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Yu H, Thompson Z, Kiran S, Jones GL, Mundada L, Rubinstein M, Low MJ. Expression of a hypomorphic Pomc allele alters leptin dynamics during late pregnancy. J Endocrinol 2020; 245:115-127. [PMID: 32027603 DOI: 10.1530/joe-19-0576] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/06/2020] [Indexed: 12/11/2022]
Abstract
Proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus (ARC) are essential for normal energy homeostasis. Maximal ARC Pomc transcription is dependent on neuronal Pomc enhancer 1 (nPE1), located 12 kb upstream from the promoter. Selective deletion of nPE1 in mice decreases ARC Pomc expression by 70%, sufficient to induce mild obesity. Because nPE1 is located exclusively in the genomes of placental mammals, we questioned whether its hypomorphic mutation would also alter placental Pomc expression and the metabolic adaptations associated with pregnancy and lactation. We assessed placental development, pup growth, circulating leptin and expression of Pomc, Agrp and alternatively spliced leptin receptor (LepR) isoforms in the ARC and placenta of Pomc∆1/∆1 and Pomc+/+ dams. Despite indistinguishable body weights, lean mass, food intake, placental histology and Pomc expression and overall pregnancy outcomes between the genotypes, Pomc ∆1/∆1 females had increased pre-pregnancy fat mass that paradoxically decreased to control levels by parturition. However, Pomc∆1/∆1 dams had exaggerated increases in circulating leptin, up to twice of that of the typically elevated levels in Pomc+/+ mice at the end of pregnancy, despite their equivalent fat mass. Pomc∆1/∆1dams also had increased placental expression of soluble leptin receptor (LepRe), although the protein levels of LEPRE in circulation were the same as Pomc+/+ controls. Together, these data suggest that the hypomorphic Pomc∆1/∆1 allele is responsible for the perinatal super hyperleptinemia of Pomc∆1/∆1 dams, possibly due to upregulated leptin secretion from individual adipocytes.
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Affiliation(s)
- Hui Yu
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Zoe Thompson
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Sylee Kiran
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,School of Literature, Science, and Arts, University of Michigan, Ann Arbor, Michigan, USA
| | - Graham L Jones
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, USA
| | - Lakshmi Mundada
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Marcelo Rubinstein
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Instituto de Investigaciones en Ingeniería Genética y Biología Molecular Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos, Buenos Aires, Argentina
| | - Malcolm J Low
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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Sudhakar M, Silambanan S, Chandran AS, Prabhakaran AA, Ramakrishnan R. C-Reactive Protein (CRP) and Leptin Receptor in Obesity: Binding of Monomeric CRP to Leptin Receptor. Front Immunol 2018; 9:1167. [PMID: 29910808 PMCID: PMC5992430 DOI: 10.3389/fimmu.2018.01167] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 05/09/2018] [Indexed: 02/04/2023] Open
Abstract
While leptin deficiency or dysfunction leads to morbid obesity, obese subjects are characterized paradoxically by hyperleptinemia indicating lack of response to leptin. C-reactive protein (CRP) has been suggested to be a key plasma protein that could bind to leptin. To examine whether CRP interferes with leptin action, mediated through its cell surface receptor, docking studies of CRP with the extracellular domain of the leptin receptor were done employing bioinformatics tools. Monomeric CRP docked with better Z-rank score and more non-bond interactions than pentameric CRP at the CRH2–FNIII domain proximal to the cell membrane, distinct from the leptin-docking site. Interaction of CRP with leptin receptor was validated by solid phase binding assay and co-immunoprecipitation of CRP and soluble leptin receptor (sOb R) from human plasma. Analysis of the serum levels of leptin, CRP, and sOb R by ELISA showed that CRP levels were significantly elevated (p < 0.0001) in non-morbid obese subjects (n = 42) compared to lean subjects (n = 32) and correlated positively with body mass index (BMI) (r = 0.74, p < 0.0001) and leptin (r = 0.8, p < 0.0001); levels of sOb R were significantly low in obese subjects (p < 0.001) and showed a negative correlation with BMI (r = −0.26, p < 0.05) and leptin (r = −0.23, p < 0.05) indicating a minimal role for sOb R in sequestering leptin.
