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Mishra S, Harris TB, Hue T, Miljkovic I, Satterfield S, de Rekeneire N, Mehta M, Sahyoun NR. Hyperleptinemia, adiposity, and risk of metabolic syndrome in older adults. J Nutr Metab 2013; 2013:327079. [PMID: 24455217 PMCID: PMC3888758 DOI: 10.1155/2013/327079] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 10/03/2013] [Indexed: 11/29/2022] Open
Abstract
Background. Abdominal adiposity and serum leptin increase with age as does risk of metabolic syndrome. This study investigates the prospective association between leptin and metabolic syndrome risk in relation to adiposity and cytokines. Methods. The Health, Aging, and Body Composition study is a prospective cohort of older adults aged 70 to 79 years. Baseline measurements included leptin, cytokines, BMI, total percent fat, and visceral and subcutaneous fat. Multivariate logistic regression was used to determine the association between leptin and metabolic syndrome (defined per NCEP ATP III) incidence after 6 years of follow-up among 1,120 men and women. Results. Leptin predicted metabolic syndrome in men (P for trend = 0.0002) and women (P for trend = 0.0001). In women, risk of metabolic syndrome increased with higher levels of leptin (compared with quintile 1, quintile 2 RR = 3.29, CI = 1.36, 7.95; quintile 3 RR = 3.25, CI = 1.33, 7.93; quintile 4 RR = 5.21, CI = 2.16, 12.56; and quintile 5 RR = 7.97, CI = 3.30, 19.24) after adjusting for potential confounders. Leptin remained independently associated with metabolic syndrome risk after additional adjustment for adiposity, cytokines, and CRP. Among men, this association was no longer significant after controlling for adiposity. Conclusion. Among older women, elevated concentrations of leptin may increase the risk of metabolic syndrome independent of adiposity and cytokines.
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Affiliation(s)
- Suruchi Mishra
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA
| | | | - Trisha Hue
- University of California, San Francisco, CA 94107, USA
| | - Iva Miljkovic
- Department of Epidemiology, University of Pittsburg, Pittsburgh, PA 15213, USA
| | | | | | - Mira Mehta
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA
| | - Nadine R. Sahyoun
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA
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Chouliaras G, Panayotou I, Margoni D, Mantzou E, Pervanidou P, Manios Y, Chrousos GP, Roma E. Circulating leptin and adiponectin and their relation to glucose metabolism in children with Crohn's disease and ulcerative colitis. Pediatr Res 2013; 74:420-6. [PMID: 23823177 DOI: 10.1038/pr.2013.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/04/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Crohn's disease (CD) and ulcerative colitis (UC) result in metabolic consequences. We assessed circulating leptin and adiponectin concentrations and examined their relations to glucose metabolism in children with CD and UC. METHODS Circulating morning fasting concentrations of leptin, adiponectin, glucose, and insulin were measured in 32 children with CD and 18 children with UC. Insulin resistance (IR) and β-cell function were evaluated by the updated homeostatic model assessments (HOMA2-IR and HOMA2-B). RESULTS Leptin was positively related to BMI z-scores overall and in the CD and the UC subgroups (P < 0.001). A negative correlation between leptin and disease activity was observed in the entire population (P = 0.034) and in the UC (P = 0.03) group. None of the assessed parameters was related to adiponectin. Fourteen percent of the participants were insulin resistant (15.6% in the CD group and 11.1% in the UC group), significantly more than expected (P < 0.001). Leptin was associated with HOMA2-IR (overall: r = 0.29, P = 0.045). Pathway analysis suggested that, overall, disease activity and BMI significantly affect leptin, which in turn is the only correlate of HOMA2-IR. CONCLUSION Disease activity was significantly and inversely related to leptin in children with inflammatory bowel disease (IBD). A significant proportion of the patients had increased IR, which is positively related to circulating leptin.
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Affiliation(s)
- Giorgos Chouliaras
- 1] First Department of Pediatrics, University of Athens, Athens, Greece [2] Research Division of Endocrinology and Metabolic Diseases, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
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Holmström MH, Tom RZ, Björnholm M, Garcia-Roves PM, Zierath JR. Effect of leptin treatment on mitochondrial function in obese leptin-deficient ob/ob mice. Metabolism 2013; 62:1258-67. [PMID: 23664724 DOI: 10.1016/j.metabol.2013.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/15/2013] [Accepted: 04/02/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Leptin stimulates peripheral lipid oxidation, but the influence on mitochondrial function is partly unknown. We investigated tissue-specific mitochondrial function in leptin-deficient obese C57BL/6J-ob/ob mice compared to lean littermates following leptin treatment. MATERIALS AND METHODS Lean and obese ob/ob mice were treated with saline or leptin for 5 days. At day six, liver, extensor digitorum longus (EDL) and soleus muscle were dissected and mitochondrial respiration analyzed in freshly dissected tissues. Expression of key proteins in the regulation of mitochondrial function was determined. RESULTS In liver, mitochondrial respiration was reduced in ob/ob mice compared to lean mice. Expression of mitochondrial transcription factor A (TFAM) was decreased in ob/ob mice, but increased with leptin treatment. In glycolytic EDL muscle, mitochondrial respiration was increased in ob/ob mice. Protein markers of complex II, IV and ATP synthase were increased in EDL muscle from both saline- and leptin-treated ob/ob mice. TFAM protein abundance was decreased, while dynamin-1-like protein was increased in EDL muscle from saline-treated ob/ob mice and restored by leptin treatment. In oxidative soleus muscle, mitochondrial respiration and electron transport system protein abundance were unchanged, while TFAM was reduced in ob/ob mice. CONCLUSIONS In conclusion, leptin-deficient ob/ob mice display tissue-specific mitochondrial adaptations under basal conditions and in response to leptin treatment. Mitochondrial respiration was decreased in liver, increased in glycolytic muscle and unaltered in oxidative muscle from ob/ob mice. Insight into the tissue-specific regulation of mitochondrial function in response to energy supply and demand may provide new opportunities for the treatment of insulin resistance.
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Affiliation(s)
- Maria H Holmström
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Lee H, Lee IS, Choue R. Obesity, inflammation and diet. Pediatr Gastroenterol Hepatol Nutr 2013; 16:143-52. [PMID: 24224147 PMCID: PMC3819692 DOI: 10.5223/pghn.2013.16.3.143] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 09/06/2013] [Indexed: 12/24/2022] Open
Abstract
Obesity is a state in which there is an over-accumulation of subcutaneous and/or abdominal adipose tissue. This adipose tissue is no longer considered inert and mainly devoted to storing energy; it is emerging as an active tissue in the regulation of physiological and pathological processes, including immunity and inflammation. Adipose tissue produces and releases a variety of adipokines (leptin, adiponectin, resistin, and visfatin), as well as pro- and anti-inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-4, IL-6, and others). Adipose tissue is also implicated in the development of chronic metabolic diseases such as type 2 diabetes mellitus or cardiovascular disease. Obesity is thus an underlying condition for inflammatory and metabolic diseases. Diet or dietary patterns play critical roles in obesity and other pathophysiological conditions. A healthy diet and some nutrients are generally considered beneficial; however, some dietary nutrients are still considered controversial. In this article, dietary factors that influence inflammation associated with obesity are discussed.
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Affiliation(s)
- Hansongyi Lee
- Department of Medical Nutrition, Graduate School of East-West Medical Science, Kyung Hee University, Yongin, Korea. ; Research Institute of Medical Nutrition, Kyung Hee University, Seoul, Korea
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Nazarians-Armavil A, Menchella JA, Belsham DD. Cellular insulin resistance disrupts leptin-mediated control of neuronal signaling and transcription. Mol Endocrinol 2013; 27:990-1003. [PMID: 23579487 DOI: 10.1210/me.2012-1338] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Central resistance to the actions of insulin and leptin is associated with the onset of obesity and type 2 diabetes mellitus, whereas leptin and insulin signaling is essential for both glucose and energy homeostasis. Although it is known that leptin resistance can lead to attenuated insulin signaling, whether insulin resistance can lead to or exacerbate leptin resistance is unknown. To investigate the molecular events underlying crosstalk between these signaling pathways, immortalized hypothalamic neuronal models, rHypoE-19 and mHypoA-2/10, were used. Prolonged insulin exposure was used to induce cellular insulin resistance, and thereafter leptin-mediated regulation of signal transduction and gene expression was assessed. Leptin directly repressed agouti-related peptide mRNA levels but induced urocortin-2, insulin receptor substrate (IRS)-1, IRS2, and IR transcription, through leptin-mediated phosphatidylinositol 3-kinase/Akt activation. Neuronal insulin resistance, as assessed by attenuated Akt phosphorylation, blocked leptin-mediated signal transduction and agouti-related peptide, urocortin-2, IRS1, IRS2, and insulin receptor synthesis. Insulin resistance caused a substantial decrease in insulin receptor protein levels, forkhead box protein 1 phosphorylation, and an increase in suppressor of cytokine signaling 3 protein levels. Cellular insulin resistance may cause or exacerbate neuronal leptin resistance and, by extension, obesity. It is essential to unravel the effects of neuronal insulin resistance given that both peripheral, as well as the less widely studied central insulin resistance, may contribute to the development of metabolic, reproductive, and cardiovascular disorders. This study provides improved understanding of the complex cellular crosstalk between insulin-leptin signal transduction that is disrupted during neuronal insulin resistance.
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Affiliation(s)
- Anaies Nazarians-Armavil
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 Kings College Circle, Toronto, Ontario, Canada M5S 1A8
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Zuo H, Shi Z, Yuan B, Dai Y, Wu G, Hussain A. Association between serum leptin concentrations and insulin resistance: a population-based study from China. PLoS One 2013; 8:e54615. [PMID: 23349940 PMCID: PMC3551759 DOI: 10.1371/journal.pone.0054615] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 12/13/2012] [Indexed: 12/22/2022] Open
Abstract
Background Insulin resistance contributes to the cardio-metabolic risk. The effect of leptin in obese and overweight population on insulin resistance was seldom reported. Methods A total of 1234 subjects (572 men and 662 women) aged ≥18 y was sampled by the procedure. Adiposity measures included BMI, waist circumference, hip circumference, WHR, upper arm circumference, triceps skinfold and body fat percentage. Serum leptin concentrations were measured by an ELISA method. The homeostasis model (HOMA-IR) was applied to estimate insulin resistance. Results In men, BMI was the variable which was most strongly correlated with leptin, whereas triceps skinfold was most sensitive for women. More importantly, serum leptin levels among insulin resistant subjects were almost double compared to the subjects who had normal insulin sensitivity at the same level of adiposity in both men and women, after controlling for potential confounders. In addition, HOMA-IR increased significantly across leptin quintiles after adjustment for age, BMI, total energy intake, physical activity and smoking status in both men and women (p for trend <0.0001). Conclusions There was a significant association between HOMA-IR and serum leptin concentrations in Chinese men and women, independently of adiposity levels. This may suggest that serum leptin concentration is an important predictor of insulin resistance and other metabolic risks irrespective of obesity levels. Furthermore, leptin levels may be used to identify the cardio-metabolic risk in obese and overweight population.
