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Diker-Cohen T, Cochran E, Gorden P, Brown RJ. Partial and generalized lipodystrophy: comparison of baseline characteristics and response to metreleptin. J Clin Endocrinol Metab 2015; 100:1802-10. [PMID: 25734254 PMCID: PMC4422900 DOI: 10.1210/jc.2014-4491] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CONTEXT Lipodystrophies are extreme forms of metabolic syndrome. Metreleptin was approved in the United States for generalized lipodystrophy (GLD) but not partial lipodystrophy (PLD). OBJECTIVE The objective of the study was to test metreleptin's efficacy in PLD vs GLD and find predictors for treatment response. DESIGN This was a prospective, single-arm, open-label study since 2000 with continuous enrollment. Current analysis included metreleptin treatment for 6 months or longer as of January 2014. SETTING The study was conducted at the National Institutes of Health (Bethesda, Maryland). PARTICIPANTS Patients clinically diagnosed with lipodystrophy, leptin less than 8 ng/mL (males) or less than 12 (females), age older than 6 months, and one or more metabolic abnormalities (diabetes, insulin resistance, or hypertriglyceridemia) participated in the study. INTERVENTION The interventions included sc metreleptin injections (0.06-0.24 mg/kg · d). MAIN OUTCOMES AND MEASURES Changes in glycated hemoglobin A1c (HbA1c) and triglycerides after 6 and 12 months of metreleptin were measured. RESULTS Baseline metabolic parameters were similar in 55 GLD [HbA1c 8.4% ± 2.3%; triglycerides, geometric mean (25th, 75th percentile), 467 mg/dL (200, 847)] and 31 PLD patients [HbA1c 8.1% ± 2.2%, triglycerides 483 mg/dL (232, 856)] despite different body fat and endogenous leptin. At 12 months, metreleptin decreased HbA1c (to 6.4% ± 1.5%, GLD, P < .001; 7.3% ± 1.6%, PLD, P = .004) and triglycerides [to 180 mg/dL (106, 312), GLD, P < .001; 326 mg/dL (175, 478), PLD, P = .02]. HbA1c and triglyceride changes over time significantly differed between GLD and PLD. In subgroup analyses, metreleptin improved HbA1c and triglycerides in all GLD subgroups except those with baseline triglycerides less than 300 mg/dL and all PLD subgroups except baseline triglycerides less than 500 mg/dL, HbA1c less than 8%, or endogenous leptin greater than 4 ng/mL. CONCLUSIONS In addition to its proven efficacy in GLD, metreleptin is effective in selected PLD patients with severe metabolic derangements or low leptin.
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Metreleptin (Myalept): a leptin analog for generalized lipodystrophy. THE MEDICAL LETTER ON DRUGS AND THERAPEUTICS 2015; 57:13-14. [PMID: 25581107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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Friedman JM, Mantzoros CS. 20 years of leptin: from the discovery of the leptin gene to leptin in our therapeutic armamentarium. Metabolism 2015; 64:1-4. [PMID: 25497341 DOI: 10.1016/j.metabol.2014.10.023] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 01/19/2023]
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Paz-Filho G, Mastronardi CA, Licinio J. Leptin treatment: facts and expectations. Metabolism 2015; 64:146-56. [PMID: 25156686 DOI: 10.1016/j.metabol.2014.07.014] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/03/2014] [Accepted: 07/29/2014] [Indexed: 12/20/2022]
Abstract
Leptin has key roles in the regulation of energy balance, body weight, metabolism, and endocrine function. Leptin levels are undetectable or very low in patients with lipodystrophy, hypothalamic amenorrhea, and congenital leptin deficiency (CLD) due to mutations in the leptin gene. For these patients, leptin replacement therapy with metreleptin (a recombinant leptin analog) has improved or normalized most of their phenotypes, including normalization of endocrine axes, decrease in insulin resistance, and improvement of lipid profile and hepatic steatosis. Remarkable weight loss has been observed in patients with CLD. Due to its effects, leptin therapy has also been evaluated in conditions where leptin levels are normal or high, such as common obesity, diabetes (types 1 and 2), and Rabson-Mendenhall syndrome. A better understanding of the physiological roles of leptin may lead to the development of leptin-based therapies for other prevalent disorders such as obesity-associated nonalcoholic fatty liver disease, depression and dementia.
