1
|
Clark KA, Shin AC, Sirivelu MP, MohanKumar RC, Maddineni SR, Ramachandran R, MohanKumar PS, MohanKumar SMJ. Evaluation of the Central Effects of Systemic Lentiviral-Mediated Leptin Delivery in Streptozotocin-Induced Diabetic Rats. Int J Mol Sci 2021; 22:ijms222413197. [PMID: 34947993 PMCID: PMC8703968 DOI: 10.3390/ijms222413197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/23/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
Type 1 diabetes (T1D) is characterized by hyperphagia, hyperglycemia and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We have reported previously that daily leptin injections help to alleviate these symptoms. Therefore, we hypothesized that leptin gene therapy could help to normalize the neuroendocrine dysfunction seen in T1D. Adult male Sprague Dawley rats were injected i.v. with a lentiviral vector containing the leptin gene or green fluorescent protein. Ten days later, they were injected with the vehicle or streptozotocin (STZ). HPA function was assessed by measuring norepinephrine (NE) levels in the paraventricular nucleus (PVN) and serum corticosterone (CS). Treatment with the leptin lentiviral vector (Lepvv) increased leptin and insulin levels in non-diabetic rats, but not in diabetic animals. There was a significant reduction in blood glucose levels in diabetic rats due to Lepvv treatment. Both NE levels in the PVN and serum CS were reduced in diabetic rats treated with Lepvv. Results from this study provide evidence that leptin gene therapy in STZ-induced diabetic rats was able to partially normalize some of the neuroendocrine abnormalities, but studies with higher doses of the Lepvv are needed to develop this into a viable option for treating T1D.
Collapse
MESH Headings
- Animals
- Corticosterone/blood
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/therapy
- Diabetes Mellitus, Type 1/chemically induced
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/therapy
- Disease Models, Animal
- Genetic Therapy
- Genetic Vectors/administration & dosage
- Injections, Intravenous
- Lentivirus/genetics
- Leptin/genetics
- Male
- Norepinephrine/metabolism
- Paraventricular Hypothalamic Nucleus/metabolism
- Rats
- Rats, Sprague-Dawley
Collapse
Affiliation(s)
- Kimberly A. Clark
- Neuroscience Graduate Program, Michigan State University, E. Lansing, MI 48824, USA; (K.A.C.); (P.S.M.)
| | - Andrew C. Shin
- Neurobiology of Nutrition Laboratory, Department of Nutritional Sciences, College of Human Sciences, Texas Tech University, Lubbock, TX 79409, USA;
| | - Madhu P. Sirivelu
- Pathobiology and Diagnostic Investigation, Michigan State University, E. Lansing, MI 48824, USA;
| | - Ramya C. MohanKumar
- Neuroendocrine Research Laboratory, University of Georgia, Athens, GA 30602, USA;
| | - Sreenivasa R. Maddineni
- Department of Poultry Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA; (S.R.M.); (R.R.)
| | - Ramesh Ramachandran
- Department of Poultry Science, College of Agricultural Sciences, The Pennsylvania State University, University Park, PA 16802, USA; (S.R.M.); (R.R.)
| | - Puliyur S. MohanKumar
- Neuroscience Graduate Program, Michigan State University, E. Lansing, MI 48824, USA; (K.A.C.); (P.S.M.)
- Pathobiology and Diagnostic Investigation, Michigan State University, E. Lansing, MI 48824, USA;
- Neuroendocrine Research Laboratory, University of Georgia, Athens, GA 30602, USA;
- Department of Biomedical Sciences, University of Georgia, Athens, GA 30602, USA
| | - Sheba M. J. MohanKumar
- Neuroscience Graduate Program, Michigan State University, E. Lansing, MI 48824, USA; (K.A.C.); (P.S.M.)
- Neuroendocrine Research Laboratory, University of Georgia, Athens, GA 30602, USA;
- Department of Biomedical Sciences, University of Georgia, Athens, GA 30602, USA
- Correspondence: ; Tel.: +1-706-542-1945
| |
Collapse
|
2
|
Abstract
Type 2 diabetes mellitus (T2DM) and other metabolic diseases are essential links in the structure of morbidity and mortality in the modern world. The accepted strategy for the correction of T2DM and insulin resistance is drug therapy aimed at delivering insulin from the outside, stimulating the secretion of own insulin and reducing the concentration of blood glucose. However, modern studies demonstrate a great potential for the use of gene therapy approaches for the correction of T2DM and insulin resistance. In the present review, the main variants of plasmid gene therapy of T2DM using the genes of adiponectin and type 1 glucagon-like peptide, as well as the main variants of viral gene therapy of T2DM using the genes of type 1 and leptin are considered. T2DM gene therapy is currently not ready to enter into routine clinical practice, but, subject to improvements in delivery systems, it can be a powerful link in combination therapy for diabetes.
Collapse
Affiliation(s)
- Yu S Stafeev
- National Medical Research Centre for Cardiology of the Ministry of Health of the Russian Federation, Moscow, Russia.,M.V. Lomonosov Moscow State University, Moscow, Russia
| | - M Yu Menshikov
- National Medical Research Centre for Cardiology of the Ministry of Health of the Russian Federation, Moscow, Russia
| | - Ye V Parfyonova
- National Medical Research Centre for Cardiology of the Ministry of Health of the Russian Federation, Moscow, Russia.,M.V. Lomonosov Moscow State University, Moscow, Russia
| |
Collapse
|
3
|
Xu Y, Tong Q. Central leptin action on euglycemia restoration in type 1 diabetes: Restraining responses normally induced by fasting? Int J Biochem Cell Biol 2016; 88:198-203. [PMID: 27702650 DOI: 10.1016/j.biocel.2016.09.027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 01/29/2023]
Abstract
Leptin monotherapy is sufficient to restore euglycemia in insulinopenic type 1 diabetes (T1D), yet the underlying mechanism remains poorly understood. Accumulating evidence demonstrates that the brain mediates the leptin action on euglycemia restoration. Here, we first review evidence supporting that symptoms in T1D resemble an uncontrolled response to fasting. Then, we discuss recent research progress on brain neurons and their neurotransmitters that potentially mediate the leptin action. Finally, peripheral effective pathways, which are normally involved in fasting responses and associated with leptin action on euglycemia restoration in T1D, will also be discussed. This summary complements several previous excellent reviews on this topic (Meek and Morton, 2016; Perry et al., 2016; Fujikawa and Coppari, 2015). A deep understanding of neurocircuitry and the peripheral effective pathways that mediate the leptin action on euglycemia restoration will likely lead to novel targets for an insulin-independent therapeutics against T1D.
Collapse
Affiliation(s)
- Yuanzhong Xu
- Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases of McGovern Medical School, The University of Texas Health Science Center at Houston, United States
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases of McGovern Medical School, The University of Texas Health Science Center at Houston, United States.
| |
Collapse
|
4
|
Ladyman SR, Grattan DR. Central Effects of Leptin on Glucose Homeostasis are Modified during Pregnancy in the Rat. J Neuroendocrinol 2016; 28. [PMID: 27623562 DOI: 10.1111/jne.12431] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 08/03/2016] [Accepted: 09/10/2016] [Indexed: 01/03/2023]
Abstract
Despite increased leptin concentrations during pregnancy, fat mass and food intake are increased. The satiety response to central leptin is suppressed, indicating a state of leptin insensitivity in the hypothalamus. Although the regulation of food intake is a major function of leptin, this hormone also influences a wide range of functions within the body. These actions include the regulation of glucose homeostasis, which undergoes major adaptation in the maternal body to generate optimal conditions for foetal development and growth. The present study aimed to investigate the effects of central leptin treatment on glucose homeostasis in pregnant rats to determine whether pregnancy-induced leptin insensitivity is functionally specific, and to further investigate changes in glucose homeostasis during pregnancy. After an overnight fast, nonpregnant and day 14 pregnant rats received an i.c.v. injection of leptin (100 ng or 4 μg) or vehicle then underwent a glucose tolerance test (GTT). Further groups of nonpregnant and day 14 pregnant rats were killed 30 min after leptin (doses ranging from 40 ng-4 μg) or vehicle i.c.v. injections for western blot analysis of phospho-signal transducer and activator of transcription 3 (STAT3) and phospho-Akt in various hypothalamic nuclei. Central leptin injection prior to a GTT lead to lowered basal insulin concentrations and impaired glucose tolerance in nonpregnant female rats, whereas the same doses of leptin had no significant effect on glucose tolerance in day 14 pregnant rats, indicating that, similar to the satiety actions of leptin, the effects of leptin on glucose homeostasis are suppressed during pregnancy. Furthermore, in the arcuate nucleus and ventromedial and dorsomedial nuclei of the hypothalamus, comprising three leptin-sensitive areas, there was no evidence that leptin induced Akt phosphorylation despite significant increases in phospho-STAT3, suggesting that leptin does not act through phospho-Akt in these areas in female rats.