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Affiliation(s)
- Manu Sudhakar
- Department of Biochemistry, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India
| | - Santhi Silambanan
- Department of Biochemistry, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India
| | - Abhinand S Chandran
- Department of Computational Biology and Bioinformatics, University of Kerala, Thiruvananthapuram, Kerala, India
| | - Athira A Prabhakaran
- Department of Computational Biology and Bioinformatics, University of Kerala, Thiruvananthapuram, Kerala, India
| | - Ramya Ramakrishnan
- Department of Surgery, Sri Ramachandra Medical College and Research Institute, Chennai, Tamil Nadu, India
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3
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Dahlhoff M, Pfister S, Blutke A, Rozman J, Klingenspor M, Deutsch MJ, Rathkolb B, Fink B, Gimpfl M, Hrabě de Angelis M, Roscher AA, Wolf E, Ensenauer R. Peri-conceptional obesogenic exposure induces sex-specific programming of disease susceptibilities in adult mouse offspring. Biochim Biophys Acta Mol Basis Dis 2013; 1842:304-17. [PMID: 24275555 DOI: 10.1016/j.bbadis.2013.11.021] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/20/2013] [Accepted: 11/19/2013] [Indexed: 12/23/2022]
Abstract
Vulnerability of the fetus upon maternal obesity can potentially occur during all developmental phases. We aimed at elaborating longer-term health outcomes of fetal overnutrition during the earliest stages of development. We utilized Naval Medical Research Institute (NMRI) mice to induce pre-conceptional and gestational obesity and followed offspring outcomes in the absence of any postnatal obesogenic influences. Male adult offspring developed overweight, insulin resistance, hyperleptinemia, hyperuricemia and hepatic steatosis; all these features were not observed in females. Instead, they showed impaired fasting glucose and a reduced fat mass and adipocyte size. Influences of the interaction of maternal diet∗sex concerned offspring genes involved in fatty liver disease, lipid droplet size regulation and fat mass expansion. These data suggest that a peri-conceptional obesogenic exposure is sufficient to shape offspring gene expression patterns and health outcomes in a sex- and organ-specific manner, indicating varying developmental vulnerabilities between sexes towards metabolic disease in response to maternal overnutrition.
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Key Words
- ANOVA
- ATP citrate lyase
- AUC
- Acaca
- Acetyl-Coenzyme A carboxylase 1
- Acly
- Actb
- Analysis of variance
- Area under the curve
- B cell leukemia/lymphoma 2
- BW
- Bax
- Bcl2
- Bcl2-associated X protein
- Berardinelli–Seip congenital lipodystrophy 2 (also known as seipin)
- Beta-actin
- Body weight
- Bscl2
- CD
- CET
- CT
- Carbon dioxide production
- Carnitine palmitoyltransferase 1
- Cd36
- Cd36 antigen
- Cell death-inducing DNA fragmentation factor, alpha subunit-like effector A
- Central European Time
- Cidea
- Computed tomography
- Control diet
- Cpt1
- Day post coitum
- EEC
- European Economic Commission
- Exposure to maternal control diet
- Exposure to maternal high-fat, high-calorie diet
- FA
- Fabp4
- Fasn
- Fatty acid
- Fatty acid binding protein 4
- Fatty acid synthase
- GR
- GTT
- Glucocorticoid receptor
- Glucose tolerance test
- H&E
- HFD
- HMW
- HOMA-IR
- HP
- Hairy and enhancer of split 1
- Heat production
- Hematoxylin–eosin
- Hes1
- High-fat, high-calorie diet
- High-molecular-weight
- Homeostatic model assessment of insulin resistance
- Lep
- Leptin
- MD
- MDA
- MRI
- Magnetic resonance imaging
- Maintenance diet
- Malic enzyme 1
- Malondialdehyde
- Me1
- Mesoderm-specific transcript/imprinted paternally expressed gene 1 (also known as Peg1)
- Mest
- N
- NAFLD
- NEFA
- NMRI
- NRL
- Naval Medical Research Institute
- Nitrogen
- Non-alcoholic fatty liver disease
- Non-esterified fatty acid
- Nose–rump-length
- Nr1h3
- Nr3c1
- Nuclear receptor subfamily 1, group H, member 3 (also known as Lxra, liver X receptor alpha)
- Nuclear receptor subfamily 3, group C, member 1 (also known as Gr, glucocorticoid receptor)
- Obesity
- Offspring
- Oxygen consumption
- PFA
- Paraformaldehyde
- Patatin-like phospholipase domain-containing protein 2 (also known as Atgl, adipose triglyceride lipase)
- Peptidylprolyl isomerase A
- Peri-conceptional
- Perilipin 2
- Peroxisome proliferator activated receptor alpha
- Peroxisome proliferator activated receptor gamma
- Plin2
- Pnpla2
- Ppara
- Pparg
- Ppia
- Pregnancy
- Programming
- RER
- ROI
- Region of interest
- Respiratory exchange ratio
- S.e.m.