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Polyzos SA, Mantzoros CS. Leptin in health and disease: facts and expectations at its twentieth anniversary. Metabolism 2015; 64:5-12. [PMID: 25467841 DOI: 10.1016/j.metabol.2014.10.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 10/20/2014] [Accepted: 10/20/2014] [Indexed: 02/07/2023]
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Wabitsch M, Funcke JB, Lennerz B, Kuhnle-Krahl U, Lahr G, Debatin KM, Vatter P, Gierschik P, Moepps B, Fischer-Posovszky P. Biologically inactive leptin and early-onset extreme obesity. N Engl J Med 2015; 372:48-54. [PMID: 25551525 DOI: 10.1056/nejmoa1406653] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mutations in the gene encoding leptin (LEP) typically lead to an absence of circulating leptin and to extreme obesity. We describe a 2-year-old boy with early-onset extreme obesity due to a novel homozygous transversion (c.298G→T) in LEP, leading to a change from aspartic acid to tyrosine at amino acid position 100 (p.D100Y) and high immunoreactive levels of leptin. Overexpression studies confirmed that the mutant protein is secreted but neither binds to nor activates the leptin receptor. The mutant protein failed to reduce food intake and body weight in leptin-deficient ob/ob mice. Treatment of the patient with recombinant human leptin (metreleptin) rapidly normalized eating behavior and resulted in weight loss.
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Jaworek J, Konturek SJ. Hormonal protection in acute pancreatitis by ghrelin, leptin and melatonin. World J Gastroenterol 2014; 20:16902-16912. [PMID: 25493003 PMCID: PMC4258559 DOI: 10.3748/wjg.v20.i45.16902] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 04/15/2014] [Accepted: 08/28/2014] [Indexed: 02/06/2023] Open
Abstract
Acute pancreatitis is a nonbacterial disease of the pancreas. The severe form of this ailment is characterized by high mortality. Whether acute pancreatitis develops as the severe type or resolves depends on the intensity of the inflammatory process which is counteracted by the recruitment of innate defense mechanisms. It has been shown that the hormones ghrelin, leptin and melatonin are able to modulate the immune function of the organism and to protect the pancreas against inflammatory damage. Experimental studies have demonstrated that the application of these substances prior to the induction of acute pancreatitis significantly attenuated the intensity of the inflammation and reduced pancreatic tissue damage. The pancreatic protective mechanisms of the above hormones have been related to the mobilization of non-specific immune defense, to the inhibition of nuclear factor kappa B and modulation of cytokine production, to the stimulation of heat shock proteins and changes of apoptotic processes in the acinar cells, as well as to the activation of antioxidant system of the pancreatic tissue. The protective effect of ghrelin seems to be indirect and perhaps dependent on the release of growth hormone and insulin-like growth factor 1. Leptin and ghrelin, but not melatonin, employ sensory nerves in their beneficial action on acute pancreatitis. It is very likely that ghrelin, leptin and melatonin could be implicated in the natural protection of the pancreatic gland against inflammatory damage because the blood levels of these substances increase in the initial phase of pancreatic inflammation. The above hormones could be a part of the innate resistance system which might remove noxious factors and could suppress or attenuate the inflammatory process in the pancreas.
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Farr OM, Fiorenza C, Papageorgiou P, Brinkoetter M, Ziemke F, Koo BB, Rojas R, Mantzoros CS. Leptin therapy alters appetite and neural responses to food stimuli in brain areas of leptin-sensitive subjects without altering brain structure. J Clin Endocrinol Metab 2014; 99:E2529-38. [PMID: 25279500 PMCID: PMC4255115 DOI: 10.1210/jc.2014-2774] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Leptin is a key regulator of energy intake and expenditure. Individuals with congenital leptin deficiency demonstrate structural and functional brain changes when given leptin. However, whether acquired leptin deficiency may operate similarly is unclear. OBJECTIVE We set out to determine whether the brains of individuals with acquired leptin deficiency may react to leptin in a similar manner. DESIGN We used functional magnetic resonance imaging before and after short- and long-term metreleptin treatment in three leptin-sensitive patients with acquired hypoleptinemia. Nine healthy women were scanned as normoleptinemic controls. SETTING The setting was an academic medical center. PATIENTS OR OTHER PARTICIPANTS The participants were 3 hypoleptinemic women and nine normoleptinemic, matched women. INTERVENTIONS We used metreleptin, recombinant leptin, therapy for 24 weeks in hypoleptinemic women only. MAIN OUTCOME MEASURE We measured neural changes in response to viewing food as compared to nonfood images. We hypothesized that metreleptin treatment would increase brain activity in areas related to cognitive control and inhibition and would decrease brain activity in areas related to reward processing, as compared to the normoleptinemic counterparts. RESULTS Unlike patients with congenital leptin deficiency, hypoleptinemic patients demonstrated no structural brain differences from healthy controls and/or structural changes in response to treatment. Short-term metreleptin treatment in leptin-sensitive hypoleptinemic subjects enhances areas involved in detecting the salience and rewarding value of food during fasting, whereas long-term treatment decreases attention to food and the rewarding value of food after feeding. Furthermore, hypothalamic activity is modulated by metreleptin treatment, and leptin decreases functional connectivity of the hypothalamus to key feeding-related areas in these hypoleptinemic subjects. CONCLUSIONS Leptin replacement in acutely hypoleptinemic women did not alter brain structure but did alter functional cortical activity to food cues in key feeding and reward-related areas.