Collapse
Affiliation(s)
- S R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | - D R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand
| |
Collapse
|
5
|
Liu W, Han X, Zhou X, Zhang S, Cai X, Zhang L, Li Y, Li M, Gong S, Ji L. Brain derived neurotrophic factor in newly diagnosed diabetes and prediabetes. Mol Cell Endocrinol 2016; 429:106-13. [PMID: 27062899 DOI: 10.1016/j.mce.2016.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/04/2016] [Accepted: 04/06/2016] [Indexed: 01/03/2023]
Abstract
Brain derived neurotrophic factor (BDNF) is thought to play an important role in glucose metabolism, but the exact mechanism has not been elucidated. The aim was to assess differences in serum BDNF levels across individuals with varying levels of glucose tolerance, and the association of serum BDNF levels with genetic variants and DNA methylation. Participants were selected from an ongoing population-based cohort study in rural China. In a randomly selected subsample of healthy participants (n = 33 males, n = 52 female), we assessed serum BDNF and in n = 50 of these, also DNA methylation. In a second subsample (all women; n = 28 with diabetes, n = 104 with prediabetes, and n = 105 age- and body mass index (BMI)-matched controls), we assessed serum BDNF and genetic variants. In a third subsample (all with diabetes; n = 7 normal BMI + low insulin level, n = 9 normal BMI + high insulin level, n = 9 obese + high insulin level), we assessed DNA methylation. Compared to age- and BMI-matched controls (24.71 (IQR, 20.44, 29.80) ng/ml), serum BDNF was higher in participants with prediabetes (27.38 (IQR, 20.64, 34.29) ng/ml), but lower in those with diabetes (23.40 (IQR, 18.12, 30.34) ng/ml) (P < 0.05). Two genetic variants near BDNF (rs4074134 and rs6265) were confirmed to be associated with BMI. BDNF CpG-6 methylation was positively associated with waist-to-hip ratio (P < 0.05). Furthermore, hyper-methylation in this site was found in participants with diabetes and high fasting insulin levels compared to those with diabetes and low fasting insulin levels, regardless of BMI status (P < 0.001 and P = 0.001, respectively). Observed differences in serum BDNF levels, genetic variants, and DNA methylation patterns across different glucose metabolic state suggest that BDNF may be involved in the pathophysiological process of insulin resistance and type 2 diabetes.
Collapse
Affiliation(s)
- Wei Liu
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Xueyao Han
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Xianghai Zhou
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Simin Zhang
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Xiaoling Cai
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Lihua Zhang
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Yufeng Li
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Meng Li
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Siqian Gong
- Department of Endocrinology, Peking University People's Hospital, Beijing, China
| | - Linong Ji
- Department of Endocrinology, Peking University People's Hospital, Beijing, China.
| |
Collapse
|
6
|
Denroche HC, Glavas MM, Tudurí E, Karunakaran S, Quong WL, Philippe M, Britton HM, Clee SM, Kieffer TJ. Disrupted Leptin Signaling in the Lateral Hypothalamus and Ventral Premammillary Nucleus Alters Insulin and Glucagon Secretion and Protects Against Diet-Induced Obesity. Endocrinology 2016; 157:2671-85. [PMID: 27183315 DOI: 10.1210/en.2015-1998] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Leptin signaling in the central nervous system, and particularly the arcuate hypothalamic nucleus, is important for regulating energy and glucose homeostasis. However, the roles of extra-arcuate leptin responsive neurons are less defined. In the current study, we generated mice with widespread inactivation of the long leptin receptor isoform in the central nervous system via Synapsin promoter-driven Cre (Lepr(flox/flox) Syn-cre mice). Within the hypothalamus, leptin signaling was disrupted in the lateral hypothalamic area (LHA) and ventral premammillary nucleus (PMV) but remained intact in the arcuate hypothalamic nucleus and ventromedial hypothalamic nucleus, dorsomedial hypothalamic nucleus, and nucleus of the tractus solitarius. To investigate the role of LHA/PMV neuronal leptin signaling, we examined glucose and energy homeostasis in Lepr(flox/flox) Syn-cre mice and Lepr(flox/flox) littermates under basal and diet-induced obese conditions and tested the role of LHA/PMV neurons in leptin-mediated glucose lowering in streptozotocin-induced diabetes. Lepr(flox/flox) Syn-cre mice did not have altered body weight or blood glucose levels but were hyperinsulinemic and had enhanced glucagon secretion in response to experimental hypoglycemia. Surprisingly, when placed on a high-fat diet, Lepr(flox/flox) Syn-cre mice were protected from weight gain, glucose intolerance, and diet-induced hyperinsulinemia. Peripheral leptin administration lowered blood glucose in streptozotocin-induced diabetic Lepr(flox/flox) Syn-cre mice as effectively as in Lepr(flox/flox) littermate controls. Collectively these findings suggest that leptin signaling in LHA/PMV neurons is not critical for regulating glucose levels but has an indispensable role in the regulation of insulin and glucagon levels and, may promote the development of diet-induced hyperinsulinemia and weight gain.
Collapse
Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Subashini Karunakaran
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Whitney L Quong
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Marion Philippe
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Heidi M Britton
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Susanne M Clee
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine (H.C.D., M.M.G., E.T., W.L.Q., M.P., H.M.B., T.J.K.) and Laboratory of the Genetics of Obesity and Diabetes (S.K., S.M.C.), Department of Cellular and Physiological Sciences, Life Sciences Institute, and Department of Surgery (T.J.K.), University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| |
Collapse
|
7
|
Denroche HC, Kwon MM, Glavas MM, Tudurí E, Philippe M, Quong WL, Kieffer TJ. The role of autonomic efferents and uncoupling protein 1 in the glucose-lowering effect of leptin therapy. Mol Metab 2016; 5:716-724. [PMID: 27656409 PMCID: PMC5021671 DOI: 10.1016/j.molmet.2016.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 06/19/2016] [Indexed: 01/06/2023] Open
Abstract
Objective Leptin reverses hyperglycemia in rodent models of type 1 diabetes (T1D). Direct application of leptin to the brain can lower blood glucose in diabetic rodents, and can activate autonomic efferents and non-shivering thermogenesis in brown adipose tissue (BAT). We investigated whether leptin reverses hyperglycemia through a mechanism that requires autonomic innervation, or uncoupling protein 1 (UCP1)-mediated thermogenesis. Methods To examine the role of parasympathetic and sympathetic efferents in the glucose-lowering action of leptin, mice with a subdiaphragmatic vagotomy or 6-hydroxydopamine induced chemical sympathectomy were injected with streptozotocin (STZ) to induce hyperglycemia, and subsequently leptin treated. To test whether the glucose-lowering action of leptin requires activation of UCP1-mediated thermogenesis in BAT, we administered leptin in STZ-diabetic Ucp1 knockout (Ucp1−/−) mice and wildtype controls. Results Leptin ameliorated STZ-induced hyperglycemia in both intact and vagotomised mice. Similarly, mice with a partial chemical sympathectomy did not have an attenuated response to leptin-mediated glucose lowering relative to sham controls, and showed intact leptin-induced Ucp1 expression in BAT. Although leptin activated BAT thermogenesis in STZ-diabetic mice, the anti-diabetic effect of leptin was not blunted in Ucp1−/− mice. Conclusions These results suggest that leptin lowers blood glucose in insulin-deficient diabetes through a manner that does not require parasympathetic or sympathetic innervation, and thus imply that leptin lowers blood glucose through an alternative CNS-mediated mechanism or redundant target tissues. Furthermore, we conclude that the glucose lowering action of leptin is independent of UCP1-dependent thermogenesis. Leptin does not require vagal innervation to reverse hyperglycemia. Leptin therapy reverses hyperglycemia in mice with a partial chemical sympathectomy. Leptin reverses hyperglycemia independent of uncoupling protein 1.