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Affiliation(s)
- Hui Zuo
- Department of Nutrition and Food Hygiene, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China.
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Mohammadzadeh G, Zarghami N. Serum leptin level is reduced in non-obese subjects with type 2 diabetes. Int J Endocrinol Metab 2013; 11:3-10. [PMID: 23853613 PMCID: PMC3693653 DOI: 10.5812/ijem.6535] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 06/06/2012] [Accepted: 07/22/2012] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Leptin, a protein released from adipose tissue, could have significant role in pathogenesis of obesity and type 2 diabetes mellitus. OBJECTIVES This study aimed to evaluate variations in serum leptin levels in non-obese subjects with type 2 diabetes mellitus (T2DM). PATIENTS AND METHODS We studied forty-one patients with type 2 diabetes. Fasting lipid profile, Hemoglobin A1c (HbA1c), serum leptin, insulin, and glucose levels were measured by standard methods. RESULTS The serum leptin level in type 2 diabetic patients (19.32 ± 11.43 ng/mL) was significantly lower than that in non-diabetic subjects (32.16 ± 11.02 ng/mL). Serum leptin level was strongly and positively correlated with body mass index (BMI) (r = 0.658, P < 0.0001) and calculated body fat percentage (r = 0.431, P < 0.0001) in all the study subjects with a better corrlation in the control subjcts compared to control cases (r = 0.661 for BMI and r = 0.466 for body fat). On the other hand, leptin showed a positive and significant correlation with insulin and HOMA- β (homeostasis model assessment for β-cell function) in both groups. Furthermore, leptin related to homeostasis model assessment for insulin resistance (HOMA-IR) (r = 0.422, P = 0.006) was observed only in T2DM subjects. Leptin showed negative correlation with waist to hip ratio in diabetic (r = -0.407, P =0.008) and non-diabetic subjects (r = -0.318, P =0.049). In the regression model, BMI, HOMA-β, and gender were independent predictors of leptin in all subjects. However, in non-diabetic and diabetic subjects, β-cell function and insulin were independent predictors, respectively (P =0.01). CONCLUSIONS It is speculated that lower serum leptin levels in diabetic patients may be a consequence of male gender. Moreover, results suggest that serum leptin level in women is influenced differently than that in men.
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Affiliation(s)
- Ghorban Mohammadzadeh
- Hyperlipidemia Research Center, Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran
- Corresponding author: Ghorban Mohammadzadeh, Hyperlipidemia Research Center, Department of Clinical Biochemistry, Faculty of Medicine, Ahvaz University of Medical Sciences, Ahvaz, IR Iran. Tel.: +98-91134368125, Fax: +98-6113332036, E-mail:
| | - Nosratollah Zarghami
- Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
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Sakuma K, Yamaguchi A. Sarcopenic obesity and endocrinal adaptation with age. Int J Endocrinol 2013; 2013:204164. [PMID: 23690769 PMCID: PMC3639625 DOI: 10.1155/2013/204164] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/01/2013] [Indexed: 02/06/2023] Open
Abstract
In normal aging, changes in the body composition occur that result in a shift toward decreased muscle mass and increased fat mass. The loss of muscle mass that occurs with aging is termed sarcopenia and is an important cause of frailty, disability, and loss of independence in older adults. Age-related changes in the body composition as well as the increased prevalence of obesity determine a combination of excess weight and reduced muscle mass or strength, recently defined as sarcopenic obesity. Weight gain increases total/abdominal fat, which, in turn, elicits inflammation and fatty infiltration in muscle. Sarcopenic obesity appears to be linked with the upregulation of TNF-α, interleukin (IL)-6, leptin, and myostatin and the downregulation of adiponectin and IL-15. Multiple combined exercise and mild caloric restriction markedly attenuate the symptoms of sarcopenic obesity. Intriguingly, the inhibition of myostatin induced by gene manipulation or neutralizing antibody ameliorates sarcopenic obesity via increased skeletal muscle mass and improved glucose homeostasis. In this review, we describe the possible influence of endocrinal changes with age on sarcopenic obesity.
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Affiliation(s)
- Kunihiro Sakuma
- Research Center for Physical Fitness, Sports and Health, Toyohashi University of Technology, 1-1 Hibarigaoka, Tenpaku-cho, Toyohashi 441-8580, Japan
- *Kunihiro Sakuma:
| | - Akihiko Yamaguchi
- School of Dentistry, Health Sciences University of Hokkaido, Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
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Paz-Filho G, Mastronardi C, Wong ML, Licinio J. Leptin therapy, insulin sensitivity, and glucose homeostasis. Indian J Endocrinol Metab 2012; 16:S549-S555. [PMID: 23565489 PMCID: PMC3602983 DOI: 10.4103/2230-8210.105571] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Glucose homeostasis is closely regulated not only by insulin, but also by leptin. Both hormones act centrally, regulating food intake and adiposity in humans. Leptin has several effects on the glucose-insulin homeostasis, some of which are independent of body weight and adiposity. Those effects of leptin are determined centrally in the hypothalamus and peripherally in the pancreas, muscles and liver. Leptin has beneficial effects on the glucose-insulin metabolism, by decreasing glycemia, insulinemia and insulin resistance. The understanding of the effects of leptin on the glucose-insulin homeostasis will lead to the development of leptin-based therapies against diabetes and other insulin resistance syndromes. In these review, we summarize the interactions between leptin and insulin, and their effects on the glucose metabolism.
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Affiliation(s)
- Gilberto Paz-Filho
- Department of Translational Medicine, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Claudio Mastronardi
- Department of Translational Medicine, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Ma-Li Wong
- Department of Translational Medicine, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Julio Licinio
- Department of Translational Medicine, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
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Gui Y, Silha JV, Murphy LJ. Sexual Dimorphism and Regulation of Resistin, Adiponectin, and Leptin Expression in the Mouse. ACTA ACUST UNITED AC 2012; 12:1481-91. [PMID: 15483213 DOI: 10.1038/oby.2004.185] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE To examine gender differences and hormonal regulation of resistin, adiponectin, and leptin. RESEARCH METHODS AND PROCEDURES Plasma levels were measured, and mRNA expression in perigonadal fat was quantified by RNase protection assays. RESULTS Plasma resistin declined with age despite an increase in adiposity in both genders. In male mice, plasma leptin increased, whereas adiponectin levels were constant. In females, both adiponectin and leptin levels increased with age. Resistin mRNA levels were significantly higher in female than male mice at all ages, whereas leptin and adiponectin mRNA levels were similar in fat from 6-week-old male and female mice, and sexual dimorphism was apparent only in the older mice, with higher levels apparent in females. Castration did not abolish gender differences in plasma levels or resistin, adiponectin, or leptin mRNAs. Castration of male mice did not significantly change adipokine mRNA levels or plasma levels of resistin or leptin; however, adiponectin was significantly increased. Dihydrotestosterone treatment had no effect on adipokine mRNA expression or resistin and adiponectin levels but increased leptin levels. In contrast, ovariectomy significantly increased resistin mRNA abundance and decreased leptin and adiponectin mRNAs. Plasma leptin levels were also increased by ovariectomy, whereas resistin and adiponectin levels were unchanged. Estrogen replacement significantly reduced resistin mRNA and increased leptin and adiponectin mRNA levels but had no effect on plasma adipokine levels. DISCUSSION The gender differences in adipokine mRNA expression and plasma levels were not ablated by castration and seem to be dependent on other factors in addition to gonadal steroids.
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Affiliation(s)
- Yaoting Gui
- Department of Physiology, University of Manitoba, Winnipeg, Canada
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de Luis DA, Aller R, Izaola O, Conde R, Sagrado MG, Primo D, Castro MJ. Relationship among metabolic syndrome, C358A polymorphism of the endocannabinoid degrading enzyme fatty acid amide hydrolase (FAAH) and insulin resistance. J Diabetes Complications 2012; 26:328-32. [PMID: 22609216 DOI: 10.1016/j.jdiacomp.2012.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Revised: 04/02/2012] [Accepted: 04/06/2012] [Indexed: 11/21/2022]
Abstract
BACKGROUND It has been demonstrated that the polymorphism 385 C/A of FAAH (fatty acid amide hydrolase) was associated with obesity and metabolic disorders. OBJECTIVE The aim of our study was to investigate the relationship of the polymorphism (cDNA 385 C->A) of FAAH gene and insulin resistance in obese patients with and without metabolic syndrome. DESIGN A population of 799 obese patients was analyzed in cross-sectional survey. A bioimpedance, blood pressure, serial assessment of nutritional intake with 3 days written food records and biochemical analysis were performed. Genotype of FAAH gene polymorphism was studied. RESULTS Prevalence of metabolic syndrome (MS) with ATP III definition was 49.8% (398 patients) and 50.2% patients without MS (n=401 patients). Prevalence of FAAH genotypes was similar in patients with metabolic syndrome (69.6% wild genotype and 30.4% mutant genotype) and without metabolic syndrome (66.6% wild genotype and 33.4% mutant genotype). In patients without metabolic syndrome, insulin and HOMA levels were higher in mutant genotype than wild type group. CONCLUSION The main finding is the lack of association of the FAAH genotypes with metabolic syndrome prevalence. Patients with mutant genotype group of FAAH gene and without metabolic syndrome have higher insulin and HOMA levels than wild type group.
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Affiliation(s)
- D A de Luis
- Center of Investigation of Endocrinology and Clinical Nutrition, Medicine School and Unit of Investigation, Hospital Rio Hortega, University of Valladolid, Valladolid, Spain.