- Scd2
- Secreted frizzled-related sequence protein 5
- Sex-specificity
- Sfrp5
- Srebf1
- Standard error of the mean
- Stearoyl-Coenzyme A desaturase 2
- Sterol regulatory element binding transcription factor 1
- TBARS
- Thiobarbituric acid-reactive substances
- Ube2d2
- Ubiquitin-conjugating enzyme E2D 2
- VCO(2)
- VO(2)
- dpc
- mat-CD
- mat-HFD
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Affiliation(s)
- M Dahlhoff
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
| | - S Pfister
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
| | - A Blutke
- Institute of Veterinary Pathology at the Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-Universität München, Veterinärstrasse 13, 80539 Munich, Germany.
| | - J Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 München-Neuherberg, Germany; Molecular Nutritional Medicine, Else-Kröner Fresenius Center, Technische Universität München, Gregor-Mendel-Strasse 2, 85350 Freising-Weihenstephan, Germany.
| | - M Klingenspor
- Molecular Nutritional Medicine, Else-Kröner Fresenius Center, Technische Universität München, Gregor-Mendel-Strasse 2, 85350 Freising-Weihenstephan, Germany.
| | - M J Deutsch
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
| | - B Rathkolb
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany; German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 München-Neuherberg, Germany.
| | - B Fink
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
| | - M Gimpfl
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
| | - M Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 München-Neuherberg, Germany; Lehrstuhl für Experimentelle Genetik, Wissenschaftszentrum Weihenstephan, Technische Universität München, Alte Akademie 8, 85354 Freising, Germany; Member of German Center for Diabetes Research (DZD), Ingolstädter Landstrasse 1, 85764 München-Neuherberg, Germany.
| | - A A Roscher
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
| | - E Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
| | - R Ensenauer
- Research Center, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-Universität München, Lindwurmstrasse 4, 80337 Munich, Germany.
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Schlitt JM, Schulz LC. The source of leptin, but not leptin depletion in response to food restriction, changes during early pregnancy in mice. Endocrine 2012; 41:227-35. [PMID: 22042484 PMCID: PMC3291745 DOI: 10.1007/s12020-011-9548-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 10/14/2011] [Indexed: 12/21/2022]
Abstract
Maternal food restriction during pregnancy results in adverse consequences for offspring, including obesity and cardiovascular disease. Early pregnancy is a critical period for this programming effect. Leptin is a regulator of energy homeostasis that also affects placental and fetal development. As food restriction results in decreased serum leptin levels, at least in non-pregnant animals, leptin depletion may be one mechanism by which food restriction affects development. The objective of this study was to test whether moderate food restriction affects serum leptin concentrations during the first half of pregnancy. We found that restriction to 50% of ad libitum consumption levels resulted in a significant decrease in serum leptin concentrations in both pregnant and non-pregnant female mice. There was no significant difference in serum leptin concentrations between non-pregnant females and at pregnancy day 11.5 when fed ad libitum. However, there was a difference in the source of leptin during pregnancy, with greater production in visceral fat in pregnant mice, and greater production in subcutaneous fat in non-pregnant mice. Leptin concentrations were dependent on time of day and time of sampling relative to feeding, particularly in restricted mice. There was a significant difference in serum leptin concentrations between fed and restricted mice when they were fed and sampled in afternoon, but not when they were fed and sampled in morning. We conclude that food restriction results in a significant decrease in leptin concentration during the first half of pregnancy in mice, but that detection of this relationship is subject to experimental design considerations.
