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Harvey J. Novel Leptin-Based Therapeutic Strategies to Limit Synaptic Dysfunction in Alzheimer's Disease. Int J Mol Sci 2024; 25:7352. [PMID: 39000459 PMCID: PMC11242278 DOI: 10.3390/ijms25137352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/16/2024] Open
Abstract
Accumulation of hyper-phosphorylated tau and amyloid beta (Aβ) are key pathological hallmarks of Alzheimer's disease (AD). Increasing evidence indicates that in the early pre-clinical stages of AD, phosphorylation and build-up of tau drives impairments in hippocampal excitatory synaptic function, which ultimately leads to cognitive deficits. Consequently, limiting tau-related synaptic abnormalities may have beneficial effects in AD. There is now significant evidence that the hippocampus is an important brain target for the endocrine hormone leptin and that leptin has pro-cognitive properties, as activation of synaptic leptin receptors markedly influences higher cognitive processes including learning and memory. Clinical studies have identified a link between the circulating leptin levels and the risk of AD, such that AD risk is elevated when leptin levels fall outwith the physiological range. This has fuelled interest in targeting the leptin system therapeutically. Accumulating evidence supports this possibility, as numerous studies have shown that leptin has protective effects in a variety of models of AD. Recent findings have demonstrated that leptin has beneficial effects in the preclinical stages of AD, as leptin prevents the early synaptic impairments driven by tau protein and amyloid β. Here we review recent findings that implicate the leptin system as a potential novel therapeutic target in AD.
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Affiliation(s)
- Jenni Harvey
- Department of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
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2
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Harvey J. Food for Thought: Leptin and Hippocampal Synaptic Function. Front Pharmacol 2022; 13:882158. [PMID: 35784728 PMCID: PMC9247348 DOI: 10.3389/fphar.2022.882158] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/02/2022] [Indexed: 11/13/2022] Open
Abstract
It is well documented that the endocrine hormone, leptin controls energy homeostasis by providing key signals to specific hypothalamic nuclei. However, our knowledge of leptin’s central actions has advanced considerably over the last 20 years, with the hippocampus now established as an important brain target for this hormone. Leptin receptors are highly localised to hippocampal synapses, and increasing evidence reveals that activation of synaptically located leptin receptors markedly impacts cognitive processes, and specifically hippocampal-dependent learning and memory. Here, we review the recent actions of leptin at hippocampal synapses and explore the consequences for brain health and disease.
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Farhadi Z, Khaksari M, Azizian H, Dabiri S. The brain neuropeptides and STAT3 mediate the inhibitory effect of 17-β Estradiol on central leptin resistance in young but not aged female high-fat diet mice. Metab Brain Dis 2022; 37:625-637. [PMID: 35031929 DOI: 10.1007/s11011-021-00884-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 12/05/2021] [Indexed: 11/24/2022]
Abstract
Aging and menopause effect on body composition and energy balance. Estrogen (E2) plays an important role in body's metabolism. The aim of the present study was to determine changes in leptin function in young intact and ovariectomized (OVX) animals in comparison to the aged animals treated with E2. Young (Intact and OVX 4 months) and aged (19-21 months) female mice were fed High-fat diet (HFD) for 12 weeks and, then they were divided into eight groups including: Intact + OIL, Intact + E2, Intact + Pair body weight (PBW), OVX + OIL, OVX + E2, OVX + PBW, Aged + OIL, and Aged + E2. E2 was administered subcutaneously every four days for four weeks. Responsiveness to leptin was assessed by measuring energy balance components. Results showed that eating HFD increased weight and calorie consumption in young mice, and chronic treatment with E2 decreased both these variables in young animals. E2 only improved the sensitivity to leptin in young animals. Treatment with E2 resulted in increased α-MSH neuropeptide, reduced NPY and AgRP neuropeptides in the brain, and decreased serum leptin in the young animals. Also, treatment with E2 increased the expression of p-STAT3 molecular level in the hypothalamic arcuate nucleus (ARC) in the young animals. Our results indicated that response to E2 depended on age and E2 protects young HFD fed mice from obesity and improves leptin sensitivity.
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Affiliation(s)
- Zeinab Farhadi
- Department of Physiology and Pharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Khaksari
- Endocrinology and Metabolism Research Center, Kerman University of Medical Sciences, Kerman, Iran.
| | - Hossein Azizian
- Department of Physiology, School of Medicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Shahriar Dabiri
- Pathology and Stem Cell Research Center, Kerman University of Medical Sciences, Kerman, Iran
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Rubio C, Lizárraga E, Álvarez-Cilleros D, Pérez-Pardo P, Sanmartín-Salinas P, Toledo-Lobo MV, Alvarez C, Escrivá F, Fernández-Lobato M, Guijarro LG, Valverde AM, Carrascosa JM. Aging in Male Wistar Rats Associates With Changes in Intestinal Microbiota, Gut Structure, and Cholecystokinin-Mediated Gut-Brain Axis Function. J Gerontol A Biol Sci Med Sci 2021; 76:1915-1921. [PMID: 33315062 DOI: 10.1093/gerona/glaa313] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Indexed: 11/14/2022] Open
Abstract
Aging in mammals is characterized by failure of the homeostatic mechanisms that regulate energy balance. Several mechanisms have been proposed such as the presence of a low-grade chronic inflammation in different tissues, as well as leptin and insulin resistance, but the primary alteration is not fully elucidated. The gut microbiota has recently emerged as a key player in a variety of metabolic and neurological disorders. A main concept in this context is the gut-brain axis that refers to alterations in the gut that mediate effects in the central nervous system, including those related with the control of energy balance. Using 16S rRNA analysis, we demonstrate that aged male Wistar rats have increased presence of mucin-degrading and lipopolysaccharide (LPS)-producing bacteria. In addition, old animals exhibit a lower number of neutral mucin secreting goblet cells, and a decrease of tight junctions and adherens junctions marker proteins, zonula occludens protein-1 (ZO-1) and β-catenin, respectively. These data are compatible with a thinner mucus layer and a weaker gut barrier in older animals that likely facilitate LPS leakage. Our data also show that cholecystokinin (CCK) satiating effect is impaired in aged rats, one of the expected effects of increased LPS leakage. In contrast, no overt signs of gut or systemic inflammation are observed. Changes in microbiota in old male Wistar rats present features of situations of increased adiposity, but different from those of obese animals. These could partly explain the increased adiposity and fat deposition in liver and heart as observed here.
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Affiliation(s)
- Carmen Rubio
- Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (UAM-CSIC), Universidad Autónoma de Madrid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII, Madrid, Spain
| | - Esther Lizárraga
- Departamento de Bioquímica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - David Álvarez-Cilleros
- Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Spain
| | - Paula Pérez-Pardo
- Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Spain
| | - Patricia Sanmartín-Salinas
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), ISCIII, Madrid, Spain
| | - M Val Toledo-Lobo
- Departamento de Biomedicina y Biotecnología, Facultad de Medicina, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain.,IRYCIS, Hospital Ramón y Cajal, Madrid, Spain
| | - Carmen Alvarez
- Departamento de Bioquímica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Fernando Escrivá
- Departamento de Bioquímica, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - María Fernández-Lobato
- Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Spain
| | - Luis G Guijarro
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), ISCIII, Madrid, Spain
| | - Angela M Valverde
- Instituto de Investigaciones Biomédicas "Alberto Sols" (UAM-CSIC), Universidad Autónoma de Madrid, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), ISCIII, Madrid, Spain
| | - José M Carrascosa
- Centro de Biología Molecular "Severo Ochoa" (UAM-CSIC), Universidad Autónoma de Madrid, Spain
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Alldred MJ, Lee SH, Ginsberg SD. Adiponectin Modulation by Genotype and Maternal Choline Supplementation in a Mouse Model of Down Syndrome and Alzheimer's Disease. J Clin Med 2021; 10:2994. [PMID: 34279477 PMCID: PMC8267749 DOI: 10.3390/jcm10132994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/01/2021] [Accepted: 07/03/2021] [Indexed: 12/13/2022] Open
Abstract
Down syndrome (DS) is a genetic disorder caused by the triplication of human chromosome 21, which results in neurological and physiological pathologies. These deficits increase during aging and are exacerbated by cognitive decline and increase of Alzheimer's disease (AD) neuropathology. A nontoxic, noninvasive treatment, maternal choline supplementation (MCS) attenuates cognitive decline in mouse models of DS and AD. To evaluate potential underlying mechanisms, laser capture microdissection of individual neuronal populations of MCS offspring was performed, followed by RNA sequencing and bioinformatic inquiry. Results at ~6 months of age (MO) revealed DS mice (the well-established Ts65Dn model) have significant dysregulation of select genes within the Type 2 Diabetes Mellitus (T2DM) signaling pathway relative to normal disomic (2N) littermates. Accordingly, we interrogated key T2DM protein hormones by ELISA assay in addition to gene and encoded protein levels in the brain. We found dysregulation of adiponectin (APN) protein levels in the frontal cortex of ~6 MO trisomic mice, which was attenuated by MCS. APN receptors also displayed expression level changes in response to MCS. APN is a potential biomarker for AD pathology and may be relevant in DS. We posit that changes in APN signaling may be an early marker of cognitive decline and neurodegeneration.
