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Misch M, Puthanveetil P. The Head-to-Toe Hormone: Leptin as an Extensive Modulator of Physiologic Systems. Int J Mol Sci 2022; 23:ijms23105439. [PMID: 35628271 PMCID: PMC9141226 DOI: 10.3390/ijms23105439] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/30/2022] [Accepted: 05/10/2022] [Indexed: 12/12/2022] Open
Abstract
Leptin is a well-known hunger-sensing peptide hormone. The role of leptin in weight gain and metabolic homeostasis has been explored for the past two decades. In this review, we have tried to shed light upon the impact of leptin signaling on health and diseases. At low or moderate levels, this peptide hormone supports physiological roles, but at chronically higher doses exhibits detrimental effects on various systems. The untoward effects we observe with chronically higher levels of leptin are due to their receptor-mediated effect or due to leptin resistance and are not well studied. This review will help us in understanding the non-anorexic roles of leptin, including their contribution to the metabolism of various systems and inflammation. We will be able to get an alternative perspective regarding the physiological and pathological roles of this mysterious peptide hormone.
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Affiliation(s)
- Monica Misch
- Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, IL 60515, USA;
| | - Prasanth Puthanveetil
- Department of Pharmacology, College of Graduate Studies, Midwestern University, Downers Grove, IL 60515, USA
- Correspondence: ; Tel.: +1-630-960-3935
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Characteristics of NAFLD Based on Hypopituitarism. Can J Gastroenterol Hepatol 2020; 2020:8814435. [PMID: 33102399 PMCID: PMC7569462 DOI: 10.1155/2020/8814435] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/17/2020] [Accepted: 09/28/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Hypopituitarism and hypothalamic disorders, which induce central obesity and appetite disorder, are associated with nonalcoholic fatty liver disease (NAFLD). We retrospectively analyzed the clinical features of NAFLD patients with hypopituitarism. Patients. We examined the cases of 15 NAFLD patients with hypopituitarism (mean age, 39.4 years; males/females, 11/4). The causes of hypopituitarism were surgical in eight cases (six with craniopharyngioma and two with prolactinoma) and nonsurgical in seven cases, including unexplained hypopituitarism in five cases, Sheehan syndrome in one case, and one case that occurred after the radiation therapy. Serum adiponectin, soluble tumor necrosis factor receptor-2 (TNFR-2), and leptin levels were measured. RESULTS We compared the cases of the eight patients who underwent cranial surgery due to craniopharyngioma or prolactinoma and seven nonsurgical cases. The body mass index (surgery group, 30.2 ± 4.1; nonsurgery group, 29.2 ± 14.2) and the rate of diabetes (75% in surgery group, 14.3% in nonsurgery group) tended to be higher in the surgery group, and the hepatic fibrosis grade (surgery group, 3.75 ± 0.38; nonsurgery group, 1.64 ± 1.07) was significantly higher in the surgery group. The levels of adipocytokines, serum adiponectin, and serum soluble TNFR-2 showed no correlation with hepatic fibrosis, whereas the serum leptin levels were significantly correlated with liver fibrosis (R = 0.696). CONCLUSION The hepatic fibrosis grade rapidly progressed in the cranial surgery cases of NAFLD patients with hypopituitarism, possibly in association with BMI, diabetes mellitus, and leptin. In such cranial surgery patients, strong interventions should be considered from the early stage, including diet education, hormone replacement, and more.
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Hypertriglyceridemia in female rats during pregnancy induces obesity in male offspring via altering hypothalamic leptin signaling. Oncotarget 2017; 8:53450-53464. [PMID: 28881823 PMCID: PMC5581122 DOI: 10.18632/oncotarget.18519] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 05/10/2017] [Indexed: 01/09/2023] Open
Abstract
Maternal obesity influence the child's long-term development and health. Though, the mechanism concerned in this process is still uncertain. In the present study, we explored whether overfeeding of a high-fat diet during pregnancy in female rats altered metabolic phenotypes in an F1 generation and authenticated the contribution of hypothalamic leptin signaling. Leptin responsiveness and the number of immunopositive neurons for phosphorylated signal transducer and activator transcription 3 (pSTAT3) were analyzed. Neuropeptide Y in the arcuate nucleus of the hypothalamus and in nucleus tractus solitaries was examined. Triglycerides and leptin levels were increased in the high-fat diet mother. The number of neuropeptide Y positive cell bodies and neurons was significantly increased in the high-fat diet-F1 offspring (HDF-F1) as compared to Chow-F1. Leptin administration significantly decreased the food intake and increased the pSTAT3 expression levels in neurons in the arcuate nucleus of Chow-F1. However, leptin did not show any effect on food intake and had a reduced effect on pSTAT3 expression levels in neurons in the arcuate nucleus of HDF-F1. From the present domino effect, we conclude that mothers exposed to high-fat diet during pregnancy may pass the obese phenotype to the succeeding generation via altering hypothalamic leptin signaling.