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Affiliation(s)
| | - Laura C. Schulz
- Corresponding author ADDRESS: Dept. of Obstetrics, Gynecology and Women’s Health, University of Missouri, N625 Health Sciences Center, 1 Hospital Drive, Columbia, MO 65212, , Phone: (573)-884-1408, Fax (573)882-9010
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5
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Thio LL, Erbayat-Altay E, Rensing N, Yamada KA. Leptin contributes to slower weight gain in juvenile rodents on a ketogenic diet. Pediatr Res 2006; 60:413-7. [PMID: 16940251 DOI: 10.1203/01.pdr.0000238244.54610.27] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The ketogenic diet (KD) is an efficacious therapy for medically refractory childhood epilepsy that also slows weight gain. We tested the hypothesis that the KD slows weight gain via neurohormones involved in energy homeostasis. We found that juvenile rodents fed a KD had slower weight gain than those fed a standard diet (SD). Rats fed a KD had higher serum leptin levels and lower insulin levels compared with those fed an SD. We investigated the increase in leptin further because this change was the only one consistent with slower weight gain. Although rats fed the SD experienced slower weight gain when calorie restricted, they had serum leptin levels similar to those fed the SD ad libitum. Furthermore, leptin deficient (ob/ob) and leptin receptor deficient (db/db) mice did not show slower weight gain on the KD. All animals on the KD had elevated serum beta-hydroxybutyrate (betaHB) levels. Thus, ketosis is insufficient and a functioning leptin signaling system appears necessary for the KD to slow weight gain. The increase in leptin may contribute to the anticonvulsant effects of the KD.
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Affiliation(s)
- Liu Lin Thio
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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6
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Malik NM, Carter ND, Wilson CA, Scaramuzzi RJ, Stock MJ, Murray JF. Leptin expression in the fetus and placenta during mouse pregnancy. Placenta 2005; 26:47-52. [PMID: 15664410 DOI: 10.1016/j.placenta.2004.03.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/31/2004] [Indexed: 11/22/2022]
Abstract
During pregnancy, leptin concentrations in the maternal circulation are elevated in both humans and rodents but decrease to pre-pregnancy levels at birth, suggesting a role for leptin in the maintenance of pregnancy. Synthesis of leptin by the human placenta is established but whether the murine placenta synthesizes leptin remains controversial. The aims of this study were to determine (a) if the mouse wild-type placenta expresses the ob gene using Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and (b) whether the mouse fetus and placenta contribute to the significant increase of leptin in the maternal circulation during pregnancy. The mouse placenta did not express the ob gene at a level that could be readily detected using RT-PCR. Moreover, both maternal gain in weight and undetectable concentrations of leptin in sera in leptin-deficient ob/ob mothers bearing heterozygote (ob/+) fetuses suggested that the mouse fetus and placenta do not make a significant contribution to the dramatic increase in maternal plasma concentrations of leptin during late gestation. It is therefore concluded that neither fetal- nor placental-derived leptin modulates maternal weight gain during pregnancy.
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Affiliation(s)
- N M Malik
- Department of Basic Medical Sciences, St Georges Hospital Medical School, London SW17 0RE, UK.
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7
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Zastrow O, Seidel B, Kiess W, Thiery J, Keller E, Böttner A, Kratzsch J. The soluble leptin receptor is crucial for leptin action: evidence from clinical and experimental data. Int J Obes (Lond) 2004; 27:1472-8. [PMID: 14634677 DOI: 10.1038/sj.ijo.0802432] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The soluble leptin receptor (sOB-R) was recently identified as the main leptin-binding protein in human blood. The aim of our study was to elucidate the effects of physiologically relevant amounts of sOB-R on leptin-induced proliferation in a cell model. SUBJECTS AND MEASUREMENTS To determine molar ratios between sOB-R and leptin in vivo, we measured both parameters in the serum of 529 healthy children and adolescents. For our in vitro cell model, mouse pre-B cells, transfected with the long form of the murine leptin receptor (BAF3/L46), were incubated with recombinant human leptin at two different basal levels (0.5 and 0.1 nM) and with the sOB-R at varying levels. The proliferative response of the cells was quantified by a (3)H-thymidine uptake assay. RESULTS Significantly higher molar sOB-R/leptin ratios were observed during the first years of life, up to a 7.67-fold excess of sOB-R (quartiles: 4.43/10.27) in boys, compared to the states of prepuberty and puberty. An up to 10-fold molar excess of the sOB-R, reflecting the in vivo situation, resulted in a significant suppression of leptin action in the cell model. In contrast, gradually decreasing ratios of lower than two, as calculated during the progression of childhood and in early puberty, corresponded to proliferative rates in vitro as determined at basal leptin concentrations. CONCLUSION At a distinct molar excess, sOB-R may suppress leptin action through inhibition of specific leptin binding to membrane-bound receptors in vitro. In vivo, sOB-R may further function to delay leptin clearance and increase the available leptin pool in the circulation. In the case of a massive excess of sOB-R, is it likely to be inhibitory to leptin interaction with the tissue membrane-bound OB-R.