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Meek TH, Matsen ME, Damian V, Cubelo A, Chua SC, Morton GJ. Role of melanocortin signaling in neuroendocrine and metabolic actions of leptin in male rats with uncontrolled diabetes. Endocrinology 2014; 155:4157-67. [PMID: 25137027 PMCID: PMC4197991 DOI: 10.1210/en.2014-1169] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although the antidiabetic effects of leptin require intact neuronal melanocortin signaling in rodents with uncontrolled diabetes (uDM), increased melanocortin signaling is not sufficient to mimic leptin's glucose-lowering effects. The current studies were undertaken to clarify the role of melanocortin signaling in leptin's ability to correct metabolic and neuroendocrine disturbances associated with uDM. To accomplish this, bilateral cannulae were implanted in the lateral ventricle of rats with streptozotocin-induced diabetes, and leptin was coinfused with varying doses of the melanocortin 3/4 receptor (MC3/4R) antagonist, SHU9119. An additional cohort of streptozotocin-induced diabetes rats received intracerebroventricular administration of either the MC3/4R agonist, melanotan-II, or its vehicle. Consistent with previous findings, leptin's glucose-lowering effects were blocked by intracerebroventricular SHU9119. In contrast, leptin-mediated suppression of hyperglucagonemia involves both melanocortin dependent and independent mechanisms, and the degree of glucagon inhibition was associated with reduced plasma ketone body levels. Increased central nervous system melanocortin signaling alone fails to mimic leptin's ability to correct any of the metabolic or neuroendocrine disturbances associated with uDM. Moreover, the inability of increased melanocortin signaling to lower diabetic hyperglycemia does not appear to be secondary to release of the endogenous MC3/4R inverse agonist, Agouti-related peptide (AgRP), because AgRP knockout mice did not show increased susceptibility to the antidiabetic effects of increased MC3/4R signaling. Overall, these data suggest that 1) AgRP is not a major driver of diabetic hyperglycemia, 2) mechanisms independent of melanocortin signaling contribute to leptin's antidiabetic effects, and 3) melanocortin receptor blockade dissociates leptin's glucose-lowering effect from its action on other features of uDM, including reversal of hyperglucagonemia and ketosis, suggesting that brain control of ketosis, but not blood glucose levels, is glucagon dependent.
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Foo JP, Polyzos SA, Anastasilakis AD, Chou S, Mantzoros CS. The effect of leptin replacement on parathyroid hormone, RANKL-osteoprotegerin axis, and Wnt inhibitors in young women with hypothalamic amenorrhea. J Clin Endocrinol Metab 2014; 99:E2252-8. [PMID: 25148234 PMCID: PMC5393498 DOI: 10.1210/jc.2014-2491] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CONTEXT Recombinant leptin (metreleptin) treatment restores bone mineral density in women with hypothalamic amenorrhea (HA), a condition characterized by hypoleptinemia, which has adverse impact on bone health. OBJECTIVE The objective of the study was to investigate how metreleptin exerts its positive effect on bone metabolism in humans. DESIGN This was a randomized, double-blinded, placebo-controlled study. SETTING The study was conducted at Beth Israel Deaconess Medical Center (Boston, Massachusetts). PATIENTS AND INTERVENTIONS Women (n = 18) with HA and hypoleptinemia for at least 6 months were randomized to receive either metreleptin or placebo for 36 weeks. Serum samples were obtained at baseline and 12, 24, and 36 weeks of treatment. MAIN OUTCOME MEASURES Circulating levels of leptin, intact PTH (iPTH), receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), sclerostin, dickkopf-1, and fibroblast growth factor-23. RESULTS Metreleptin administration significantly increased leptin levels throughout the treatment period (P = .001). iPTH decreased over the 36 weeks of treatment (P = .01). There was a trend toward a decrease in serum RANKL and increase in serum OPG in the metreleptin-treated group. The RANKL to OPG ratio was significantly decreased within the metreleptin (P = .04) but not the placebo group. Metreleptin had no effect on serum sclerostin, dickkopf-1, and fibroblast growth factor-23. CONCLUSIONS Metreleptin treatment over 36 weeks decreases iPTH and RANKL to OPG ratio levels in hypoleptinemic women with HA.
