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Stark R, Dempsey H, Kleeman E, Sassi M, Osborne-Lawrence S, Sheybani-Deloui S, Rushby HJ, Mirth CK, Austin-Muttitt K, Mullins J, Zigman JM, Davies JS, Andrews ZB. Hunger signalling in the olfactory bulb primes exploration, food-seeking and peripheral metabolism. Mol Metab 2024; 89:102025. [PMID: 39236785 PMCID: PMC11471258 DOI: 10.1016/j.molmet.2024.102025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 08/15/2024] [Accepted: 09/02/2024] [Indexed: 09/07/2024] Open
Abstract
OBJECTIVE Although the metabolic state of an organism affects olfactory function, the precise mechanisms and their impact on behavior and metabolism remain unknown. Here, we assess whether ghrelin receptors (GHSRs) in the olfactory bulb (OB) increase olfactory function and influence foraging behaviors and metabolism. METHODS We performed a detailed behavioural and metabolic analysis in mice lacking GHSRs in the OB (OBGHSR deletion). We also analsyed OB scRNA-seq and spatial transcriptomic datasets to assess GHSR+ cells in the main and accessory olfactory bulbs, as well as the anterior olfactory nucleus. RESULTS OBGHSR deletion affected olfactory discrimination and habituation to both food and non-food odors. Anxiety-like and depression-like behaviors were significantly greater after OBGHSR deletion, whereas exploratory behavior was reduced, with the greatest effect under fasted conditions. OBGHSR deletion impacted feeding behavior as evidenced by altered bout number and duration, as well as buried food-seeking. OBGHSR deletion increased body weight and fat mass, spared fat utilisation on a chow diet and impaired glucose metabolism indicating metabolic dysfunction. Cross referenced analysis of OB scRNA-seq and spatial transcriptomic datasets revealed GHSR+ glutamate neurons in the main and accessory olfactory bulbs, as well as the anterior olfactory nucleus. Ablation of glutamate neurons in the OB reduced ghrelin-induced food finding and phenocopied results seen after OBGHSR deletion. CONCLUSIONS OBGHSRs help to maintain olfactory function, particularly during hunger, and facilitate behavioral adaptations that optimise food-seeking in anxiogenic environments, priming metabolic pathways in preparation for food consumption.
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Affiliation(s)
- Romana Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia.
| | - Harry Dempsey
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Elizabeth Kleeman
- The Florey Institute of Neuroscience and Mental Health, Mental Health Division, Parkville, Melbourne, Australia
| | - Martina Sassi
- Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sepideh Sheybani-Deloui
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Helen J Rushby
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Christen K Mirth
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Karl Austin-Muttitt
- Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Jonathan Mullins
- Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey S Davies
- Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Zane B Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, Victoria, Australia.
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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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3
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Nie H, Zhao R, Ai Y, Yang Y, Cao B, Han P. Comparison between human olfactory sensitivity in the fasted and fed states: A systematic review and meta-analysis. Appetite 2023; 181:106395. [PMID: 36450324 DOI: 10.1016/j.appet.2022.106395] [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: 09/15/2022] [Revised: 11/14/2022] [Accepted: 11/22/2022] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Olfaction is tightly regulated by internal status such as hunger level. The influence of fasted and fed states on olfactory sensitivity in humans has reached mixed results. This study aims to systematically review, integrate and meta-analyze evidence of the impact of fasting on olfactory sensitivity in humans and to explore the impact of potential moderators. METHOD Electronic databases (PubMed, PsycINFO, Web of Science, COCHRANE and Ovid) were searched for studies with human participants investigating the effect of fasting on olfactory sensitivity. Studies were included in the review if they measured odor threshold both at fasted and sated status. The data extraction was determined based on the change in odor threshold from the fasted state to the fed state. Meta-analysis was conducted using a random-effect model to estimate the standardized mean difference transformed olfactory sensitivity change between fasted and fed states with 95% confidence interval (CI). RESULTS Thirteen studies (12 articles) were included in the meta-analysis with a total of 550 participants. Olfactory sensitivity was higher in the fasted state compared to the fed state (SMD = -0.251, 95% CI = -0.426, -0.075, Z = -2.804, p = 0.005). Separated analyses for food and non-food odors revealed a significant elevated sensitivity to non-food odors during the fasted state compared to the fed state. The meta-regression analysis revealed that fasting time positively moderate the increased olfactory sensitivity from the fasted to fed states (β = -0.013, 95% CI = -0.023, -0.002, p = 0.016). CONCLUSION Fasting improves human olfactory sensitivity to non-food odors, and this effect increases with longer fasting time. Future research design on olfactory sensitivity should take both the fasted state and fasting period of the participants into consideration.
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Affiliation(s)
- Haoyu Nie
- Faculty of Psychology, Southwest University, Chongqing, China
| | - Rong Zhao
- Faculty of Psychology, Southwest University, Chongqing, China
| | - Yun Ai
- Faculty of Psychology, Southwest University, Chongqing, China
| | - Yingkai Yang
- Faculty of Psychology, Southwest University, Chongqing, China; MOE Key Laboratory of Cognition and Personality, Southwest University, Chongqing, China
| | - Bing Cao
- Faculty of Psychology, Southwest University, Chongqing, China; MOE Key Laboratory of Cognition and Personality, Southwest University, Chongqing, China
| | - Pengfei Han
- Faculty of Psychology, Southwest University, Chongqing, China; MOE Key Laboratory of Cognition and Personality, Southwest University, Chongqing, China.