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Sahu M, Sahu A. Leptin receptor expressing neurons express phosphodiesterase-3B (PDE3B) and leptin induces STAT3 activation in PDE3B neurons in the mouse hypothalamus. Peptides 2015; 73:35-42. [PMID: 26297880 PMCID: PMC4641794 DOI: 10.1016/j.peptides.2015.08.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 08/16/2015] [Accepted: 08/18/2015] [Indexed: 12/12/2022]
Abstract
Leptin signaling in the hypothalamus is critical for normal food intake and body weight regulation. Cumulative evidence suggests that besides the signal transducer and activator of transcription-3 (STAT3) pathway, several non-STAT3 pathways including the phosphodiesterase-3B (PDE3B) pathway mediate leptin signaling in the hypothalamus. We have shown that PDE3B is localized in various hypothalamic sites implicated in the regulation of energy homeostasis and that the anorectic and body weight reducing effects of leptin are mediated by the activation of PDE3B. It is still unknown if PDE3B is expressed in the long form of the leptin-receptor (ObRb)-expressing neurons in the hypothalamus and whether leptin induces STAT3 activation in PDE3B-expressing neurons. In this study, we examined co-localization of PDE3B with ObRb neurons in various hypothalamic nuclei in ObRb-GFP mice that were treated with leptin (5mg/kg, ip) for 2h. Results showed that most of the ObRb neurons in the arcuate nucleus (ARC, 93%), ventromedial nucleus (VMN, 94%), dorsomedial nucleus (DMN, 95%), ventral premammillary nucleus (PMv, 97%) and lateral hypothalamus (LH, 97%) co-expressed PDE3B. We next examined co-localization of p-STAT3 and PDE3B in the hypothalamus in C57BL6 mice that were treated with leptin (5mg/kg, ip) for 1h. The results showed that almost all p-STAT3 positive neurons in different hypothalamic nuclei including ARC, VMN, DMN, LH and PMv areas expressed PDE3B. These results suggest the possibility for a direct role for the PDE3B pathway in mediating leptin action in the hypothalamus.
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Affiliation(s)
- Maitrayee Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Abhiram Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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Santoro A, Mattace Raso G, Meli R. Drug targeting of leptin resistance. Life Sci 2015; 140:64-74. [DOI: 10.1016/j.lfs.2015.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/06/2015] [Accepted: 05/13/2015] [Indexed: 12/21/2022]
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Sahu M, Anamthathmakula P, Sahu A. Phosphodiesterase-3B-cAMP pathway of leptin signalling in the hypothalamus is impaired during the development of diet-induced obesity in FVB/N mice. J Neuroendocrinol 2015; 27:293-302. [PMID: 25702569 DOI: 10.1111/jne.12266] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/16/2015] [Accepted: 02/12/2015] [Indexed: 01/05/2023]
Abstract
The phosphodiesterase-3B (PDE3B)-cAMP pathway plays an important role in transducing the action of leptin in the hypothalamus. Obesity is usually associated with hyperleptinaemia and resistance to anorectic and body weight-reducing effects of leptin. To determine whether the hypothalamic PDE3B-cAMP pathway of leptin signalling is impaired during the development of diet-induced obesity (DIO), we fed male FVB/N mice a high-fat diet (HFD: 58% kcal as fat) or low-fat diet (LFD: 6% kcal as fat) for 4 weeks. HFD fed mice developed DIO in association with hyperphagia, hyperleptinaemia and hyperinsulinaemia. Leptin (i.p.) significantly increased hypothalamic PDE3B activity and phosphorylated (p)-Akt levels in LFD-fed but not in HFD-fed mice. However, basal p-Akt levels in hypothalamus were increased in DIO mice. Additionally, amongst six-microdissected brain nuclei examined, leptin selectively decreased cAMP levels in the arcuate nucleus (ARC) of LFD-fed mice but failed to do so in HFD-fed mice. We next tested whether both the PBE3B and Akt pathways of leptin signalling remained impaired in DIO mice on the HFD for 12 weeks (long-term). DIO mice were hyperinsulinaemic and hyperleptinaemic in association with impaired glucose and insulin tolerance. Although, in LFD-fed mice, leptin significantly increased PDE3B activity and p-Akt levels in the hypothalamus, it failed to do so in HFD-fed mice. Also, basal p-Akt levels in the hypothalamus were increased in DIO mice and leptin had no further effect. Similarly, immunocytochemistry showed that leptin increased the number of p-Akt-positive cells in the ARC of LFD-fed but not in HFD-fed mice, and there was an increased basal number of p-Akt positive cells in the ARC of DIO mice. These results suggest that the PDE3B-cAMP- and Akt-pathways of leptin signalling in the hypothalamus are impaired during the development of DIO. Thus, a defect in the regulation by leptin of the hypothalamic PDE3B-cAMP pathway and Akt signalling may be one of the mechanisms of central leptin resistance and the development of DIO.
