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Abstract
Animals that lack the hormone leptin become grossly obese, purportedly for 2 reasons: increased food intake and decreased energy expenditure (thermogenesis). This review examines the experimental evidence for the thermogenesis component. Analysis of the data available led us to conclude that the reports indicating hypometabolism in the leptin-deficient ob/ob mice (as well as in the leptin-receptor-deficient db/db mice and fa/fa rats) derive from a misleading calculation artefact resulting from expression of energy expenditure per gram of body weight and not per intact organism. Correspondingly, the body weight-reducing effects of leptin are not augmented by enhanced thermogenesis. Congruent with this, there is no evidence that the ob/ob mouse demonstrates atrophied brown adipose tissue or diminished levels of total UCP1 mRNA or protein when the ob mutation is studied on the inbred C57BL/6 mouse background, but a reduced sympathetic nerve activity is observed. On the outbred "Aston" mouse background, brown adipose tissue atrophy is seen, but whether this is of quantitative significance for the development of obesity has not been demonstrated. We conclude that leptin is not a thermogenic hormone. Rather, leptin has effects on body temperature regulation, by opposing torpor bouts and by shifting thermoregulatory thresholds. The central pathways behind these effects are largely unexplored.
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Affiliation(s)
- Alexander W Fischer
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden.,Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Barbara Cannon
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, Stockholm, Sweden
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Srivastava S, Veech RL. Brown and Brite: The Fat Soldiers in the Anti-obesity Fight. Front Physiol 2019; 10:38. [PMID: 30761017 PMCID: PMC6363669 DOI: 10.3389/fphys.2019.00038] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022] Open
Abstract
Brown adipose tissue (BAT) is proposed to maintain thermal homeostasis through dissipation of chemical energy as heat by the uncoupling proteins (UCPs) present in their mitochondria. The recent demonstration of the presence of BAT in humans has invigorated research in this area. The research has provided many new insights into the biology and functioning of this tissue and the biological implications of its altered activities. Another finding of interest is browning of white adipose tissue (WAT) resulting in what is known as beige/brite cells, which have increased mitochondrial proteins and UCPs. In general, it has been observed that the activation of BAT is associated with various physiological improvements such as a reduction in blood glucose levels increased resting energy expenditure and reduced weight. Given the similar physiological functions of BAT and beige/ brite cells and the higher mass of WAT compared to BAT, it is likely that increasing the brite/beige cells in WATs may also lead to greater metabolic benefits. However, development of treatments targeting brown fat or WAT browning would require not only a substantial understanding of the biology of these tissues but also the effect of altering their activity levels on whole body metabolism and physiology. In this review, we present evidence from recent literature on the substrates utilized by BAT, regulation of BAT activity and browning by circulating molecules. We also present dietary and pharmacological activators of brown and beige/brite adipose tissue and the effect of physical exercise on BAT activity and browning.
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Affiliation(s)
- Shireesh Srivastava
- Systems Biology for Biofuels Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Richard L Veech
- Laboratory of Metabolic Control, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH), Bethesda, MD, United States
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Yasmeen R, Shen Q, Lee A, Leung JH, Kowdley D, DiSilvestro DJ, Xu L, Yang K, Maiseyeu A, Bal NC, Periasamy M, Fadda P, Ziouzenkova O. Epiregulin induces leptin secretion and energy expenditure in high-fat diet-fed mice. J Endocrinol 2018; 239:377-388. [PMID: 30400011 PMCID: PMC6226053 DOI: 10.1530/joe-18-0289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/19/2018] [Indexed: 01/30/2023]
Abstract
Adipokine leptin regulates neuroendocrine circuits that control energy expenditure, thermogenesis and weight loss. However, canonic regulators of leptin secretion, such as insulin and malonyl CoA, do not support these processes. We hypothesize that epiregulin (EREG), a growth factor that is secreted from fibroblasts under thermogenic and cachexia conditions, induces leptin secretion associated with energy dissipation. The effects of EREG on leptin secretion were studied ex vivo, in the intra-abdominal white adipose tissue (iAb WAT) explants, as well as in vivo, in WT mice with diet-induced obesity (DIO) and in ob/ob mice. These mice were pair fed a high-fat diet and treated with intraperitoneal injections of EREG. EREG increased leptin production and secretion in a dose-dependent manner in iAb fat explants via the EGFR/MAPK pathway. After 2 weeks, the plasma leptin concentration was increased by 215% in the EREG-treated group compared to the control DIO group. EREG-treated DIO mice had an increased metabolic rate and core temperature during the active dark cycle and displayed cold-induced thermogenesis. EREG treatment reduced iAb fat mass, the major site of leptin protein production and secretion, but did not reduce the mass of the other fat depots. In the iAb fat, expression of genes supporting mitochondrial oxidation and thermogenesis was increased in EREG-treated mice vs control DIO mice. All metabolic and gene regulation effects of EREG treatment were abolished in leptin-deficient ob/ob mice. Our data revealed a new role of EREG in induction of leptin secretion leading to the energy expenditure state. EREG could be a potential target protein to regulate hypo- and hyperleptinemia, underlying metabolic and immune diseases.