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Zhao Y, Bhutani S, Kahnt T. Appetite-regulating hormones modulate odor perception and odor-evoked activity in hypothalamus and olfactory cortices. Chem Senses 2023; 48:bjad039. [PMID: 37796827 PMCID: PMC10590159 DOI: 10.1093/chemse/bjad039] [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: 08/16/2023] [Indexed: 10/07/2023] Open
Abstract
Odors guide food seeking, and food intake modulates olfactory function. This interaction is mediated by appetite-regulating hormones like ghrelin, insulin, and leptin, which alter activity in the rodent olfactory bulb, but their effects on downstream olfactory cortices have not yet been established in humans. The olfactory tract connects the olfactory bulb to the cortex through 3 main striae, terminating in the piriform cortex (PirC), amygdala (AMY), olfactory tubercule (OT), and anterior olfactory nucleus (AON). Here, we test the hypothesis that appetite-regulating hormones modulate olfactory processing in the endpoints of the olfactory tract and the hypothalamus. We collected odor-evoked functional magnetic resonance imaging (fMRI) responses and plasma levels of ghrelin, insulin, and leptin from human subjects (n = 25) after a standardized meal. We found that a hormonal composite measure, capturing variance relating positively to insulin and negatively to ghrelin, correlated inversely with odor intensity ratings and fMRI responses to odorized vs. clean air in the hypothalamus, OT, and AON. No significant correlations were found with activity in PirC or AMY, the endpoints of the lateral stria. Exploratory whole-brain analyses revealed significant correlations near the diagonal band of Broca and parahippocampal gyrus. These results demonstrate that high (low) blood plasma concentrations of insulin (ghrelin) decrease perceived odor intensity and odor-evoked activity in the cortical targets of the medial and intermediate striae of the olfactory tract, as well as the hypothalamus. These findings expand our understanding of the cortical mechanisms by which metabolic hormones in humans modulate olfactory processing after a meal.
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Affiliation(s)
- Yao Zhao
- National Institute on Drug Abuse Intramural Research Program, Cellular and Neurocomputational Systems Branch, Baltimore, MD,United States
| | - Surabhi Bhutani
- San Diego State University, School of Exercise and Nutritional Sciences, San Diego, CA, United States
| | - Thorsten Kahnt
- National Institute on Drug Abuse Intramural Research Program, Cellular and Neurocomputational Systems Branch, Baltimore, MD,United States
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Pfabigan DM, Vezzani C, Thorsby PM, Sailer U. Sex difference in human olfactory sensitivity is associated with plasma adiponectin. Horm Behav 2022; 145:105235. [PMID: 35868172 DOI: 10.1016/j.yhbeh.2022.105235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 11/16/2022]
Abstract
Energy deprivation as well as hormones that regulate appetite and eating can influence olfactory function. This study investigated olfactory sensitivity for a food-related and a non-food odour prior to and after a meal, and its relationship to the energy-regulating hormones ghrelin and adiponectin. The olfactory sensitivity for orange and rose (PEA) odour in healthy, normal-weight volunteers (19 women, 45 men, 1 undisclosed individual) was not affected by the consumption of a meal. Olfactory sensitivity was not associated with concentrations of circulating ghrelin. However, olfactory sensitivity was higher for women than for men, indicating better olfactory performance. This difference between women and men was related to concentrations of plasma adiponectin, an adipose-specific hormone. Adiponectin may thus explain why sex differences in olfactory sensitivity emerge, and may also account for some of the inconsistencies in previous findings on sex differences. Our findings add to the limited literature on the impact of stomach and adipose tissue-derived hormones on olfactory sensitivity. Further studies are needed to establish a causal link between circulating adiponectin and a sex difference in olfactory sensitivity.
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Affiliation(s)
- Daniela M Pfabigan
- Dept. of Behavioural Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway; Morbid Obesity Centre, Department of Medicine, Vestfold Hospital Trust, Tønsberg, Norway
| | - Cecilia Vezzani
- Dept. of Behavioural Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Per Medbøe Thorsby
- Hormone Laboratory, Dep of Medical Biochemistry and Biochemical Endocrinology and Metabolism Research Group, Oslo University Hospital, Aker, Oslo, Norway
| | - Uta Sailer
- Dept. of Behavioural Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Oslo, Norway.