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Affiliation(s)
- M Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Fink BD, Herlein JA, Guo DF, Kulkarni C, Weidemann BJ, Yu L, Grobe JL, Rahmouni K, Kerns RJ, Sivitz WI. A mitochondrial-targeted coenzyme q analog prevents weight gain and ameliorates hepatic dysfunction in high-fat-fed mice. J Pharmacol Exp Ther 2014; 351:699-708. [PMID: 25301169 DOI: 10.1124/jpet.114.219329] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that the mitochondrial-targeted antioxidant, mitoquinone (mitoQ), known to have mitochondrial uncoupling properties, might prevent the development of obesity and mitigate liver dysfunction by increasing energy expenditure, as opposed to reducing energy intake. We administered mitoQ or vehicle (ethanol) to obesity-prone C57BL/6 mice fed high-fat (HF) or normal-fat (NF) diets. MitoQ (500 µM) or vehicle (ethanol) was added to the drinking water for 28 weeks. MitoQ significantly reduced total body mass and fat mass in the HF-fed mice but had no effect on these parameters in NF mice. Food intake was reduced by mitoQ in the HF-fed but not in the NF-fed mice. Average daily water intake was reduced by mitoQ in both the NF- and HF-fed mice. Hypothalamic expression of neuropeptide Y, agouti-related peptide, and the long form of the leptin receptor were reduced in the HF but not in the NF mice. Hepatic total fat and triglyceride content did not differ between the mitoQ-treated and control HF-fed mice. However, mitoQ markedly reduced hepatic lipid hydroperoxides and reduced circulating alanine aminotransferase, a marker of liver function. MitoQ did not alter whole-body oxygen consumption or liver mitochondrial oxygen utilization, membrane potential, ATP production, or production of reactive oxygen species. In summary, mitoQ added to drinking water mitigated the development of obesity. Contrary to our hypothesis, the mechanism involved decreased energy intake likely mediated at the hypothalamic level. MitoQ also ameliorated HF-induced liver dysfunction by virtue of its antioxidant properties without altering liver fat or mitochondrial bioenergetics.
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Affiliation(s)
- Brian D Fink
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Judith A Herlein
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Deng Fu Guo
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Chaitanya Kulkarni
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Benjamin J Weidemann
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Liping Yu
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Justin L Grobe
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Kamal Rahmouni
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - Robert J Kerns
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
| | - William I Sivitz
- Department of Internal Medicine/Endocrinology, University of Iowa and the Iowa City Veterans Affairs Medical Center (B.D.F., J.A.H., W.I.S.), and the Departments of Pharmacology (D.F.G., B.J.W., J.L.G.), Pharmaceutical Sciences and Experimental Therapeutics (C.K., R.J.K.), Biochemistry (L.Y.), Pharmacology and Internal Medicine/Cardiology (K.R.), and Primary Laboratory (W.I.S.), University of Iowa, Iowa City, Iowa
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Ladyman SR, Grattan DR. JAK-STAT and feeding. JAKSTAT 2014; 2:e23675. [PMID: 24058809 PMCID: PMC3710322 DOI: 10.4161/jkst.23675] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/17/2013] [Accepted: 01/18/2013] [Indexed: 12/26/2022] Open
Abstract
The regulation of energy balance requires a complex system to homeostatically maintain the adult body at a precise set point. The central nervous system, particularly the hypothalamus, plays a key role in integrating a variety of signals that can relay information about the body's energy stores. As part of this system, numerous cytokines and hormones contribute to the regulation of food intake and energy homeostasis. Cytokines, and some hormones, are known to act through JAK-STAT intracellular signaling pathways. The hormone leptin, which plays a vital role in appetite regulation, signals through the JAK-STAT pathway, and it is through this involvement that the JAK-STAT pathway has become an established component in the mechanisms regulating food intake within the body. Emerging research, however, is now showing that this involvement of JAK-STAT is not limited to its activation by leptin. Furthermore, while the JAK-STAT pathway may simply act to transmit the anorectic signal of circulating factors, this intracellular signaling pathway may also become impaired when normal regulation of energy balance is disrupted. Thus, altered JAK-STAT signaling may contribute to the breakdown of the normal homeostatic mechanisms maintaining body weight in obesity.