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Affiliation(s)
- O Zastrow
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, and Hospital for Children and Adolescents, University of Leipzig, Germany
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8
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Harris RBS, Bowen HM, Mitchell TD. Leptin resistance in mice is determined by gender and duration of exposure to high-fat diet. Physiol Behav 2003; 78:543-55. [PMID: 12782207 DOI: 10.1016/s0031-9384(03)00035-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Mice fed a high-fat diet are reported to be resistant to peripheral injections of leptin. We previously failed to induce leptin resistance in female mice fed a high-fat diet for 15 weeks. Therefore, we measured the responsiveness to peripheral infusions (10 microg/day) of leptin, and the responsiveness to third ventricle injections of leptin (1 microg) in male and female NIH Swiss mice fed low-fat (10% kcal) or high-fat (45% kcal) diets. Male and female 15-week-old mice that had been fed low- or high-fat diet from 10 days of age lost fat during a 13-day intraperitoneal infusion of leptin and lost weight in response to a single central injection of leptin. Fifteen-week-old male mice fed a high-fat diet for 5 weeks did not lose body fat during a peripheral infusion of leptin and did not lose weight in response to a central injection of leptin. Female mice fed high-fat diet for 5 weeks remained leptin-responsive. Weight loss was achieved without a significant voluntary decrease in food intake, suggesting that both peripherally and centrally administered leptin increases energy expenditure. These results demonstrate that the development of leptin resistance in NIH Swiss mice fed a high-fat diet is dependent upon the gender of the mice and either the duration of exposure to high-fat diet or the age at which the mice are first exposed to the diet.
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Affiliation(s)
- Ruth B S Harris
- Department of Foods and Nutrition, Dawson Hall, University of Georgia, Athens, GA 30602, USA.
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9
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Friedman-Einat M, Camoin L, Faltin Z, Rosenblum CI, Kaliouta V, Eshdat Y, Strosberg AD. Serum leptin activity in obese and lean patients. REGULATORY PEPTIDES 2003; 111:77-82. [PMID: 12609752 DOI: 10.1016/s0167-0115(02)00259-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Blood levels of the satiety hormone leptin are directly correlated to fat stores in obese and lean people. Therefore, leptin resistance is the logical explanation for the phenomenon of common obesity. However, the important question of whether or not the intrinsic leptin activity could differ between obese and lean people has not been examined before. In the present study, serum leptin activity was measured by an in vitro assay of leptin signaling in a modified culture of HEK-293 cells. The system is based on activation of a luciferase reporter gene through a leptin receptor-dependent activation of the signal transducer and activator of transcription (STAT3). Serum samples from 20 obese and 20 non-obese individuals with leptin levels ranging from 3 to 75 ng/ml, as determined by radioimmunoassay (RIA), were used. A high correlation was observed for each serum sample between leptin RIA values and leptin activity in the bioassay. The results indicate that obesity in the 20 obese patients among the 40 individuals examined cannot be accounted for by alterations in leptin activity in our assay. The assay system provides a tool to screen for possible rare cases exhibiting alteration in leptin activity either due to a change in leptin itself or through interaction with other serum factors.
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Affiliation(s)
- M Friedman-Einat
- Institute of Animal Science, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50250, Israel.
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10
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Bowen H, Mitchell TD, Harris RBS. Method of leptin dosing, strain, and group housing influence leptin sensitivity in high-fat-fed weanling mice. Am J Physiol Regul Integr Comp Physiol 2003; 284:R87-100. [PMID: 12482747 DOI: 10.1152/ajpregu.00431.2002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-fat diets are reported to induce resistance to peripherally administered leptin. In an attempt to develop a model of juvenile diet-induced obesity, mice were weaned onto high-fat diet. Male and female, 35-day-old, C57BL/6J high-fat (45% kcal fat) diet-fed mice housed individually on grid floors did not decrease food intake or body weight in response to intraperitoneal (30 microg), lateral ventricle (5 microg), or third ventricle (0.5 microg) injections of leptin. Body weight and fat were significantly reduced by 13-day intraperitoneal infusions of 10 microg leptin/day, which doubled circulating leptin. Leptin infusion also reduced body fat in weanling, high-fat diet-fed NIH Swiss mice. Group housing mice on bedding prevented loss of fat in high-fat diet-fed male and female NIH Swiss and female C57BL/6J mice. These results indicate that peripherally infused leptin reduces fat in part by increasing thermogenesis and that inhibition of food intake in high-fat diet-fed mice requires either chronic activation of central leptin receptors or is independent of receptors that inhibit feeding in response to an acute central injection of leptin.