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Ho GYF, Wang T, Gunter MJ, Strickler HD, Cushman M, Kaplan RC, Wassertheil-Smoller S, Xue X, Rajpathak SN, Chlebowski RT, Vitolins MZ, Scherer PE, Rohan TE. Adipokines linking obesity with colorectal cancer risk in postmenopausal women. Cancer Res 2012; 72:3029-37. [PMID: 22511581 PMCID: PMC3790260 DOI: 10.1158/0008-5472.can-11-2771] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mechanistic associations between obesity and colorectal cancer remain unclear. In this study, we investigated whether adipokines are risk factors for colorectal cancer and whether they may mediate its association with obesity. In a case-cohort study nested within the Women's Health Initiative cohort of postmenopausal women, baseline plasma samples from 457 colorectal cancer cases and 841 subcohort subjects were assayed for seven adipokines-adiponectin, leptin, plasminogen activator inhibitor-1 (PAI-1), resistin, hepatocyte growth factor, interleukin-6 (IL-6), and TNF-α. Serum insulin and estradiol values measured previously were also available for data analysis. After adjusting for age, race, smoking, colonoscopy history, and estrogen level, a low level of anti-inflammatory adiponectin and high levels of proinflammatory leptin, PAI-1, and IL-6 were associated with increased colorectal cancer risk, though only leptin remained significant after further adjustment for insulin [HRs comparing extreme quartiles (HR(Q4-Q1)), 1.84; 95% CI, 1.17-2.90]. Mediation analyses showed that leptin and insulin partially explained the association between waist circumference and colorectal cancer and attenuated it by 25% and 37%, respectively, with insulin being a significant mediator (P = 0.041). Our findings support the conclusion that adipokines involved in inflammation are associated with colorectal cancer risk, but that their effects may be mediated mostly by insulin, with leptin exerting an independent effect. Hyperinsulinemia and hyperleptinemia may therefore partially explain the adiposity association with colorectal cancer in postmenopausal women.
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Affiliation(s)
- Gloria Y F Ho
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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De Solís AJ, Fernández-Agulló T, García-SanFrutos M, Pérez-Pardo P, Bogónez E, Andrés A, Ros M, Carrascosa JM. Impairment of skeletal muscle insulin action with aging in Wistar rats: Role of leptin and caloric restriction. Mech Ageing Dev 2012; 133:306-16. [DOI: 10.1016/j.mad.2012.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 02/13/2012] [Accepted: 03/06/2012] [Indexed: 01/04/2023]
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Chen ZH, Li J, Liu J, Zhao Y, Zhang P, Zhang MX, Zhang L. Saponins Isolated from the Root of Panax notoginseng Showed Significant Anti-Diabetic Effects in KK-Ay Mice. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2012; 36:939-51. [PMID: 19051359 DOI: 10.1142/s0192415x08006363] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Panax notoginseng, a well-known and commonly used traditional Chinese herb, has been used in China for six hundred years. Panax notoginseng Saponins (PNS) were extracted from the root of the plant. This is the first study on anti-hyperglycemic and anti-obese effects of PNS in genetic model mice. Additionally, the preventive effect on diabetic nephropathy was investigated. Animals received intraperitoneal injections of PNS 50 or 200 mg/kg daily. On day 12, 22 and 30, PNS-treated groups had significantly lower fasting blood glucose levels and smaller body weight incremental percentage. After a 12-day treatment, glucose tolerance of PNS groups were significantly improved; these indices in PNS-treated mice exhibited a dose-dependent improvement. Furthermore, on day 30, the serum insulin resistance index and triglyceride levels of PNS-treated groups decreased significantly, and the development of the mice glomerular lesions was prevented significantly. The results in this present paper indicate that PNS possesses anti-diabetes and anti-obese activities and may prove to be of clinical importance in improving the management of type 2 diabetes.
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Affiliation(s)
- Zhong-Hua Chen
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Jie Li
- Department of Pharmacognosy, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Jie Liu
- Key Laboratory of Drug Targeting, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Yuan Zhao
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Pu Zhang
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Meng-Xue Zhang
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Liu Zhang
- Department of Pharmacology, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
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Abstract
Obesity, deregulation of adipocytokines, and insulin resistance are interrelated and have been implicated in carcinogenesis. In search of novel risk factors for melanoma, we explored the association of this disease with insulin resistance in a small size, case-control study. Homeostasis Model Assessment for Insulin Resistance (HOMA-IR), serum leptin, and adiponectin levels were determined in 55 patients with incident melanoma and 165 age-matched and sex-matched controls. Odds ratios were derived after adjusting for skin type, medical history, sociodemographic, lifestyle, and anthropometric parameters. Among the controls, HOMA-IR correlated positively with BMI (r=0.34; P=0.0001), waist-to-hip ratio (r=0.20; P=0.01) and negatively with serum adiponectin (r=-0.21; P=0.006), whereas the correlation with leptin was essentially null (r=0.09; P=0.27). The mean HOMA-IR was approximately 1.5 times higher in cases than in controls (P=0.05). The established positive association of melanoma with skin type was evident in multiple logistic regression models and so was the association with increasing HOMA-IR quintile (odds ratio for the fifth quintile=3.68; 95% confidence intervals 1.15-11.79, P=0.02). The latter persisted after adjustment for anthropometric variables and adiponectin but was attenuated when leptin was introduced in the model. These findings point to insulin resistance as a potentially independent risk factor for melanoma and need to be confirmed by future larger studies, ideally allowing the control of the directionality of the association.
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66
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Sáinz N, Rodríguez A, Catalán V, Becerril S, Ramírez B, Lancha A, Burgos-Ramos E, Gómez-Ambrosi J, Frühbeck G. Leptin reduces the expression and increases the phosphorylation of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4 in muscle of ob/ob mice. PLoS One 2012; 7:e29389. [PMID: 22253718 PMCID: PMC3253781 DOI: 10.1371/journal.pone.0029389] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 11/28/2011] [Indexed: 02/01/2023] Open
Abstract
Leptin improves insulin sensitivity in skeletal muscle. Our goal was to determine whether proteins controlling GLUT4 traffic are altered by leptin deficiency and in vivo leptin administration in skeletal muscle of wild type and ob/ob mice. Leptin-deficient ob/ob mice were divided in three groups: control, leptin-treated (1 mg/kg/d) and leptin pair-fed ob/ob mice. Microarray analysis revealed that 1,546 and 1,127 genes were regulated by leptin deficiency and leptin treatment, respectively. Among these, we identified 24 genes involved in intracellular vesicle-mediated transport in ob/ob mice. TBC1 domain family, member 1 (Tbc1d1), a negative regulator of GLUT4 translocation, was up-regulated (P = 0.001) in ob/ob mice as compared to wild types. Importantly, leptin treatment reduced the transcript levels of Tbc1d1 (P<0.001) and Tbc1d4 (P = 0.004) in the leptin-treated ob/ob as compared to pair-fed ob/ob animals. In addition, phosphorylation levels of TBC1D1 and TBC1D4 were enhanced in leptin-treated ob/ob as compared to control ob/ob (P = 0.015 and P = 0.023, respectively) and pair-fed ob/ob (P = 0.036 and P = 0.034, respectively) mice. Despite similar GLUT4 protein expression in wild type and ob/ob groups a different immunolocalization of this protein was evidenced in muscle sections. Leptin treatment increased GLUT4 immunoreactivity in gastrocnemius and extensor digitorum longus sections of leptin-treated ob/ob mice. Moreover, GLUT4 protein detected in immunoprecipitates from TBC1D4 was reduced by leptin replacement compared to control ob/ob (P = 0.013) and pair-fed ob/ob (P = 0.037) mice. Our findings suggest that leptin enhances the intracellular GLUT4 transport in skeletal muscle of ob/ob animals by reducing the expression and activity of the negative regulators of GLUT4 traffic TBC1D1 and TBC1D4.
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Affiliation(s)
- Neira Sáinz
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Amaia Rodríguez
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Victoria Catalán
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Sara Becerril
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Beatriz Ramírez
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Andoni Lancha
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Emma Burgos-Ramos
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Javier Gómez-Ambrosi
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
| | - Gema Frühbeck
- Metabolic Research Laboratory, Universidad de Navarra, Pamplona, Spain
- Department of Endocrinology and Nutrition, Clínica Universidad de Navarra, Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, Pamplona, Spain
- * E-mail:
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Pereira M, Vidotti DB, Borra RC, Simões MDJ, Da Silva IDCG, Haidar MA. Involvement of GDF-9, leptin, and IGF1 receptors associated with adipose tissue transplantation on fertility restoration in obese anovulatory mice. Gynecol Endocrinol 2011; 27:759-66. [PMID: 21557698 DOI: 10.3109/09513590.2010.534330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The aim was to analyze the effect of adipose tissue transplantation on growth differentiation factor-9 (GDF-9), insulin growth factor 1 receptor (IGF1R), and leptin receptor (LEPR) protein expression in ovaries of obese anovulatory mice. Leptin-deficient female (ob/ob) and wild-type mice were divided into untreated ob/ob mice and gonadal white adipose tissue transplanted ob/ob mice, with evaluation after 7, 15, and 45 days and compared to control wild-type mice. The corporal weight and glycemia levels increased in the obese group concomitant with polymicrocyst formation and abundant estrone, mimicking anovulatory disease. In the treated group after 45 days, glycemia, weight, ovarian size, and number of follicles were decreased and corpora lutea were decreased. The analysis of GDF-9 revealed that, whereas control ovaries presented follicular localization, the obese ovary lacked this protein. On the other hand, obese ovaries showed elevated expression of IGF1R that was normalized after the transplantation. Finally, LEPR was reduced in obese ovaries, and adipose tissue transplantation was efficient in returning it to normal levels. In conclusion, the adipose tissue transplantation, especially after 45 days, seems to stimulate ovulation, supported by the fact that several proteins involved in ovulation returned to basal levels.
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Affiliation(s)
- Melquíades Pereira
- Department of Gynecology, Federal University of São Paulo, São Paulo, Brazil
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de Luis DA, Aller R, Izaola O, Conde R, Gonzalez Sagrado M. The ratio of adiponectin to HOMA as an index of metabolic syndrome in obese women. ANNALS OF NUTRITION AND METABOLISM 2011; 58:301-6. [PMID: 21912107 DOI: 10.1159/000331216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 07/24/2011] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The aim of our study was to investigate the role of the ratio of adiponectin concentration to homeostasis model assessment insulin resistance (HOMA-IR) as a predictor of metabolic syndrome (MS) in obese subjects. METHODS We studied a population-based cross-sectional sample of 217 obese women. To estimate the prevalence of MS, the definitions of the Adult Treatment Panel III (ATP III) were considered. RESULTS The area under the curve (AUC) of the receiver-operating characteristic (ROC) curve for the detection of each MS component on the basis of the ratio of the serum adiponectin concentration to HOMA-IR (A/H ratio) was higher than that for the detection based on serum adiponectin concentration (for central obesity: 0.722 vs. 0.316, for increased triglycerides: 0.579 vs. 0.500, for increased blood pressure: 0.573 vs. 0.493, and for elevated fasting plasma glucose: 0.718 vs. 0.465). The AUC of the ROC curve for the detection of MS on the basis of the A/H ratio was higher than that for the detection based on serum adiponectin concentration (0.700 vs. 0.481). CONCLUSION The A/H ratio appears to provide a discriminatory marker for MS risk and some components of MS (central obesity, increased blood pressure and elevated fasting plasma glucose) in obese women.
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Affiliation(s)
- Daniel Antonio de Luis
- Center of Investigation of Endocrinology and Clinical Nutrition, Medicine School and Unit of Investigation, Hospital Rio Hortega, University of Valladolid, Valladolid, Spain.