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Affiliation(s)
- Melissa J. Alldred
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA
- Departments of Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Sang Han Lee
- Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute, Orangeburg, NY 10962, USA;
- Child & Adolescent Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, USA
| | - Stephen D. Ginsberg
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, NY 10962, USA
- Departments of Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, USA
- Neuroscience & Physiology, New York University Grossman School of Medicine, New York, NY 10016, USA
- NYU Neuroscience Institute, New York University Grossman School of Medicine, New York, NY 10016, USA
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Rodríguez M, Pintado C, Torrillas-de la Cal R, Moltó E, Gallardo N, Andrés A, Arribas C. Ageing alters the lipid sensing process in the hypothalamus of Wistar rats. Effect of food restriction. Nutr Neurosci 2021; 25:1509-1523. [PMID: 33544062 DOI: 10.1080/1028415x.2021.1872990] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Lipids regulate a wide range of biological processes. The mechanisms by which fatty acids (FA) and its metabolites influence the hypothalamic regulation of energy homeostasis have been highly studied. However, the effect of ageing and food restriction (FR) on this process is unknown. METHODS Herein, we analyzed the gene expression, protein and phosphorylation levels of hypothalamic enzymes and transcription factors related to lipid metabolism. Experiments were performed in male Wistar rats of 3-, 8- and 24-month-old Wistar rats fed ad libitum (AL), as ageing model. Besides, 5- and 21-month-old rats were subjected to a moderate FR protocol (equivalent to ≈ 80% of normal food intake) for three months before the sacrifice. RESULTS Aged Wistar rats showed a situation of chronic lipid excess as a result of an increase in de novo FA synthesis and FA levels that reach the brain, contributing likely to the development of central leptin and insulin resistance. We observe a hypothalamic downregulation of AMP-activated protein kinase (AMPK) and stearoyl-CoA desaturase (SCD1) and an increase of carnitine palmitoyltransferase-1c (CPT1c) expression. DISCUSSION Our results suggest an impairment in the physiological lipid sensing system of aged Wistar rats, which would alter the balance of the intracellular mobilization and trafficking of lipids between the mitochondria and the Endoplasmic Reticulum (ER) in the hypothalamus, leading probably to the development of neurolipotoxicity in aged rats. Lastly, FR can only partially restore this imbalance.Schematic representation of the fate of LCFA-CoA in the hypothalamus of young and old rats. Blood circulating LCFAs in young Wistar rats reach the hypothalamus, where they are esterified to LCFA-CoA. Into glial cells or neurons, LCFA-CoA are driven to mitochondria (CPT1a) or ER (CPT1c) where could be desaturated by SDC1 and, thereby, converted into structural and signaling unsaturated lipids as oleic acid, related with neuronal myelinization and differentiation. However, the excess of LCFA that reach to the hypothalamus in old animals, could generate an increase in LCFA-CoA, which together with an increase in CPT1c levels, could favor the capture of LCFA-CoA to the ER. The decrease in the levels of SCD1 in old rats would decrease FA unsaturation degree that could trigger lipotoxicity process and neurodegeneration, both related to the development of neurodegenerative diseases linked to age.
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Affiliation(s)
- María Rodríguez
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Cristina Pintado
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Rodrigo Torrillas-de la Cal
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Eduardo Moltó
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
| | - Nilda Gallardo
- Biochemistry Section, Faculty of Science and Chemical Technologies and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Antonio Andrés
- Biochemistry Section, Faculty of Science and Chemical Technologies and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Carmen Arribas
- Biochemistry Section, Faculty of Biochemistry and Environmental Sciences and Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, Toledo, Spain
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Hamilton K, Harvey J. Leptin regulation of hippocampal synaptic function in health and disease. VITAMINS AND HORMONES 2021; 115:105-127. [PMID: 33706945 DOI: 10.1016/bs.vh.2020.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It is widely accepted that the metabolic hormone leptin regulates food intake and body weight via activation of hypothalamic leptin receptors. However, as leptin receptors are also highly expressed in other brain regions, such as the hippocampus, alterations in leptin responsiveness also impacts on key functions of the hippocampus, like learning and memory. Within the hippocampus, high levels of leptin receptors are expressed at excitatory synapses, and in accordance with a synaptic localization, leptin potently regulates synaptic transmission at both Schaffer collateral (SC) and temporoammonic (TA) inputs to CA1 pyramidal neurons. Increasing evidence from cellular and behavioral studies examining leptin action at CA1 synapses support the notion that leptin is a potential cognitive enhancer. However, the capacity of leptin to regulate synaptic efficacy at SC-CA1 and TA-CA1 synapses declines in an age-dependent manner. Moreover, clinical evidence that supports a link between circulating leptin levels and the risk of the age-related neurodegenerative disorder, Alzheimer's disease (AD) is accumulating. Consequently, it has been proposed that the leptin system is a potential therapeutic target in AD, and that boosting the hippocampal actions of leptin may be beneficial in the treatment of AD. Here we review recent progress in our understanding of the neuronal and hippocampal synaptic functions that are regulated by leptin and how alterations in the leptin system influence age-related CNS-related disorders like AD.
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Affiliation(s)
- Kirsty Hamilton
- Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom
| | - Jenni Harvey
- Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, United Kingdom.
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Chellian R, Wilson R, Polmann M, Knight P, Behnood-Rod A, Bruijnzeel AW. Evaluation of Sex Differences in the Elasticity of Demand for Nicotine and Food in Rats. Nicotine Tob Res 2020; 22:925-934. [PMID: 31603225 DOI: 10.1093/ntr/ntz171] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/04/2019] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Animal studies can inform policy regarding nicotine levels in tobacco products and e-cigarette solutions. Increasing the price of nicotine-containing products decreases their use, but it is unknown how the relationship between price and consumption is affected by both sex and nicotine dose. METHODS A behavioral economics procedure was used to determine the demand elasticity for nicotine in male and female rats. Demand elasticity describes the relationship between price and consumption. A high level of elasticity indicates that consumption is relatively sensitive to increases in price. The rats self-administered a low dose (0.01 mg/kg/inf) or a standard dose (0.03 mg/kg/inf) of nicotine for 9 days under a fixed-ratio (FR) 1 schedule. Then the price (FR schedule) of nicotine was increased, and a demand analysis was conducted. A similar study was conducted with palatable food pellets. RESULTS There were no sex differences in nicotine or food intake under the FR1 schedule. However, demand for 0.03 mg/kg/inf of nicotine was more elastic in females than males. Demand for 0.01 mg/kg/inf of nicotine and food was more elastic in males than females. CONCLUSIONS These findings indicate that there are no differences in nicotine and food intake between males and females when the price is low. When the price of nicotine or food is increased, males maintain their old level of intake longer than females when they have access to a standard dose of nicotine, and females maintain their intake longer when they have access to a low dose of nicotine or food. IMPLICATIONS This behavioral economics analysis indicates that there is no sex difference in nicotine intake when the price of nicotine is low. Increasing the price of nicotine decreases nicotine intake in a dose- and sex-specific manner. Males maintain their old level of intake longer when they have access to a standard dose of nicotine and females when they have access to a low dose. This has implications for tobacco regulatory policy. In a regulatory environment where only low nicotine-containing products are allowed, increasing the price of nicotine products may lead to a greater decrease in nicotine use in males than females.
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Affiliation(s)
| | - Ryann Wilson
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Michaela Polmann
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Parker Knight
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Azin Behnood-Rod
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
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Quirós Cognuck S, Reis WL, Silva M, Debarba LK, Mecawi AS, de Paula FJ, Rodrigues Franci C, Elias LL, Antunes‐Rodrigues J. Sex differences in body composition, metabolism-related hormones, and energy homeostasis during aging in Wistar rats. Physiol Rep 2020; 8:e14597. [PMID: 33075214 PMCID: PMC7571994 DOI: 10.14814/phy2.14597] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/14/2022] Open
Abstract
Aging affects the body composition and balance of energy metabolism. Here, we collected in a single work several physiological parameters to show how aging and sex differences can influence energy homeostasis. Body mass index (BMI), Lee index, glucose tolerance, glycemia, and lipidogram in fasting were measured in male and female Wistar rats at the ages of 2, 6, 9, 12, and 18 months. We also measured the lipid profile, free fatty acids, glycerol, glycemia, leptin, adiponectin, insulin, corticosterone (CORT), prolactin (PRL), thyroid stimulated hormone, and triiodothyronine (T3) in 3- and 18-month-old rats of both sexes, fed ad libitum. Animals were classified as obese beginning at 2 months in males and 6 months in females. Aged male rats showed hyperglycemia and glucose intolerance compared to young males and old females. In the ad libitum condition, the 18-month males presented higher serum levels of triglycerides, total cholesterol, and free fatty acids than females. The 18-month-old females had higher PRL and CORT concentration than males, but insulin and T3 were higher in 18-month-old males than females. Our work demonstrated that aging processes on energy metabolism in rats is sex specific, with a better lipid profile and glucose tolerance in aged females.
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Affiliation(s)
- Susana Quirós Cognuck
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Wagner L. Reis
- Department of Physiological ScienceCenter of Biological SciencesFederal University of Santa CatarinaFlorianópolosBrazil
| | - Marcia Silva
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Lucas K. Debarba
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Andre S. Mecawi
- Laboratory of NeuroendocrinologyDepartment of BiophysicsEscola Paulista de MedicinaUniversidade Federal de Sao PauloSao PauloBrazil
| | - Francisco J.A. de Paula
- Medical Clinic DepartmentRibeirao Preto Medicine SchoolUniversity of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Celso Rodrigues Franci
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Lucila L.K. Elias
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
| | - Jose Antunes‐Rodrigues
- Physiology DepartmentRibeirao Preto Medicine School, University of Sao PauloRibeirao Preto, Sao PauloBrazil
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Geste JR, Levin B, Wilks I, Pompilus M, Zhang X, Esser KA, Febo M, O'Dell L, Bruijnzeel AW. Relationship Between Nicotine Intake and Reward Function in Rats With Intermittent Short Versus Long Access to Nicotine. Nicotine Tob Res 2020; 22:213-223. [PMID: 30958557 DOI: 10.1093/ntr/ntz052] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 04/01/2019] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Tobacco use improves mood states and smoking cessation leads to anhedonia, which contributes to relapse. Animal studies have shown that noncontingent nicotine administration enhances brain reward function and leads to dependence. However, little is known about the effects of nicotine self-administration on the state of the reward system. METHODS To investigate the relationship between nicotine self-administration and reward function, rats were prepared with intracranial self-stimulation electrodes and intravenous catheters. The rats were trained on the intracranial self-stimulation procedure and allowed to self-administer 0.03 mg/kg/infusion of nicotine. All rats self-administered nicotine daily for 10 days (1 hour/day) and were then switched to an intermittent short access (ShA, 1 hour/day) or long access (LgA, 23 hour/day) schedule (2 days/week, 5 weeks). RESULTS During the first 10 daily, 1-hour sessions, nicotine self-administration decreased the reward thresholds, which indicates that nicotine potentiates reward function. After switching to the intermittent LgA or ShA schedule, nicotine intake was lower in the ShA rats than the LgA rats. The LgA rats increased their nicotine intake over time and they gradually consumed a higher percentage of their nicotine during the light phase. The nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine induced a larger increase in reward thresholds (ie, anhedonia) in the LgA rats than the ShA rats. In the LgA rats, nAChR blockade with mecamylamine decreased nicotine intake for 2 hours and this was followed by a rebound increase in nicotine intake. CONCLUSIONS A brief period of nicotine self-administration enhances reward function and a high level of nicotine intake leads to dependence. IMPLICATIONS These animal studies indicate that there is a strong relationship between the level of nicotine intake and brain reward function. A high level of nicotine intake was more rewarding than a low level of nicotine intake and nicotine dependence was observed after long, but not short, access to nicotine. This powerful combination of nicotine reward and withdrawal makes it difficult to quit smoking. Blockade of nAChRs temporarily decreased nicotine intake, but this was followed by a large rebound increase in nicotine intake. Therefore, nAChR blockade might not decrease the use of combustible cigarettes or electronic cigarettes.