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Shankar K, Metzger NP, Singh O, Mani BK, Osborne-Lawrence S, Varshney S, Gupta D, Ogden SB, Takemi S, Richard CP, Nandy K, Liu C, Zigman JM. LEAP2 deletion in mice enhances ghrelin's actions as an orexigen and growth hormone secretagogue. Mol Metab 2021; 53:101327. [PMID: 34428557 PMCID: PMC8452786 DOI: 10.1016/j.molmet.2021.101327] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/13/2021] [Accepted: 08/19/2021] [Indexed: 02/03/2023] Open
Abstract
Objective The hormone liver-expressed antimicrobial peptide-2 (LEAP2) is a recently identified antagonist and an inverse agonist of the growth hormone secretagogue receptor (GHSR). GHSR's other well-known endogenous ligand, acyl-ghrelin, increases food intake, body weight, and GH secretion and is lowered in obesity but elevated upon fasting. In contrast, LEAP2 reduces acyl-ghrelin-induced food intake and GH secretion and is found elevated in obesity but lowered upon fasting. Thus, the plasma LEAP2/acyl-ghrelin molar ratio could be a key determinant modulating GHSR signaling in response to changes in body mass and feeding status. In particular, LEAP2 may serve to dampen acyl-ghrelin action in the setting of obesity, which is associated with ghrelin resistance. Here, we sought to determine the metabolic effects of genetic LEAP2 deletion. Methods We generated the first known LEAP2-KO mouse line. Food intake, GH secretion, and cellular activation (c-fos induction) in different brain regions following s.c. acyl-ghrelin administration in LEAP2-KO mice and wild-type littermates were determined. LEAP2-KO mice and wild-type littermates were submitted to a battery of tests (such as measurements of body weight, food intake, and body composition; indirect calorimetry, determination of locomotor activity, and meal patterning while housed in metabolic cages) over the course of 16 weeks of high-fat diet and/or standard chow feeding. Fat accumulation was assessed in hematoxylin & eosin-stained and oil red O-stained liver sections from these mice. Results LEAP2-KO mice were more sensitive to s.c. ghrelin. In particular, acyl-ghrelin acutely stimulated food intake at a dose of 0.5 mg/kg BW in standard chow-fed LEAP2-KO mice while a 2× higher dose was required by wild-type littermates. Also, acyl-ghrelin stimulated food intake at a dose of 1 mg/kg BW in high-fat diet-fed LEAP2-KO mice while not even a 10× higher dose was effective in wild-type littermates. Acyl-ghrelin induced a 90.9% higher plasma GH level and 77.2–119.7% higher numbers of c-fos-immunoreactive cells in the arcuate nucleus and olfactory bulb, respectively, in LEAP2-KO mice than in wild-type littermates. LEAP2 deletion raised body weight (by 15.0%), food intake (by 18.4%), lean mass (by 6.1%), hepatic fat (by 42.1%), and body length (by 1.7%) in females on long-term high-fat diet as compared to wild-type littermates. After only 4 weeks on the high-fat diet, female LEAP2-KO mice exhibited lower O2 consumption (by 13%), heat production (by 9.5%), and locomotor activity (by 49%) than by wild-type littermates during the first part of the dark period. These genotype-dependent differences were not observed in high-fat diet-exposed males or female and male mice exposed for long term to standard chow diet. Conclusions LEAP2 deletion sensitizes lean and obese mice to the acute effects of administered acyl-ghrelin on food intake and GH secretion. LEAP2 deletion increases body weight in females chronically fed a high-fat diet as a result of lowered energy expenditure, reduced locomotor activity, and increased food intake. Furthermore, in female mice, LEAP2 deletion increases body length and exaggerates the hepatic fat accumulation normally associated with chronic high-fat diet feeding. A novel line of LEAP2-knockout mice was generated. LEAP2 deletion sensitizes mice to the GH secretory effects of administered ghrelin. LEAP2 deletion reduces ghrelin resistance in diet-induced obese mice. HFD-fed female LEAP2-KO mice eat more and gain more body weight and hepatic fat. HFD-fed female LEAP2-KO mice exhibit lowered energy expenditure and activity.
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Affiliation(s)
- Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Nathan P Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Omprakash Singh
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Bharath K Mani
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Salil Varshney
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Sean B Ogden
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Shota Takemi
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Corine P Richard
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Karabi Nandy
- Division of Biostatistics, Department of Population and Data Sciences, UT Southwestern Medical Center, Dallas, TX, USA
| | - Chen Liu
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, UT Southwestern Medical Center, Dallas, TX, USA.
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Kokocińska-Kusiak A, Woszczyło M, Zybala M, Maciocha J, Barłowska K, Dzięcioł M. Canine Olfaction: Physiology, Behavior, and Possibilities for Practical Applications. Animals (Basel) 2021; 11:ani11082463. [PMID: 34438920 PMCID: PMC8388720 DOI: 10.3390/ani11082463] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 08/03/2021] [Accepted: 08/19/2021] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Dogs have an extraordinary olfactory capability, which far exceeds that of humans. Dogs’ sense of smell seems to be the main sense, allowing them to not only gather both current and historical information about their surrounding environment, but also to find the source of the smell, which is crucial for locating food, danger, or partners for reproduction. Dogs can be trained by humans to use their olfactory abilities in a variety of fields, with a detection limit often much lower than that of sophisticated laboratory instruments. The specific anatomical and physiological features of dog olfaction allow humans to achieve outstanding results in the detection of drugs, explosives, and different illnesses, such as cancer, diabetes, or infectious disease. This article provides an overview of the anatomical features and physiological mechanisms involved in the process of odor detection and identification, as well as behavioral aspects of canine olfaction and its use in the service of humans in many fields. Abstract Olfaction in dogs is crucial for gathering important information about the environment, recognizing individuals, making decisions, and learning. It is far more specialized and sensitive than humans’ sense of smell. Using the strength of dogs’ sense of smell, humans work with dogs for the recognition of different odors, with a precision far exceeding the analytical capabilities of most modern instruments. Due to their extremely sensitive sense of smell, dogs could be used as modern, super-sensitive mobile area scanners, detecting specific chemical signals in real time in various environments outside the laboratory, and then tracking the odor of dynamic targets to their source, also in crowded places. Recent studies show that dogs can detect not only specific scents of drugs or explosives, but also changes in emotions as well as in human cell metabolism during various illnesses, including COVID-19 infection. Here, we provide an overview of canine olfaction, discussing aspects connected with anatomy, physiology, behavioral aspects of sniffing, and factors influencing the olfactory abilities of the domestic dog (Canis familiaris).