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Petridou ET, Sergentanis TN, Antonopoulos CN, Dessypris N, Matsoukis IL, Aronis K, Efremidis A, Syrigos C, Mantzoros CS. Insulin resistance: an independent risk factor for lung cancer? Metabolism 2011; 60:1100-6. [PMID: 21251684 DOI: 10.1016/j.metabol.2010.12.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Revised: 12/03/2010] [Accepted: 12/08/2010] [Indexed: 12/15/2022]
Abstract
Insulin resistance is closely associated with numerous metabolic disorders. Although studies have supported the importance of insulin resistance in carcinogenesis, the existing data have not established its relevance in the context of lung cancer. The aim of the present case-control study was to evaluate the association between insulin resistance and lung cancer after adjusting for possible confounders. Homeostasis model assessment of insulin resistance (HOMA-IR) and serum leptin and adiponectin levels were determined in 81 lung cancer cases and 162 age- and sex-matched controls; anthropometric and lifestyle variables were recorded. Mean HOMA-IR in the cases was more than 2-fold higher compared with the mean value of controls (P < .001). Among controls, HOMA-IR correlated positively with serum leptin (r = 0.16; P = .04), body mass index (r = 0.43; P = .0001), and waist-to-hip ratio (r = 0.21; P = .01) but negatively with serum adiponectin (r = -0.29; P = .0002). As expected, smoking was associated with an approximately 10-fold increase in lung cancer risk in multiple logistic regression models. A positive association between HOMA-IR, treated as continuous variable, and lung cancer (odds ratio [OR] = 1.52, 95% confidence interval [CI]: 1.16-1.99, P = .002, model 1) was demonstrated, which persisted after adjustment for somatometric and lifestyle variables (OR = 2.36, 95% CI: 1.00-5.55, P = .05, model 2). When serum adiponectin was also taken into account, the association seemed fairly robust (OR = 2.58, 95% CI: 1.11-6.01, P = .03, model 3); on the contrary, when serum leptin was added, the association remained positive, but lost its statistical significance (OR = 1.76, 95% CI: 0.78-3.98, P = .17, model 4). In the fully adjusted model, HOMA-IR was still positively, but only marginally, associated with lung cancer risk (OR = 2.02, 95% CI: 0.88-4.65, P = .10, model 5). Insulin resistance may represent a meaningful risk factor for lung cancer.
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Affiliation(s)
- Eleni Th Petridou
- Department of Hygiene, Epidemiology and Medical Statistics, Athens University Medical School, 115 27 Athens, Greece.
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Verkest KR, Fleeman LM, Morton JM, Ishioka K, Rand JS. Compensation for obesity-induced insulin resistance in dogs: assessment of the effects of leptin, adiponectin, and glucagon-like peptide-1 using path analysis. Domest Anim Endocrinol 2011; 41:24-34. [PMID: 21474268 DOI: 10.1016/j.domaniend.2011.02.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/06/2011] [Accepted: 02/11/2011] [Indexed: 01/25/2023]
Abstract
The hormonal mediators of obesity-induced insulin resistance and compensatory hyperinsulinemia in dogs have not been identified. Plasma samples were obtained after a 24-h fast from 104 client-owned lean, overweight, and obese dogs. Plasma glucose and insulin concentrations were used to calculate insulin sensitivity and β-cell function with the use of the homeostasis model assessment (HOMA(insulin sensitivity) and HOMA(β-cell function), respectively). Path analysis with multivariable linear regression was used to identify whether fasting plasma leptin, adiponectin, or glucagon-like peptide-1 concentrations were associated with adiposity, insulin sensitivity, and basal insulin secretion. None of the dogs were hyperglycemic. In the final path model, adiposity was positively associated with leptin (P < 0.01) and glucagon-like peptide-1 (P = 0.04) concentrations. No significant total effect of adiposity on adiponectin in dogs (P = 0.24) was observed. If there is a direct effect of leptin on adiponectin, then our results indicate that this is a positive relationship, which at least partly counters a negative direct relationship between adiposity and adiponectin. Fasting plasma leptin concentration was directly negatively associated with fasting insulin sensitivity (P = 0.01) and positively associated with β-cell function (P < 0.01), but no direct association was observed between adiponectin concentration and either insulin sensitivity or β-cell function (P = 0.42 and 0.11, respectively). We conclude that dogs compensate effectively for obesity-induced insulin resistance. Fasting plasma leptin concentrations appear to be associated with obesity-associated changes in insulin sensitivity and compensatory hyperinsulinemia in naturally occurring obese dogs. Adiponectin does not appear to be involved in the pathophysiology of obesity-associated changes in insulin sensitivity.
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Affiliation(s)
- K R Verkest
- Centre for Companion Animal Health, School of Veterinary Science, The University of Queensland, Brisbane, Australia.
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71
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Maternal serum leptin concentration in gestational diabetes. Taiwan J Obstet Gynecol 2011; 50:149-53. [DOI: 10.1016/j.tjog.2011.01.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2010] [Indexed: 11/17/2022] Open
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72
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Mittendorfer B, Horowitz JF, DePaoli AM, McCamish MA, Patterson BW, Klein S. Recombinant human leptin treatment does not improve insulin action in obese subjects with type 2 diabetes. Diabetes 2011; 60:1474-7. [PMID: 21411512 PMCID: PMC3292320 DOI: 10.2337/db10-1302] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Leptin therapy improves insulin sensitivity in people with leptin deficiency, but it is not known whether it improves insulin action in people who are not leptin deficient. The purpose of the current study was to determine whether leptin treatment has weight loss-independent effects on insulin action in obese subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS We conducted a randomized, placebo-controlled trial in obese subjects (BMI: 35.4 ± 0.6 kg/m(2); mean ± SE) with newly diagnosed type 2 diabetes. Subjects were randomized to treatment with placebo (saline), low-dose (30 mg/day), or high-dose (80 mg/day) recombinant methionyl human (r-Met hu) leptin for 14 days. Multiorgan insulin sensitivity before and after treatment was evaluated by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled tracer infusions to measure glucose, glycerol, and fatty acid kinetics. RESULTS Low-dose and high-dose leptin treatment resulted in a threefold (P < 0.01) and 150-fold (P < 0.001) increase in basal plasma leptin concentrations, respectively. However, neither low-dose nor high-dose therapy had an effect on insulin-mediated suppression of glucose, glycerol, or palmitate rates of appearance into plasma compared with placebo. In addition, leptin treatment did not increase insulin-mediated stimulation of glucose disposal compared with placebo (14.3 ± 3.1, 18.4 ± 3.6, 16.7 ± 2.4 vs. 17.5 ± 2.5, 20.7 ± 3.0, 19.1 ± 3.3 μmol/kg body wt/min before vs. after treatment in the placebo, low-dose, and high-dose leptin groups, respectively). CONCLUSIONS r-Met hu leptin does not have weight loss-independent, clinically important effects on insulin sensitivity in obese people with type 2 diabetes.
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Affiliation(s)
- Bettina Mittendorfer
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jeffrey F. Horowitz
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, Missouri
| | | | | | - Bruce W. Patterson
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Samuel Klein
- Center for Human Nutrition and Atkins Center of Excellence in Obesity Medicine, Washington University School of Medicine, St. Louis, Missouri
- Corresponding author: Samuel Klein,
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Bonzón-Kulichenko E, Fernández-Agulló T, Moltó E, Serrano R, Fernández A, Ros M, Carrascosa JM, Arribas C, Martínez C, Andrés A, Gallardo N. Regulation of insulin-stimulated glucose uptake in rat white adipose tissue upon chronic central leptin infusion: effects on adiposity. Endocrinology 2011; 152:1366-77. [PMID: 21285320 DOI: 10.1210/en.2010-0858] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin enhances the glucose utilization in most insulin target tissues and paradoxically decreases it in white adipose tissue (WAT), but knowledge of the mechanisms underlying the inhibitory effect of central leptin on the insulin-dependent glucose uptake in WAT is limited. After 7 d intracerebroventricular leptin treatment (0.2 μg/d) of rats, the overall insulin sensitivity and the responsiveness of WAT after acute in vivo insulin administration were analyzed. We also performed unilateral WAT denervation to clarify the role of the autonomic nervous system in leptin effects on the insulin-stimulated [(3)H]-2-deoxyglucose transport in WAT. Central leptin improved the overall insulin sensitivity but decreased the in vivo insulin action in WAT, including insulin receptor autophosphorylation, insulin receptor substrate-1 tyrosine-phosphorylation, and Akt activation. In this tissue, insulin receptor substrate-1 and glucose transporter 4 mRNA and protein levels were down-regulated after central leptin treatment. Additionally, a remarkable up-regulation of resistin, together with an augmented expression of suppressor of cytokine signaling 3 in WAT, was also observed in leptin-treated rats. As a result, the insulin-stimulated glucose transporter 4 insertion at the plasma membrane and the glucose uptake in WAT were impaired in leptin-treated rats. Finally, denervation of WAT abolished the inhibitory effect of central leptin on glucose transport and decreased suppressor of cytokine signaling 3 and resistin levels in this tissue, suggesting that resistin, in an autocrine/paracrine manner, might be a mediator of central leptin antagonism of insulin action in WAT. We conclude that central leptin, inhibiting the insulin-stimulated glucose uptake in WAT, may regulate glucose availability for triacylglyceride formation and accumulation in this tissue, thereby contributing to the control of adiposity.
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Affiliation(s)
- Elena Bonzón-Kulichenko
- Area de Bioquímica, Facultad de Químicas, Regional Centre for Biomedical Research, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
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Begriche K, Massart J, Robin MA, Borgne-Sanchez A, Fromenty B. Drug-induced toxicity on mitochondria and lipid metabolism: mechanistic diversity and deleterious consequences for the liver. J Hepatol 2011; 54:773-94. [PMID: 21145849 DOI: 10.1016/j.jhep.2010.11.006] [Citation(s) in RCA: 349] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 11/05/2010] [Accepted: 11/09/2010] [Indexed: 02/08/2023]
Abstract
Numerous investigations have shown that mitochondrial dysfunction is a major mechanism of drug-induced liver injury, which involves the parent drug or a reactive metabolite generated through cytochromes P450. Depending of their nature and their severity, the mitochondrial alterations are able to induce mild to fulminant hepatic cytolysis and steatosis (lipid accumulation), which can have different clinical and pathological features. Microvesicular steatosis, a potentially severe liver lesion usually associated with liver failure and profound hypoglycemia, is due to a major inhibition of mitochondrial fatty acid oxidation (FAO). Macrovacuolar steatosis, a relatively benign liver lesion in the short term, can be induced not only by a moderate reduction of mitochondrial FAO but also by an increased hepatic de novo lipid synthesis and a decreased secretion of VLDL-associated triglycerides. Moreover, recent investigations suggest that some drugs could favor lipid deposition in the liver through primary alterations of white adipose tissue (WAT) homeostasis. If the treatment is not interrupted, steatosis can evolve toward steatohepatitis, which is characterized not only by lipid accumulation but also by necroinflammation and fibrosis. Although the mechanisms involved in this aggravation are not fully characterized, it appears that overproduction of reactive oxygen species by the damaged mitochondria could play a salient role. Numerous factors could favor drug-induced mitochondrial and metabolic toxicity, such as the structure of the parent molecule, genetic predispositions (in particular those involving mitochondrial enzymes), alcohol intoxication, hepatitis virus C infection, and obesity. In obese and diabetic patients, some drugs may induce acute liver injury more frequently while others may worsen the pre-existent steatosis (or steatohepatitis).