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Affiliation(s)
- Jean R Geste
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Brandon Levin
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Isaac Wilks
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Marjory Pompilus
- Department of Psychiatry, University of Florida, Gainesville, FL
| | - Xiping Zhang
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL
| | - Karyn A Esser
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL
| | - Marcelo Febo
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
| | - Laura O'Dell
- Department of Psychology, University of Texas at El Paso, El Paso, TX
| | - Adriaan W Bruijnzeel
- Department of Psychiatry, University of Florida, Gainesville, FL.,Department of Neuroscience, University of Florida, Gainesville, FL
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11
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Farhadi Z, Khaksari M, Azizian H, Dabiri S, Fallah H, Nozari M. Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines. Mech Ageing Dev 2020; 186:111198. [PMID: 31904410 DOI: 10.1016/j.mad.2019.111198] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/27/2019] [Accepted: 12/19/2019] [Indexed: 01/25/2023]
Abstract
Aging causes changes in body composition and energy balance. Estrogen plays an important role in body's metabolism. The aim of this study was to determine whether estrogen has beneficial effects on leptin responsiveness in aged mice. Young 4 months and aged 19-21 female mice fed High Fat Diet (HFD) or Standard Diet (SD) for 12 weeks and following received estrogen for 4 weeks. Responsiveness to leptin was compared by measuring energy balance parameters. Results showed that HFD caused weight gain compared to SD in young, but had no effect on aged animals. Estrogen reduced body weight, energy intake and visceral fat in young, while none of these parameters was affected in aged animals. Although there was leptin sensitivity in aged compared to ovariectomized animals, estrogen only improved the sensitivity of young to leptin. Estrogen prevented increase in TNF-α and a decrease in IL-10 in HFD young and aged animals. Response to estrogen depended on age, and estrogen increased leptin sensitivity only in young animals. Determining the exact mechanism of this action is suggested in future studies.
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Affiliation(s)
- Zeinab Farhadi
- Department of Physiology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Khaksari
- Endocrinology and Metabolism Research, and Physiology Research Centers, Kerman University of Medical Sciences, Kerman, Iran.
| | - Hossein Azizian
- Neurobiomedical Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Shahriar Dabiri
- Pathology and Stem Cell Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Hossein Fallah
- Department of Clinical Biochemistry, Afzalipour School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | - Masoumeh Nozari
- Neuroscience Research, and Physiology Research Centers, Kerman University of Medical Sciences, Kerman, Iran
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12
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Bonzón-Kulichenko E, Moltó E, Pintado C, Fernández A, Arribas C, Schwudke D, Gallardo N, Shevchenko A, Andrés A. Changes in Visceral Adipose Tissue Plasma Membrane Lipid Composition in Old Rats Are Associated With Adipocyte Hypertrophy With Aging. J Gerontol A Biol Sci Med Sci 2019; 73:1139-1146. [PMID: 29668887 DOI: 10.1093/gerona/gly081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 04/13/2018] [Indexed: 12/17/2022] Open
Abstract
Increased adiposity, through adipocyte hypertrophy, and/or hyperplasia, characterizes aging and obesity. Both are leptin-resistant states, associated with disturbed lipid metabolism, reduced insulin sensitivity and inflammation. Nevertheless, fat tissue dysfunction appears earlier in obesity than in normal aging. In contrast, lipodystrophy is accompanied by diabetes, and improving the fat cell capacity to expand rescues the diabetic phenotype. Fat tissue dysfunction is extensively studied in the diet-induced obesity, but remains relatively neglected in the aging-associated obesity. In the Wistar rat, as occurs in humans, early or middle aging is accompanied by an increase in adiposity. Using this experimental model, we describe the molecular mechanisms contributing to the white adipose tissue (WAT) hypertrophy. WAT from middle-old age rats is characterized by decreased basal lipogenesis and lipolysis, increased esterification, as demonstrated by the higher TAG and cholesterol content in visceral WAT, and the maintenance of total ceramide levels within normal values. In addition, we describe alterations in the adipose tissue plasma membrane lipid composition, as increased total ether-phosphatidylcholine, sphingomyelin, and free cholesterol levels that favor an enlarged fat cell size with aging. All these metabolic changes may be regarded as a survival advantage that prevents the aged rats from becoming overtly diabetic.
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Affiliation(s)
- Elena Bonzón-Kulichenko
- Área de Bioquímica, Facultad de Ciencias y Tecnologías Químicas, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Ciudad Real, Spain
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Eduardo Moltó
- Área de Bioquímica, Facultad de Ciencias Medioambientales y Bioquímica, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Toledo, Spain
| | - Cristina Pintado
- Área de Bioquímica, Facultad de Ciencias Medioambientales y Bioquímica, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Toledo, Spain
| | - Alejandro Fernández
- Área de Bioquímica, Facultad de Ciencias y Tecnologías Químicas, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Carmen Arribas
- Área de Bioquímica, Facultad de Ciencias Medioambientales y Bioquímica, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Toledo, Spain
| | - Dominik Schwudke
- Division of Bioanalytical Chemistry, Priority Area Infections, Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Germany
| | - Nilda Gallardo
- Área de Bioquímica, Facultad de Ciencias y Tecnologías Químicas, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Ciudad Real, Spain
| | - Andrej Shevchenko
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Antonio Andrés
- Área de Bioquímica, Facultad de Ciencias y Tecnologías Químicas, Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, Ciudad Real, Spain
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13
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Yu HR, Sheen JM, Tiao MM, Tain YL, Chen CC, Lin IC, Lai YJ, Tsai CC, Lin YJ, Tsai CC, Chang KA, Huang LT. Resveratrol Treatment Ameliorates Leptin Resistance and Adiposity Programed by the Combined Effect of Maternal and Post-Weaning High-Fat Diet. Mol Nutr Food Res 2019; 63:e1801385. [PMID: 31004461 DOI: 10.1002/mnfr.201801385] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/08/2019] [Indexed: 01/24/2023]
Abstract
SCOPE Prenatal high-fat (HF) and postnatal HF diet are both associated with obesity and metabolic disturbances in adults. Leptin resistance induced by obesity limits its biological effects. The anti-obesity mechanism of resveratrol in visceral adiposity is investigated here. METHODS AND RESULTS During mating and lactation, Sprague-Dawley dams are fed either control or a HF diet. Subsequently, the offspring are fed chow or an HF diet. A fifth group that received maternal/postnatal HF diet and resveratrol after weaning (HHR) is used to study the effects of resveratrol treatment. Resveratrol treatment alleviates adiposity programed by maternal and postnatal HF diet by decreasing feed intake or inducing metabolic changes. Resveratrol treatment is also found to ameliorate the decrease in SIRT1 abundance observed in retroperitoneal adipose tissue, programed by maternal and postnatal HF diet. Moreover, resveratrol therapy decreases plasma leptin level and increases leptin receptor expression in retroperitoneal adipose tissue through DNA methylation modification. CONCLUSION These results suggest that resveratrol can alleviate peripheral leptin resistance programed by the combined effect of prenatal and postnatal HF diet through epigenetic regulation of genes coding leptin and its receptor. It provides insights into a novel mechanism explaining the beneficial effects of resveratrol in obesity management.
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Affiliation(s)
- Hong-Ren Yu
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - Jiunn-Ming Sheen
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - Mao-Meng Tiao
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - You-Lin Tain
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - Chih-Cheng Chen
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - I-Chun Lin
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
| | - Yun-Ju Lai
- Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
| | - Ching-Chou Tsai
- Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
| | - Yu-Ju Lin
- Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
| | - Ching-Chang Tsai
- Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Kaohsiung, Taiwan
| | - Kow-Aung Chang
- Department of Anesthesiology, Kaohsiung Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Kaohsiung, 83301, Taiwan
| | - Li-Tung Huang
- Department of Pediatrics, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Graduate Institute of Clinical Medical Science, College of Medicine, Chang Gung University,, Kaohsiung, Taiwan
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14
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Chellappa K, Perron IJ, Naidoo N, Baur JA. The leptin sensitizer celastrol reduces age-associated obesity and modulates behavioral rhythms. Aging Cell 2019; 18:e12874. [PMID: 30821426 PMCID: PMC6516176 DOI: 10.1111/acel.12874] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 08/05/2018] [Accepted: 10/15/2018] [Indexed: 01/01/2023] Open
Abstract
The prevalence of obesity increases with age in humans and in rodents. Age‐related obesity is characterized by leptin resistance and associated with heightened risk of metabolic disorders. However, the effect of leptin resistance per se has been difficult to disentangle from other effects of aging. Here we demonstrate that celastrol, a natural phytochemical that was previously shown to act as a leptin sensitizer, induces weight loss in aged animals, but not in young controls. Celastrol reduces food intake and lowers fasting glucose without affecting energy expenditure. Unexpectedly, administration of celastrol just before the dark period disrupted circadian rhythms of sleep and activity. This regimen was also associated with loss of lean mass an outcome that would not be desirable in elderly patients. Adjusting the timing of celastrol administration by 12 hr, to the beginning of the light period, avoided interference with circadian rhythms while retaining the reductions in body weight and adiposity. Thus, targeting leptin signaling is an effective strategy to ameliorate age‐associated weight gain, and can profoundly impact circadian rhythms.
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Affiliation(s)
- Karthikeyani Chellappa
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Isaac J. Perron
- Center for Sleep and Circadian Neurobiology Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Nirinjini Naidoo
- Center for Sleep and Circadian Neurobiology Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania
| | - Joseph A. Baur
- Department of Physiology and Institute for Diabetes, Obesity and Metabolism Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania
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15
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McGregor G, Harvey J. Leptin Regulation of Synaptic Function at Hippocampal TA-CA1 and SC-CA1 Synapses: Implications for Health and Disease. Neurochem Res 2019; 44:650-660. [PMID: 28819795 PMCID: PMC6420429 DOI: 10.1007/s11064-017-2362-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/05/2017] [Accepted: 07/21/2017] [Indexed: 12/16/2022]
Abstract
Growing evidence indicates that the endocrine hormone leptin regulates hippocampal synaptic function in addition to its established role as a hypothalamic satiety signal. Indeed, numerous studies show that leptin facilitates the cellular events that underlie hippocampal learning and memory including activity-dependent synaptic plasticity and glutamate receptor trafficking, indicating that leptin may be a potential cognitive enhancer. Although there has been extensive investigation into the modulatory role of leptin at hippocampal Schaffer collateral (SC)-CA1 synapses, recent evidence indicates that leptin also potently regulates excitatory synaptic transmission at the anatomically distinct temporoammonic (TA) input to hippocampal CA1 neurons. The cellular mechanisms underlying activity-dependent synaptic plasticity at TA-CA1 synapses differ from those at SC-CA1 synapses and the TA input is implicated in spatial and episodic memory formation. Furthermore, the TA input is an early target for neurodegeneration in Alzheimer's disease (AD) and aberrant leptin function is linked to AD. Here, we review the evidence that leptin regulates hippocampal synaptic function at both SC- and TA-CA1 synapses and discuss the consequences for neurodegenerative disorders like AD.