Collapse
Key Words
- 6OHDA, 6-hydroxydopamine
- ANS, autonomic nervous system
- BAT, brown adipose tissue
- Brown adipose tissue
- CCK, cholecystokinin
- CNS, central nervous system
- Glucose
- STZ, streptozotocin
- Streptozotocin
- Sympathectomy
- T1D, type 1 diabetes
- TH, tyrosine hydroxylase
- Type 1 diabetes
- UCP1, uncoupling protein 1
- Vagotomy
- iBAT, interscapular BAT
Collapse
Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michelle M Kwon
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria M Glavas
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marion Philippe
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Whitney L Quong
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, 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.
| |
Collapse
|
8
|
Coleman SK, Rebalka IA, D’Souza DM, Hawke TJ. Skeletal muscle as a therapeutic target for delaying type 1 diabetic complications. World J Diabetes 2015; 6:1323-1336. [PMID: 26674848 PMCID: PMC4673386 DOI: 10.4239/wjd.v6.i17.1323] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/01/2015] [Accepted: 11/25/2015] [Indexed: 02/05/2023] Open
Abstract
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease targeting the pancreatic beta-cells and rendering the person hypoinsulinemic and hyperglycemic. Despite exogenous insulin therapy, individuals with T1DM will invariably develop long-term complications such as blindness, kidney failure and cardiovascular disease. Though often overlooked, skeletal muscle is also adversely affected in T1DM, with both physical and metabolic derangements reported. As the largest metabolic organ in the body, impairments to skeletal muscle health in T1DM would impact insulin sensitivity, glucose/lipid disposal and basal metabolic rate and thus affect the ability of persons with T1DM to manage their disease. In this review, we discuss the impact of T1DM on skeletal muscle health with a particular focus on the proposed mechanisms involved. We then identify and discuss established and potential adjuvant therapies which, in association with insulin therapy, would improve the health of skeletal muscle in those with T1DM and thereby improve disease management- ultimately delaying the onset and severity of other long-term diabetic complications.
Collapse
|
9
|
Brain signaling systems in the Type 2 diabetes and metabolic syndrome: promising target to treat and prevent these diseases. Future Sci OA 2015; 1:FSO25. [PMID: 28031898 PMCID: PMC5137856 DOI: 10.4155/fso.15.23] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The changes in the brain signaling systems play an important role in etiology and pathogenesis of Type 2 diabetes mellitus (T2DM) and metabolic syndrome (MS), being a possible cause of these diseases. Therefore, their restoration at the early stages of T2DM and MS can be regarded as a promising way to treat and prevent these diseases and their complications. The data on the functional state of the brain signaling systems regulated by insulin, IGF-1, leptin, dopamine, serotonin, melanocortins and glucagon-like peptide-1, in T2DM and MS, are analyzed. The pharmacological approaches to restoration of these systems and improvement of insulin sensitivity, energy expenditure, lipid metabolism, and to prevent diabetic complications are discussed.
Collapse
|
10
|
Wang X, Yu Q, Yue H, Zeng S, Cui F. Effect of Intermittent Hypoxia and Rimonabant on Glucose Metabolism in Rats: Involvement of Expression of GLUT4 in Skeletal Muscle. Med Sci Monit 2015; 21:3252-60. [PMID: 26503060 PMCID: PMC4629628 DOI: 10.12659/msm.896039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background Obstructive sleep apnea (OSA) and its main feature, chronic intermittent hypoxia (IH) during sleep, is closely associated with insulin resistance (IR) and diabetes. Rimonabant can regulate glucose metabolism and improve IR. The present study aimed to assess the effect of IH and rimonabant on glucose metabolism and insulin sensitivity, and to explore the possible mechanisms. Material/Methods Thirty-two rats were randomly assigned into 4 groups: Control group, subjected to intermittent air only; IH group, subjected to IH only; IH+NS group, subjected to IH and treated with normal saline; and IH+Rim group, subjected to IH and treated with 10 mg/kg/day of rimonabant. All rats were killed after 28 days of exposure. Then, the blood and skeletal muscle were collected. We measured fasting blood glucose levels, fasting blood insulin levels, and the expression of glucose transporter 4 (GLUT4) in both mRNA and protein levels in skeletal muscle. Results IH can slow weight gain, increase serum insulin level, and reduce insulin sensitivity in rats. The expressions of GLUT4 mRNA, total GLUT4, and plasma membrane protein of GLUT4 (PM GLUT4) in skeletal muscle were decreased. Rimonabant treatment was demonstrated to improve weight gain and insulin sensitivity of the rats induced by IH. Rimonabant significantly upregulated the expression of GLUT4 mRNA, PM GLUT4, and total GLUT4 in skeletal muscle. Conclusions The present study demonstrates that IH can cause IR and reduced expression of GLUT4 in both mRNA and protein levels in skeletal muscle of rats. Rimonabant treatment can improve IH – induced IR, and the upregulation of GLUT4 expression may be involved in this process.
Collapse
Affiliation(s)
- Xiaoya Wang
- Department of Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China (mainland)
| | - Qin Yu
- Department of Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China (mainland)
| | - Hongmei Yue
- Department of Respiratory Medicine, The First Hospital of Lanzhou University, Lanzhou, Gansu, China (mainland)
| | - Shuang Zeng
- The First Clinical Medical College of Lanzhou University, Lanzhou, Gansu, China (mainland)
| | - Fenfen Cui
- The First Clinical Medical College of Lanzhou University, Lanzhou, Gansu, China (mainland)
| |
Collapse
|
11
|
Denroche HC, Kwon MM, Quong WL, Neumann UH, Kulpa JE, Karunakaran S, Clee SM, Brownsey RW, Covey SD, Kieffer TJ. Leptin induces fasting hypoglycaemia in a mouse model of diabetes through the depletion of glycerol. Diabetologia 2015; 58:1100-8. [PMID: 25715699 DOI: 10.1007/s00125-015-3529-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 01/28/2015] [Indexed: 12/27/2022]
Abstract
AIMS/HYPOTHESIS Leptin has profound glucose-lowering effects in rodent models of type 1 diabetes, and is currently being tested clinically to treat this disease. In addition to reversing hyperglycaemia, leptin therapy corrects multiple lipid, energy and neuroendocrine imbalances in rodent models of type 1 diabetes, yet the precise mechanism has not been fully defined. Thus, we performed metabolic analyses to delineate the downstream metabolic pathway mediating leptin-induced glucose lowering in diabetic mice. METHODS Mice were injected with streptozotocin (STZ) to induce insulin-deficient diabetes, and were subsequently treated with 20 μg/day recombinant murine leptin or vehicle for 5 to 14 days. Energy-yielding substrates were measured in the liver and plasma, and endogenous glucose production was assessed by tolerance to extended fasting. RESULTS STZ-leptin-treated mice developed severe hypoketotic hypoglycaemia during prolonged fasting, indicative of suppressed endogenous ketone and glucose production. STZ-leptin mice displayed normal gluconeogenic and glycogenolytic capacity, but had depleted circulating glycerol and NEFA. The depletion of glycerol and NEFA correlated tightly with the kinetics of glucose lowering in response to chronic leptin administration, and was not mimicked by single leptin injection. Administration of glycerol acutely reversed fasting-induced hypoglycaemia in leptin-treated mice. CONCLUSIONS/INTERPRETATION The findings of this study suggest that the diminution of circulating glycerol reduces endogenous glucose production, contributing to severe fasting-induced hypoglycaemia in leptin-treated rodent models of type 1 diabetes, and support that depletion of glycerol contributes to the glucose-lowering action of leptin.