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Affiliation(s)
- Agata Kokocińska-Kusiak
- Institute of Animal Sciences, Warsaw University of Life Sciences, ul. Ciszewskiego 8, 02-786 Warszawa, Poland; (A.K.-K.); (J.M.)
| | - Martyna Woszczyło
- Department of Reproduction and Clinic of Farm Animals, Wroclaw University of Environmental and Life Sciences, Plac Grunwaldzki 49, 50-366 Wrocław, Poland;
| | - Mikołaj Zybala
- Institute of Biological Sciences, Doctoral School, Siedlce University of Natural Sciences and Humanities, ul. Konarskiego 2, 08-110 Siedlce, Poland;
| | - Julia Maciocha
- Institute of Animal Sciences, Warsaw University of Life Sciences, ul. Ciszewskiego 8, 02-786 Warszawa, Poland; (A.K.-K.); (J.M.)
| | - Katarzyna Barłowska
- Department of Biotechnology and Nutrigenomics, Institute of Genetics and Animal Biotechnology, Polish Academy of Sciences, Jastrzębiec, 05-552 Magdalenka, Poland;
| | - Michał Dzięcioł
- Department of Reproduction and Clinic of Farm Animals, Wroclaw University of Environmental and Life Sciences, Plac Grunwaldzki 49, 50-366 Wrocław, Poland;
- Correspondence:
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Bryche B, Baly C, Meunier N. Modulation of olfactory signal detection in the olfactory epithelium: focus on the internal and external environment, and the emerging role of the immune system. Cell Tissue Res 2021; 384:589-605. [PMID: 33961125 PMCID: PMC8102665 DOI: 10.1007/s00441-021-03467-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 04/26/2021] [Indexed: 12/18/2022]
Abstract
Detection and discrimination of odorants by the olfactory system plays a pivotal role in animal survival. Olfactory-based behaviors must be adapted to an ever-changing environment. Part of these adaptations includes changes of odorant detection by olfactory sensory neurons localized in the olfactory epithelium. It is now well established that internal signals such as hormones, neurotransmitters, or paracrine signals directly affect the electric activity of olfactory neurons. Furthermore, recent data have shown that activity-dependent survival of olfactory neurons is important in the olfactory epithelium. Finally, as olfactory neurons are directly exposed to environmental toxicants and pathogens, the olfactory epithelium also interacts closely with the immune system leading to neuroimmune modulations. Here, we review how detection of odorants can be modulated in the vertebrate olfactory epithelium. We choose to focus on three cellular types of the olfactory epithelium (the olfactory sensory neuron, the sustentacular and microvillar cells) to present the diversity of modulation of the detection of odorant in the olfactory epithelium. We also present some of the growing literature on the importance of immune cells in the functioning of the olfactory epithelium, although their impact on odorant detection is only just beginning to be unravelled.
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Affiliation(s)
- Bertrand Bryche
- Université Paris-Saclay, INRAE, UVSQ, 78350, Jouy-en-Josas, VIM, France
| | - Christine Baly
- Université Paris Saclay, INRAE, UVSQ, BREED, 78350, Jouy-en-Josas, France
| | - Nicolas Meunier
- Université Paris-Saclay, INRAE, UVSQ, 78350, Jouy-en-Josas, VIM, France.
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Guzmán-Ruiz MA, Jiménez A, Cárdenas-Rivera A, Guerrero-Vargas NN, Organista-Juárez D, Guevara-Guzmán R. Regulation of Metabolic Health by an "Olfactory-Hypothalamic Axis" and Its Possible Implications for the Development of Therapeutic Approaches for Obesity and T2D. Cell Mol Neurobiol 2021; 42:1727-1743. [PMID: 33813677 DOI: 10.1007/s10571-021-01080-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/12/2021] [Indexed: 12/12/2022]
Abstract
The olfactory system is responsible for the reception, integration and interpretation of odors. However, in the last years, it has been discovered that the olfactory perception of food can rapidly modulate the activity of hypothalamic neurons involved in the regulation of energy balance. Conversely, the hormonal signals derived from changes in the metabolic status of the body can also change the sensitivity of the olfactory system, suggesting that the bidirectional relationship established between the olfactory and the hypothalamic systems is key for the maintenance of metabolic homeostasis. In the first part of this review, we describe the possible mechanisms and anatomical pathways involved in the modulation of energy balance regulated by the olfactory system. Hence, we propose a model to explain its implication in the maintenance of the metabolic homeostasis of the organism. In the second part, we discuss how the olfactory system could be involved in the development of metabolic diseases such as obesity and type two diabetes and, finally, we propose the use of intranasal therapies aimed to regulate and improve the activity of the olfactory system that in turn will be able to control the neuronal activity of hypothalamic centers to prevent or ameliorate metabolic diseases.
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Affiliation(s)
- Mara Alaide Guzmán-Ruiz
- Laboratorio Sensorial, Departamento de Fisiología, Facultad de Medicina, Edificio A, 4º piso, Universidad Nacional Autónoma de México (UNAM), 04510, Ciudad de México, México.
| | - Adriana Jiménez
- Laboratorio Sensorial, Departamento de Fisiología, Facultad de Medicina, Edificio A, 4º piso, Universidad Nacional Autónoma de México (UNAM), 04510, Ciudad de México, México
| | - Alfredo Cárdenas-Rivera
- Centro de Investigación en Bioingeniería, Universidad de Ingeniería y Tecnología, Lima, Perú
| | - Natalí N Guerrero-Vargas
- Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de México, México City, México
| | - Diana Organista-Juárez
- Laboratorio Sensorial, Departamento de Fisiología, Facultad de Medicina, Edificio A, 4º piso, Universidad Nacional Autónoma de México (UNAM), 04510, Ciudad de México, México
| | - Rosalinda Guevara-Guzmán
- Laboratorio Sensorial, Departamento de Fisiología, Facultad de Medicina, Edificio A, 4º piso, Universidad Nacional Autónoma de México (UNAM), 04510, Ciudad de México, México.