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Affiliation(s)
- Gemma McGregor
- Division of Neuroscience, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Jenni Harvey
- Division of Neuroscience, School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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16
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Self-administration of the synthetic cathinone MDPV enhances reward function via a nicotinic receptor dependent mechanism. Neuropharmacology 2018; 137:286-296. [PMID: 29778945 DOI: 10.1016/j.neuropharm.2018.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 03/30/2018] [Accepted: 05/06/2018] [Indexed: 01/28/2023]
Abstract
Methylenedioxypyrovalerone (MDPV) is an addictive synthetic drug with severe side effects. Previous studies have shown that MDPV has positive reinforcing properties. However, little is known about the effect of MDPV self-administration on the state of the brain reward system and the neuronal mechanisms by which MDPV mediates its effects. The goal of the present studies was to determine the effect of MDPV self-administration on reward function and the role of cholinergic neurotransmission in the reinforcing effects of MDPV. To study the effect of MDPV self-administration on the brain reward system, rats were prepared with intravenous catheters and intracranial self-stimulation electrodes (ICSS). For 10 days, the reward thresholds were assessed immediately before (23 h post prior session) and after 1 h of MDPV self-administration. The reward thresholds were decreased immediately after MDPV self-administration, which is indicative of a potentiation of brain reward function. The reward thresholds 23 h after MDPV intake gradually increased over time, which is indicative of anhedonia. Pretreatment with the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine decreased the self-administration of MDPV and completely prevented the decrease in reward thresholds. A control study with palatable chocolate pellets showed that responding for a natural reinforcer does not affect the state of the brain reward system. Furthermore, mecamylamine did not affect responding for food pellets. In conclusion, the self-administration of MDPV potentiates reward function and nAChR blockade prevents the reward enhancing effects of MDPV self-administration. Preventing the MDPV-induced increase in cholinergic neurotransmission might be a safe approach to diminish MDPV abuse.
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17
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López V, Bonzón-Kulichenko E, Moltó E, Fernández-Agulló T, Arribas C, Andrés A, Gallardo N. Food Restriction is Required to Preserve the Antisteatotic Effects of Central Leptin in the Liver of Middle-Aged Rats. Obesity (Silver Spring) 2018; 26:877-884. [PMID: 29575696 DOI: 10.1002/oby.22152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 01/17/2018] [Accepted: 02/05/2018] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Aging is a significant risk factor for the development of obesity and hepatic steatosis associated with insulin and leptin resistance. Food restriction (FR) is commonly used for reducing body weight (BW), adiposity, and liver steatosis. Thus, this study aimed to determine whether FR in middle-aged rats can recover the central leptin antisteatotic effects observed in the liver in young animals. METHODS Two groups of 4-month-old Wistar rats were fed ad libitum (AL) or were on FR for 3 months. At 7 months of age, both groups were centrally treated with rat leptin (0.2 μg/d, 7 days) or saline. RESULTS Central leptin reduced food intake and BW, but not the hepatic triglyceride content, in 7-month-old rats fed AL. However, in 7-month-old FR rats, leptin did not affect BW but markedly reduced serum leptin, serum and hepatic triglyceride levels, and the expression of hepatic lipogenic genes. In addition, central leptin decreased serum and hepatic endogenous norepinephrine levels of FR rats, exerting a homeostatic effect beyond its antisteatotic actions. CONCLUSIONS These findings suggest that in middle-aged rats, moderate FR is required for both preserving the antisteatotic actions of central leptin and avoiding excessive weight loss.
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Affiliation(s)
- Virginia López
- Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Elena Bonzón-Kulichenko
- Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
- National Center for Cardiovascular Research Carlos III, Madrid, Spain
| | - Eduardo Moltó
- Biochemistry Section, Faculty of Environmental Sciences and Biochemistry, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Toledo, Spain
| | | | - Carmen Arribas
- Biochemistry Section, Faculty of Environmental Sciences and Biochemistry, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Toledo, Spain
| | - Antonio Andrés
- Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Nilda Gallardo
- Biochemistry Section, Faculty of Science and Chemical Technologies, and Regional Center for Biomedical Research, University of Castilla-La Mancha, Ciudad Real, Spain
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18
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Silva VRR, Katashima CK, Bueno Silva CG, Lenhare L, Micheletti TO, Camargo RL, Ghezzi AC, Camargo JA, Assis AM, Tobar N, Morari J, Razolli DS, Moura LP, Pauli JR, Cintra DE, Velloso LA, Saad MJA, Ropelle ER. Hypothalamic S1P/S1PR1 axis controls energy homeostasis in Middle-Aged Rodents: the reversal effects of physical exercise. Aging (Albany NY) 2017; 9:142-155. [PMID: 28039439 PMCID: PMC5310661 DOI: 10.18632/aging.101138] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 11/29/2016] [Indexed: 02/06/2023]
Abstract
Recently, we demonstrated that the hypothalamic S1PR1/STAT3 axis plays a critical role in the control of food consumption and energy expenditure in rodents. Here, we found that reduction of hypothalamic S1PR1 expression occurs in an age-dependent manner, and was associated with defective thermogenic signaling and weight gain. To address the physiological relevance of these findings, we investigated the effects of chronic and acute exercise on the hypothalamic S1PR1/STAT3 axis. Chronic exercise increased S1PR1 expression and STAT3 phosphorylation in the hypothalamus, restoring the anorexigenic and thermogenic signals in middle-aged mice. Acutely, exercise increased sphingosine-1-phosphate (S1P) levels in the cerebrospinal fluid (CSF) of young rats, whereas the administration of CSF from exercised young rats into the hypothalamus of middle-aged rats at rest was sufficient to reduce the food intake. Finally, the intracerebroventricular (ICV) administration of S1PR1 activators, including the bioactive lipid molecule S1P, and pharmacological S1PR1 activator, SEW2871, induced a potent STAT3 phosphorylation and anorexigenic response in middle-aged rats. Overall, these results suggest that hypothalamic S1PR1 is important for the maintenance of energy balance and provide new insights into the mechanism by which exercise controls the anorexigenic and thermogenic signals in the central nervous system during the aging process.
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Affiliation(s)
- Vagner Ramon Rodrigues Silva
- School of Applied Sciences, University of Campinas, Limeira, SP, Brazil.,Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | | | - Carla G Bueno Silva
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | - Luciene Lenhare
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | | | | | - Ana Carolina Ghezzi
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | | | | | - Natalia Tobar
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | - Joseane Morari
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | - Daniela S Razolli
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | | | - José Rodrigo Pauli
- School of Applied Sciences, University of Campinas, Limeira, SP, Brazil.,Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil.,CEPECE - Research Center of Sport Sciences, School of Applied Sciences, University of Campinas, Limeira, SP, Brazil
| | | | - Lício Augusto Velloso
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil.,Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
| | - Mario J A Saad
- Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil
| | - Eduardo Rochete Ropelle
- School of Applied Sciences, University of Campinas, Limeira, SP, Brazil.,Department of Internal Medicine, University of Campinas, Campinas, SP, Brazil.,CEPECE - Research Center of Sport Sciences, School of Applied Sciences, University of Campinas, Limeira, SP, Brazil.,Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, University of Campinas, Campinas, 1308-970, Brazil
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19
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McGregor G, Harvey J. Food for thought: Leptin regulation of hippocampal function and its role in Alzheimer's disease. Neuropharmacology 2017; 136:298-306. [PMID: 28987937 DOI: 10.1016/j.neuropharm.2017.09.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/27/2017] [Accepted: 09/30/2017] [Indexed: 01/08/2023]
Abstract
Accumulating evidence indicates that diet and body weight are important factors associated with Alzheimer's disease (AD), with a significant increase in AD risk linked to mid-life obesity, and weight loss frequently occurring in the early stages of AD. This has fuelled interest in the hormone leptin, as it is an important hypothalamic regulator of food intake and body weight, but leptin also markedly influences the functioning of the hippocampus; a key brain region that degenerates in AD. Increasing evidence indicates that leptin has cognitive enhancing properties as it facilitates the cellular events that underlie hippocampal-dependent learning and memory. However, significant reductions in leptin's capacity to regulate hippocampal synaptic function occurs with age and dysfunctions in the leptin system are associated with an increased risk of AD. Moreover, leptin is a potential novel target in AD as leptin treatment has beneficial effects in various models of AD. Here we summarise recent advances in leptin neurobiology with particular focus on regulation of hippocampal synaptic function by leptin and the implications of this for neurodegenerative disorders like AD. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'
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Affiliation(s)
- Gemma McGregor
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, United Kingdom
| | - Jenni Harvey
- Division of Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, United Kingdom.
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20
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Albala C, Angel B, Lera L, Sanchez H, Marquez C, Fuentes P. Low Leptin Availability as a Risk Factor for Dementia in Chilean Older People. Dement Geriatr Cogn Dis Extra 2016; 6:295-302. [PMID: 27504118 PMCID: PMC4965539 DOI: 10.1159/000447447] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE The aim was to study the role of leptin in the development of dementia. METHODS Follow-up of the ALEXANDROS cohorts, with baseline measurements in 2000. From 1,136 available subjects free of dementia at baseline, 667 subjects had frozen baseline blood samples for measuring leptin and soluble leptin receptor (sOB-R). The free leptin index (FLI) was calculated as the ratio of leptin to sOB-R. Dementia was defined as an MMSE score <22 and a score >5 in the Pfeffer Activities Questionnaire. RESULTS After 15 years of follow-up, 42 incident cases of dementia were identified. No difference in serum leptin was observed between people with and without dementia, but sOB-R was higher in demented than in nondemented subjects (sOB-R: 44.94 ± 23.97 vs. 33.73 ± 21.13 ng/ml). The adjusted risk for dementia increased, the higher the log sOB (hazard ratio = 3.58; 95% CI 1.72-7.45, p = 0.001). CONCLUSION Lower availability of free leptin was found in demented than in nondemented people, suggesting a role of leptin in cognition.