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Affiliation(s)
- Karima Begriche
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
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Burgos-Ramos E, Chowen JA, Arilla-Ferreiro E, Canelles S, Argente J, Barrios V. Chronic central leptin infusion modifies the response to acute central insulin injection by reducing the interaction of the insulin receptor with IRS2 and increasing its association with SOCS3. J Neurochem 2011; 117:175-85. [PMID: 21255014 DOI: 10.1111/j.1471-4159.2011.07191.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leptin and insulin have overlapping intracellular signaling mechanisms and exert anorexigenic actions in the hypothalamus. We aimed to determine how chronic exposure to increased leptin affects the hypothalamic response to a rise in insulin. We analyzed the activation and interactions of components of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in the hypothalamus of rats treated icv for 14 days with leptin followed by a central injection of insulin and killed 15 min later. Insulin increased glycemia and chronic leptin reduced this insulin induced rise in glucose. Leptin decreased the association between the insulin receptor beta chain (IRβ) and insulin receptor substrate 2 (IRS2), augmented the association between Janus kinase 2 and IRS2, increased levels of the catalytic subunit of PI3K and pAkt-Ser473 and decreased forkhead box O number 1 levels. Insulin reduced the association between suppressor of the cytokine signaling 3 and IRβ, increased IRβ-IRS2 association and pAkt-Thr308 levels, with chronic leptin exposure blunting these effects. In conclusion, chronic exposure to leptin decreases the central response to insulin by increasing suppressor of the cytokine signaling 3 association to IR, which inhibits insulin signaling at the level of interaction of its receptor with IRS2 and activates PI3K by promoting Janus kinase 2-IRS2 association. Thus, these results suggest that this mechanism could be a target for the treatment of insulin resistance.
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Affiliation(s)
- Emma Burgos-Ramos
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto Investigación Sanitaria Princesa, Madrid, Spain
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Ozen A, Furman A, Berber M, Karatepe HO, Mutlu N, Sarıçoban HE, Büyükgebiz B. The effect of Helicobacter pylori and economic status on growth parameters and leptin, ghrelin, and insulin-like growth factor (IGF)-I concentrations in children. Helicobacter 2011; 16:55-65. [PMID: 21241414 DOI: 10.1111/j.1523-5378.2010.00814.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND It was suggested that gastric colonization with Helicobacter pylori (H. pylori) was associated with suboptimal nutrition and growth in childhood. Furthermore, several studies indicated a relationship between H. pylori colonization and alterations in the circulating levels of growth-related molecules (GRM). Accordingly, in this study, we investigate the effect of H. pylori infection on GRMs and on the growth of healthy school children, taking into consideration the effect of their economic status (ES) and anthropometric indices of their parents. METHODS To acquire sociodemographic and anthropometric nutritional parameters and to detect H. pylori-specific serum IgG antibodies and growth-related molecules, we evaluated a total of 473 children attending four different primary and secondary schools in Istanbul. Subsequently, we assessed the effect of H. pylori on growth-related parameters (weight for age SDS, height for age SDS, BMI SDS, TSF, and waist-to-hip ratio) and on GRMs (leptin, ghrelin, and insulin-like growth factor-1 (IGF-1)), controlling for age, gender, family income, household crowding (HC), breastfeeding, maternal and paternal BMI SDS, and midparental height SDS with complex statistical models. RESULTS Of the 473 children (275 F/198 M, age 6-15 years; mean: 10.3 ± 0.1 years), 161 (34%) were H. pylori-positive. The prevalence of H. pylori was significantly higher in lower economic status (ES) groups, in children living in crowded houses, and in older age groups. Using simple statistical models, we did not find any significant associations between H. pylori infection and the growth parameters. However, in complex models for height for age SDS and for weight for age SDS, there was a significant interaction between H. pylori infection status and ES. Whereas in H. pylori-positive subjects, mid-income family children were both taller and heavier than the low-income group, there was no such an association in H. pylori-negative subjects. Among biochemical parameters, only ghrelin levels were associated with H. pylori infection in all models. Leptin levels were associated with HC in girls, whereas none of the parameters was significantly associated with leptin levels in boys. For IGF-1 levels, for boys, age and maternal BMI, and for girls, age and HC were significantly associated with IGF-1 levels. CONCLUSION We suggest that H. pylori may impair growth significantly only in susceptible children where unfavorable socioeconomic conditions facilitate its action, probably through mechanisms, at least in part, involving growth-related molecules.
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Affiliation(s)
- Ahmet Ozen
- Department of Pediatrics, Medical Faculty, Yeditepe University
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Huynh FK, Levi J, Denroche HC, Gray SL, Voshol PJ, Neumann UH, Speck M, Chua SC, Covey SD, Kieffer TJ. Disruption of hepatic leptin signaling protects mice from age- and diet-related glucose intolerance. Diabetes 2010; 59:3032-40. [PMID: 20876720 PMCID: PMC2992763 DOI: 10.2337/db10-0074] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The liver plays a critical role in integrating and controlling glucose metabolism. Thus, it is important that the liver receive and react to signals from other tissues regarding the nutrient status of the body. Leptin, which is produced and secreted from adipose tissue, is a hormone that relays information regarding the status of adipose depots to other parts of the body. Leptin has a profound influence on glucose metabolism, so we sought to determine if leptin may exert this effect in part through the liver. RESEARCH DESIGN AND METHODS To explore this possibility, we created mice that have disrupted hepatic leptin signaling using a Cre-lox approach and then investigated aspects of glucose metabolism in these animals. RESULTS The loss of hepatic leptin signaling did not alter body weight, body composition, or blood glucose levels in the mild fasting or random-fed state. However, mice with ablated hepatic leptin signaling had increased lipid accumulation in the liver. Further, as male mice aged or were fed a high-fat diet, the loss of hepatic leptin signaling protected the mice from glucose intolerance. Moreover, the mice displayed increased liver insulin sensitivity and a trend toward enhanced glucose-stimulated plasma insulin levels. Consistent with increased insulin sensitivity, mice with ablated hepatic leptin signaling had increased insulin-stimulated phosphorylation of Akt in the liver. CONCLUSIONS These data reveal that unlike a complete deficiency of leptin action, which results in impaired glucose homeostasis, disruption of leptin action in the liver alone increases hepatic insulin sensitivity and protects against age- and diet-related glucose intolerance. Thus, leptin appears to act as a negative regulator of insulin action in the liver.
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Affiliation(s)
- Frank K. Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jasna Levi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Heather C. Denroche
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sarah L. Gray
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter J. Voshol
- Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Cambridge, U.K
| | - Ursula H. Neumann
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Madeleine Speck
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Streamson C. Chua
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, New York, New York
| | - Scott D. Covey
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding authors: Scott D. Covey, , and Timothy J. Kieffer,
| | - Timothy J. Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding authors: Scott D. Covey, , and Timothy J. Kieffer,
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78
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Varga O, Harangi M, Olsson IAS, Hansen AK. Contribution of animal models to the understanding of the metabolic syndrome: a systematic overview. Obes Rev 2010; 11:792-807. [PMID: 19845867 DOI: 10.1111/j.1467-789x.2009.00667.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The metabolic syndrome (MetS) is one of the most important challenges to public health and biomedical research. Animal models of MetS, such as leptin-deficient obese mice, obese spontaneously hypertensive rats, JCR: LA-cp rats and the Ossabaw and Göttingen minipigs, have contributed to our understanding of the pathophysiological basis and the development of novel therapies. For a complex disease syndrome, no animal model can be expected to serve all needs of research. Although each animal model has limitations and strengths, used together in a complementary fashion, they are essential for research on the MetS and for rapid progress in understanding the aetiology and pathogenesis towards a cure. The purpose of this review is to assess how current animal models contributed to our knowledge of the human MetS, and to systematically evaluate the strengths and weaknesses of the currently available 78 animal models from 11 species.
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Affiliation(s)
- O Varga
- Laboratory Animal Science group, Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal.
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79
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Sakurai H, Katoh A, Kiss T, Jakusch T, Hattori M. Metallo-allixinate complexes with anti-diabetic and anti-metabolic syndrome activities. Metallomics 2010; 2:670-82. [PMID: 21072358 DOI: 10.1039/c0mt00025f] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Metabolic syndrome and the accompanied diabetes mellitus are both important diseases worldwide due to changes of lifestyle and eating habits. The number of patients with diabetes worldwide is estimated to increase to 300 million by 2025 from 150-220 million in 2010. There are two main types of diabetes. In type 1 diabetes, caused by destruction of pancreatic β-cells resulting in absolute deficiency of intrinsic insulin secretion, the patients require exogenous insulin injections several times a day. In type 2 diabetes, characterized by insulin resistance and abnormal insulin secretion, the patients need exercise, diet control and/or several types of hypoglycemics. The idea of using metal ions for the treatment of diabetes originates from the report in 1899. The research on the role of metal ions that may contribute to the improvement of diabetes began. The orally active metal complexes containing vanadyl (oxidovanadium(iv)) ion and cysteine or other ligands were first proposed in 1990, and a wide class of vanadium, copper and zinc complexes was found to be effective for treating diabetes in experimental animals. We noticed a characteristic compound, allixin, which is a non-sulfur component in dry garlic. Its vanadyl and zinc complexes improved both types of diabetes following oral administration in diabetic animals. We then developed a new zinc complex with thioxoallixin-N-methyl (tanm), which is both a sulfur and N-methyl derivative of allixin, and found that this complex improves not only diabetes but also metabolic syndrome. Furthermore, new zinc complexes inspired from the zinc-tanm were prepared; one of them exceeded the activity of zinc-tanm. The mechanism of such complexes was studied in adipocytes. We describe here the usefulness of the development of metal-based complexes in the context of potential therapeutic application for diabetes and metabolic syndrome.
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Affiliation(s)
- Hiromu Sakurai
- Department of Pharmaco-analytical and Biocoordination Chemistry, Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, 3500-3 Minami-Tamagaki-cho, Suzuka, Mie, Japan.