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Cornejo MP, Mustafá ER, Barrile F, Cassano D, De Francesco PN, Raingo J, Perello M. THE INTRIGUING LIGAND-DEPENDENT AND LIGAND-INDEPENDENT ACTIONS OF THE GROWTH HORMONE SECRETAGOGUE RECEPTOR ON REWARD-RELATED BEHAVIORS. Neurosci Biobehav Rev 2020; 120:401-416. [PMID: 33157147 DOI: 10.1016/j.neubiorev.2020.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023]
Abstract
The growth hormone secretagogue receptor (GHSR) is a G-protein-coupled receptor (GPCR) highly expressed in the brain, and also in some peripheral tissues. GHSR activity is evoked by the stomach-derived peptide hormone ghrelin and abrogated by the intestine-derived liver-expressed antimicrobial peptide 2 (LEAP2). In vitro, GHSR displays ligand-independent actions, including a high constitutive activity and an allosteric modulation of other GPCRs. Beyond its neuroendocrine and metabolic effects, cumulative evidence shows that GHSR regulates the activity of the mesocorticolimbic pathway and modulates complex reward-related behaviors towards different stimuli. Here, we review current evidence indicating that ligand-dependent and ligand-independent actions of GHSR enhance reward-related behaviors towards appetitive stimuli and drugs of abuse. We discuss putative neuronal networks and molecular mechanisms that GHSR would engage to modulate such reward-related behaviors. Finally, we briefly discuss imaging studies showing that ghrelin would also regulate reward processing in humans. Overall, we conclude that GHSR is a key regulator of the mesocorticolimbic pathway that influences its activity and, consequently, modulates reward-related behaviors via ligand-dependent and ligand-independent actions.
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Affiliation(s)
- María P Cornejo
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Emilio R Mustafá
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Franco Barrile
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Daniela Cassano
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Pablo N De Francesco
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina.
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11
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Russo C, Patanè M, Vicario N, Di Bella V, Cosentini I, Barresi V, Gulino R, Pellitteri R, Russo A, Stanzani S. Olfactory Ensheathing Cells express both Ghrelin and Ghrelin Receptor in vitro: a new hypothesis in favor of a neurotrophic effect. Neuropeptides 2020; 79:101997. [PMID: 31784044 DOI: 10.1016/j.npep.2019.101997] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 11/18/2019] [Accepted: 11/20/2019] [Indexed: 12/16/2022]
Abstract
Olfactory Ensheathing Cells (OECs) are glial cells able to secrete different neurotrophic growth factors and thus promote axonal growth, also acting as a mechanical support. In the olfactory system, during development, they drive the non-myelinated axons of the Olfactory Receptor Neurons (ORNs) towards the Olfactory Bulb (OB). Ghrelin (Ghre), a gut-brain peptide hormone, and its receptor (GHS-R 1a) are expressed in different parts of the central nervous system. In the last few years, this peptide has stimulated particular interest as results show it to be a neuroprotective factor with antioxidant, anti-inflammatory and anti-apoptotic properties. Our previous studies showed that OB mitral cells express Ghre, thus being able to play an important role in regulating food behavior in response to odors. In this study, we investigated the presence of Ghre and GHS-R 1a in primary mouse OECs. The expression of both Ghre and its receptor was assessed by an immunocytochemical technique, Western Blot and Polymerase Chain Reaction (PCR) analysis. Our results demonstrated that OECs are able to express both Ghre and GHS-R 1a and that these proteins are detectable after extensive passages in vitro; in addition, PCR analysis further confirmed these data. Therefore, we can hypothesize that Ghre and GHS-R 1a interact with a reinforcement function, in the peripheral olfactory circuit, providing a neurotrophic support to the synaptic interaction between ORNs and mitral cells.
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Affiliation(s)
- Cristina Russo
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy
| | - Martina Patanè
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy
| | - Nunzio Vicario
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy
| | - Virginia Di Bella
- Dept Biomedical and Biotechnological Sciences, Section of Medical Biochemistry, University of Catania, Italy
| | - Ilaria Cosentini
- Dept Biomedical and Biotechnological Sciences, Section of Medical Biochemistry, University of Catania, Italy
| | - Vincenza Barresi
- Dept Biomedical and Biotechnological Sciences, Section of Medical Biochemistry, University of Catania, Italy
| | - Rosario Gulino
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy
| | - Rosalia Pellitteri
- Inst for Biomedical Research and Innovation, National Research Council, Catania, Italy
| | - Antonella Russo
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy.
| | - Stefania Stanzani
- Dept Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, Italy
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12
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Montalbano G, Levanti M, Abbate F, Laurà R, Cavallaro M, Guerrera MC, Germanà A. Expression of ghrelin and leptin in the chemosensory system of adult zebrafish. Ann Anat 2020; 229:151460. [PMID: 31978567 DOI: 10.1016/j.aanat.2020.151460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 12/10/2019] [Accepted: 01/06/2020] [Indexed: 11/19/2022]
Abstract
Numerous data show that the chemosensory system seems to be modulated by changes in the circulating levels of different molecules such as ghrelin, orexin, leptin, NPY, CCK. The chemosensory system of the zebrafish is represented by the taste buds (skin, oral and oropharyngeal), the olfactory rosette and the solitary chemosensorial cells (SCCs). The purpose of our study was to analyze the distribution of two peripheral hormones such as ghrelin and leptin in the chemosensory organs of the zebrafish. Our results demonstrated the presence of immunoreaction for all antibodies used in the zebrafish chemosensory organs even if with different distribution. In particular, IR was observed for ghrelin in the olfactory rosette while IR for leptin was found in the olfactory rosette, in the skin and oropharyngeal taste buds and in the gills. Both these hormones were detected in the intestine, used as a control.