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Affiliation(s)
| | | | - Lydia Lera
- INTA, University of Chile, Santiago, Chile
| | | | | | - Patricio Fuentes
- Department of Neurology, Clinic Hospital, University of Chile, Santiago, Chile
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21
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McGregor G, Malekizadeh Y, Harvey J. Minireview: Food for thought: regulation of synaptic function by metabolic hormones. Mol Endocrinol 2016; 29:3-13. [PMID: 25470238 DOI: 10.1210/me.2014-1328] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The peripheral actions of the metabolic hormones, leptin and insulin, are well documented. However, the functions of these hormones are not restricted to the periphery because evidence is growing that both leptin and insulin can readily cross the blood-brain barrier and have widespread central actions. The hippocampus in particular expresses high levels of both insulin and leptin receptors as well as key components of their associated signaling cascades. Moreover, recent studies indicate that both hormones are potential cognitive enhancers. Indeed, it has been demonstrated that both leptin and insulin markedly influence key cellular events that underlie hippocampal learning and memory including activity-dependent synaptic plasticity and the trafficking of glutamate receptors to and away from hippocampal synapses. The hippocampal formation is also a prime site for the neurodegenerative processes that occur during Alzheimer's disease, and impairments in either leptin or insulin function have been linked to central nervous system-driven diseases like Alzheimer's disease. Thus, the capacity of the metabolic hormones, leptin and insulin, to regulate hippocampal synaptic function has significant implications for normal brain function and also central nervous system-driven disease.
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Affiliation(s)
- Gemma McGregor
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, United Kingdom
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22
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Chowen JA, Argente J. Leptin and the brain. Horm Mol Biol Clin Investig 2015; 7:351-60. [PMID: 25961273 DOI: 10.1515/hmbci.2011.113] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 07/13/2011] [Indexed: 02/03/2023]
Abstract
Leptin, which comes from the Greek root leptos meaning thin, has been the focus of intense investigation since its discovery in 1994. This hormone belongs to the cytokine family and is produced by adipocytes and circulates in proportion to fat mass, thus serving as a satiety signal and informing central metabolic control centers as to the status of peripheral energy stores. However, it participates in numerous other functions both peripherally and centrally, as indicated by the wide distribution of its various receptor isoforms. Leptin is involved in brain development, most notably in development of hypothalamic centers that control metabolism, but also in other brain areas. It acts as a nutritional cue to indicate adequacy of energy stores for pubertal development and reproductive capacity. The effects of this hormone on behavior and cognition are less well studied, but it clearly is involved in specific aspects of these physiological phenomena. As obesity is a major health problem in many areas of the world, the search for pharmacological treatments to decrease appetite and increase energy expenditure is intense. Understanding the mechanisms of actions of all physiological effects of this hormone is of great interest in the pursuit of such treatment.
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23
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Qi X, Yamada H, Corrie LW, Ji Y, Bauzo RM, Alexander JC, Bruijnzeel AW. A critical role for the melanocortin 4 receptor in stress-induced relapse to nicotine seeking in rats. Addict Biol 2015; 20:324-35. [PMID: 24612112 DOI: 10.1111/adb.12129] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tobacco addiction is characterized by a lack of control over smoking and relapse after periods of abstinence. Smoking cessation leads to a dysphoric state that contributes to relapse to smoking. After the acute withdrawal phase, exposure to stressors increases the risk for relapse. Blockade of melanocortin 4 (MC4 ) receptors has anxiolytic and antidepressant-like effects in animal models. The aim of these studies was to investigate the role of MC4 receptors in the dysphoria associated with nicotine withdrawal and stress-induced reinstatement of nicotine seeking. To study stress-induced reinstatement, rats self-administered nicotine for 16 days and then nicotine seeking was extinguished by substituting saline for nicotine. Nicotine seeking was reinstated by intermittent footshock stress. The intracranial self-stimulation (ICSS) procedure was used to assess the negative mood state associated with nicotine withdrawal. Elevations in the ICSS thresholds are indicative of a dysphoric state. The selective MC4 receptor antagonists HS014 and HS024 prevented stress-induced reinstatement of extinguished nicotine seeking. Drug doses that prevented stress-induced relapse did not affect responding for food pellets, which indicates that the drugs did not induce sedation or motor impairments. In the ICSS experiments, the nicotinic acetylcholine receptor antagonist mecamylamine elevated the ICSS thresholds of the nicotine-dependent rats. Pre-treatment with HS014 or HS024 did not prevent the elevations in ICSS thresholds. These studies indicate that MC4 receptors play a critical role in stress-induced reinstatement of nicotine seeking, but these receptors may not play a role in the dysphoria associated with acute nicotine withdrawal.
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Affiliation(s)
- Xiaoli Qi
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Hidetaka Yamada
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Lu W. Corrie
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Yue Ji
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Rayna M. Bauzo
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Jon C. Alexander
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
| | - Adrie W. Bruijnzeel
- Department of Psychiatry; McKnight Brain Institute; University of Florida; Gainesville FL USA
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Sasaki T. Age-Associated Weight Gain, Leptin, and SIRT1: A Possible Role for Hypothalamic SIRT1 in the Prevention of Weight Gain and Aging through Modulation of Leptin Sensitivity. Front Endocrinol (Lausanne) 2015; 6:109. [PMID: 26236282 PMCID: PMC4504171 DOI: 10.3389/fendo.2015.00109] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 07/01/2015] [Indexed: 12/14/2022] Open
Abstract
The hypothalamus is the principal regulator of body weight and energy balance. It modulates both energy intake and energy expenditure by sensing the energy status of the body through neural inputs from the periphery as well as direct humoral inputs. Leptin, an adipokine, is one of the humoral factors responsible for alerting the hypothalamus that enough energy is stored in the periphery. Plasma leptin levels are positively linked to adiposity; leptin suppress energy intake and stimulates energy expenditure. However, prolonged increases in plasma leptin levels due to obesity cause leptin resistance, affecting both leptin access to hypothalamic neurons and leptin signal transduction within hypothalamic neurons. Decreased sensing of peripheral energy status through leptin may lead to a positive energy balance and gradual gains in weight and adiposity, further worsening leptin resistance. Leptin resistance, increased adiposity, and weight gain are all associated with aging in both humans and animals. Central insulin resistance is associated with similar observations. Therefore, improving the action of humoral factors in the hypothalamus may prevent gradual weight gain, especially during middle age. SIRT1 is a NAD(+)-dependent protein deacetylase with numerous substrates, including histones, transcription factors, co-factors, and various enzymes. SIRT1 improves both leptin sensitivity and insulin sensitivity by decreasing the levels of several molecules that impair leptin and insulin signal transduction. SIRT1 and NAD(+) levels decrease with age in the hypothalamus; increased hypothalamic SIRT1 levels prevent age-associated weight gain and improve leptin sensitivity in mice. Therefore, preventing the age-dependent loss of SIRT1 function in the hypothalamus could improve the action of humoral factors in the hypothalamus as well as central regulation of energy balance.
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Affiliation(s)
- Tsutomu Sasaki
- Laboratory for Metabolic Signaling, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- *Correspondence: Tsutomu Sasaki, Laboratory for Metabolic Signaling, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512, Japan,
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Davis C, Mudd J, Hawkins M. Neuroprotective effects of leptin in the context of obesity and metabolic disorders. Neurobiol Dis 2014; 72 Pt A:61-71. [DOI: 10.1016/j.nbd.2014.04.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/09/2014] [Accepted: 04/21/2014] [Indexed: 12/16/2022] Open
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Arnold AC, Diz DI. Endogenous leptin contributes to baroreflex suppression within the solitary tract nucleus of aged rats. Am J Physiol Heart Circ Physiol 2014; 307:H1539-46. [PMID: 25260611 DOI: 10.1152/ajpheart.00282.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The decline in cardiovagal baroreflex function that occurs with aging is accompanied by an increase in circulating leptin levels. Our previous studies showed that exogenous leptin impairs the baroreflex sensitivity for control of heart rate in younger rats, but the contribution of this hormone to baroreflex dysfunction during aging is unknown. Thus we assessed the effect of bilateral leptin microinjection (500 fmol/60 nl) within the solitary tract nucleus (NTS) on the baroreflex sensitivity in older (66 ± 2 wk of age) urethane/chloralose anesthetized Sprague-Dawley rats with elevated circulating leptin levels. In contrast to the 63% reduction observed in younger rats, leptin did not alter the baroreflex sensitivity for bradycardia evoked by phenylephrine in older rats (0.76 ± 0.19 baseline vs. 0.71 ± 0.15 ms/mmHg after leptin; P = 0.806). We hypothesized that this loss of sensitivity reflected endogenous suppression of the baroreflex by elevated leptin, rather than cardiovascular resistance to the peptide. Indeed, NTS administration of a leptin receptor antagonist (75 pmol/120 nl) improved the baroreflex sensitivity for bradycardia in older rats (0.73 ± 0.13 baseline vs. 1.19 ± 0.26 at 10 min vs. 1.87 ± 0.32 at 60 min vs. 1.22 ± 0.54 ms/mmHg at 120 min; P = 0.002), with no effect in younger rats. There was no effect of the leptin antagonist on the baroreflex sensitivity for tachycardia, responses to cardiac vagal chemosensitive fiber activation, or resting hemodynamics in older rats. These findings suggest that the actions of endogenous leptin within the NTS, either produced locally or derived from the circulation, contribute to baroreflex suppression during aging.
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Affiliation(s)
- Amy C Arnold
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Debra I Diz
- Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina
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Leptin and aging: Review and questions with particular emphasis on its role in the central regulation of energy balance. J Chem Neuroanat 2014; 61-62:248-55. [PMID: 25218974 DOI: 10.1016/j.jchemneu.2014.08.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 08/07/2014] [Accepted: 08/13/2014] [Indexed: 01/12/2023]
Abstract
Leptin is produced mainly in the white adipose tissue and emerged as one of the key catabolic regulators of food intake and energy expenditure. During the course of aging characteristic alterations in body weight and body composition in humans and mammals, i.e. middle-aged obesity and aging anorexia and cachexia, suggest age-related regulatory changes in energy balance in the background. Aging has been associated with increased fat mass, central and peripheral leptin resistance as indicated by its failure to reduce food intake, to increase metabolic rate and thereby to induce weight loss. Leptin resistance is a common feature of aging and obesity (even in the young). The question arises whether aging or fat accumulation plays the primary role in the development of this resistance. The review focuses mainly on mechanisms and development of central leptin resistance. Age-related decline primarily affects the hypermetabolic component of central catabolic leptin actions, while the anorexigenic component is even growing stronger in the late phase of aging. Obesity enhances resistance to leptin at any age, particularly in old rats, calorie-restriction, on the other hand, increases responsiveness to leptin, especially in the oldest age-group. Thus, without obesity, leptin sensitivity appears not to decrease but to increase by old age. Interactions with other substances (e.g. insulin, cholecystokinin, endogenous cannabinoids) and life-style factors (e.g. exercise) in these age-related changes need to be investigated.