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80
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Temporal analysis of mechanisms leading to stimulation of glucose uptake in skeletal muscle cells by an adipokine mixture derived from primary rat adipocytes. Int J Obes (Lond) 2010; 35:355-63. [PMID: 20697414 DOI: 10.1038/ijo.2010.160] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The direct effects of adipokines on skeletal muscle metabolism have been well established. As the combinatorial effects of adipokine mixtures are likely to be of more physiological relevance, we used a coculture system of primary rat adipocytes and L6 skeletal muscle cells to examine the effects of adiponectin derived from primary rat adipocytes on rat skeletal muscle cells. RESULTS We showed that coculture with adipocytes stimulated glucose uptake in L6 cells within 30 min and this correlated with an increase of glucose transporter isoform 4 (GLUT4) localization to the plasma membrane. These effects were dependent on the reorganization of the actin cytoskeleton, demonstrated by rhodamine-labeled phalloidin immunofluorescence, as cytochalasin D attenuated the glucose uptake induced by adipocyte-conditioned media. Temporal analysis revealed that enhanced glucose uptake was maintained after 24 h of coculture, and this was attributed to an increase in both GLUT1 expression and the cell surface content of GLUT4. We established a role for adiponectin in mediating these effects as antibody-mediated neutralization attenuated the metabolic effects of adipocyte-conditioned media. Furthermore, compound C blocked these effects, suggesting an important role for AMPK. Importantly, when we compared the effects of full-length recombinant adiponectin with adipocyte-conditioned media, we confirmed that recombinant adiponectin was unable to stimulate glucose uptake in L6 cells despite having an important role in adipocyte-conditioned media. CONCLUSIONS Our results demonstrate the importance of examining the effects of adipokines in the context of physiologically relevant mixtures to accurately determine their metabolic effects on skeletal muscle.
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81
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He L, Pan Y, He G, Lin B, Liao CC, Zuo X, Yuan L. Structural and functional studies of leptins from hibernating and non-hibernating bats. Gen Comp Endocrinol 2010; 168:29-35. [PMID: 20394750 DOI: 10.1016/j.ygcen.2010.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/16/2010] [Accepted: 04/06/2010] [Indexed: 12/30/2022]
Abstract
Leptin, a 16-kDa hormone produced by mature adipocytes, has been shown to regulate the hibernation of mammals. In this study, the leptin gene sequences of both hibernating (Rhinolophus ferrumequinum) and non-hibernating (Rousettus leschenaultii) bats were determined, and the leptin proteins from these two different species of bats were expressed in Escherichia coli for the first time. Results showed that the amino acid sequence of the leptin protein from hibernating bats had a lower degree of identity than that from non-hibernating bats to those of several non-hibernating mammals. The leptin protein of hibernating bats had a stronger growth inhibitory effect on 3T3-L1 cells than that of non-hibernating bats. Structural modeling revealed that the structures of the receptor binding site III, which is critical for signal transduction, of the two bat leptins were very different. Similar to the human leptin, the leptin protein of non-hibernating bats was predicted to have a random loop, whereas that of hibernating bats had a helical structure in this region. This observation provided a clue as to the differential effects of the two different leptins on 3T3-L1 cells.
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Affiliation(s)
- Lingjiang He
- School of Life Sciences, East China Normal University, Shanghai 200062, China
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82
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Effects of three antidiabetics on insulin and leptin in Chinese type 2 diabetes. Diabetes Metab Syndr 2010. [DOI: 10.1016/j.dsx.2009.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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83
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Sun Q, van Dam RM, Meigs JB, Franco OH, Mantzoros CS, Hu FB. Leptin and soluble leptin receptor levels in plasma and risk of type 2 diabetes in U.S. women: a prospective study. Diabetes 2010; 59:611-8. [PMID: 19959759 PMCID: PMC2828671 DOI: 10.2337/db09-1343] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE We prospectively examined plasma levels of leptin and soluble leptin receptor (sOB-R), as well as their interactions with other diabetes risk factors, in relation to type 2 diabetes to elucidate the complex relation between these two biomarkers and diabetes risk. RESEARCH DESIGN AND METHODS Of 32,826 Nurses' Health Study participants who provided blood samples during 1989-1990, 1,054 incident case subjects of type 2 diabetes were identified and confirmed during 1990-2004 and 1,254 matched control subjects were selected. Plasma leptin and sOB-R levels were measured among these participants. RESULTS After multivariate adjustment for BMI, lifestyle practices, and dietary factors, sOB-R levels were significantly associated with a lower risk of type 2 diabetes. In comparison with women in the lowest quintile, the ORs (95% CI) of developing type 2 diabetes were 0.73 (0.55-0.96), 0.51 (0.38-0.68), 0.42 (0.31-0.57), and 0.39 (0.28-0.54; P for trend < 0.0001) for women in the second to fifth quintiles of sOB-R levels, respectively. In contrast, plasma leptin levels were not significantly associated with the risk of type 2 diabetes: The OR (95% CI) was 0.82 (0.62-1.10; P for trend = 0.46) comparing the highest with the lowest quintile of leptin levels. sOB-R levels were consistently associated with a decreased risk of type 2 diabetes at various levels of leptin or high-molecular-weight adiponectin. CONCLUSIONS These data suggest a strong inverse association between plasma sOB-R levels and risk of type 2 diabetes, independent of BMI, leptin, and adiponectin levels.
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Affiliation(s)
- Qi Sun
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.
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84
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Saha TK, Yoshikawa Y, Sakurai H. Improvement of hyperglycaemia and metabolic syndromes in type 2 diabetic KKAy mice by oral treatment with [meso-tetrakis(4-sulfonatophenyl) porphyrinato]oxovanadium(IV)(4-) complex. J Pharm Pharmacol 2010; 59:437-44. [PMID: 17331348 DOI: 10.1211/jpp.59.3.0014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Recently, we reported that [meso-tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadium(IV)(4-), VO(tpps), shows in-vitro insulin-mimetic and in-vivo anti-diabetic activity in streptozotocin (STZ)-induced type 1 diabetic mice. This result prompted us to examine its ability in type 2 diabetic model KKAy mice with insulin resistance. We studied the in-vivo anti-diabetic activity of VO(tpps), compared with that of vanadium(IV) oxide sulfate, VS, as control. Both compounds were orally administered at doses of 5–10 mg (0.1-0.2 mmol) V/kg body weight to the KKAy mice for 28 days. VO(tpps) normalized the hyperglycaemia within 15 days, while VS lowered the blood glucose concentration only by a small degree. In addition, metabolic syndromes characterized by insulin and leptin resistance were significantly improved in VO(tpps)-treated KKAy mice compared with those treated with VS. The improvement in diabetes was validated by oral glucose tolerance test and decrease in HbA1c concentration. Based on these observations, VO(tpps) is proposed to be an orally active oxovanadium(IV)-porphyrin complex for treating not only type 2 diabetes but also metabolic syndromes in animals.
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Affiliation(s)
- Tapan Kumar Saha
- Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
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85
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Lang K, Ratke J. Leptin and Adiponectin: new players in the field of tumor cell and leukocyte migration. Cell Commun Signal 2009; 7:27. [PMID: 20030801 PMCID: PMC2804604 DOI: 10.1186/1478-811x-7-27] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 12/23/2009] [Indexed: 01/27/2023] Open
Abstract
Adipose tissue is no longer considered to be solely an energy storage, but exerts important endocrine functions, which are primarily mediated by a network of various soluble factors derived from fat cells, called adipocytokines. In addition to their responsibility to influence energy homeostasis, new studies have identified important pathways linking metabolism with the immune system, and demonstrating a modulatory role of adipocytokines in immune function. Additionally, epidemiological studies underline that obesity represents a significant risk factor for the development of cancer, although the exact mechanism of this relationship remains to be determined. Whereas a possible influence of adipocytokines on the proliferation of tumor cells is already known, new evidence has come to light elucidating a modulatory role of this signaling substances in the regulation of migration of leukocytes and tumor cells. The migration of leukocytes is a key feature to fight cancer cells, whereas the locomotion of tumor cells is a prerequisite for tumor formation and metastasis. We herein review the latest tumor biological findings on the role of the most prominent adipocytokines leptin and adiponectin, which are secreted by fat cells, and which are involved in leukocyte migration, tumor growth, invasion and metastasis. This review thus accentuates the complex, interactive involvement of adipocytokines in the regulation of migration of both leukocytes and tumor cells, and gives an insight in the underlying molecular mechanisms.
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Affiliation(s)
- Kerstin Lang
- Institute of Immunology, Witten/Herdecke University, Stockumer Str. 10, 58448 Witten, Germany
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86
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Mehebik-Mojaat N, Ribière C, Niang F, Forest C, Jaubert AM. Leptin and insulin induce mutual resistance for nitric oxide synthase III activation in adipocytes. J Cell Biochem 2009; 108:982-8. [DOI: 10.1002/jcb.22331] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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87
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Hoffler U, Hobbie K, Wilson R, Bai R, Rahman A, Malarkey D, Travlos G, Ghanayem BI. Diet-induced obesity is associated with hyperleptinemia, hyperinsulinemia, hepatic steatosis, and glomerulopathy in C57Bl/6J mice. Endocrine 2009; 36:311-25. [PMID: 19669948 PMCID: PMC4219357 DOI: 10.1007/s12020-009-9224-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 04/23/2009] [Accepted: 07/03/2009] [Indexed: 01/03/2023]
Abstract
Obesity and obesity-related illnesses are global epidemics impacting the health of adults and children. The purpose of the present work is to evaluate a genetically intact obese mouse model that more accurately reflects the impact of aging on diet-induced obesity and type 2 diabetes in humans. Male C57Bl/6J mice consumed either a control diet or one in which 60% kcal were due to lard beginning at 5-6 weeks of age. Body weight and fat measurements were obtained and necropsy performed at 15, 20, 30, and 40 weeks of age. Serum chemistry, histopathology, gene expression of the liver, and renal and hepatic function were also evaluated. In concert with significant increases in percent body fat and weight, mice fed the high-fat versus control diet had significantly increased levels of serum cholesterol. At ages 20 and 30 weeks, serum glucose was significantly higher in obese versus controls, while serum insulin levels were >/=4-fold higher in obese mice at ages 30 and 40 weeks. The effect of age exacerbated the effects of consuming a high-fat diet. In addition to being hyperinsulinemic and leptin resistant, older obese mice exhibited elevated hepatic PAI-1 and downregulation of GLUT4, G6PC, IGFBP-1, and leptin receptor mRNA in the liver, steatosis with subsequent inflammation, glomerular mesangial proliferation, elevated serum ALT, AST, and BUN, and increased numbers of pancreatic islets.