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Affiliation(s)
- Heather Bowen
- Department of Foods and Nutrition, University of Georgia, Athens, Georgia 30602, USA
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11
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van Dielen FMH, van 't Veer C, Buurman WA, Greve JWM. Leptin and soluble leptin receptor levels in obese and weight-losing individuals. J Clin Endocrinol Metab 2002; 87:1708-16. [PMID: 11932305 DOI: 10.1210/jcem.87.4.8381] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To investigate soluble leptin receptor (sLR) in plasma, specific anti-sLR monoclonal antibodies were developed. Western blot analysis and size exclusion fractionation demonstrated sLR in plasma with a molecular mass of approximately 180,000. Next to this, the presence of sLR-leptin complexes in plasma was confirmed. Using the developed monoclonal antibodies, a specific sLR ELISA was developed, which measured in plasma both free and sLR bound to leptin. sLR appeared to inhibit leptin concentrations measured in four different leptin assays indicating that these assays primarily measure free leptin and underestimate the total leptin present in plasma. Furthermore, plasma levels of sLR and leptin were measured in 21 lean individuals and in 30 morbidly obese subjects before and 3, 6, and 12 months after gastric restrictive surgery. Preoperatively, leptin concentrations significantly correlated with body mass index (r = 0.796, P < 0.001). In contrast, sLR significantly inversely correlated with body mass index (r = -0.294, P < 0.05). In lean subjects, the molar ratio of free leptin to sLR was 1:1, whereas in morbidly obese subjects a ratio of 25:1 was found. After weight loss due to surgery, leptin levels rapidly decreased and sLR levels slowly increased to reach normal values at 12 months postoperatively. We conclude that sLR levels are significantly decreased, whereas leptin levels are significantly increased in morbidly obese subjects compared with lean individuals.
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12
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Ingvartsen KL, Boisclair YR. Leptin and the regulation of food intake, energy homeostasis and immunity with special focus on periparturient ruminants. Domest Anim Endocrinol 2001; 21:215-50. [PMID: 11872319 DOI: 10.1016/s0739-7240(02)00119-4] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The biology of leptin has been studied most extensively in rodents and in humans. Leptin is involved in the regulation of food intake, energy homeostasis and immunity. Leptin is primarily produced in white adipose tissue and acts via a family of membrane bound receptors, including an isoform with a long intracellular domain (OB-Rb), and many isoforms with short intracellular domains (Ob-Rs). OB-Rb is predominantly expressed in the hypothalamic regions involved in the regulation of food intake and energy homeostasis. The other isoforms are distributed ubiquitously and are found in most peripheral tissues in far greater abundance than OB-Rb. The effects of leptin on food intake and energy homeostasis are central and are mediated via a network of orexigenic neuropeptides (neuropeptide Y, galanin, galanin-like peptide, melanin-concentrating hormone, orexins, agouti-related peptide) and anorexigenic neuropeptides (corticotropin-releasing hormone, pro-opiomelanocortin, alpha-melanocyte stimulating hormone and cocaine- and amphetamine-regulated transcript). In addition, leptin acts directly on immune cells to stimulate hematopoesis, T-cell immunity, phagocytosis, cytokine production, and to attenuate susceptibility to infectious insults. Emerging data in ruminants suggest that leptin is dynamically regulated by many factors and physiological states. Thus, leptin is secreted in a pulsatile fashion, but without a marked diurnal rhythm. A positive relationship between adiposity and plasma leptin concentration exists in growing and lactating ruminants. The concentration of plasma leptin increases during pregnancy, starts to decline 1--2 wk before parturition, and reaches a nadir in early lactation. The reduction of plasma leptin at parturition is likely to promote centrally mediated adaptations required in periods of energy deficit, but could have negative effects on immune cell function. Future research is needed in ruminants to address the roles played by leptin and the central nervous system in orchestrating metabolism during the periparturient period and during infectious diseases.
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Affiliation(s)
- K L Ingvartsen
- Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, DK-8830, Tjele, Denmark.
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