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Sakai T, Kusakabe T, Ebihara K, Aotani D, Yamamoto-Kataoka S, Zhao M, Gumbilai VMJ, Ebihara C, Aizawa-Abe M, Yamamoto Y, Noguchi M, Fujikura J, Hosoda K, Inagaki N, Nakao K. Leptin restores the insulinotropic effect of exenatide in a mouse model of type 2 diabetes with increased adiposity induced by streptozotocin and high-fat diet. Am J Physiol Endocrinol Metab 2014; 307:E712-9. [PMID: 25159327 DOI: 10.1152/ajpendo.00272.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Leptin may reduce pancreatic lipid deposition, which increases with progression of obesity and can impair β-cell function. The insulinotropic effect of glucagon-like peptide-1 (GLP-1) and the efficacy of GLP-1 receptor agonist are reduced associated with impaired β-cell function. In this study, we examined whether leptin could restore the efficacy of exenatide, a GLP-1 receptor agonist, in type 2 diabetes with increased adiposity. We chronically administered leptin (500 μg·kg⁻¹·day⁻¹) and/or exenatide (20 μg·kg⁻¹·day⁻¹) for 2 wk in a mouse model of type 2 diabetes with increased adiposity induced by streptozotocin and high-fat diet (STZ/HFD mice). The STZ/HFD mice exhibited hyperglycemia, overweight, increased pancreatic triglyceride level, and reduced glucose-stimulated insulin secretion (GSIS); moreover, the insulinotropic effect of exenatide was reduced. However, leptin significantly reduced pancreatic triglyceride level, and adding leptin to exenatide (LEP/EX) remarkably enhanced GSIS. These results suggested that the leptin treatment restored the insulinotropic effect of exenatide in the mice. In addition, LEP/EX reduced food intake, body weight, and triglyceride levels in the skeletal muscle and liver, and corrected hyperglycemia to a greater extent than either monotherapy. The pair-feeding experiment indicated that the marked reduction of pancreatic triglyceride level and enhancement of GSIS by LEP/EX occurred via mechanisms other than calorie restriction. These results suggest that leptin treatment may restore the insulinotropic effect of exenatide associated with the reduction of pancreatic lipid deposition in type 2 diabetes with increased adiposity. Combination therapy with leptin and exenatide could be an effective treatment for patients with type 2 diabetes with increased adiposity.
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Abstract
The molecular mechanisms of body weight and body composition regulation have long been a research focus in the hopes of identifying tractable pathways for therapeutic interventions for obesity and diabetes, as well as related disorders such as nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) and polycystic ovary syndrome. The metabolic consequences of obesity and type 2 diabetes (T2D) were already a focus of the world's attention in 1994 when the discovery of leptin generated enormous enthusiasm for the potential to treat common (non-monogenic) obesity and its associated metabolic disorders with an adipokine hormone that regulated body weight as well as lipid and carbohydrate metabolism. Recombinant human leptin and many leptin analogs were developed and studied in animals and a few in human clinical trials. Overall, the opportunity for leptin as a therapeutic in unselected patients with obesity and T2D has not been substantiated in clinical trials. The potential for combination therapy suggested by clinical studies with leptin and pramlintide supports a path toward obesity treatment through the leptin pathway. The profound metabolic benefits seen with leptin in numerous forms of leptin deficiency, including lipodystrophy, provide hope for the opportunity to identify selected subsets of patients who could benefit from leptin treatment. This review provides a comprehensive overview of the clinical data on a subset of the potential utilities of leptin, specifically as a therapeutic for general or common obesity and its metabolic consequences including T2D and NAFLD/NASH.