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Affiliation(s)
- Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy; School of Medical Sciences; University of Otago; Dunedin, New Zealand
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Manarin R, Villar SR, Fernández Bussy R, González FB, Deschutter EV, Bonantini AP, Roggero E, Pérez AR, Bottasso O. Reciprocal influences between leptin and glucocorticoids during acute Trypanosoma cruzi infection. Med Microbiol Immunol 2013; 202:339-52. [DOI: 10.1007/s00430-013-0294-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 04/09/2013] [Indexed: 02/06/2023]
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10
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Kim YW. Improvement of Leptin Resistance. Yeungnam Univ J Med 2013. [DOI: 10.12701/yujm.2013.30.1.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Yong Woon Kim
- Department of Physiology, College of Medicine, Yeungnam Univesity, Daegu, Korea
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Seth R, Terry DE, Parrish B, Bhatt R, Overton JM. Amylin–leptin coadministration stimulates central histaminergic signaling in rats. Brain Res 2012; 1442:15-24. [DOI: 10.1016/j.brainres.2011.12.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 12/09/2011] [Accepted: 12/10/2011] [Indexed: 01/05/2023]
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Gamber KM, Huo L, Ha S, Hairston JE, Greeley S, Bjørbæk C. Over-expression of leptin receptors in hypothalamic POMC neurons increases susceptibility to diet-induced obesity. PLoS One 2012; 7:e30485. [PMID: 22276206 PMCID: PMC3262822 DOI: 10.1371/journal.pone.0030485] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 12/21/2011] [Indexed: 12/22/2022] Open
Abstract
Diet-induced obesity (DIO) in rodents is characterized by impaired activation of signal-transducer and activator of transcription 3 (STAT3) by leptin receptors (LepRb) within the hypothalamic arcuate nucleus. This signaling defect likely plays an important role in development of DIO. However, the neuro-chemical identity of the leptin-STAT3 resistant arcuate neurons has not been determined and the underlying mechanisms responsible for development of cellular leptin resistance remain unclear. To investigate this, we first measured arcuate gene expression of known key signaling components of the LepRb signaling pathway and tested whether specifically the critical arcuate pro-opiomelanocortin (POMC) neurons are resistant to LepRb-STAT3 signaling in mice given a high-fat-diet (HFD) compared to mice provided a low-fat control diet (LFD). We found that leptin-dependent STAT3 phosphorylation was decreased within POMC neurons of HFD mice. In addition, Leprb mRNA and suppressor of cytokine signaling 3 (Socs3) mRNA were elevated in the arcuate of HFD mice. To investigate whether increased LepRb expression per se in POMC neurons can influence development of DIO and Socs3 expression, we created mice that over-express LepRb selectively in POMC neurons (POMC-LepRb). No differences in body weight, fat mass or food intake were found between LFD POMC-LepRb mice and LFD controls. Surprisingly, body weight, fat mass and caloric intake of HFD POMC-LepRb mice was markedly higher than HFD control mice. In addition, arcuate Socs3 mRNA was increased in HFD POMC-LepRb mice compared to HFD controls. These data show that specifically POMC neurons of DIO mice are resistant to STAT3 activation by leptin, indicating that those cells might play a role in development of DIO. Furthermore, over-expression of LepRb selectively in POMC neurons increases susceptibility to the development of DIO. We propose a model where over-reactivity of the leptin-LepRb signaling system in arcuate neurons may play causal a role in development of diet-induced obesity.
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Affiliation(s)
- Kevin M. Gamber
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lihong Huo
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sangdeuk Ha
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Joyce E. Hairston
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sarah Greeley
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Christian Bjørbæk
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Estadella D, Oyama LM, Bueno AA, Habitante CA, Souza GI, Ribeiro EB, Motoyama CSM, Oller do Nascimento CM. A palatable hyperlipidic diet causes obesity and affects brain glucose metabolism in rats. Lipids Health Dis 2011; 10:168. [PMID: 21943199 PMCID: PMC3198928 DOI: 10.1186/1476-511x-10-168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 09/23/2011] [Indexed: 12/11/2022] Open
Abstract
Background We have previously shown that either the continuous intake of a palatable hyperlipidic diet (H) or the alternation of chow (C) and an H diet (CH regimen) induced obesity in rats. Here, we investigated whether the time of the start and duration of these feeding regimens are relevant and whether they affect brain glucose metabolism. Methods Male Wistar rats received C, H, or CH diets during various periods of their life spans: days 30-60, days 30-90, or days 60-90. Experiments were performed the 60th or the 90th day of life. Rats were killed by decapitation. The glucose, insulin, leptin plasma concentration, and lipid content of the carcasses were determined. The brain was sliced and incubated with or without insulin for the analysis of glucose uptake, oxidation, and the conversion of [1-14C]-glucose to lipids. Results The relative carcass lipid content increased in all of the H and CH groups, and the H30-60 and H30-90 groups had the highest levels. Groups H30-60, H30-90, CH30-60, and CH30-90 exhibited a higher serum glucose level. Serum leptin increased in all H groups and in the CH60-90 and CH30-90 groups. Serum insulin was elevated in the H30-60, H60-90, CH60-90, CH30-90 groups. Basal brain glucose consumption and hypothalamic insulin receptor density were lower only in the CH30-60 group. The rate of brain lipogenesis was increased in the H30-90 and CH30-90 groups. Conclusion These findings indicate that both H and CH diet regimens increased body adiposity independent treatment and the age at which treatment was started, whereas these diets caused hyperglycemia and affected brain metabolism when started at an early age.