Collapse
Affiliation(s)
- Heather C Denroche
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
| | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
Collapse
Affiliation(s)
- Heather C Denroche
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, The Life Sciences Institute ; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
13
|
Zhuang XD, Hu X, Long M, Dong XB, Liu DH, Liao XX. Exogenous hydrogen sulfide alleviates high glucose-induced cardiotoxicity via inhibition of leptin signaling in H9c2 cells. Mol Cell Biochem 2014; 391:147-55. [PMID: 24687304 DOI: 10.1007/s11010-014-1997-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 02/21/2014] [Indexed: 11/24/2022]
Abstract
Hydrogen sulfide (H₂S) protects cardiomyoblasts against high glucose (HG)-induced injury by inhibiting the activation of p38 mitogen-activated protein kinase (MAPK). This study aims to determine whether the leptin-p38 MAPK pathway is involved in HG-induced injury and whether exogenous H2S prevents the HG-induced insult through inhibition of the leptin-p38 MAPK pathway in H9c2 cells. H9c2 cells were treated with 35 mM glucose (HG) for 24 h to establish a HG-induced cardiomyocyte injury model. Cell viability; mitochondrial membrane potential (ΔΨ m); apoptosis; reactive oxygen species (ROS) level; and leptin, leptin receptor, and p38 MAPK expression level were measured by the methods indicated. The results showed pretreatment of H9c2 cells with NaHS before exposure to HG led to an increase in cell viability, decrease in apoptotic cells, ROS generation, and a loss of ΔΨ m. Exposure of H9c2 cells to 35 mM glucose for 24 h significantly upregulated the expression levels of leptin and leptin receptors. The increased expression levels of leptin and leptin receptors were markedly attenuated by pretreatment with 400 μM NaHS. In addition, the HG-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with 50 ng/ml leptin antagonist. In conclusion, the present study has demonstrated for the first time that the leptin-p38 MAPK pathway contributes to the HG-induced injury in H9c2 cells and that exogenous H₂S protects H9c2 cells against HG-induced injury at least in part by inhibiting the activation of leptin-p38 MAPK pathway.
Collapse
Affiliation(s)
- Xiao-Dong Zhuang
- Department of Cardiovasology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, People's Republic of China
| | | | | | | | | | | |
Collapse
|
14
|
Meek TH, Matsen ME, Dorfman MD, Guyenet SJ, Damian V, Nguyen HT, Taborsky GJ, Morton GJ. Leptin action in the ventromedial hypothalamic nucleus is sufficient, but not necessary, to normalize diabetic hyperglycemia. Endocrinology 2013; 154:3067-76. [PMID: 23782941 PMCID: PMC3749482 DOI: 10.1210/en.2013-1328] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In rodent models of type 1 diabetes, leptin administration into brain ventricles normalizes blood glucose at doses that have no effect when given peripherally. The ventromedial nucleus of the hypothalamus (VMN) is a potential target for leptin's antidiabetic effects because leptin-sensitive neurons in this brain area are implicated in glucose homeostasis. To test this hypothesis, we injected leptin directly into the bilateral VMN of rats with streptozotocin-induced uncontrolled diabetes mellitus. This intervention completely normalized both hyperglycemia and the elevated rates of hepatic glucose production and plasma glucagon levels but had no effect on tissue glucose uptake in the skeletal muscle or brown adipose tissue as measured using tracer dilution techniques during a basal clamp. To determine whether VMN leptin signaling is required for leptin-mediated normalization of diabetic hyperglycemia, we studied mice in which the leptin receptor gene was deleted in VMN steroidogenic factor 1 neurons using cre-loxP technology. Our findings indicate leptin action within these neurons is not required for the correction of diabetic hyperglycemia by central leptin infusion. We conclude that leptin signaling in the VMN is sufficient to mediate leptin's antidiabetic action but may not be necessary for this effect. Leptin action within a distributed neuronal network may mediate its effects on glucose homeostasis.
Collapse
MESH Headings
- Animals
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 1/pathology
- Glucagon/blood
- Glucagon/metabolism
- Glucagon-Secreting Cells/drug effects
- Glucagon-Secreting Cells/metabolism
- Gluconeogenesis/drug effects
- Hyperglycemia/prevention & control
- Hypoglycemic Agents/administration & dosage
- Hypoglycemic Agents/metabolism
- Hypoglycemic Agents/therapeutic use
- Infusions, Intraventricular
- Injections, Intraventricular
- Leptin/administration & dosage
- Leptin/genetics
- Leptin/metabolism
- Leptin/therapeutic use
- Liver/drug effects
- Liver/metabolism
- Male
- Mice
- Mice, Knockout
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Neurons/pathology
- Rats
- Rats, Wistar
- Receptors, Leptin/agonists
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Recombinant Proteins/administration & dosage
- Recombinant Proteins/metabolism
- Recombinant Proteins/therapeutic use
- Signal Transduction/drug effects
- Ventromedial Hypothalamic Nucleus/drug effects
- Ventromedial Hypothalamic Nucleus/metabolism
- Ventromedial Hypothalamic Nucleus/pathology
Collapse
Affiliation(s)
- Thomas H Meek
- Diabetes and Obesity Center of Excellence, University of Washington at South Lake Union, 850 Republican Street, N334, Box 358055, Seattle, Washington 98195, USA
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Meek TH, Wisse BE, Thaler JP, Guyenet SJ, Matsen ME, Fischer JD, Taborsky GJ, Schwartz MW, Morton GJ. BDNF action in the brain attenuates diabetic hyperglycemia via insulin-independent inhibition of hepatic glucose production. Diabetes 2013; 62:1512-8. [PMID: 23274899 PMCID: PMC3636618 DOI: 10.2337/db12-0837] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [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
Recent evidence suggests that central leptin administration fully normalizes hyperglycemia in a rodent model of uncontrolled insulin-deficient diabetes by reducing hepatic glucose production (HGP) and by increasing glucose uptake. The current studies were undertaken to determine whether brain-derived neurotrophic factor (BDNF) action in the brain lowers blood glucose in uncontrolled insulin-deficient diabetes and to investigate the mechanisms mediating this effect. Adult male rats implanted with cannulas to either the lateral cerebral ventricle or the ventromedial hypothalamic nucleus (VMN) received either vehicle or streptozotocin to induce uncontrolled insulin-deficient diabetes. Three days later, animals received daily intracerebroventricular or intra-VMN injections of either BDNF or its vehicle. We found that repeated daily intracerebroventricular administration of BDNF attenuated diabetic hyperglycemia independent of changes in food intake. Instead, using tracer dilution techniques during a basal clamp, we found that BDNF lowered blood glucose levels by potently suppressing HGP, without affecting tissue glucose uptake, an effect associated with normalization of both plasma glucagon levels and hepatic expression of gluconeogenic genes. Moreover, BDNF microinjection directly into the VMN also lowered fasting blood glucose levels in uncontrolled insulin-deficient diabetes, but this effect was modest compared with intracerebroventricular administration. We conclude that central nervous system BDNF attenuates diabetic hyperglycemia via an insulin-independent mechanism. This action of BDNF likely involves the VMN and is associated with inhibition of glucagon secretion and a decrease in the rate of HGP.