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Abstract
The hyperphagia, low sympathetic nervous system tone, and decreased circulating concentrations of bioactive thyroid hormones that are common to states of congenital leptin deficiency and hypoleptinemia following and during weight loss suggest that the major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. In weight-reduced humans, these phenotypes together with pronounced hypometabolism and increased parasympathetic nervous system tone create the optimal circumstance for weight regain. Based on the weight loss induced by leptin administration in states of leptin deficiency (obese) and observed similarity of phenotypes in states of congenital and dietary-induced states of hypoleptinemia (reduced obese), it has been suggested that exogenous leptin could potentially be useful in initiating, promoting, and sustaining weight reduction. However, the responses of human beings to exogenous leptin administration are dependent not only on extant energy stores but also on energy balance. Leptin administration to humans at usual weight has little, if any, effect on body weight while leptin administration during weight loss mitigates hunger, especially if given in supraphysiological doses during severe caloric restriction. Leptin repletion is most effective following weight loss by dietary restriction. In this state of weight stability but reduced energy stores, leptin at least partially reverses many of the metabolic, autonomic, neuroendocrine, and behavioral adaptations that favor weight regain. The major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. Leptin, and pharmacotherapies affecting leptin signaling pathways, is likely to be most useful in sustaining weight loss.
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Abstract
The discovery of leptin has provided a robust framework upon which our current understanding of the mechanisms involved in energy homeostasis has been built. In this review, we describe how the identification of humans with mutations in the genes encoding leptin and the leptin receptor and the characterisation of the associated clinical phenotypes have provided insights into the role of leptin-responsive pathways in the regulation of eating behaviour, intermediary metabolism and the onset of puberty. Importantly, administration of recombinant human leptin in leptin deficiency represents the first mechanistically based targeted therapy for obesity and has provided immense clinical benefits for the patients concerned. In subsequent years, we and others have shown that human obesity can result from a multiplicity of defects in the pathways downstream of leptin signalling within the brain.
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Abstract
Historically, adipose tissue was considered to be a passive storage vessel discharging nutrients in times of famine and accumulating fat in times of surfeit. This view changed with the identification of leptin as an adipocyte hormone. Leptin functions as an afferent signal in a negative feedback loop that regulates food intake and metabolism to maintain homeostatic control of adipose tissue mass. Before this, the existence of a system maintaining homeostatic control of energy balance was unclear. The identification of leptin has thus uncovered a new endocrine system that also links changes in nutrition to adaptive responses in most if not all other physiologic systems. Further studies have revealed a set of clinical syndromes caused by leptin deficiency, including lipodystrophy and hypothalamic amenorrhea. This work has led to new therapeutic approaches for a number of human conditions and has also established a conceptual framework for studying the pathogenesis of obesity.
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Abstract
Leptin, as a key hormone in energy homeostasis, regulates neuroendocrine function, including reproduction. It has a permissive role in the initiation of puberty and maintenance of the hypothalamic-pituitary-gonadal axis. This is notable in patients with either congenital or acquired leptin deficiency from a state of chronic energy insufficiency. Hypothalamic amenorrhea is the best-studied, with clinical trials confirming a causative role of leptin in hypogonadotropic hypogonadism. Implications of leptin deficiency have also emerged in the pathophysiology of hypogonadism in type 1 diabetes. At the other end of the spectrum, hyperleptinemia may play a role in hypogonadism associated with obesity, polycystic ovarian syndrome, and type 2 diabetes. In these conditions of energy excess, mechanisms of reproductive dysfunction include central leptin resistance as well as direct effects at the gonadal level. Thus, reproductive dysfunction due to energy imbalance at both ends can be linked to leptin.