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Affiliation(s)
- Debora Estadella
- Disciplina de Fisiologia da Nutrição, Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil
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Dutra SCP, de Moura EG, Lisboa PC, Trevenzoli IH, Passos MCF. Leptin-programmed rats respond to cold exposure changing hypothalamic leptin receptor and thyroid function differently from cold-exposed controls. ACTA ACUST UNITED AC 2011; 171:58-64. [PMID: 21803077 DOI: 10.1016/j.regpep.2011.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/29/2011] [Accepted: 07/14/2011] [Indexed: 11/17/2022]
Abstract
We showed that neonatal leptin treatment programmes for hyperleptinemia and central leptin resistance both at 30days-old and adulthood, while programmes for lower serum T3 at 30days-old, but higher thyroid hormones (TH) at adulthood. As in these animals, acute cold at 30days-old normalized leptinemia and restored the expression of hypothalamic leptin receptor (OBR), here we evaluate the effect of cold exposure on the thyroid function and OBR in adult rats programmed by neonatal hyperleptinemia. Pups were divided into 2 groups: Lep-injected with leptin (8μg/100g/BW, sc) for the first 10days of lactation, and C-injected with saline. At 150days, both groups were subdivided into: LepC and CC, which were exposed to 8°C for 12h. Serum leptin, TH, TSH, liver type I and brown adipose tissue (BAT) type II deiodinases (D1 and D2) activities, liver mitochondrial alpha-glycerol-3-phosphate dehydrogenase (mGPD) activity and adrenal catecholamine content were measured. Hypothalamic and thyroid OBR protein contents were evaluated. Differences were significant when p<0.05. Lep group had hyperleptinemia (+19%), higher T4 (+20%) and T3 (+30%) with lower TSH (-55%), higher liver D1 (1.4 fold-increase), lower BAT D2 (-44%) and liver mGPD activities (-55%), higher adrenal catecholamines (+44%), lower hypothalamic OBR (-51%) and normal thyroid OBR. Cold exposure normalized leptinemia, D1, mGPD, catecholamine and hypothalamic OBR. However, cold exposure further increased TH and decreased D2. Thus, cold exposure normalizes most of the changes programmed by neonatal hyperleptinemia, at the expense of worsening the hyperthyroidism and BAT thermogenesis.
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Abstract
OBJECTIVE To examine the cardiovascular effects of combined amylin (AMN) and leptin (LEP) treatment in lean and obese rats. RESEARCH DESIGN Rats were instrumented for telemetry and given LEP (300 μg kg(-1) day(-1)), AMN (100 μg kg(-1) day(-1)), AMN+LEP or vehicle (VEH; 0.9% normal saline) via a subcutaneous mini-osmotic pump for 7 days. The VEH group was subdivided into ad libitum fed and pair-fed to the amount of food AMN+LEP animals ate daily. Rats were housed in metabolic chambers for analysis of cardiovascular physiology and metabolism. SUBJECTS Male Fisher 344 × Brown Norway (FBNF1; Harlan; age=3-5 months; n=72) rats were placed on standard rodent chow (LEAN, n=41) or moderately high-fat diet (OBESE; n=31) to produce obesity. RESULTS AMN+LEP potently reduced food intake (LEAN: 57% OBESE: 59%) and abdominal fat mass (LEAN: 56% OBESE: 41%). Pair-fed rats displayed bradycardia and metabolic suppression. In contrast, AMN+LEP increased heart rate and oxygen consumption above levels in LEP or AMN-treated rats. LEP reduced blood pressure in both lean and obese rats but AMN had no effect. LEP-induced reductions in blood pressure were not altered by AMN+LEP treatment. Thus, AMN+LEP treatment decreased food intake, body fat and blood pressure in lean and obese rats. CONCLUSION We conclude that the potent anti-adiposity actions of AMN+LEP are due in part to prevention of the bradycardia and metabolic suppression typically observed with negative energy balance. Furthermore, the hypotensive actions of peripheral LEP treatment are observable in spite of the potent AMN+LEP activation of anorexic and thermogenic mechanisms in the central nervous system.