Collapse
Affiliation(s)
- Thomas H. Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Brent E. Wisse
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Joshua P. Thaler
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Stephan J. Guyenet
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Miles E. Matsen
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Jonathan D. Fischer
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Gerald J. Taborsky
- Veterans Affairs Puget Sound Health Care System, Veterans Affairs Medical Center, Seattle, Washington
| | - Michael W. Schwartz
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
| | - Gregory J. Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, Washington
- Corresponding author: Gregory J. Morton,
| |
Collapse
|
16
|
Amitani M, Asakawa A, Amitani H, Inui A. The role of leptin in the control of insulin-glucose axis. Front Neurosci 2013; 7:51. [PMID: 23579596 PMCID: PMC3619125 DOI: 10.3389/fnins.2013.00051] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/18/2013] [Indexed: 12/21/2022] Open
Abstract
Obesity and diabetes mellitus are great public health concerns throughout the world because of their increasing incidence and prevalence. Leptin, the adipocyte hormone, is well known for its role in the regulation of food intake and energy expenditure. In addition to the regulation of appetite and satiety that recently has attracted much attentions, insight has also been gained into the critical role of leptin in the control of the insulin-glucose axis, peripheral glucose and insulin responsiveness. Since the discovery of leptin, leptin has been taken for its therapeutic potential to obesity and diabetes. Recently, the therapeutic effects of central leptin gene therapy have been reported in insulin-deficient diabetes in obesity animal models such as ob/ob mise, diet-induced obese mice, and insulin-deficient type 1 diabetes mice, and also in patients with inactivating mutations in the leptin gene. Herein, we review the role of leptin in regulating feeding behavior and glucose metabolism and also the therapeutic potential of leptin in obesity and diabetes mellitus.
Collapse
Affiliation(s)
- Marie Amitani
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima, Japan
| | | | | | | |
Collapse
|
17
|
Abstract
Diabetes is a major worldwide problem. Despite some progress in the development of new antidiabetic agents, the ability to maintain tight glycemic control in order to prevent renal, retinal, and neuropathic complications of diabetes without adverse complications still remains a challenge. Recent evidence suggests, however, that in addition to playing a key role in the regulation of energy homeostasis, the adiposity hormone leptin also plays an important role in the control of glucose metabolism via its actions in the brain. This review examines the role of leptin action in the central nervous system and the mechanisms whereby leptin mediates its effects to regulate glucose metabolism. These findings suggest that defects or dysfunction in leptin signaling may contribute to the etiology of diabetes and raise the possibility that either leptin or downstream targets of leptin may have therapeutic potential for the treatment of diabetes.
Collapse
Affiliation(s)
- Thomas H. Meek
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Gregory J. Morton
- Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, WA, USA
| |
Collapse
|
18
|
Minokoshi Y, Toda C, Okamoto S. Regulatory role of leptin in glucose and lipid metabolism in skeletal muscle. Indian J Endocrinol Metab 2012; 16:S562-S568. [PMID: 23565491 PMCID: PMC3602985 DOI: 10.4103/2230-8210.105573] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Leptin is a hormone secreted by adipocytes that plays a pivotal role in regulation of food intake, energy expenditure, and neuroendocrine function. Several lines of evidences indicate that independent of the anorexic effect, leptin regulates glucose and lipid metabolism in peripheral tissues in rodents and humans. It has been shown that leptin improves the diabetes phenotype in lipodystrophic patients and rodents. Moreover, leptin suppresses the development of severe, progressive impairment of glucose metabolism in insulin-deficient diabetes in rodents. We found that leptin increases glucose uptake and fatty acid oxidation in skeletal muscle in rats and mice in vivo. Leptin increases glucose uptake in skeletal muscle via the hypothalamic-sympathetic nervous system axis and β-adrenergic mechanism, while leptin stimulates fatty acid oxidation in muscle via AMP-activated protein kinase (AMPK). Leptin-induced fatty acid oxidation results in the decrease of lipid accumulation in muscle, which can lead to functional impairments called as "lipotoxicity." Activation of AMPK occurs by direct action of leptin on muscle and through the medial hypothalamus-sympathetic nervous system and α-adrenergic mechanism. Thus, leptin plays an important role in the regulation of glucose and fatty acid metabolism in skeletal muscle.
Collapse
Affiliation(s)
- Yasuhiko Minokoshi
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Myodaiji, Okazaki, Aichi - 444-8787, Japan
| | - Chitoku Toda
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Myodaiji, Okazaki, Aichi - 444-8787, Japan
| | - Shiki Okamoto
- Division of Endocrinology and Metabolism, National Institute for Physiological Sciences, Myodaiji, Okazaki, Aichi - 444-8787, Japan
| |
Collapse
|
19
|
Nakano M, Asakawa A, Inui A. Long-term correction of type 1 and 2 diabetes by central leptin gene therapy independent of effects on appetite and energy expenditure. Indian J Endocrinol Metab 2012; 16:S556-S561. [PMID: 23565490 PMCID: PMC3602984 DOI: 10.4103/2230-8210.105572] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Adipocyte-derived leptin is a hormone associated with the regulation of energy homeostasis, including glucose metabolism. Hyperleptinemia, induced by the consumption of energy-enriched diets, inhibits leptin transport across the blood-brain barrier, and thereby produces leptin insufficiency in the hypothalamus. As a result of sustained leptin insufficiency, the hypothalamic restraint on pancreatic insulin secretion is lost. Additionally, both glucose metabolism and energy expenditure are also diminished, and both type 1 and type 2 diabetes are induced. A replication-deficient recombinant adeno-associated virus vector engineered to encode the leptin gene (rAVV-LEP) has been used in models of diabetes as a novel therapeutic approach. After rAVV-LEP injection in ob/ob mice, hypothalamic leptin expression was increased, body weight was suppressed, and hyperinsulinemia was ameliorated. Additionally injection of rAVV-LEP into the hypothalamus suppressed the expression of orexigenic neuropeptide Y (NPY) and enhanced anorexigenic pro-opiomelanocortin (POMC) in the arcuate nucleus (ARC) in rats. It is proposed that central leptin gene therapy should be tested clinically to reduce the worldwide epidemic of obesity, diabetes, and shortened life span. In this article, the information has been assembled from published review articles on this topic.
Collapse
Affiliation(s)
- Masako Nakano
- Department of Social and Behavioral Medicine, Kagoshima University Graduate Medical and Dental Sciences, Kagoshima, Japan
| | - Akihiro Asakawa
- Department of Social and Behavioral Medicine, Kagoshima University Graduate Medical and Dental Sciences, Kagoshima, Japan
| | - Akio Inui
- Department of Social and Behavioral Medicine, Kagoshima University Graduate Medical and Dental Sciences, Kagoshima, Japan
| |
Collapse
|
20
|
Affiliation(s)
- Satya P. Kalra
- Department of Neuroscience and McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA
| |
Collapse
|
21
|
Shpakov AO, Derkach KV, Chistyakova OV, Moyseyuk IV, Bondareva VM. Alteration of hormonal sensitivity of adenylyl cyclase in the brain of rats with prolonged streptozotocin diabetes. DOKL BIOCHEM BIOPHYS 2012; 446:217-9. [PMID: 23132712 DOI: 10.1134/s160767291205002x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Indexed: 11/23/2022]
Affiliation(s)
- A O Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | | | | | | | | |
Collapse
|
22
|
Coppari R, Bjørbæk C. Leptin revisited: its mechanism of action and potential for treating diabetes. Nat Rev Drug Discov 2012; 11:692-708. [PMID: 22935803 PMCID: PMC4019022 DOI: 10.1038/nrd3757] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Since the discovery of leptin in 1994, we now have a better understanding of the cellular and molecular mechanisms underlying its biological effects. In addition to its established anti-obesity effects, leptin exerts antidiabetic actions that are independent of its regulation of body weight and food intake. In particular, leptin can correct diabetes in animal models of type 1 and type 2 diabetes. In addition, long-term leptin replacement therapy improves glycaemic control, insulin sensitivity and plasma triglycerides in patients with severe insulin resistance due to lipodystrophy. These results have spurred enthusiasm for the use of leptin therapy to treat diabetes. Here, we review the current understanding of the glucoregulatory functions of leptin, emphasizing its central mechanisms of action and lessons learned from clinical studies, and discuss possible therapeutic applications of leptin in the treatment of type 1 and type 2 diabetes.