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Affiliation(s)
- Undi Hoffler
- Laboratory of Pharmacology, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
- To whom correspondence should be addressed Undi Hoffler Laboratory of Pharmacology National Institutes of Health National Institute of Environmental Health Sciences RTP, NC 27709 (919) 541-0427
| | | | - Ralph Wilson
- Cellular and Molecular Pathology Branch, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - Re Bai
- Laboratory of Pharmacology, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - Akef Rahman
- Laboratory of Pharmacology, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - David Malarkey
- Cellular and Molecular Pathology Branch, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - Greg Travlos
- Cellular and Molecular Pathology Branch, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
| | - Burhan I Ghanayem
- Laboratory of Pharmacology, National Institutes of Health, National Institute of Environmental Health Sciences, National Institutes of Health, RTP, NC
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88
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Fang X, Fetros J, Dadson KE, Xu A, Sweeney G. Leptin prevents the metabolic effects of adiponectin in L6 myotubes. Diabetologia 2009; 52:2190-200. [PMID: 19636528 DOI: 10.1007/s00125-009-1462-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Accepted: 06/22/2009] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS Adiponectin and leptin are negatively and positively correlated with human obesity respectively, and have both been shown to regulate energy metabolism in skeletal muscle. However, little is known about their signalling and functional crosstalk. Here we investigated the effects of leptin on metabolic actions of (1) globular adiponectin (gAd) and (2) full-length adiponectin (fAd) in L6 cells. METHODS Glucose uptake was measured upon gAd and fAd treatment after incubation with different doses (0.3, 0.6, 3, 6, 60 nmol/l) of leptin for 6, 12 and 24 h. We also measured adiponectin receptor (ADIPOR) expression and stimulation of downstream signalling by gAd and fAd using co-immunoprecipitation and western blotting following leptin pretreatment, as well as analysis of fatty acid uptake and oxidation using radiolabelled tracers. RESULTS Leptin attenuated the stimulation of glucose uptake by gAd and fAd in a dose- and time-dependent manner, a finding correlated with decreased levels of ADIPOR1 and ADIPOR2. gAd and fAd increased palmitate uptake via activation of AMP protein kinase (T172), enhanced expression of the fatty acid transporter CD36, phosphorylated acetyl-CoA carboxylase (S79) and enhanced palmitate oxidation, all of which were attenuated by leptin pretreatment. Adiponectin can also enhance insulin sensitivity via direct signalling crosstalk; here we show that enhanced insulin-stimulated IRS-1 (Y612) and Akt (T308) phosphorylation in response to fAd was attenuated by leptin. APPL1 was recently identified as a critical mediator of adiponectin action in skeletal muscle. We demonstrated that leptin attenuated binding of APPL1 to LKB1, a downstream target leading to AMPK phosphorylation. CONCLUSIONS/INTERPRETATION The direct metabolic and insulin-sensitising effects of adiponectin were attenuated in the presence of leptin.
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Affiliation(s)
- X Fang
- Department of Biology, York University, Toronto, ON, Canada
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89
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Lusby AL, Kirk CA, Bartges JW. The role of key adipokines in obesity and insulin resistance in cats. J Am Vet Med Assoc 2009; 235:518-22. [DOI: 10.2460/javma.235.5.518] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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90
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Mostad IL, Qvigstad E, Bjerve KS, Grill VE. Effects of a 3‐day low‐fat diet on metabolic control, insulin sensitivity, lipids and adipocyte hormones in Norwegian subjects with hypertriacylglycerolaemia and type 2 diabetes. Scandinavian Journal of Clinical and Laboratory Investigation 2009; 64:565-74. [PMID: 15370462 DOI: 10.1080/00365510410007053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The metabolic and hormonal impact of rapid dietary changes in type 2 diabetes has not been clarified. The objective of this study was to test whether a short-term, low-fat diet affected metabolic control, insulin sensitivity, lipids and adipocyte hormones in patients with type 2 diabetes with hypertriacylglycerolaemia. Nineteen outpatient subjects (10 M, 9 F) with type 2 diabetes and triacylglycerols >2.2 mmol/L at screening were included in the study. Dietary intake was assessed by weighing during two periods of 3-day baseline diet followed by a 3-day low-fat dietary intervention. The two periods of baseline diet did not differ with respect to relevant variables during intervention. Subjects were advised to increase fibre-rich and low-fat foods and to decrease intake of visible fat in an isoenergetic manner. The percentage of energy from fat was reduced from 39 to 22 (p < 0.0001), median values. Daytime blood glucose did not change and fasting insulin and fasting glucose to insulin ratios were unaffected. Total cholesterol decreased from 6.3 to 6.2 mmol/L (p < 0.005), high-density lipoprotein cholesterol from 1.13 to 1.10 mmol/L (p < 0.048) and the ratio of n-6 to n-3 fatty acids in phospholipids from 2.5 to 1.9 (p < 0.003). Concentrations of leptin decreased from 12.1 to 9.9 ng/mL (p < 0.005) and adiponectin increased from 8.6 to 10.5 microg/mL (p < 0.024). The effect on leptin was confined to women. A low-fat diet intervention for 3 days in insulin-resistant type 2 diabetes affects lipid, adiponectin and leptin levels but fails to improve insulin sensitivity and metabolic control.
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Affiliation(s)
- I L Mostad
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine Norwegian University of Science and Technology, Trondheim, Norway.
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91
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Lu G, Thomas-Geevarghese A, Anuurad E, Raghavan S, Minolfo R, Ormsby B, Karmally W, El-Sadr WM, Albu J, Berglund L. Relationship of postprandial nonesterified fatty acids, adipokines, and insulin across gender in human immunodeficiency virus-positive patients undergoing highly active antiretroviral therapy. Metab Syndr Relat Disord 2009; 7:199-204. [PMID: 19320559 DOI: 10.1089/met.2008.0066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Metabolic derangements are common in human immunodeficiency virus (HIV)-positive subjects undergoing antiretroviral therapy, but little is known about postprandial conditions. METHODS We investigated the relationship between leptin, adiponectin, nonesterified fatty acids (NEFA), and insulin in response to a day-long meal pattern and evaluated gender differences in HIV-positive men (n = 12) and women (n = 13) undergoing highly active antiretroviral therapy (HAART). RESULTS For both men and women, a significant decrease in postprandial NEFA levels was observed following breakfast (0.53 vs. 0.22 mmol/L, P < 0.001, baseline and at 3 hours, respectively), whereas day-long postprandial leptin and adiponectin levels showed small nonsignificant oscillations. In contrast to NEFA and adiponectin, postprandial leptin levels were significantly higher among women compared to men (P < 0.05). Postprandial NEFA levels correlated positively with fasting insulin levels (r(2) = 0.25, P = 0.016), and the postbreakfast decrease in NEFA levels correlated significantly with the postbreakfast increase in insulin levels (r(2) = 0.17, P = 0.038). No significant association between postprandial adipokines and insulin was observed. CONCLUSIONS In HAART-treated, HIV-infected men and women, levels of NEFA, but not adipokines, showed significant postprandial variation. Furthermore, food intake resulted in significant NEFA suppression in proportion to the food-stimulated insulin increase.
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Affiliation(s)
- Guijing Lu
- Department of Medicine, University of California Davis, Sacramento, California 95817, USA
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92
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Delibegovic M, Zimmer D, Kauffman C, Rak K, Hong EG, Cho YR, Kim JK, Kahn BB, Neel BG, Bence KK. Liver-specific deletion of protein-tyrosine phosphatase 1B (PTP1B) improves metabolic syndrome and attenuates diet-induced endoplasmic reticulum stress. Diabetes 2009; 58:590-9. [PMID: 19074988 PMCID: PMC2646057 DOI: 10.2337/db08-0913] [Citation(s) in RCA: 210] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The protein tyrosine phosphatase PTP1B is a negative regulator of insulin signaling; consequently, mice deficient in PTP1B are hypersensitive to insulin. Because PTP1B(-/-) mice have diminished fat stores, the extent to which PTP1B directly regulates glucose homeostasis is unclear. Previously, we showed that brain-specific PTP1B(-/-) mice are protected against high-fat diet-induced obesity and glucose intolerance, whereas muscle-specific PTP1B(-/-) mice have increased insulin sensitivity independent of changes in adiposity. Here we studied the role of liver PTP1B in glucose homeostasis and lipid metabolism. RESEARCH DESIGN AND METHODS We analyzed body mass/adiposity, insulin sensitivity, glucose tolerance, and lipid metabolism in liver-specific PTP1B(-/-) and PTP1Bfl/fl control mice, fed a chow or high-fat diet. RESULTS Compared with normal littermates, liver-specific PTP1B(-/-) mice exhibit improved glucose homeostasis and lipid profiles, independent of changes in adiposity. Liver-specific PTP1B(-/-) mice have increased hepatic insulin signaling, decreased expression of gluconeogenic genes PEPCK and G-6-Pase, enhanced insulin-induced suppression of hepatic glucose production, and improved glucose tolerance. Liver-specific PTP1B(-/-) mice exhibit decreased triglyceride and cholesterol levels and diminished expression of lipogenic genes SREBPs, FAS, and ACC. Liver-specific PTP1B deletion also protects against high-fat diet-induced endoplasmic reticulum stress response in vivo, as evidenced by decreased phosphorylation of p38MAPK, JNK, PERK, and eIF2alpha and lower expression of the transcription factors C/EBP homologous protein and spliced X box-binding protein 1. CONCLUSIONS Liver PTP1B plays an important role in glucose and lipid metabolism, independent of alterations in adiposity. Inhibition of PTP1B in peripheral tissues may be useful for the treatment of metabolic syndrome and reduction of cardiovascular risk in addition to diabetes.
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Affiliation(s)
- Mirela Delibegovic
- Cancer Biology Program, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.
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93
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Mohiti J, Talebi F, Afkhami-Ardekani M. Circulation free leptin in diabetic patients and its correlation to insulin level. Pak J Biol Sci 2009; 12:397-400. [PMID: 19579977 DOI: 10.3923/pjbs.2009.397.400] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Present researchers studied the relation between insulin with free and total leptin in type 2 diabetic patients. Thirty non insulin dependent diabetic obese patients (age: 50 +/- 12 year and BMI>30 kg m(-2)) and thirty non insulin dependent diabetic non obese patients (age: 49 +/- 25 year and BMI<25 kg m(-2)) were studied. Free leptin was purified by Gel filtration Chromatography and the fractions were collected and then their free leptin was measured by a high sensitive ELISA Kit. Circulation total leptin and insulin were measured by ELISA. Circulation free and total leptin were significantly correlated to insulin (p < 0.005). Free leptin concentrations were higher in women than in men (p < 0.001). Ratio of free leptin to total in obese subjects is more than non-obese subjects (0.27 +/- 0.1 vs. 0.03 +/- 0.04, p < 0.001). Ratio of free to total leptin showed a positive correlations with insulin (r = 0.58, p < 0.001) insulin resistance (r = 31, p < 0.015) and BMI (r = 0.86, p < 0.001). The majority of leptin which circulates in obese individuals was free form. Presumably it is bioactive portion of hormone and thus obese subjects are resistant to free leptin. These observations are consistent with the view that free leptin levels in diabetes patients attributed to changes in serum insulin level and insulin resistant.