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Hur YN, Hong GH, Choi SH, Shin KH, Chun BG. High fat diet altered the mechanism of energy homeostasis induced by nicotine and withdrawal in C57BL/6 mice. Mol Cells 2010; 30:219-26. [PMID: 20803089 DOI: 10.1007/s10059-010-0110-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 05/01/2010] [Accepted: 06/04/2010] [Indexed: 12/30/2022] Open
Abstract
Nicotine treatment has known to produce an inverse relationship between body weight and food intake in rodents. Present study determined the effect of repeated treatment with nicotine and withdrawal in control and obese mice, on: (1) body weight, caloric intake and energy expenditure; (2) hypothalamic neuropeptides mRNA expression; and (3) serum leptin. 21-week-old C57BL/6 mice (n = 65) received nicotine (3.0 mg/kg/day; 2 weeks) and saline (1 ml/kg/day; 2 weeks) subcutaneously. Animals were given either a normal-fat (10% kcal from fat, NF) or a high-fat diet (45% kcal from fat, HF) from the 12th week to 25th week. While, nicotine treatment for 14 days induced an increase in hypothalamic agouti-related protein, cocaine- and amphetamine- regulated transcript, pro-opiomelanocortin mRNA expressions, nicotine also produced a reducing effect in body weight gain and leptin concentration in NF mice. High-fat diet induced obese mice showed a blunted hypothalamic and leptin response to nicotine. Remarkable weight loss in obese mice was mediated not just by decreasing caloric intake, but also by increasing total energy expenditure (EE). During nicotine withdrawal period, weight gain occurred in NF and HF groups, which was ascribed to a decrease in EE rather than changes in caloric intake. Hypothalamic AgRP might play a role for maintaining energy balance under the nicotine-induced negative energy status.
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Affiliation(s)
- Young-Na Hur
- Department of Pharmacology, Korea University College of Medicine, Seoul, 136-705, Korea
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Wrann CD, Ehmer U, Lautenbach A, Kuhlmann S, Nave H. Obesity and NK cells affect the expression of the long form of the leptin receptor Ob-Rb in liver of F344 rats. ACTA ACUST UNITED AC 2010; 62:1-8. [DOI: 10.1016/j.etp.2008.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Revised: 12/19/2008] [Accepted: 12/21/2008] [Indexed: 12/16/2022]
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Anorexic vs. metabolic effects of central leptin infusion in rats of various ages and nutritional states. J Mol Neurosci 2009; 41:97-104. [PMID: 19777381 DOI: 10.1007/s12031-009-9294-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 09/09/2009] [Indexed: 12/21/2022]
Abstract
Age-related obesity is known to be adjoined by leptin resistance. It has not been clarified whether the resistance is cause or result of obesity. In the present experiments, the anorexic (suppressing food intake and body weight) and hypermetabolic (increasing body temperature (Tc), activity, and heart rate (HR), indicating metabolic rate) responses to 7-day-long intracerebroventricular leptin infusion were compared in 2- and 6-month-old normally fed (NF2 and NF6 groups), 6-month-old high-fat-diet-induced obese (HF6), and 6-month-old calorie-restricted (CR6) rats. The anorexic effects were inversely related to fat content: They were most pronounced in NF2, less in NF6, non-significant in HF6 rats, but also absent in CR6 animals of the lowest fat content. This virtual leptin resistance in CR6 rats was due to their high orexigenic activity (enhanced feeding response to NPY). In contrast, CR6 rats were hypersensitive to the metabolic effects of leptin infusion (rise in Tc and HR; biotelemetric measurements), NF2 were still sensitive, while NF6 and HF6 rats exhibited moderate or low sensitivity. In conclusion, leptin resistance depends on body fat content rather than on age itself, although with age the proportion of fat tissue increases and contributes to self-perpetuating rise in body weight.