Collapse
Affiliation(s)
- Roberto Coppari
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas TX, 75390, USA
- Department of Cellular Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
- The Center for Epigenetics and Metabolism, University of California Irvine, Irvine, CA, 92697, USA
| | - Christian Bjørbæk
- Department of Medicine, Division of Endocrinology and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston MA, 02215, USA
| |
Collapse
|
23
|
Marroquí L, Gonzalez A, Ñeco P, Caballero-Garrido E, Vieira E, Ripoll C, Nadal A, Quesada I. Role of leptin in the pancreatic β-cell: effects and signaling pathways. J Mol Endocrinol 2012; 49:R9-17. [PMID: 22448029 DOI: 10.1530/jme-12-0025] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Leptin plays an important role in the control of food intake, energy expenditure, metabolism, and body weight. This hormone also has a key function in the regulation of glucose homeostasis. Although leptin acts through central and peripheral mechanisms to modulate glucose metabolism, the pancreatic β-cell of the endocrine pancreas is a critical target of leptin actions. Leptin receptors are present in the β-cell, and their activation directly inhibits insulin secretion from these endocrine cells. The effects of leptin on insulin occur also in the long term, since this hormone inhibits insulin gene expression as well. Additionally, β-cell mass can be affected by leptin through changes in proliferation, apoptosis, or cell size. All these different functions in the β-cell are triggered by leptin as a result of the large diversity of signaling pathways that this hormone is able to activate in the endocrine pancreas. Therefore, leptin can participate in glucose homeostasis owing to different levels of modulation of the pancreatic β-cell population. Furthermore, it has been proposed that alterations in this level of regulation could contribute to the impairment of β-cell function in obesity states. In the present review, we will discuss all these issues with special emphasis on the effects and pathways of leptin signaling in the pancreatic β-cell.
Collapse
Affiliation(s)
- Laura Marroquí
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas-CIBERDEM, Elche, Spain
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Silva E, Paczkowski M, Krisher RL. The effect of leptin on maturing porcine oocytes is dependent on glucose concentration. Mol Reprod Dev 2012; 79:296-307. [PMID: 22368147 DOI: 10.1002/mrd.22029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 01/27/2012] [Indexed: 12/23/2022]
Abstract
Increased body weight is often accompanied by increased circulating levels of leptin and glucose, which alters glucose metabolism in various tissues, including perhaps the oocyte. Alteration of glucose metabolism impacts oocyte function and may contribute to the subfertility often associated with obese individuals. The objective of this study was to determine the effect of leptin (0, 10, and 100 ng/ml) on the oocyte and cumulus cells during in vitro maturation under differing glucose concentrations. We examined the effects of leptin on oocyte maturation, blastocyst development, and/or gene expression in oocytes and cumulus cells (IRS1, IGF1, PPARγ, IL6, GLUT1) in a physiological glucose (2 mM) and high glucose (50 mM) environment. We also evaluated the effect of leptin on glucose metabolism via glycolysis and the pentose phosphate pathway. In a physiological glucose environment, leptin did not have an influence on oocyte maturation, blastocyst development, or oocyte gene expression. Expression of GLUT1 in cumulus cells was downregulated with 100 ng/ml leptin treatment, but did not affect oocyte glucose metabolism. In a high glucose environment, oocyte maturation and glycolysis were decreased, but in the presence of 100 ng/ml leptin, these parameters were improved to levels similar to control. This effect is potentially mediated by an upregulation of oocyte IRS1 and a correction of cumulus cell IGF1 expression. The present study demonstrates that in a physiological glucose concentration, leptin plays a negligible role in oocyte function. However, leptin appears to modulate the deleterious impact of a high glucose environment on oocyte function.
Collapse
Affiliation(s)
- Elena Silva
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | | | | |
Collapse
|
25
|
Marino JS, Xu Y, Hill JW. Central insulin and leptin-mediated autonomic control of glucose homeostasis. Trends Endocrinol Metab 2011; 22:275-85. [PMID: 21489811 PMCID: PMC5154334 DOI: 10.1016/j.tem.2011.03.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 02/25/2011] [Accepted: 03/05/2011] [Indexed: 12/17/2022]
Abstract
Largely as a result of rising obesity rates, the incidence of type 2 diabetes is escalating rapidly. Type 2 diabetes results from multi-organ dysfunctional glucose metabolism. Recent publications have highlighted hypothalamic insulin- and adipokine-sensing as a major determinant of peripheral glucose and insulin responsiveness. The preponderance of evidence indicates that the brain is the master regulator of glucose homeostasis, and that hypothalamic insulin and leptin signaling in particular play a crucial role in the development of insulin resistance. This review discusses the neuronal crosstalk between the hypothalamus, autonomic nervous system, and tissues associated with the pathogenesis of type 2 diabetes, and how hypothalamic insulin and leptin signaling are integral to maintaining normal glucose homeostasis.
Collapse
Affiliation(s)
- Joseph S Marino
- Center for Diabetes and Endocrine Research, College of Medicine, The University of Toledo, Toledo, OH 43614, USA
| | | | | |
Collapse
|
26
|
Gautron L, Elmquist JK. Sixteen years and counting: an update on leptin in energy balance. J Clin Invest 2011; 121:2087-93. [PMID: 21633176 DOI: 10.1172/jci45888] [Citation(s) in RCA: 245] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cloned in 1994, the ob gene encodes the protein hormone leptin, which is produced and secreted by white adipose tissue. Since its discovery, leptin has been found to have profound effects on behavior, metabolic rate, endocrine axes, and glucose fluxes. Leptin deficiency in mice and humans causes morbid obesity, diabetes, and various neuroendocrine anomalies, and replacement leads to decreased food intake, normalized glucose homeostasis, and increased energy expenditure. Here, we provide an update on the most current understanding of leptin-sensitive neural pathways in terms of both anatomical organization and physiological roles.
Collapse
Affiliation(s)
- Laurent Gautron
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | |
Collapse
|
27
|
Denroche HC, Levi J, Wideman RD, Sequeira RM, Huynh FK, Covey SD, Kieffer TJ. Leptin therapy reverses hyperglycemia in mice with streptozotocin-induced diabetes, independent of hepatic leptin signaling. Diabetes 2011; 60:1414-23. [PMID: 21464443 PMCID: PMC3292314 DOI: 10.2337/db10-0958] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE Leptin therapy has been found to reverse hyperglycemia and prevent mortality in several rodent models of type 1 diabetes. Yet the mechanism of leptin-mediated reversal of hyperglycemia has not been fully defined. The liver is a key organ regulating glucose metabolism and is also a target of leptin action. Thus we hypothesized that exogenous leptin administered to mice with streptozotocin (STZ)-induced diabetes reverses hyperglycemia through direct action on hepatocytes. RESEARCH DESIGN AND METHODS After the induction of diabetes in mice with a high dose of STZ, recombinant mouse leptin was delivered at a supraphysiological dose for 14 days by an osmotic pump implant. We characterized the effect of leptin administration in C57Bl/6J mice with STZ-induced diabetes and then examined whether leptin therapy could reverse STZ-induced hyperglycemia in mice in which hepatic leptin signaling was specifically disrupted. RESULTS Hyperleptinemia reversed hyperglycemia and hyperketonemia in diabetic C57Bl/6J mice and dramatically improved glucose tolerance. These effects were associated with reduced plasma glucagon and growth hormone levels and dramatically enhanced insulin sensitivity, without changes in glucose uptake by skeletal muscle. Leptin therapy also ameliorated STZ-induced hyperglycemia and hyperketonemia in mice with disrupted hepatic leptin signaling to a similar extent as observed in wild-type littermates with STZ-induced diabetes. CONCLUSIONS These observations reveal that hyperleptinemia reverses the symptoms of STZ-induced diabetes in mice and that this action does not require direct leptin signaling in the liver.