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Affiliation(s)
- G Montalbano
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
| | - M Levanti
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy.
| | - F Abbate
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
| | - R Laurà
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
| | - M Cavallaro
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
| | - M C Guerrera
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
| | - A Germanà
- Department of Veterinary Science, University of Messina, Neuromorphology Lab, Italy
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13
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Akalu Y, Molla MD, Dessie G, Ayelign B. Physiological Effect of Ghrelin on Body Systems. Int J Endocrinol 2020; 2020:1385138. [PMID: 32565790 PMCID: PMC7267865 DOI: 10.1155/2020/1385138] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/08/2020] [Accepted: 05/13/2020] [Indexed: 02/06/2023] Open
Abstract
Ghrelin is a relatively novel multifaceted hormone that has been found to exert a plethora of physiological effects. In this review, we found/confirmed that ghrelin has effect on all body systems. It induces appetite; promotes the use of carbohydrates as a source of fuel while sparing fat; inhibits lipid oxidation and promotes lipogenesis; stimulates the gastric acid secretion and motility; improves cardiac performance; decreases blood pressure; and protects the kidneys, heart, and brain. Ghrelin is important for learning, memory, cognition, reward, sleep, taste sensation, olfaction, and sniffing. It has sympatholytic, analgesic, antimicrobial, antifibrotic, and osteogenic effects. Moreover, ghrelin makes the skeletal muscle more excitable and stimulates its regeneration following injury; delays puberty; promotes fetal lung development; decreases thyroid hormone and testosterone; stimulates release of growth hormone, prolactin, glucagon, adrenocorticotropic hormone, cortisol, vasopressin, and oxytocin; inhibits insulin release; and promotes wound healing. Ghrelin protects the body by different mechanisms including inhibition of unwanted inflammation and induction of autophagy. Having a clear understanding of the ghrelin effect in each system has therapeutic implications. Future studies are necessary to elucidate the molecular mechanisms of ghrelin actions as well as its application as a GHSR agonist to treat most common diseases in each system without any paradoxical outcomes on the other systems.
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Affiliation(s)
- Yonas Akalu
- Department of Physiology, School of Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Meseret Derbew Molla
- Department of Biochemistry, School of Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Gashaw Dessie
- Department of Biochemistry, School of Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Birhanu Ayelign
- Department of Immunology and Molecular Biology, School of Biomedical and Laboratory Science, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
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14
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Makaronidis JM, Batterham RL. The role of gut hormones in the pathogenesis and management of obesity. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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15
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Ratcliff M, Rees D, McGrady S, Buntwal L, Hornsby AKE, Bayliss J, Kent BA, Bussey T, Saksida L, Beynon AL, Howell OW, Morgan AH, Sun Y, Andrews ZB, Wells T, Davies JS. Calorie restriction activates new adult born olfactory-bulb neurones in a ghrelin-dependent manner but acyl-ghrelin does not enhance subventricular zone neurogenesis. J Neuroendocrinol 2019; 31:e12755. [PMID: 31179562 DOI: 10.1111/jne.12755] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 12/25/2022]
Abstract
The ageing and degenerating brain show deficits in neural stem/progenitor cell (NSPC) plasticity that are accompanied by impairments in olfactory discrimination. Emerging evidence suggests that the gut hormone ghrelin plays an important role in protecting neurones, promoting synaptic plasticity and increasing hippocampal neurogenesis in the adult brain. In the present study, we investigated the role of ghrelin with respect to modulating adult subventricular zone (SVZ) NSPCs that give rise to new olfactory bulb (OB) neurones. We characterised the expression of the ghrelin receptor, growth hormone secretagogue receptor (GHSR), using an immunohistochemical approach in GHSR-eGFP reporter mice to show that GHSR is expressed in several regions, including the OB but not in the SVZ of the lateral ventricle. These data suggest that acyl-ghrelin does not mediate a direct effect on NSPC in the SVZ. Consistent with these findings, treatment with acyl-ghrelin or genetic silencing of GHSR did not alter NSPC proliferation within the SVZ. Similarly, using a bromodeoxyuridine pulse-chase approach, we show that peripheral treatment of adult rats with acyl-ghrelin did not increase the number of new adult-born neurones in the granule cell layer of the OB. These data demonstrate that acyl-ghrelin does not increase adult OB neurogenesis. Finally, we investigated whether elevating ghrelin indirectly, via calorie restriction (CR), regulated the activity of new adult-born cells in the OB. Overnight CR induced c-Fos expression in new adult-born OB cells but not in developmentally born cells, whereas neuronal activity was absent following re-feeding. These effects were not present in ghrelin-/- mice, suggesting that adult-born cells are uniquely sensitive to changes in ghrelin mediated by fasting and re-feeding. In summary, ghrelin does not promote neurogenesis in the SVZ and OB; however, new adult-born OB cells are activated by CR in a ghrelin-dependent manner.