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Huang W, Dedousis N, Bhatt BA, O'Doherty RM. Polymorphism of human leptin receptor gene is associated with type 2 diabetic patients complicated with non-alcoholic fatty liver disease in China. J Biol Chem 2009; 279:21695-700. [PMID: 14993225 DOI: 10.1074/jbc.m401546200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND AND AIM To investigate the relationship between human leptin receptor (LEPR) gene G3057A polymorphism and type 2 diabetes mellitus (T2DM) patients complicated with or without non-alcoholic fatty liver disease (NAFLD). METHODS Two hundred and sixteen cases of newly diagnosed T2DM patients (104 cases complicated with NAFLD) and 108 cases of normal glucose tolerances (NGT) were recruited. Hemi-nested polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and PCR-direct sequence analysis were conducted to detect the polymorphism of LEPR G3057A variation. Plasma leptin levels were measured by enzyme-linked immunosorbent assay kit. Plasma lipid and glucose metabolic parameters were measured routinely. Liver ultrasound was carried out for all subjects. RESULTS T2DM patients complicated with NAFLD had higher plasma insulin, leptin, triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) levels than those without NAFLD and NGT subjects. The variant frequency at nucleotide 3057 G-->A transversion was 76.0% in type 2 diabetic patients complicated with NAFLD, which was also significantly higher than those without NAFLD (62.1%) and NGT cases (53.2%). There was also significant difference in genotype distribution between the three groups (chi(2) = 14.63, P < 0.01). CONCLUSION The polymorphism of LEPR gene 3057 probably contributes to the onset of NAFLD by regulating lipid metabolism and affecting insulin sensitivity.
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Affiliation(s)
- Wan Huang
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Sellayah D, Sek K, Anthony FW, Watkins AJ, Osmond C, Fleming TP, Hanson MA, Cagampang FR. Appetite regulatory mechanisms and food intake in mice are sensitive to mismatch in diets between pregnancy and postnatal periods. Brain Res 2008; 1237:146-52. [DOI: 10.1016/j.brainres.2008.07.126] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 07/22/2008] [Accepted: 07/26/2008] [Indexed: 10/21/2022]
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Metlakunta AS, Sahu M, Sahu A. Hypothalamic phosphatidylinositol 3-kinase pathway of leptin signaling is impaired during the development of diet-induced obesity in FVB/N mice. Endocrinology 2008; 149:1121-8. [PMID: 18048492 PMCID: PMC2275357 DOI: 10.1210/en.2007-1307] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Phosphatidylinositol 3-kinase (PI3K) pathway of leptin signaling plays an important role in transducing leptin action in the hypothalamus. Obesity is usually associated with resistance to the effect of leptin on food intake and energy homeostasis. Although central leptin resistance is thought to be involved in the development of diet-induced obesity (DIO), the mechanism behind this phenomenon is not clearly understood. To determine whether DIO impairs the effect of leptin on hypothalamic PI3K signaling, we fed 4-wk-old FVB/N mice a high-fat diet (HFD) or low-fat diet (LFD) for 19 wk. HFD-fed mice developed DIO in association with hyperleptinemia, hyperinsulinemia, and impaired glucose and insulin tolerance. Leptin (ip) significantly increased hypothalamic PI3K activity and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) levels in LFD-fed mice but not in DIO mice. Immunocytochemical study confirmed impaired p-STAT3 activation in various hypothalamic areas, including the arcuate nucleus. We next tested whether both PI3K and STAT3 pathways of leptin signaling were impaired during the early period of DIO. Leptin failed to increase PI3K activity in DIO mice that were on a HFD for 4 wk. However, leptin-induced p-STAT3 activation in the hypothalamus measured by Western blotting and immunocytochemistry remained comparable between LFD- and HFD-fed mice. These results suggest that the PI3K pathway but not the STAT3 pathway of leptin signaling is impaired during the development of DIO in FVB/N mice. Thus, a defective PI3K pathway of leptin signaling in the hypothalamus may be one of the mechanisms of central leptin resistance and DIO.
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Affiliation(s)
- Anantha S Metlakunta
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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22
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Archer ZA, Corneloup J, Rayner DV, Barrett P, Moar KM, Mercer JG. Solid and liquid obesogenic diets induce obesity and counter-regulatory changes in hypothalamic gene expression in juvenile Sprague-Dawley rats. J Nutr 2007; 137:1483-90. [PMID: 17513411 DOI: 10.1093/jn/137.6.1483] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Contemporary foods and beverages that constitute the diets of adults and children almost certainly contribute to the obesity problem. To develop a model of childhood obesity, we examined the effects of feeding juvenile rats 2 solid diets, either alone or in combination [nonpurified control diet (C), high-energy (HE), or C+HE] with or without the liquid supplement Ensure (EN). Rats were fed C until 4 wk of age and then were assigned to 1 of 6 weight-matched groups that were fed C, HE, C+HE, C+EN, HE+EN, or C+HE+EN for 5 wk. EN accelerated weight gain and increased energy intake and adiposity irrespective of the solid diet consumed. Serum leptin concentrations were increased after the consumption of all diets when compared with C rats, but there was dissociation between leptin levels and adiposity. The type of solid diet had no effect on the expression of a panel of hypothalamic genes except for glutamate-decarboxylase-67. EN decreased mRNA for agouti-related peptide and neuropeptide Y in the arcuate nucleus and DYN in the paraventricular nucleus. Dynorphin and CART mRNA were decreased in the supraoptic retrochiasmatic nucleus. The reduction in orexigenic signaling in the hypothalamus suggests that overconsumption of EN is sensed by the hypothalamus but that any initiated physiological responses fail to compensate effectively and may be negated or overwhelmed by other systems. Providing diets in solid and liquid form, with choice, mimics more closely the human environment. Understanding the interactions between these diets and peripheral and central energy balance systems could be crucial in unraveling the events underlying human obesity and its early development.