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Clinicotherapeutic Potential of Leptin in Alzheimer’s Disease and Parkinson’s Disease. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/181325] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Chronic neurodegenerative diseases are a group of devastating neurological disorders that result in significant morbidity and mortality in the elderly population worldwide. Recent researches have shown some interesting associations of the classical antiobesity hormone leptin with two most important neurodegenerative diseases—Alzheimer’s disease (AD) and Parkinson’s disease (PD). Although several clinical studies have found the procognitive and memory-enhancing role of this peptide hormone in leptin-deficient patients, surprisingly it has not been used in any clinical trials involving patients with developing or full-blown neurodegenerative conditions. This review article is an attempt to bring together the existing information about the clinical associations of leptin with AD and PD. It starts with the basic understanding of leptin action in the brain and its derangements in these diseases and eventually discusses the potential of this hormone as a neuroprotective agent in clinical scenario.
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Guadalupe-Grau A, Larsen S, Guerra B, Calbet JAL, Dela F, Helge JW. Influence of age on leptin induced skeletal muscle signalling. Acta Physiol (Oxf) 2014; 211:214-28. [PMID: 24605926 DOI: 10.1111/apha.12273] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/03/2013] [Accepted: 03/04/2014] [Indexed: 12/27/2022]
Abstract
AIM Age associated fat mass accumulation could be because of dysregulation of leptin signalling in skeletal muscle. Thus, we investigated total protein expression and phosphorylation levels of the long isoform of the leptin receptor (OB-Rb), and leptin signalling through janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3), insulin receptor substrate 1 (IRS-1), AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC), combined with the leptin signalling inhibitors suppressor of cytokine signalling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) in human skeletal muscle of different age. METHODS Vastus lateralis muscle biopsies were obtained from 39 men matched for BMI < 30 kg m(-2) and separated into three groups: 13 young (Y, 24 ± 4 years); 14 middle aged (MA, 44 ± 5 years) and 12 aged (A, 58 ± 8 years) subjects. RESULTS Whole body fat percentage and plasma leptin were higher (P < 0.05), whereas lean mass, plasma free testosterone and total testosterone were lower (P < 0.05) in A compared to Y. Skeletal muscle OB-Rb (170 KDa) protein expression and pTyr(1141) -OB-R170 were comparable between groups, whereas pTyr(985) -OB-R170 was lower in A compared to Y (P < 0.05). pSTAT3 levels tended (P = 0.09) to be lower (50%) in A compared to Y. In A, muscle PTP1B was greater and IRS-1 lower than Y and MA respectively (P < 0.05). PTyr(612) -IRS-1 tended to be lower in A than in Y (P = 0.09). Suppressor of cytokine signalling 3 (SOCS3) protein expression, pJAK2, pSer(1101) -IRS-1, pAMPKα and pACCβ were similar between groups. CONCLUSION Age is associated with dysregulation of the leptin signalling and increased PTP1B protein expression in skeletal muscle.
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Affiliation(s)
- A. Guadalupe-Grau
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - S. Larsen
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - B. Guerra
- Department of Clinical Sciences; Molecular and Translational Endocrinology Group; Associate Unit of University of Las Palmas de Gran Canaria and Biomedical Institute “Alberto Sols” - CSIC; Las Palmas de Gran Canaria Spain
- ICIC; Cancer Research Institute of the Canary Islands; Las Palmas de Gran Canaria Spain
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias; Las Palmas de Gran Canaria Spain
| | - J. A. L. Calbet
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias; Las Palmas de Gran Canaria Spain
| | - F. Dela
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - J. W. Helge
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
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Roujeau C, Jockers R, Dam J. New pharmacological perspectives for the leptin receptor in the treatment of obesity. Front Endocrinol (Lausanne) 2014; 5:167. [PMID: 25352831 PMCID: PMC4195360 DOI: 10.3389/fendo.2014.00167] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/26/2014] [Indexed: 12/24/2022] Open
Abstract
After its discovery in 1994, leptin became the great hope as an anti-obesity treatment based on its ability to reduce food intake and increase energy expenditure. However, treating obese people with exogenous leptin was unsuccessful in most cases since most of them present already high circulating leptin levels to which they do not respond anymore defining the so-called state of "leptin resistance." Indeed, leptin therapy is unsuccessful to lower body weight in commonly obese people but effective in people with rare single gene mutations of the leptin gene. Consequently, treatment of obese people with leptin was given less attention and the focus of obesity research shifted toward the prevention and reversal of the state of leptin resistance. Many of these new promising approaches aim to restore or sensitize the impaired function of the leptin receptor by pharmacological means. The current review will focus on the different emerging therapeutic strategies in obesity research that are related to leptin and its receptor.
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Affiliation(s)
- Clara Roujeau
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS UMR 8104, Paris, France
- University of Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Ralf Jockers
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS UMR 8104, Paris, France
- University of Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Julie Dam
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS UMR 8104, Paris, France
- University of Paris Descartes, Sorbonne Paris Cité, Paris, France
- *Correspondence: Julie Dam, Institut Cochin, 22 rue Méchain, 75014, Paris, France e-mail:
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Carter S, Caron A, Richard D, Picard F. Role of leptin resistance in the development of obesity in older patients. Clin Interv Aging 2013; 8:829-44. [PMID: 23869170 PMCID: PMC3706252 DOI: 10.2147/cia.s36367] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Obesity is a global epidemic associated with aging-like cellular processes; in both aging and obesity, resistance to hormones such as insulin and leptin can be observed. Leptin is a circulating hormone/cytokine with central and peripheral effects that is released mainly by subcutaneous white adipose tissue. Centrally, leptin controls food intake, energy expenditure, and fat distribution, whereas it controls (among several others) insulin sensitivity, free fatty acids (FFAs) oxidation, and lipolysis in the periphery. Aging is associated with important changes in both the distribution and the composition of adipose tissue. Fat is redistributed from the subcutaneous to the visceral depot and increased inflammation participates in adipocyte dysfunction. This redistribution of adipose tissue in favor of visceral fat influences negatively both longevity and healthy aging as shown in numerous animal models. These modifications observed during aging are also associated with leptin resistance. This resistance blunts normal central and peripheral functions of leptin, which leads to a decrease in neuroendocrine function and insulin sensitivity, an imbalance in energy regulation, and disturbances in lipid metabolism. Here, we review how age-related leptin resistance triggers metabolic disturbances and affects the longevity of obese patients. Furthermore, we discuss the potential impacts of leptin resistance on the decline of brown adipose tissue thermogenesis observed in elderly individuals.
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Affiliation(s)
- Sophie Carter
- Faculty of Pharmacy, Department of Anatomy and Physiology, Université Laval, Québec, QC, Canada
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Fadel JR, Jolivalt CG, Reagan LP. Food for thought: the role of appetitive peptides in age-related cognitive decline. Ageing Res Rev 2013; 12:764-76. [PMID: 23416469 DOI: 10.1016/j.arr.2013.01.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/22/2013] [Accepted: 01/25/2013] [Indexed: 01/25/2023]
Abstract
Through their well described actions in the hypothalamus, appetitive peptides such as insulin, orexin and leptin are recognized as important regulators of food intake, body weight and body composition. Beyond these metabolic activities, these peptides also are critically involved in a wide variety of activities ranging from modulation of immune and neuroendocrine function to addictive behaviors and reproduction. The neurological activities of insulin, orexin and leptin also include facilitation of hippocampal synaptic plasticity and enhancement of cognitive performance. While patients with metabolic disorders such as obesity and diabetes have greater risk of developing cognitive deficits, dementia and Alzheimer's disease (AD), the underlying mechanisms that are responsible for, or contribute to, age-related cognitive decline are poorly understood. In view of the importance of these peptides in metabolic disorders, it is not surprising that there is a greater focus on their potential role in cognitive deficits associated with aging. The goal of this review is to describe the evidence from clinical and pre-clinical studies implicating insulin, orexin and leptin in the etiology and progression of age-related cognitive decline. Collectively, these studies support the hypothesis that leptin and insulin resistance, concepts normally associated with the hypothalamus, are also applicable to the hippocampus.
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Affiliation(s)
- Jim R Fadel
- Department of Pharmacology, Physiology and Neuroscience, School of Medicine, University of South Carolina, 6439 Garners Ferry Road, Columbia, SC 29208, USA
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Doherty GH, Beccano-Kelly D, Yan SD, Gunn-Moore FJ, Harvey J. Leptin prevents hippocampal synaptic disruption and neuronal cell death induced by amyloid β. Neurobiol Aging 2013; 34:226-37. [PMID: 22921154 DOI: 10.1016/j.neurobiolaging.2012.08.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/01/2012] [Accepted: 08/02/2012] [Indexed: 11/24/2022]
Abstract
Accumulation of amyloid-β (Aβ) is a key event mediating the cognitive deficits in Alzheimer's disease (AD) as Aβ promotes synaptic dysfunction and triggers neuronal death. Recent evidence has linked the hormone leptin to AD as leptin levels are markedly attenuated in AD patients. Leptin is also a potential cognitive enhancer as it facilitates the cellular events underlying hippocampal learning and memory. Here we show that leptin prevents the detrimental effects of Aβ(1-42) on hippocampal long-term potentiation. Moreover leptin inhibits Aβ(1-42)-driven facilitation of long-term depression and internalization of the 2-amino-3-(5-methyl-3-oxo-1,2- oxazol-4-yl)propanoic acid (AMPA) receptor subunit, GluR1, via activation of PI3-kinase. Leptin also protects cortical neurons from Aβ(1-42)-induced cell death by a signal transducer and activator of transcription-3 (STAT-3)-dependent mechanism. Furthermore, leptin inhibits Aβ(1-42)-mediated upregulation of endophilin I and phosphorylated tau in vitro, whereas cortical levels of endophilin I and phosphorylated tau are enhanced in leptin-insensitive Zucker fa/fa rats. Thus leptin benefits the functional characteristics and viability of neurons that degenerate in AD. These novel findings establish that the leptin system is an important therapeutic target in neurodegenerative conditions.