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Affiliation(s)
- Michael Ratcliff
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Daniel Rees
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Scott McGrady
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Luke Buntwal
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Amanda K E Hornsby
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Jaqueline Bayliss
- Biomedical Discovery Unit, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Brianne A Kent
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | | | | | - Amy L Beynon
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Owain W Howell
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Alwena H Morgan
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Yuxiang Sun
- Department of Nutrition and Food Science, Texas A&M University, College Station, Texas, USA
| | - Zane B Andrews
- Biomedical Discovery Unit, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Timothy Wells
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Jeffrey S Davies
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
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16
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Sex separation induces differences in the olfactory sensory receptor repertoires of male and female mice. Nat Commun 2018; 9:5081. [PMID: 30514924 PMCID: PMC6279840 DOI: 10.1038/s41467-018-07120-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 10/13/2018] [Indexed: 01/12/2023] Open
Abstract
Within the mammalian olfactory sensory epithelium, experience-dependent changes in the rate of neuronal turnover can alter the relative abundance of neurons expressing specific chemoreceptors. Here we investigate how the mouse olfactory sensory receptor repertoire changes as a function of exposure to odors emitted from members of the opposite sex, which are highly complex and sexually dimorphic. Upon housing mice either sex-separated or sex-combined until six months of age, we find that sex-separated mice exhibit significantly more numerous differentially expressed genes within their olfactory epithelia. A subset of these chemoreceptors exhibit altered expression frequencies following both sex-separation and olfactory deprivation. We show that several of these receptors detect either male- or female-specific odors. We conclude that the distinct odor experiences of sex-separated male and female mice induce sex-specific differences in the abundance of neurons that detect sexually dimorphic odors.
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17
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Loss of odor-induced c-Fos expression of juxtaglomerular activity following maintenance of mice on fatty diets. J Bioenerg Biomembr 2018; 51:3-13. [PMID: 30203289 DOI: 10.1007/s10863-018-9769-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/27/2018] [Indexed: 10/28/2022]
Abstract
Diet-induced obesity (DIO) decreases the number of OMP+ olfactory sensory neurons (OSN) in the olfactory epithelium by 25% and reduces correlate axonal projections to the olfactory bulb (OB). Whether surviving OSNs have equivalent odor responsivity is largely unknown. Herein, we utilized c-fos immediate-early gene expression to map neuronal activity and determine whether mice weaned to control (CF), moderately-high fat (MHF), or high-fat (HF) diet for a period of 6 months had changes in odor activation. Diet-challenged M72-IRES-tau-GFP mice were exposed to either a preferred M72 (Olfr160) ligand, isopropyl tiglate, or clean air in a custom-made Bell-jar infusion chamber using an alternating odor exposure pattern generated by a picosprizer™. Mice maintained on fatty diets weighed significantly more and cleared glucose less efficiently as determined by an intraperitoneal glucose tolerance test (IPGTT). The number of juxtaglomerular cells (JGs) decreased following maintenance of the mice on the MHF diet for cells surrounding the medial but not lateral M72 glomerulus within a 4 cell-column distance. The percentage of c-fos + JGs surrounding the lateral M72 glomerulus decreased in fat-challenged mice whereas those surrounding the medial glomerulus were not affected by diet. Altogether, these results show an asymmetry in the responsiveness of the 'mirror image' glomerular map for the M72 receptor that shows greater sensitivity of the lateral vs. medial glomerulus upon exposure to fatty diet.
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18
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Makaronidis JM, Batterham RL. Obesity, body weight regulation and the brain: insights from fMRI. Br J Radiol 2018; 91:20170910. [PMID: 29365284 DOI: 10.1259/bjr.20170910] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Obesity constitutes a major global health threat. Despite the success of bariatric surgery in delivering sustainable weight loss and improvement in obesity-related morbidity, effective non-surgical treatments are urgently needed, necessitating an increased understanding of body weight regulation. Neuroimaging studies undertaken in people with healthy weight, overweight, obesity and following bariatric surgery have contributed to identifying the neurophysiological changes seen in obesity and help increase our understanding of the mechanisms driving the favourable eating behaviour changes and sustained weight loss engendered by bariatric surgery. These studies have revealed a key interplay between peripheral metabolic signals, homeostatic and hedonic brain regions and genetics. Findings from brain functional magnetic resonance imaging (fMRI) studies have consistently associated obesity with an increased motivational drive to eat, increased reward responses to food cues and impaired food-related self-control processes. Interestingly, new data link these obesity-associated changes with structural and connectivity changes within the central nervous system. Moreover, emerging data suggest that bariatric surgery leads to neuroplastic recovery. A greater understanding of the interactions between peripheral signals of energy balance, the neural substrates that regulate eating behaviour, the environment and genetics will be key for the development of novel therapeutic strategies for obesity. This review provides an overview of our current understanding of the pathoaetiology of obesity with a focus upon the role that fMRI studies have played in enhancing our understanding of the central regulation of eating behaviour and energy homeostasis.