Collapse
Affiliation(s)
- Heather C. Denroche
- 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
| | - Rhonda D. Wideman
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Roveena M. Sequeira
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Frank K. Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Scott D. Covey
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - 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 author: Timothy J. Kieffer,
| |
Collapse
|
28
|
Poplawski MM, Mastaitis JW, Isoda F, Grosjean F, Zheng F, Mobbs CV. Reversal of diabetic nephropathy by a ketogenic diet. PLoS One 2011; 6:e18604. [PMID: 21533091 PMCID: PMC3080383 DOI: 10.1371/journal.pone.0018604] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 03/11/2011] [Indexed: 01/15/2023] Open
Abstract
Intensive insulin therapy and protein restriction delay the development of nephropathy in a variety of conditions, but few interventions are known to reverse nephropathy. Having recently observed that the ketone 3-beta-hydroxybutyric acid (3-OHB) reduces molecular responses to glucose, we hypothesized that a ketogenic diet, which produces prolonged elevation of 3-OHB, may reverse pathological processes caused by diabetes. To address this hypothesis, we assessed if prolonged maintenance on a ketogenic diet would reverse nephropathy produced by diabetes. In mouse models for both Type 1 (Akita) and Type 2 (db/db) diabetes, diabetic nephropathy (as indicated by albuminuria) was allowed to develop, then half the mice were switched to a ketogenic diet. After 8 weeks on the diet, mice were sacrificed to assess gene expression and histology. Diabetic nephropathy, as indicated by albumin/creatinine ratios as well as expression of stress-induced genes, was completely reversed by 2 months maintenance on a ketogenic diet. However, histological evidence of nephropathy was only partly reversed. These studies demonstrate that diabetic nephropathy can be reversed by a relatively simple dietary intervention. Whether reduced glucose metabolism mediates the protective effects of the ketogenic diet remains to be determined.
Collapse
Affiliation(s)
- Michal M. Poplawski
- Fishberg Center for Neurobiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Jason W. Mastaitis
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Fumiko Isoda
- Fishberg Center for Neurobiology, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Fabrizio Grosjean
- Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Feng Zheng
- Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, New York, United States of America
| | - Charles V. Mobbs
- Fishberg Center for Neurobiology, Mount Sinai School of Medicine, New York, New York, United States of America
- * E-mail:
| |
Collapse
|
29
|
German JP, Thaler JP, Wisse BE, Oh-I S, Sarruf DA, Matsen ME, Fischer JD, Taborsky GJ, Schwartz MW, Morton GJ. Leptin activates a novel CNS mechanism for insulin-independent normalization of severe diabetic hyperglycemia. Endocrinology 2011; 152:394-404. [PMID: 21159853 PMCID: PMC3037161 DOI: 10.1210/en.2010-0890] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The brain has emerged as a target for the insulin-sensitizing effects of several hormonal and nutrient-related signals. The current studies were undertaken to investigate mechanisms whereby leptin lowers circulating blood glucose levels independently of insulin. After extending previous evidence that leptin infusion directly into the lateral cerebral ventricle ameliorates hyperglycemia in rats with streptozotocin-induced uncontrolled diabetes mellitus, we showed that the underlying mechanism is independent of changes of food intake, urinary glucose excretion, or recovery of pancreatic β-cells. Instead, leptin action in the brain potently suppresses hepatic glucose production while increasing tissue glucose uptake despite persistent, severe insulin deficiency. This leptin action is distinct from its previously reported effect to increase insulin sensitivity in the liver and offers compelling evidence that the brain has the capacity to normalize diabetic hyperglycemia in the presence of sufficient amounts of central nervous system leptin.
Collapse
Affiliation(s)
- Jonathan P German
- Department of Medicine, University of Washington at South Lake Union, 815 Mercer Street, N334, PO Box 358055, Seattle, Washington 98195, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Wang Y, Asakawa A, Inui A, Kosai KI. Leptin gene therapy in the fight against diabetes. Expert Opin Biol Ther 2011; 10:1405-14. [PMID: 20690892 DOI: 10.1517/14712598.2010.512286] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
IMPORTANCE OF THE FIELD The incidence of diabetes is increasing worldwide, yet current treatments are not always effective for all patient or disease types. AREAS COVERED IN THIS REVIEW Here, we summarize the biologic and clinical roles of leptin in diabetes, and discuss candidate viral vectors that may be employed in the clinical use of central leptin gene therapy for diabetes. WHAT THE READER WILL GAIN We discuss how studies on leptin, a regulator of the insulin-glucose axis, have significantly advanced our understanding of the roles of energy homeostasis and insulin resistance in the pathogeneses of metabolic syndrome and diabetes. Recent studies have demonstrated the long-term therapeutic effects of central leptin gene therapy in obesity and diabetes via decreased insulin resistance and increased glucose metabolism. Many of these studies have employed viral vectors, which afford high in vivo gene transduction efficiencies compared with non-viral vectors. TAKE HOME MESSAGE Adeno-associated viral vectors are particularly well suited for central leptin gene therapy owing to their low toxicity and ability to drive transgene expression for extended periods.
Collapse
Affiliation(s)
- Yuqing Wang
- Kagoshima University Graduate School of Medical and Dental Sciences, Department of Gene Therapy and Regenerative Medicine, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan
| | | | | | | |
Collapse
|
31
|
Kalra SP. Pivotal role of leptin-hypothalamus signaling in the etiology of diabetes uncovered by gene therapy: a new therapeutic intervention? Gene Ther 2011; 18:319-25. [PMID: 21209624 DOI: 10.1038/gt.2010.164] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The incidence of diabetes mellitus has soared to epidemic proportion worldwide. The debilitating chronic hyperglycemia is caused by either lack of insulin as in diabetes type 1 or its ineffectiveness as in diabetes type 2. Frequent replacement of insulin with or without insulin analogs for optimum glycemic control are the conventional cumbersome therapies. Recent application of leptin gene transfer technology has uncovered the participation of adipocytes-derived leptin-dependent hypothalamic neural signaling in glucose homeostasis and demonstrated that a breakdown in this communication due to leptin insufficiency in the hypothalamus underlies the etiology of chronic hyperglycemia. Reinstatement of central leptin sufficiency by hyperleptinemia produced either by intravenous leptin infusion or a single systemic injection of recombinant adenovirus vector encoding leptin gene suppressed hyperglycemia and evoked euglycemia only transiently in rodent models of diabetes type 1. In contrast, stable restoration of leptin sufficiency, solely in the hypothalamus, with biologically active leptin transduced by an intracerebroventicular injection of recombinant adeno-associated virus vector encoding leptin gene (rAAV-lep) abolished hyperglycemia and imposed euglycemia through the extended duration of experiment by stimulating glucose disposal in the periphery in models of diabetes type 1. Further, similar hypothalamic leptin transgene expression abrogated chronic hyperglycemia and hyperinsulinemia, the predisposing risk factors of the age and environmentally acquired diabetes type 2, and instituted euglycemia by independently activating relays that stimulate glucose metabolism and repress hyperinsulinemia and improve insulin sensitivity in the periphery. Consequently, this durable antidiabetic efficacy of one time rAAV-lep neurotherapy offers a potential novel substitute for insulin therapy following preclinical trials in subhuman primates and humans.