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Affiliation(s)
- J Mohiti
- Yazd Diabetes Research Center, Shahid Sadoughi University of Medical Science, Yazd, Iran
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94
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Miyazaki M, Sampath H, Liu X, Flowers MT, Chu K, Dobrzyn A, Ntambi JM. Stearoyl-CoA desaturase-1 deficiency attenuates obesity and insulin resistance in leptin-resistant obese mice. Biochem Biophys Res Commun 2009; 380:818-22. [PMID: 19338759 DOI: 10.1016/j.bbrc.2009.01.183] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 01/26/2009] [Indexed: 12/31/2022]
Abstract
Obesity and adiposity greatly increase the risk for secondary conditions such as insulin resistance. Mice deficient in the enzyme stearoyl-CoA desaturase-1 (SCD1) are lean and protected from diet-induced obesity and insulin resistance. In order to determine the effect of SCD1 deficiency on various mouse models of obesity, we introduced a global deletion of the Scd1 gene into leptin-deficient ob/ob mice, leptin-resistant Agouti (A(y)/a) mice, and high-fat diet-fed obese (DIO) mice. SCD1 deficiency lowered body weight, adiposity, hepatic lipid accumulation, and hepatic lipogenic gene expression in all three mouse models. However, glucose tolerance, insulin, and leptin sensitivity were improved by SCD1 deficiency only in A(y)/a and DIO mice, but not ob/ob mice. These data uncouple the effects of SCD1 deficiency on weight loss from those on insulin sensitivity and suggest a beneficial effect of SCD1 inhibition on insulin sensitivity in obese mice that express a functional leptin gene.
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Affiliation(s)
- Makoto Miyazaki
- Department of Biochemistry, University of Wisconsin-Madison, 433, Babcock Drive, Madison, WI 53706, USA
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95
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Lehrke M, Broedl UC, Biller-Friedmann IM, Vogeser M, Henschel V, Nassau K, Göke B, Kilger E, Parhofer KG. Serum concentrations of cortisol, interleukin 6, leptin and adiponectin predict stress induced insulin resistance in acute inflammatory reactions. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 12:R157. [PMID: 19087258 PMCID: PMC2646322 DOI: 10.1186/cc7152] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 11/08/2008] [Accepted: 12/17/2008] [Indexed: 01/04/2023]
Abstract
Introduction Inflammatory stimuli are causative for insulin resistance in obesity as well as in acute inflammatory reactions. Ongoing research has identified a variety of secreted proteins that are released from immune cells and adipocytes as mediators of insulin resistance; however, knowledge about their relevance for acute inflammatory insulin resistance remains limited. In this study we aimed for a clarification of the relevance of different insulin resistance mediating factors in an acute inflammatory situation. Methods Insulin resistance was measured in a cohort of 37 non-diabetic patients undergoing cardiac surgery by assessment of insulin requirement to maintain euglycaemia and repeated measurements of an insulin glycaemic index. The kinetics of cortisol, interleukin 6 (IL6), tumour necrosis factor α (TNFα), resistin, leptin and adiponectin were assessed by repeated measurements in a period of 48 h. Results Insulin resistance increased during the observation period and peaked 22 h after the beginning of the operation. IL6 and TNFα displayed an early increase with peak concentrations at the 4-h time point. Serum levels of cortisol, resistin and leptin increased more slowly and peaked at the 22-h time point, while adiponectin declined, reaching a base at the 22-h time point. Model assessment identified cortisol as the best predictor of insulin resistance, followed by IL6, leptin and adiponectin. No additional information was gained by modelling for TNFα, resistin, catecholamine infusion rate, sex, age, body mass index (BMI), operation time or medication. Conclusions Serum cortisol levels are the best predictor for inflammatory insulin resistance followed by IL6, leptin and adiponectin. TNFα, and resistin have minor relevance as predictors of stress dependent insulin resistance.
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Affiliation(s)
- Michael Lehrke
- Department of Internal Medicine II, University of Munich, Grosshadern Campus, Marchioninistr 15, 81377 Munich, Germany.
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96
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Paz-Filho G, Esposito K, Hurwitz B, Sharma A, Dong C, Andreev V, Delibasi T, Erol H, Ayala A, Wong ML, Licinio J. Changes in insulin sensitivity during leptin replacement therapy in leptin-deficient patients. Am J Physiol Endocrinol Metab 2008; 295:E1401-8. [PMID: 18854428 PMCID: PMC2652497 DOI: 10.1152/ajpendo.90450.2008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leptin replacement rescues the phenotype of morbid obesity and hypogonadism in leptin-deficient adults. However, leptin's effects on insulin resistance are not well understood. Our objective was to evaluate the effects of leptin on insulin resistance. Three leptin-deficient adults (male, 32 yr old, BMI 23.5 kg/m(2); female, 42 yr old, BMI 25.1 kg/m(2); female, 46 yr old, BMI 31.7 kg/m(2)) with a missense mutation of the leptin gene were evaluated during treatment with recombinant methionyl human leptin (r-metHuLeptin). Insulin resistance was determined by euglycemic hyperinsulinemic clamps and by oral glucose tolerance tests (OGTTs), whereas patients were on r-metHuLeptin and after treatment was interrupted for 2-4 wk in the 4th, 5th, and 6th years of treatment. At baseline, all patients had normal insulin levels, C-peptide, and homeostatic model assessment of insulin resistance index, except for one female diagnosed with type 2 diabetes. The glucose infusion rate was significantly lower with r-metHuLeptin (12.03 +/- 3.27 vs. 8.16 +/- 2.77 mg.kg(-1).min(-1), P = 0.0016) but did not differ in the 4th, 5th, and 6th years of treatment when all results were analyzed by a mixed model [F(1,4) = 0.57 and P = 0.5951]. The female patient with type 2 diabetes became euglycemic after treatment with r-metHuLeptin and subsequent weight loss. The OGTT suggested that two patients showed decreased insulin resistance while off treatment. During an off-leptin OGTT, one of the patients developed a moderate hypoglycemic reaction attributed to increased posthepatic insulin delivery and sensitivity. We conclude that, in leptin-deficient adults, the interruption of r-metHuLeptin decreases insulin resistance in the context of rapid weight gain. Our results suggest that hyperleptinemia may contribute to mediate the increased insulin resistance of obesity.
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Affiliation(s)
- Gilberto Paz-Filho
- Dept. of Psychiatry & Behavioral Sciences, Univ. of Miami Miller School of Medicine, Miami, FL 33136, USA
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Alarcon-Aguilar FJ, Almanza-Perez J, Blancas G, Angeles S, Garcia-Macedo R, Roman R, Cruz M. Glycine regulates the production of pro-inflammatory cytokines in lean and monosodium glutamate-obese mice. Eur J Pharmacol 2008; 599:152-8. [PMID: 18930730 DOI: 10.1016/j.ejphar.2008.09.047] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 09/10/2008] [Accepted: 09/25/2008] [Indexed: 12/22/2022]
Abstract
Fat tissue plays an important role in the regulation of inflammatory processes. Increased visceral fat has been associated with a higher production of cytokines that triggers a low-grade inflammatory response, which eventually may contribute to the development of insulin resistance. In the present study, we investigated whether glycine, an amino acid that represses the expression in vitro of pro-inflammatory cytokines in Kupffer and 3T3-L1 cells, can affect in vivo cytokine production in lean and monosodium glutamate-induced obese mice (MSG/Ob mice). Our data demonstrate that glycine treatment in lean mice suppressed TNF-alpha transcriptional expression in fat tissue, and serum protein levels of IL-6 were suppressed, while adiponectin levels were increased. In MSG/Ob mice, glycine suppressed TNF-alpha and IL-6 gene expression in fat tissue and significantly reduced protein levels of IL-6, resistin and leptin. To determine the role of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) in the modulation of this inflammatory response evoked by glycine, we examined its expression levels in fat tissue. Glycine clearly increased PPAR-gamma expression in lean mice but not in MSG/Ob mice. Finally, to identify alterations in glucose metabolism by glycine, we also examined insulin levels and other biochemical parameters during an oral glucose tolerance test. Glycine significantly reduced glucose tolerance and raised insulin levels in lean but not in obese mice. In conclusion, our findings suggest that glycine suppresses the pro-inflammatory cytokines production and increases adiponectin secretion in vivo through the activation of PPAR-gamma. Glycine might prevent insulin resistance and associated inflammatory diseases.
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Affiliation(s)
- F J Alarcon-Aguilar
- Laboratorio de Farmacologia, Departamento de Ciencias de la Salud, Div. de Ciencias Biologicas y de la Salud, Universidad Autonoma Metropolitana Unidad Iztapalapa, Mexico, D.F. Mexico.
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99
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Ealey KN, Lu S, Archer MC. Development of aberrant crypt foci in the colons of ob/ob and db/db mice: evidence that leptin is not a promoter. Mol Carcinog 2008; 47:667-77. [PMID: 18240295 DOI: 10.1002/mc.20419] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Leptin is elevated in obesity and has been suggested to increase the risk of colorectal cancer (CRC), although the evidence is conflicting. The objective of this study was to compare the susceptibility to colon carcinogenesis of db/db mice that have highly elevated circulating leptin and leptin-deficient ob/ob mice, both of which are obese. Seven-week-old male ob/ob, db/db, and WT mice received 4 weekly i.p. injections of 5 mg/kg azoxymethane (AOM) and were killed 14 wk later for the analysis of putative preneoplastic aberrant crypt foci (ACF). There were no differences in ACF number or multiplicity between ob/ob and db/db mice. Leptin has been shown to induce CYP2E1, the main enzyme that activates AOM, but we observed no differences in hepatic CYP2E1 activity or colonic CYP2E1 protein levels between ob/ob and db/db mice. We also induced ACF with 2 oral doses 3 d apart of 30 mg/kg methylnitrosourea (MNU), a direct-acting carcinogen. There were no differences in ACF number or multiplicity between the two groups of obese animals 5 wk following the last dose of MNU. The colonic mucosa of db/db mice expressed significantly lower mRNA levels of ObRa, the predominant short form of the leptin receptor, compared to ob/ob mice, and following i.p. injection with 1 mg/kg recombinant mouse leptin, exhibited significantly reduced p44/42 pMAPK compared to saline-treated controls. These results show that ObRa is functionally active in the colons of db/db mice. We conclude that leptin does not play a significant role in ACF development.
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Affiliation(s)
- Kafi N Ealey
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada
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100
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