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Affiliation(s)
- Rumana Yasmeen
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Qiwen Shen
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Aejin Lee
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Jacob H. Leung
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Devan Kowdley
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - David J. DiSilvestro
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Lu Xu
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
- Department of Minimally Invasive Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Kefeng Yang
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
- Department of Nutrition, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. 200025
| | - Andrei Maiseyeu
- Cardiovascular Research Institute, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Naresh C. Bal
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Paolo Fadda
- Nucleic Acid Shared Resource, Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio 43210, USA
| | - Ouliana Ziouzenkova
- Department of Human Sciences, The Ohio State University, Columbus, Ohio, 43210, USA
- Correspondence Ouliana Ziouzenkova, PhD, 1787 Neil Avenue, 331A Campbell Hall; Columbus, OH 43210, ; Telephone: 001 614 292 5034; Fax: 001 614 292 8880
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Côté I, Green SM, Yarrow JF, Conover CF, Toklu HZ, Morgan D, Carter CS, Tümer N, Scarpace PJ. Oestradiol and leptin have separate but additive anorexigenic effects and differentially target fat mass in rats. J Neuroendocrinol 2018; 30:e12646. [PMID: 30246441 PMCID: PMC6251747 DOI: 10.1111/jne.12646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 09/17/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022]
Abstract
We recently showed that male rats exhibit lower hypophagia and body weight loss compared to female rats following central leptin delivery, suggesting a role for oestradiol in leptin responsiveness. Accordingly, we delivered Ob (leptin) or GFP (control) gene into the brain of male rats that were simultaneously treated with oestradiol or vehicle. In a reciprocal approach, we compared oestradiol-deficient (OVX) with intact females (sham) that received leptin or control vector. Changes in food intake), body weight and body composition were examined. In males, oestradiol and leptin resulted in lower cumulative food intake (15%) and endpoint body weight (5%), although rats receiving dual treatment (oestradiol-leptin) ate 28% less and weighed 22% less than vehicle-control. Changes in food intake were unique to each treatment, with a rapid decrease in vehicle-leptin followed by gradual renormalisation. By contrast, hypophagia in oestradiol-control was of lower amplitude and sporadic. Leptin selectively targeted fat mass and endpoint abdominal fat mass was 65%-80% lower compared to their respective control groups. In females, both leptin groups had lower body weight (endpoint values 20% lower than control groups) with the highest extent in sham animals (endpoint value was 28% less in sham-leptin than in sham-control). OVX rats rapidly started regaining their lost body weight reminiscent of the pattern in males. Leptin rapidly and robustly reduced fat mass with endpoint values 30%-35% less than control treated animals. It appears that leptin and oestradiol decreased food intake and body weight via different mechanisms, with the pattern of oestradiol-leptin being reminiscent of that observed in females and the pattern of OVX-leptin reminiscent of that observed in males. Oestrogen status did not influence initial fat mass loss by leptin. It can be concluded that oestradiol modulates the long-term response to central leptin overexpression, although its actions on energy homeostasis are additive and independent of those of leptin.
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Affiliation(s)
- Isabelle Côté
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States
| | - Sara M. Green
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States
| | - Joshua F. Yarrow
- Department of Veterans Affairs Medical Center, Research Service, Malcom Randall, North Florida/South Georgia Veterans Health System, Gainesville, Florida, United States
- Division of Endocrinology, Diabetes, and Metabolism, University of Florida College of Medicine, Gainesville, Florida, United States
| | - Christine F. Conover
- Department of Veterans Affairs Medical Center, Research Service, Malcom Randall, North Florida/South Georgia Veterans Health System, Gainesville, Florida, United States
| | - Hale Z. Toklu
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States
| | - Drake Morgan
- Department of Psychiatry, University of Florida, Gainesville, Florida, United States
| | - Christy S. Carter
- Department of Aging and Geriatric Research, University of Florida, Gainesville, Florida, United States
| | - Nihal Tümer
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States
| | - Philip J. Scarpace
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States
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