Collapse
Affiliation(s)
- S P Kalra
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610-0244, USA.
| |
Collapse
|
32
|
Drager LF, Jun JC, Polotsky VY. Metabolic consequences of intermittent hypoxia: relevance to obstructive sleep apnea. Best Pract Res Clin Endocrinol Metab 2010; 24:843-51. [PMID: 21112030 PMCID: PMC3011976 DOI: 10.1016/j.beem.2010.08.011] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway leading to sleep fragmentation and intermittent hypoxia (IH) during sleep. There is growing evidence from animal models of OSA that IH is independently associated with metabolic dysfunction, including dyslipidemia and insulin resistance. The precise mechanisms by which IH induces metabolic disturbances are not fully understood. Over the last decade, several groups of investigators developed a rodent model of IH, which emulates the oxyhemoglobin profile in human OSA. In the mouse model, IH induces dyslipidemia, insulin resistance and pancreatic endocrine dysfunction, similar to those observed in human OSA. Recent reports provided new insights in possible mechanisms by which IH affects lipid and glucose metabolism. IH may induce dyslipidemia by up-regulating lipid biosynthesis in the liver, increasing adipose tissue lipolysis with subsequent free fatty acid flux to the liver, and inhibiting lipoprotein clearance. IH may affect glucose metabolism by inducing sympathetic activation, increasing systemic inflammation, increasing counter-regulatory hormones and fatty acids, and causing direct pancreatic beta-cell injury. IH models of OSA have improved our understanding of the metabolic impact of OSA, but further studies are needed before we can translate recent basic research findings to clinical practice.
Collapse
Affiliation(s)
- Luciano F Drager
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA
| | | | | |
Collapse
|
33
|
Leptin therapy improves insulin-deficient type 1 diabetes by CNS-dependent mechanisms in mice. Proc Natl Acad Sci U S A 2010; 107:17391-6. [PMID: 20855609 DOI: 10.1073/pnas.1008025107] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Leptin monotherapy reverses the deadly consequences and improves several of the metabolic imbalances caused by insulin-deficient type 1 diabetes (T1D) in rodents. However, the mechanism(s) underlying these effects is totally unknown. Here, we report that intracerebroventricular (icv) infusion of leptin reverses lethality and greatly improves hyperglycemia, hyperglucagonemia, hyperketonemia, and polyuria caused by insulin deficiency in mice. Notably, icv leptin administration leads to increased body weight while suppressing food intake, thus correcting the catabolic consequences of T1D. Also, icv leptin delivery improves expression of the metabolically relevant hypothalamic neuropeptides proopiomelanocortin, neuropeptide Y, and agouti-related peptide in T1D mice. Furthermore, this treatment normalizes phosphoenolpyruvate carboxykinase 1 contents without affecting glycogen levels in the liver. Pancreatic β-cell regeneration does not underlie these beneficial effects of leptin, because circulating insulin levels were undetectable at basal levels and following a glucose overload. Also, pancreatic preproinsulin mRNA was completely absent in these icv leptin-treated T1D mice. Furthermore, the antidiabetic effects of icv leptin administration rapidly vanished (i.e., within 48 h) after leptin treatment was interrupted. Collectively, these results unveil a key role for the brain in mediating the antidiabetic actions of leptin in the context of T1D.
Collapse
|
34
|
Gray SL, Donald C, Jetha A, Covey SD, Kieffer TJ. Hyperinsulinemia precedes insulin resistance in mice lacking pancreatic beta-cell leptin signaling. Endocrinology 2010; 151:4178-86. [PMID: 20631001 DOI: 10.1210/en.2010-0102] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The adipocyte hormone leptin acts centrally and peripherally to regulate body weight and glucose homeostasis. The pancreatic beta-cell has been shown to be a key peripheral target of leptin, with leptin suppressing insulin synthesis and secretion from beta-cells both in vitro and in vivo. Mice with disrupted leptin signaling in beta-cells (lepr(flox/flox) RIPcre tg+ mice) display hyperinsulinemia, insulin resistance, glucose intolerance, obesity, and reduced fasting blood glucose. We hypothesized that hyperinsulinemia precedes the development of insulin resistance and increased adiposity in these mice with a defective adipoinsular axis. To determine the primary defect after impaired beta-cell leptin signaling, we treated lepr(flox/flox) RIPcre tg+ mice with the insulin sensitizer metformin or the insulin-lowering agent diazoxide with the rationale that pharmacological improvement of the primary defect would alleviate the secondary symptoms. We show that improving insulin sensitivity with metformin does not normalize hyperinsulinemia, whereas lowering insulin levels with diazoxide improves insulin sensitivity. Taken together, these results suggest that hyperinsulinemia precedes insulin resistance in beta-cell leptin receptor-deficient mice, with insulin resistance developing as a secondary consequence of excessive insulin secretion. Therefore, pancreatic beta-cell leptin receptor-deficient mice may represent a model of obesity-associated insulin resistance that is initiated by hyperinsulinemia.
Collapse
Affiliation(s)
- Sarah L Gray
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, 2350 Health Sciences Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | | | | | | | | |
Collapse
|
35
|
Wong MS, Hawthorne WJ, Manolios N. Gene therapy in diabetes. SELF NONSELF 2010; 1:165-175. [PMID: 21487475 DOI: 10.4161/self.1.3.12643] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Accepted: 06/09/2010] [Indexed: 12/17/2022]
Abstract
Type 1 diabetes (T1D) is a chronic autoimmune disease, whereby auto-reactive cytotoxic T cells target and destroy insulin-secreting β-cells in pancreatic islets leading to insulin deficiency and subsequent hyperglycemia. These individuals require multiple daily insulin injections every day of their life without which they will develop life-threatening diabetic ketoacidosis (DKA) and die. Gene therapy by viral vector and non-viral transduction may be useful techniques to treat T1D as it can be applied from many different angles; such as the suppression of autoreactive T cells to prevent islet destruction (prophylactic) or the replacement of the insulin gene (post-disease). The need for a better method for providing euglycemia arose from insufficient numbers of cadaver islets for transplantation and the immunosuppression required post-transplant. Ectopic expression of insulin or islet modification have been examined, but not perfected. This review examines the various gene transfer methods, gene therapy techniques used to date and promising novel techniques for the maintenance of euglycemia in the treatment of T1D.
Collapse
Affiliation(s)
- Mary S Wong
- Department of Rheumatology; University of Sydney; Sydney, NSW Australia
| | | | | |
Collapse
|
36
|
Neuroendocrine Control of Energy Homeostasis: Update on New Insights. PROGRESS IN BRAIN RESEARCH 2010; 181:17-33. [DOI: 10.1016/s0079-6123(08)81002-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
37
|
Kalra SP. Central leptin gene therapy ameliorates diabetes type 1 and 2 through two independent hypothalamic relays; a benefit beyond weight and appetite regulation. Peptides 2009; 30:1957-63. [PMID: 19647774 PMCID: PMC2755606 DOI: 10.1016/j.peptides.2009.07.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 07/22/2009] [Accepted: 07/23/2009] [Indexed: 01/12/2023]
Abstract
Although its role in energy homeostasis is firmly established, the evidence accumulated over a decade linking the adipocyte leptin-hypothalamus axis in the pathogenesis of diabetes mellitus has received little attention in the contemporary thinking. In this context various lines of evidence are collated here to show that (1) under the direction of leptin two independent relays emanating from the hypothalamus restrain insulin secretion from the pancreas and mobilize peripheral organs--liver, skeletal muscle and brown adipose tissue--to upregulate glucose disposal, and (2), leptin insufficiency in the hypothalamus produced by either leptinopenia or restriction of leptin transport across the blood brain barrier due to hyperleptinemia of obesity and aging, initiate antecedent pathophysiological sequalae of diabetes type 1 and 2. Further, we document here the efficacy of leptin replenishment in vivo, especially by supplying it to the hypothalamus with the aid of gene therapy, in preventing the antecedent pathophysiological sequalae--hyperinsulinemia, insulin resistance and hyperglycemia--in various animal models and clinical paradigms of diabetes type 1 and 2 with or without attendant obesity. Overall, the new insights on the long-lasting antidiabetic potential of two independent hypothalamic relays engendered by central leptin gene therapy and the preclinical safety indicators in rodents warrant further validation in subhuman primates and humans.
Collapse
Affiliation(s)
- Satya P Kalra
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, PO Box 100244, Gainesville, FL 32610-0244, United States.
| |
Collapse
|