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Affiliation(s)
- Gayle H Doherty
- School of Biology, University of St. Andrews, St. Andrews, Fife, Scotland, UK
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Santollo J, Yao D, Neal-Perry G, Etgen AM. Middle-aged female rats retain sensitivity to the anorexigenic effect of exogenous estradiol. Behav Brain Res 2012; 232:159-64. [PMID: 22522024 DOI: 10.1016/j.bbr.2012.04.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 04/03/2012] [Accepted: 04/04/2012] [Indexed: 02/05/2023]
Abstract
It is well established that estradiol (E2) decreases food intake and body weight in young female rats. However, it is not clear if female rats retain responsiveness to the anorexigenic effect of E2 during middle age. Because middle-aged females exhibit reduced responsiveness to E2, manifesting as a delayed and attenuated luteinizing hormone surge, it is plausible that middle-aged rats are less responsive to the anorexigenic effect of E2. To test this we monitored food intake in ovariohysterectomized young and middle-aged rats following E2 treatment. E2 decreased food intake and body weight to a similar degree in both young and middle-aged rats. Next, we investigated whether genes that mediate the estrogenic inhibition of food intake are similarly responsive to E2 by measuring gene expression of the anorexigenic genes corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), the long form of the leptin receptor (Lepr) and serotonin 2C receptors (5HT2CR) and the orexigenic genes agouti-related peptide (AgRP), neuropeptide Y (NPY), prepromelanin-concentrating hormone (pMCH) and orexin in the hypothalamus of young and middle-aged OVX rats treated with E2. As expected, E2 increased expression of all anorexigenic genes while decreasing expression of all orexigenic genes in young rats. Although CRH, 5HT2CR, Lepr, AgRP, NPY and orexin were also sensitive to E2 treatment in middle-aged rats, POMC and pMCH expression were not influenced by E2 in middle-aged rats. These data demonstrate that young and middle-aged rats are similarly sensitive to the anorexigenic effect of E2 and that most, but not all feeding-related genes retain sensitivity to E2.
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Affiliation(s)
- Jessica Santollo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Abstract
Obesity has various deleterious effects on health largely associated with metabolic abnormalities including abnormal glucose and lipid homeostasis that are associated with vascular injury and known cardiac, renal, and cerebrovascular complications. Advanced age is also associated with increased adiposity, decreased lean mass, and increased risk for obesity-related diseases. Although many of these obesity- and age-related disease processes have long been subsumed to be secondary to metabolic or vascular dysfunction, increasing evidence indicates that obesity also modulates nonvascular diseases such as Alzheimer's disease (AD) dementia. The link between peripheral obesity and neurodegeneration will be explored, using adipokines and AD as a template. After an introduction to the neuropathology of AD, the relationship between body weight, obesity, and dementia will be reviewed. Then, population-based and experimental studies that address whether leptin modulates brain health and mitigates AD pathways will be explored. These studies will serve as a framework for understanding the role of adipokines in brain health.
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Affiliation(s)
- Edward B Lee
- Translational Neuropathology Research Laboratory, Division of Neuropathology, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
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Engineer DR, Garcia JM. Leptin in anorexia and cachexia syndrome. INTERNATIONAL JOURNAL OF PEPTIDES 2012; 2012:287457. [PMID: 22518191 PMCID: PMC3303568 DOI: 10.1155/2012/287457] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 10/25/2011] [Accepted: 10/28/2011] [Indexed: 12/31/2022]
Abstract
Leptin is a product of the obese (OB) gene secreted by adipocytes in proportion to fat mass. It decreases food intake and increases energy expenditure by affecting the balance between orexigenic and anorexigenic hypothalamic pathways. Low leptin levels are responsible for the compensatory increase in appetite and body weight and decreased energy expenditure (EE) following caloric deprivation. The anorexia-cachexia syndrome is a complication of many chronic conditions including cancer, chronic obstructive pulmonary disease, congestive heart failure, chronic kidney disease, and aging, where the decrease in body weight and food intake is not followed by a compensatory increase in appetite or decreased EE. Crosstalk between leptin and inflammatory signaling known to be activated in these conditions may be responsible for this paradox. This manuscript will review the evidence and potential mechanisms mediating changes in the leptin pathway in the setting of anorexia and cachexia associated with chronic diseases.
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Affiliation(s)
- Diana R. Engineer
- Division of Diabetes, Endocrinology and Metabolism, Michael E DeBakey Veterans Affairs Medical Center, Houston, TX 77030, USA
- Baylor College of Medicine, 2002 Holcombe Boulevored, Building 109, Room 210, Houston, TX 77030, USA
- Division of Diabetes, Department of Medicine, Endocrinology and Metabolism, St Luke's Episcopal Hospital, Houston, TX 77030, USA
| | - Jose M. Garcia
- Division of Diabetes, Endocrinology and Metabolism, Michael E DeBakey Veterans Affairs Medical Center, Houston, TX 77030, USA
- Baylor College of Medicine, 2002 Holcombe Boulevored, Building 109, Room 210, Houston, TX 77030, USA
- Huffington Center of Aging, Baylor College of Medicine, Houston, TX 77030, USA
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Obesity and the ageing brain: could leptin play a role in neurodegeneration? Curr Gerontol Geriatr Res 2011; 2011:708154. [PMID: 22013440 PMCID: PMC3195276 DOI: 10.1155/2011/708154] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 08/15/2011] [Indexed: 01/19/2023] Open
Abstract
Obesity and ageing are both characteristics of the human population that are on the increase across the globe. It has long been established that ageing is the major risk factor for neurodegenerative conditions such as Alzheimer's disease, and it is becoming increasingly evident that obesity is another such factor. Leptin resistance or insensitivity has been uncovered as a cause of obesity, and in addition the leptin signalling system is less potent in the elderly. Taken together, these findings reveal that this molecule may be a link between neurodegeneration and obesity or ageing. It is now known that leptin has beneficial effects on both the survival and neurophysiology of the neurons that are lost in Alzheimer's disease suggesting that it may be an important research target in the quest for strategies to prevent, halt, or cure this condition.
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Leptin accumulation in hypothalamic and dorsal raphe neurons is inversely correlated with brain serotonin content. Brain Res 2010; 1329:194-202. [PMID: 20211152 DOI: 10.1016/j.brainres.2010.02.085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 02/23/2010] [Accepted: 02/28/2010] [Indexed: 11/20/2022]
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Fernández CM, Moltó E, Gallardo N, del Arco A, Martínez C, Andrés A, Ros M, Carrascosa JM, Arribas C. The expression of rat resistin isoforms is differentially regulated in visceral adipose tissues: effects of aging and food restriction. Metabolism 2009; 58:204-11. [PMID: 19154953 DOI: 10.1016/j.metabol.2008.09.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 09/23/2008] [Indexed: 10/21/2022]
Abstract
Two variants of the adipose hormone resistin are generated by alternative splicing in Wistar rats. Here we analyzed the expression of these resistin variants in 2 main visceral adipose depots, epididymal and retroperitoneal, as well as the resistin serum concentration during aging and food restriction. Total protein levels of resistin were also analyzed in extracts from both visceral adipose depots. Resistin variants show similar patterns of relative expression in visceral adipose tissues in 3-month-old rats, representing the short variant, s-resistin, which is 15% of the full-length transcript. However, only epididymal, but not retroperitoneal, fat pad shows a decrease in both messenger RNA and protein levels of resistin isoforms with aging. Food restriction decreases adiposity index in 8- and 24-month-old animals to values even lower than those of 3-month-old animals. Food restriction decreases resistin expression in both adipose tissues in 8-month-old but not in 24-month-old rats. Interestingly, concomitant with the improvement of insulin sensitivity asserted by homeostasis model assessment, resistin serum levels decrease only in food-restricted 8-month-old animals. In contrast, food restriction up-regulates s-resistin messenger RNA in epididymal adipose tissue, whereas no significant changes are appreciated in retroperitoneal adipose tissue. These data indicate that both forms of resistin are differentially regulated by fat depot location, aging, and even nutritional status, suggesting that alternative splicing plays a key role in this differential regulation.
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Affiliation(s)
- Carmen M Fernández
- Area de Bioquímica, Centro Regional de Investigaciones Biomédicas (CRIB), Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Av Carlos III s/n 45071 Toledo, Spain
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Carrascosa JM, Ros M, Andrés A, Fernández-Agulló T, Arribas C. Changes in the neuroendocrine control of energy homeostasis by adiposity signals during aging. Exp Gerontol 2009; 44:20-5. [DOI: 10.1016/j.exger.2008.05.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 05/08/2008] [Accepted: 05/12/2008] [Indexed: 11/28/2022]
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Scarpace PJ, Zhang Y. Leptin resistance: a prediposing factor for diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 2008; 296:R493-500. [PMID: 19091915 DOI: 10.1152/ajpregu.90669.2008] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Obesity is a resilient and complex chronic disease. One potential causative factor in the obesity syndrome is leptin resistance. Leptin behaves as a potent anorexic and energy-enhancing hormone in most young or lean animals, but its effects are diminished or lacking in the obese state associated with a normal genetic background. Emerging evidence suggests that leptin resistance predisposes the animal to exacerbated diet-induced obesity (DIO). Elevation of central leptin in young, lean rats induces a leptin resistance that precludes obesity on a chow diet but accelerates high-fat (HF)-induced obesity. Similarly, chronic dietary fructose consumption evokes a leptin resistance that causes obesity only upon HF exposure. Inherent central leptin insensitivity also contributes to dietary weight gain in certain obesity-prone rats. Conversely, aged, leptin-resistant animals are obese with continuous chow feeding and demonstrate aggravated obesity when challenged with an HF diet. Additionally, a submaximal central blockade with a leptin antagonist leads to obesity on both chow and HF diets, as is the case in rodents with leptin receptor deficiency of genetic origin. Despite the differences in the incidence of obesity on a chow diet, all of these forms of leptin resistance predispose rodents to aggravated HF-mediated obesity. Moreover, once leptin resistance takes hold, it aggravates DIO, and the leptin resistance and obesity compound one another, promoting a vicious cycle of escalating weight gain.
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Affiliation(s)
- Philip J Scarpace
- Dept. of Pharmacology and Therapeutics, Univ. of Florida, Gainesville, FL 32610, USA.