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Schoeller EL, Chi M, Drury A, Bertschinger A, Esakky P, Moley KH. Leptin monotherapy rescues spermatogenesis in male Akita type 1 diabetic mice. Endocrinology 2014; 155:2781-6. [PMID: 24840347 PMCID: PMC5393317 DOI: 10.1210/en.2014-1119] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Type 1 diabetes is associated with subfertility in humans. The current treatment for type 1 diabetes, insulin monotherapy, is suboptimal to fully stabilize glycemia, potentially leading to this subfertility. Recent work has demonstrated that treatment with the energy-regulating hormone leptin, alone or in combination with insulin, can more effectively control glycemia in mouse models of type 1 diabetes. Here, we sought to determine whether the fertility defects in a type 1 diabetic mouse model, the Akita mouse, can be rescued with leptin monotherapy in the absence of any exogenous insulin. Akita homozygous mice treated with leptin alone had a larger total body size, testes, and seminal vesicles than their untreated siblings. Leptin treatment prevented testicular degeneration and rescued sperm motility to wild-type levels. Furthermore, sperm obtained from leptin-treated mice could successfully fertilize ooctyes in vitro. Despite completely rescuing spermatogenesis, the critical reproductive hormones LH and testosterone were only modestly higher than in untreated mice, indicating that a minimum threshold of these hormones must be met to maintain spermatogenesis. Cumulatively, these findings implicate the importance of leptin in maintaining fertility and support the use of leptin therapy in the treatment of type 1 diabetes.
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Christensen JD, Lungu AO, Cochran E, Collins MT, Gafni RI, Reynolds JC, Rother KI, Gorden P, Brown RJ. Bone mineral content in patients with congenital generalized lipodystrophy is unaffected by metreleptin replacement therapy. J Clin Endocrinol Metab 2014; 99:E1493-500. [PMID: 25070319 PMCID: PMC4121033 DOI: 10.1210/jc.2014-1353] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Leptin alters bone and mineral metabolism in rodents, but this has not been verified in humans. PATIENTS with congenital generalized lipodystrophy (CGL) have low leptin due to deficient adipose mass and serve as models of leptin deficiency and replacement. OBJECTIVE To study the effects of recombinant human methionyl leptin (metreleptin) on bone mineral content (BMC) and mineral metabolism. DESIGN AND SETTING An open-label nonrandomized study at the National Institutes of Health. PATIENTS Thirty-one patients with CGL (ages 4.3 to 46.7 y). INTERVENTION Metreleptin (0.06 to 0.24 mg/kg/d) for 6 months to 11 years. OUTCOME MEASURES BMC was assessed by dual-energy x-ray absorptiometry. SD scores (SDS) for BMC were calculated based on height, race, sex, and age using population normative data. Calcium, phosphorus, PTH, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured at baseline and follow-up. RESULTS At baseline, patients demonstrated significantly increased total body less head BMC (mean SDS, 1.8 ± 0.7), height (mean SDS, 1.3 ± 1.3), and lean mass index, defined as lean body mass per height squared (mean SDS, 1.5 ± 0.83), vs population normative data. No change in total body less head BMC was observed after metreleptin. Lean mass index decreased with metreleptin. Serum calcium decreased with metreleptin, but remained within normal limits. No changes were seen in phosphorus, PTH, or vitamin D. CONCLUSIONS In contrast to rodent models, CGL patients have increased BMC in the leptin-deficient state, which does not change with leptin replacement. The high BMC in these patients is partially explained by high lean mass and tall stature.
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Umeki H, Tokuyama R, Ide S, Okubo M, Tadokoro S, Tezuka M, Tatehara S, Satomura K. Leptin promotes wound healing in the oral mucosa. PLoS One 2014; 9:e101984. [PMID: 25033454 PMCID: PMC4102470 DOI: 10.1371/journal.pone.0101984] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 06/13/2014] [Indexed: 01/02/2023] Open
Abstract
INTRODUCTION Leptin, a 16 kDa circulating anti-obesity hormone, exhibits many physiological properties. Recently, leptin was isolated from saliva; however, its function in the oral cavity is still unclear. In this study, we investigated the physiological role of leptin in the oral cavity by focusing on its effect on wound healing in the oral mucosa. METHODS Immunohistochemical analysis was used to examine the expression of the leptin receptor (Ob-R) in human/rabbit oral mucosa. To investigate the effect of leptin on wound healing in the oral mucosa, chemical wounds were created in rabbit oral mucosa, and leptin was topically administered to the wound. The process of wound repair was histologically observed and quantitatively analyzed by measuring the area of ulceration and the duration required for complete healing. The effect of leptin on the proliferation, differentiation and migration of human oral mucosal epithelial cells (RT7 cells) was investigated using crystal violet staining, reverse transcription polymerase chain reaction (RT-PCR) and a wound healing assay, respectively. RESULTS Ob-R was expressed in spinous/granular cells in the epithelial tissue and vascular endothelial cells in the subepithelial connective tissue of the oral mucosa. Topical administration of leptin significantly promoted wound healing and shortened the duration required for complete healing. Histological analysis of gingival tissue beneath the ulceration showed a denser distribution of blood vessels in the leptin-treated group. Although the proliferation and differentiation of RT7 cells were not affected by leptin, the migration of these cells was accelerated in the presence of leptin. CONCLUSION Topically administered leptin was shown to promote wound healing in the oral mucosa by accelerating epithelial cell migration and enhancing angiogenesis around the wounded area. These results strongly suggest that topical administration of leptin may be useful as a treatment to promote wound healing in the oral mucosa.