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Affiliation(s)
- Janine M Makaronidis
- 1 Department of Medicine, Centre for Obesity Research, Rayne Institute, University College London , London , UK.,2 Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital (UCLH) Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital , London , UK.,3 Bariatric Centre for Weight Management and Metabolic Surgery, National Institute of Health Research, UCLH Biomedical Research Centre , London , UK
| | - Rachel L Batterham
- 1 Department of Medicine, Centre for Obesity Research, Rayne Institute, University College London , London , UK.,2 Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital (UCLH) Bariatric Centre for Weight Management and Metabolic Surgery, University College London Hospital , London , UK.,3 Bariatric Centre for Weight Management and Metabolic Surgery, National Institute of Health Research, UCLH Biomedical Research Centre , London , UK
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19
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Daumas-Meyer V, Champeil-Potokar G, Chaumontet C, Dahirel P, Papillon C, Congar P, Denis I. Fasting induces astroglial plasticity in the olfactory bulb glomeruli of rats. Glia 2017; 66:762-776. [DOI: 10.1002/glia.23280] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 11/22/2017] [Accepted: 11/24/2017] [Indexed: 01/20/2023]
Affiliation(s)
| | | | | | - Patrice Dahirel
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
| | | | - Patrice Congar
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
| | - Isabelle Denis
- NBO UR1197, INRA, Université Paris-Saclay; Jouy-en-Josas 78350 France
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20
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Santos VV, Stark R, Rial D, Silva HB, Bayliss JA, Lemus MB, Davies JS, Cunha RA, Prediger RD, Andrews ZB. Acyl ghrelin improves cognition, synaptic plasticity deficits and neuroinflammation following amyloid β (Aβ1-40) administration in mice. J Neuroendocrinol 2017; 29. [PMID: 28380673 DOI: 10.1111/jne.12476] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 03/16/2017] [Accepted: 04/03/2017] [Indexed: 12/24/2022]
Abstract
Ghrelin is a metabolic hormone that has neuroprotective actions in a number of neurological conditions, including Parkinson's disease (PD), stroke and traumatic brain injury. Acyl ghrelin treatment in vivo and in vitro also shows protective capacity in Alzheimer's disease (AD). In the present study, we used ghrelin knockout (KO) and their wild-type littermates to test whether or not endogenous ghrelin is protective in a mouse model of AD, in which human amyloid β peptide 1-40 (Aβ1-40 ) was injected into the lateral ventricles i.c.v. Recognition memory, using the novel object recognition task, was significantly impaired in ghrelin KO mice and after i.c.v. Aβ1-40 treatment. These deficits could be prevented by acyl ghrelin injections for 7 days. Spatial orientation, as assessed by the Y-maze task, was also significantly impaired in ghrelin KO mice and after i.c.v. Aβ1-40 treatment. These deficits could be prevented by acyl ghrelin injections for 7 days. Ghrelin KO mice had deficits in olfactory discrimination; however, neither i.c.v. Aβ1-40 treatment, nor acyl ghrelin injections affected olfactory discrimination. We used stereology to show that ghrelin KO and Aβ1-40 increased the total number of glial fibrillary acidic protein expressing astrocytes and ionised calcium-binding adapter expressing microglial in the rostral hippocampus. Finally, Aβ1-40 blocked long-term potentiation induced by high-frequency stimulation and this effect could be acutely blocked with co-administration of acyl ghrelin. Collectively, our studies demonstrate that ghrelin deletion affects memory performance and also that acyl ghrelin treatment may delay the onset of early events of AD. This supports the idea that acyl ghrelin treatment may be therapeutically beneficial with respect to restricting disease progression in AD.
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Affiliation(s)
- V V Santos
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - R Stark
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - D Rial
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina UFSC, Florianópolis, SC, Brazil
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - H B Silva
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - J A Bayliss
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - M B Lemus
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
| | - J S Davies
- Molecular Neurobiology, Institute of Life Science, Swansea University, Swansea, UK
| | - R A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - R D Prediger
- Department of Pharmacology, Center of Biological Sciences, Universidade Federal de Santa Catarina UFSC, Florianópolis, SC, Brazil
| | - Z B Andrews
- Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Clayton, VIC, Australia
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21
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Reported appetite, taste and smell changes following Roux-en-Y gastric bypass and sleeve gastrectomy: Effect of gender, type 2 diabetes and relationship to post-operative weight loss. Appetite 2016; 107:93-105. [PMID: 27453553 DOI: 10.1016/j.appet.2016.07.029] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 07/16/2016] [Accepted: 07/20/2016] [Indexed: 12/11/2022]
Abstract
Reduced energy intake drives weight loss following Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) procedures. Post-operative changes in subjective appetite, taste, and smell and food preferences are reported and suggested to contribute to reduced energy intake. We aimed to investigate the prevalence of these changes following RYGB and SG and to evaluate their relationship with weight loss. 98 patients post-RYGB and 155 post-SG from a single bariatric centre were recruited to a cross-sectional study. Participants completed a questionnaire, previously utilised in post-operative bariatric patients, to assess the prevalence of post-operative food aversions and subjective changes in appetite, taste and smell. Anthropometric data were collected and percentage weight loss (%WL) was calculated. The relationship between food aversions, changes in appetite, taste and smell and %WL was assessed. The influence of time post-surgery, gender and type 2 diabetes (T2D) were evaluated. Following RYGB and SG the majority of patients reported food aversions (RYGB = 62%, SG = 59%), appetite changes (RYGB = 91%, SG = 91%) and taste changes (RYGB = 64%, SG = 59%). Smell changes were more common post-RYGB than post-SG (RYGB = 41%, SG = 28%, p = 0.039). No temporal effect was observed post-RYGB. In contrast, the prevalence of appetite changes decreased significantly with time following SG. Post-operative appetite changes associated with and predicted higher %WL post-SG but not post-RYGB. Taste changes associated with and predicted higher %WL following RYGB but not post-SG. There was no gender effect post-RYGB. Post-SG taste changes were less common in males (female = 65%, males = 40%, p = 0.008). T2D status in females did not influence post-operative subjective changes. However, in males with T2D, taste changes were less common post-SG than post-RYGB together with lower %WL (RYGB = 27.5 ± 2.7, SG = 14.6 ± 2.1, p = 0.003). Further research is warranted to define the biology underlying these differences and to individualise treatments.
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