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Antioxidant activity of Bol d'Air Jacquier breathing sessions in Wistar rats--first studies. Int J Occup Med Environ Health 2008; 21:31-46. [PMID: 18482901 DOI: 10.2478/v10001-008-0003-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES The Bol d'Air Jacquier is used to create a molecule able to deliver oxygen at the cellular level to manage hypoxia due to environmental pollution, ageing, or inflammatory disease. This study was designed to determine, firstly, whether the device generated oxidative stress and, secondly, whether it might induce an antioxidant effect. MATERIAL AND METHODS Over a period of 62 weeks, 10 male Wistar rats were randomized into two groups: the Bol d'Air group (BA) regularly breathed peroxidizing terpens delivered by the device and the control group breathed water vapour during 9-min sessions, at the frequency of 1-12 per month. Several antioxidant compounds and KRL levels were determined in the blood and major organs. RESULTS The results showed that the two groups did not differ with respect to the organ concentrations of Cu, Zn SOD, GPx, GSH, GSSG and TBARS. The device might have a weak slimming effect over time. The BA group presented a significantly higher GR level in plasma throughout the experiment, and in the muscle at the end of the study. In the BA group, the plasma Cu, Zn SOD level was related to the number of breathing sessions per week before blood collection. The BA group also had a higher KRLantioxidant status at two different time-points: at the onset of the study, in the blood of young rats; and after three breathing sessions per week, in the blood and RBCs of old rats. CONCLUSIONS The device did not generate oxidative stress and seemed to produce global antioxidant effect depending on the number of sessions per week, especially in old rats.
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Holden KF, Lindquist K, Tylavsky FA, Rosano C, Harris TB, Yaffe K. Serum leptin level and cognition in the elderly: Findings from the Health ABC Study. Neurobiol Aging 2008; 30:1483-9. [PMID: 18358569 DOI: 10.1016/j.neurobiolaging.2007.11.024] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 11/18/2007] [Accepted: 11/20/2007] [Indexed: 11/19/2022]
Abstract
Leptin is a peptide hormone secreted by adipocytes. It has been shown to modulate production and clearance of amyloid beta (Abeta) in rodent models. We sought to determine if serum leptin was associated with cognitive decline in the elderly. We studied 2871 well-functioning elders, aged 70-79, who were enrolled in a prospective study. Serum leptin concentrations were measured at baseline and analyzed by mean+/-1S.D. Clinically significantly cognitive decline over 4 years was defined as > or =5-point drop on the Modified Mini Mental State Exam (3MS). Compared to those in the lower leptin groups, elders in the high leptin group had less cognitive decline, 20.5% versus 24.7% (OR=0.79; 95% CI 0.61-1.02, p=0.07). After adjustment for demographic and clinical variables, including body mass index and total percent body fat, those in the high leptin group had significantly less likelihood of cognitive decline, OR=0.66 (95% CI 0.48-0.91). We conclude that in elderly individuals, higher serum leptin appears to protect against cognitive decline, independent of comorbidites and body fat.
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Affiliation(s)
- Karen F Holden
- Department of Psychiatry, University of California San Francisco, 94143, USA.
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Augustine RA, Ladyman SR, Grattan DR. From feeding one to feeding many: hormone-induced changes in bodyweight homeostasis during pregnancy. J Physiol 2007; 586:387-97. [PMID: 18033810 DOI: 10.1113/jphysiol.2007.146316] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Pregnancy is associated with hyperphagia, increased fat mass, hyperleptinaemia and hyperprolactinaemia. The neuroendocrine control of bodyweight involves appetite-regulating centres in the hypothalamus, containing both orexigenic and anorexigenic neurons that express leptin receptors (LepR). In the rat, central leptin resistance develops during mid pregnancy, well after hyperphagia becomes apparent, to negate the appetite suppressing effects of leptin. We have investigated the hypothalamic response to leptin during pregnancy and examined the role of pregnancy hormones in inducing these changes. We have shown that there are multiple levels of leptin resistance during pregnancy. Despite elevated serum leptin, neuropeptide Y and agouti related peptide mRNA in the arcuate nucleus are not suppressed and may even be increased during pregnancy. LepR mRNA and leptin-induced pSTAT3 expression, however, are relatively normal in the arcuate nucleus. In contrast, both LepR and leptin-induced pSTAT3 are reduced in the ventromedial hypothalamic nucleus. Injecting alpha-melanocyte-stimulating hormone (alpha-MSH) into the brain, to bypass the first-order leptin-responsive neurons in the arcuate nucleus, also fails to suppress food intake during pregnancy, suggesting that pregnancy is also a melanocortin-resistant state. Using a pseudopregnant rat model, we have demonstrated that in addition to the changes in maternal ovarian steroid secretion, placental lactogen production is essential for the induction of leptin resistance in pregnancy. Thus, hormonal changes associated with pregnancy induce adaptive changes in the maternal hypothalamus, stimulating food intake and then allowing elevated food intake to be maintained in the face of elevated leptin levels, resulting in fat deposition to provide energy stores in preparation for the high metabolic demands of late pregnancy and lactation.
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Affiliation(s)
- Rachael A Augustine
- Centre for Neuroendocrinology, School of Medical Sciences, University of Otago, PO Box 913, Dunedin, New Zealand
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Abstract
Despite elevated plasma leptin, food intake is increased during pregnancy leading to fat deposition. We have demonstrated that intracerebroventricular (icv) leptin is unable to suppress food intake in pregnant rats, as it does in non-pregnant animals. Hence, central leptin resistance develops during pregnancy. These changes are physiologically appropriate, providing increased energy reserves to help meet the high metabolic demands of fetal development and lactation. To characterise this central leptin resistance, we have measured levels of leptin receptor (Ob-Rb) mRNA in the hypothalamus, and examined leptin-induced phosphorylation of STAT3 (pSTAT3) in specific regions of the hypothalamus. In addition, to investigate the mechanism underlying pregnancy-induced leptin resistance, we have investigated effects of hormone treatments on hypothalamic responses to leptin in a pseudopregnant rat model. We observed a significant reduction of Ob-Rb mRNA levels in the ventromedial hypothalamic nucleus (VMH) during pregnancy, with no changes detected in other hypothalamic nuclei. Levels of leptin-induced pSTAT3 were specifically suppressed in the VMH and arcuate nucleus of pregnant rats compared to non-pregnant rats. Pseudopregnant rats were hyperphagic but did not become leptin resistant, suggesting that fetal or placental factors are required for the induction of leptin resistance. These data implicate the VMH as a key hypothalamic site involved in hormone-induced leptin resistance during pregnancy, and suggest that placental hormone secretion may mediate the hormone-induced loss of response to leptin.
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Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand.
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Affiliation(s)
- Hiroyuki Shimizu
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Sahu A. Alteration in hypothalamic neuropeptide Y (NPY) secretion may underlie female reproductive ageing: induction of steroid-induced luteinising hormone surge by NPY in ovariectomised aged rats. J Neuroendocrinol 2006; 18:584-93. [PMID: 16867179 DOI: 10.1111/j.1365-2826.2006.01449.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A large body of evidence suggests that a defect in the hypothalamic function may be the primary cause of reproductive ageing in female rats. We have previously shown that luteinising hormone (LH)-surge associated changes in hypothalamic neuropeptide Y (NPY) gene expression and median eminence (ME) NPY levels seen in young rats do not occur in middle-aged (MA) rats. The present study examined whether hypothalamic NPY release is altered during the steroid-induced LH surge in ovariectomised (OVX) MA rats, and whether exogenous NPY initiates steroid-induced LH surge in OVX old rats. In the first study, NPY release from the ME-arcuate nucleus, as assessed by the push-pull cannula technique, was significantly increased before and during the progesterone-induced LH surge in oestrogen (E(2))-primed ovariectomised young rats (2-3 months old). This antecedent increase in NPY release seen in young rats was not apparent in MA rats (11-13 months old) in association with a delayed and attenuated LH surge. In the second study, whereas progesterone failed to induce LH surges in E(2)-primed ovariectomised old rats (23-25 months old), intracerebroventricular NPY (0.1-0.5 microg) injections at 1100, 1200 and 13.00 h resulted in LH surge induction in E(2) + progesterone-primed ovariectomised old rats. Because increased hypothalamic NPY synthesis and release is obligatory for the preovulatory LH discharge in young rats, the present findings suggest that alteration in NPY release from the ME-arcuate nucleus contributes to the delayed and reduced LH surges in MA rats and may be involved in the subsequent loss of the LH surges in old rats.
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Affiliation(s)
- A Sahu
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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Zhang Y, Scarpace PJ. Circumventing central leptin resistance: lessons from central leptin and POMC gene delivery. Peptides 2006; 27:350-64. [PMID: 16274846 DOI: 10.1016/j.peptides.2005.01.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Accepted: 01/10/2005] [Indexed: 10/25/2022]
Abstract
We identified that leptin resistance in aged-obese rats has both peripheral and central components. The central resistance is characterized by diminished hypothalamic leptin receptors and impaired leptin signal transduction. We developed a new model of leptin-induced leptin resistance in which application of the central leptin gene delivery produces unabated hypothalamic leptin over-expression. The chronic central elevation of leptin precipitates leptin resistance in young animals devoid of obesity and exacerbates it in mature or aged animals with obesity. Despite leptin resistance, our aged obese, DIO, and leptin-induced leptin resistant rats were fully responsive to central pharmacological melanocortin activation. We propose that the central leptin resistance resides between leptin receptor and melanocortin receptor activation. Our central POMC gene therapy overcame leptin resistance, producing weight and fat loss and improved insulin sensitivity in obese Zucker and aged rats. This success highlights the central melanocortin system as a useful drug target for combating obesity.
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Affiliation(s)
- Yi Zhang
- Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, Gainesville, FL 32608-1197, USA
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Hosoi T, Okuma Y, Ono A, Nomura Y. Alteration of leptin-induced STAT3 activation in the brain of senescence-accelerated mouse (SAM) P8. Biol Pharm Bull 2005; 28:1514-6. [PMID: 16079504 DOI: 10.1248/bpb.28.1514] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We used senescence-accelerated mouse prone 8 (SAMP8), a useful model of accelerated aging, to investigate the responsiveness to leptin with aging. The state of leptin-induced STAT3 phosphorylation in the hypothalamus was found to be higher in SAMP8 than in SAMR1, a control mouse showing normal aging, at 14-18 months of age but not at 2 months of age. Moreover, leptin receptor Ob-Rb expression in the hypothalamus was up-regulated in SAMP8. The results indicate that leptin sensitivity increases with aging in the SAM mouse brain.
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Affiliation(s)
- Toru Hosoi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan
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