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Perry RJ, Zhang XM, Zhang D, Kumashiro N, Camporez JPG, Cline GW, Rothman DL, Shulman GI. Leptin reverses diabetes by suppression of the hypothalamic-pituitary-adrenal axis. Nat Med 2014; 20:759-63. [PMID: 24929951 PMCID: PMC4344321 DOI: 10.1038/nm.3579] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 04/21/2014] [Indexed: 12/14/2022]
Abstract
Leptin treatment reverses hyperglycemia in animal models of poorly controlled type 1 diabetes (T1D), spurring great interest in the possibility of treating patients with this hormone. The antidiabetic effect of leptin has been postulated to occur through suppression of glucagon production, suppression of glucagon responsiveness or both; however, there does not appear to be a direct effect of leptin on the pancreatic alpha cell. Thus, the mechanisms responsible for the antidiabetic effect of leptin remain poorly understood. We quantified liver-specific rates of hepatic gluconeogenesis and substrate oxidation in conjunction with rates of whole-body acetate, glycerol and fatty acid turnover in three rat models of poorly controlled diabetes, including a model of diabetic ketoacidosis. We show that the higher rates of hepatic gluconeogenesis in all these models could be attributed to hypoleptinemia-induced activity of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in higher rates of adipocyte lipolysis, hepatic conversion of glycerol to glucose through a substrate push mechanism and conversion of pyruvate to glucose through greater hepatic acetyl-CoA allosteric activation of pyruvate carboxylase flux. Notably, these effects could be dissociated from changes in plasma insulin and glucagon concentrations and hepatic gluconeogenic protein expression. All the altered systemic and hepatic metabolic fluxes could be mimicked by infusing rats with Intralipid or corticosterone and were corrected by leptin replacement. These data demonstrate a critical role for lipolysis and substrate delivery to the liver, secondary to hypoleptinemia and HPA axis activity, in promoting higher hepatic gluconeogenesis and hyperglycemia in poorly controlled diabetes.
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97
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Morrow T. Myalept approved for treatment of disorders marked by loss of body fat. MANAGED CARE (LANGHORNE, PA.) 2014; 23:50-51. [PMID: 25109049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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98
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Sangiao-Alvarellos S, Pena-Bello L, Manfredi-Lozano M, Tena-Sempere M, Cordido F. Perturbation of hypothalamic microRNA expression patterns in male rats after metabolic distress: impact of obesity and conditions of negative energy balance. Endocrinology 2014; 155:1838-50. [PMID: 24517225 DOI: 10.1210/en.2013-1770] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The hypothalamus plays a crucial role in body weight homeostasis through an intricate network of neuronal circuits that are under the precise regulation of peripheral hormones and central transmitters. Although deregulated function of such circuits might be a major contributing factor in obesity, the molecular mechanisms responsible for the hypothalamic control of energy balance remain partially unknown. MicroRNAs (miRNAs) have been recognized as key regulators of different biological processes, including insulin sensitivity and glucose metabolism. However, the roles of miRNA pathways in the control of metabolism have been mostly addressed in peripheral tissues, whereas the potential deregulation of miRNA expression in the hypothalamus in conditions of metabolic distress remains as yet unexplored. In this work, we used high-throughput screening to define to what extent the hypothalamic profiles of miRNA expression are perturbed in two extreme conditions of nutritional stress in male rats, namely chronic caloric restriction and high-fat diet-induced obesity. Our analyses allowed the identification of sets of miRNAs, including let-7a, mir-9*, mir-30e, mir-132, mir-145, mir-200a, and mir-218, whose expression patterns in the hypothalamus were jointly altered by caloric restriction and/or a high-fat diet. The predicted targets of these miRNAs include several elements of key inflammatory and metabolic pathways, including insulin and leptin. Our study is the first to disclose the impact of nutritional challenges on the hypothalamic miRNA expression profiles. These data will help to characterize the molecular miRNA signature of the hypothalamus in extreme metabolic conditions and pave the way for targeted mechanistic analyses of the involvement of deregulated central miRNAs pathways in the pathogenesis of obesity and related disorders.
