytic properties in Vogel conflict and ultrasonic vocalization tests, and antidepressant actions in forced swim, isolation-induced aggression and marble-burying procedures. In contrast to SNAP-7941 and GW3430, the benzodiazepine, diazepam, decreased social recognition and dialysate levels of ACh, while the tricyclic, imipramine, reduced social recognition and failed to enhance cholinergic transmission. In conclusion, at anxiolytic and antidepressant doses, SNAP-7941 and GW3430 improve social recognition and elevate extracellular ACh levels in FCX. This profile differentiates MCH1 receptor antagonists from conventional anxiolytic and antidepressant agents.
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Francke F, Buck F, Bächner D. MYND domain specific interaction of the melanin-concentrating hormone receptor 1 interacting zinc-finger protein with alpha- and beta-tubulin. Biochem Biophys Res Commun 2005; 334:1292-8. [PMID: 16039987 DOI: 10.1016/j.bbrc.2005.07.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Accepted: 07/11/2005] [Indexed: 11/29/2022]
Abstract
MIZIP was originally identified as a highly conserved zinc-finger protein from human brain interacting with the C-terminus of the melanin-concentrating hormone receptor 1. However, the cellular functions of MIZIP are still not known. Here, we focussed on the identification of associated proteins using affinity purification from human cells. This resulted in the identification of alpha- and beta-tubulin. The interaction was confirmed in vitro and in vivo using GST pull-down and immunoprecipitation assays, and was mapped to the MYND zinc-finger of MIZIP and to the N-terminus of tubulin. Immunoprecipitation and immunocytochemistry analyses demonstrate that MIZIP binds to tubulin but not to cellular microtubules in vivo and that ectopic expression of MIZIP does not interfere with the overall structure of the microtubular cytoskeleton. Our results suggest that MIZIP might play an important role in mammalian cells by associating with tubulin and thus might provide a link between MCHR1 and tubulin functions.
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Affiliation(s)
- Felix Francke
- Institute for Cell Biochemistry and Clinical Neurobiology, University Hospital Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
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