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99
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Tudurí E, Denroche HC, Kara JA, Asadi A, Fox JK, Kieffer TJ. Partial ablation of leptin signaling in mouse pancreatic α-cells does not alter either glucose or lipid homeostasis. Am J Physiol Endocrinol Metab 2014; 306:E748-55. [PMID: 24473435 DOI: 10.1152/ajpendo.00681.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The role of glucagon in the pathological condition of diabetes is gaining interest, and it has been recently reported that its action is essential for hyperglycemia to occur. Glucagon levels, which are elevated in some diabetic models, are reduced following leptin therapy. Likewise, hyperglycemia is corrected in type 1 diabetic mice treated with leptin, although the mechanisms have not been fully determined. A direct inhibitory effect of leptin on mouse and human α-cells has been demonstrated at the levels of electrical activity, calcium signaling, and glucagon secretion. In the present study we employed the Cre-loxP strategy to generate Lepr(flox/flox) Gcg-cre mice, which specifically lack leptin receptors in glucagon-secreting α-cells, to determine whether leptin resistance in α-cells contributes to hyperglucagonemia, and also whether leptin action in α-cells is required to improve glycemia in type 1 diabetes with leptin therapy. Immunohistochemical analysis of pancreas sections revealed Cre-mediated recombination in ∼ 43% of the α-cells. We observed that in vivo Lepr(flox/flox) Gcg-cre mice display normal glucose and lipid homeostasis. In addition, leptin administration in streptozotocin-induced diabetic Lepr(flox/flox) Gcg-cre mice restored euglycemia similarly to control mice. These findings suggest that loss of leptin receptor signaling in close to one-half of α-cells does not alter glucose metabolism in vivo, nor is it sufficient to prevent the therapeutic action of leptin in type 1 diabetes.
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MESH Headings
- Animals
- Cells, Cultured
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Female
- Gene Deletion
- Glucagon-Secreting Cells/metabolism
- Glucose/metabolism
- Homeostasis/genetics
- Leptin/metabolism
- Leptin/therapeutic use
- Lipid Metabolism/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Signal Transduction/genetics
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100
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Clemmensen C, Chabenne J, Finan B, Sullivan L, Fischer K, Küchler D, Sehrer L, Ograjsek T, Hofmann SM, Schriever SC, Pfluger PT, Pinkstaff J, Tschöp MH, Dimarchi R, Müller TD. GLP-1/glucagon coagonism restores leptin responsiveness in obese mice chronically maintained on an obesogenic diet. Diabetes 2014; 63:1422-7. [PMID: 24379349 DOI: 10.2337/db13-1609] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We recently reported restoration of leptin responsiveness in diet-induced obese (DIO) mice using a pharmacologically optimized, polyethylene-glycolated (PEG)-leptin analog in combination with exendin-4 or FGF21. However, the return of leptin action required discontinuation of high-fat diet (HFD) exposure. Here we assess whether a single peptide possessing balanced coagonism at the glucagon-like peptide 1 (GLP-1) and glucagon receptors can restore leptin responsiveness in DIO mice maintained on a HFD. DIO mice were treated with PEG-GLP-1/glucagon (30 nmol/kg every fourth day) to induce an ∼15% body weight loss, upon which they were randomized to continue PEG-GLP-1/glucagon therapy or reassigned to receive supplemental daily PEG-leptin (185 nmol/kg/day). The addition of PEG-leptin to PEG-GLP-1/glucagon resulted in an ∼18% greater weight loss as compared with PEG-GLP-1/glucagon alone and was accompanied by further decreases in food intake and improved glucose and lipid metabolism. The beneficial effect of PEG-leptin supplementation occurred after an initial body weight loss similar to what we previously reported following reduced dietary fat along with PEG-leptin and exendin-4 or FGF21 cotreatment. In summary, we report that GLP-1/glucagon coagonism restores leptin responsiveness in mice maintained on a HFD, thus emphasizing the translational value of this polypharmacotherapy for the treatment of obesity and diabetes.
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