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Affiliation(s)
- Zoë A Archer
- Division of Obesity and Metabolic Health, Rowett Research Institute, Aberdeen Centre for Energy Regulation and Obesity, Bucksburn, Aberdeen, UK
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Abstract
Despite elevated plasma leptin, food intake is increased during pregnancy leading to fat deposition. We have demonstrated that intracerebroventricular (icv) leptin is unable to suppress food intake in pregnant rats, as it does in non-pregnant animals. Hence, central leptin resistance develops during pregnancy. These changes are physiologically appropriate, providing increased energy reserves to help meet the high metabolic demands of fetal development and lactation. To characterise this central leptin resistance, we have measured levels of leptin receptor (Ob-Rb) mRNA in the hypothalamus, and examined leptin-induced phosphorylation of STAT3 (pSTAT3) in specific regions of the hypothalamus. In addition, to investigate the mechanism underlying pregnancy-induced leptin resistance, we have investigated effects of hormone treatments on hypothalamic responses to leptin in a pseudopregnant rat model. We observed a significant reduction of Ob-Rb mRNA levels in the ventromedial hypothalamic nucleus (VMH) during pregnancy, with no changes detected in other hypothalamic nuclei. Levels of leptin-induced pSTAT3 were specifically suppressed in the VMH and arcuate nucleus of pregnant rats compared to non-pregnant rats. Pseudopregnant rats were hyperphagic but did not become leptin resistant, suggesting that fetal or placental factors are required for the induction of leptin resistance. These data implicate the VMH as a key hypothalamic site involved in hormone-induced leptin resistance during pregnancy, and suggest that placental hormone secretion may mediate the hormone-induced loss of response to leptin.
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Affiliation(s)
- David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy and Structural Biology, University of Otago, Dunedin, New Zealand.
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Enriori PJ, Evans AE, Sinnayah P, Jobst EE, Tonelli-Lemos L, Billes SK, Glavas MM, Grayson BE, Perello M, Nillni EA, Grove KL, Cowley MA. Diet-induced obesity causes severe but reversible leptin resistance in arcuate melanocortin neurons. Cell Metab 2007; 5:181-94. [PMID: 17339026 DOI: 10.1016/j.cmet.2007.02.004] [Citation(s) in RCA: 409] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Revised: 02/01/2007] [Accepted: 02/13/2007] [Indexed: 11/21/2022]
Abstract
Despite high leptin levels, most obese humans and rodents lack responsiveness to its appetite-suppressing effects. We demonstrate that leptin modulates NPY/AgRP and alpha-MSH secretion from the ARH of lean mice. High-fat diet-induced obese (DIO) mice have normal ObRb levels and increased SOCS-3 levels, but leptin fails to modulate peptide secretion and any element of the leptin signaling cascade. Despite this leptin resistance, the melanocortin system downstream of the ARH in DIO mice is over-responsive to melanocortin agonists, probably due to upregulation of MC4R. Lastly, we show that by decreasing the fat content of the mouse's diet, leptin responsiveness of NPY/AgRP and POMC neurons recovered simultaneously, with mice regaining normal leptin sensitivity and glycemic control. These results highlight the physiological importance of leptin sensing in the melanocortin circuits and show that their loss of leptin sensing likely contributes to the pathology of leptin resistance.
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Affiliation(s)
- Pablo J Enriori
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
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Abstract
The adipose-derived hormone leptin was first described as a satiety factor, but recent studies have demonstrated that leptin acts on various physiologic processes and plays an important role in obesity and the associated hypertension. In this article, we review recent data on leptin signaling as it relates to nutrition. Plasma leptin levels are positively correlated to body fat and adipocyte size and, therefore, levels are higher during obesity. The hyperphagia in the presence of hyperleptinemia in obesity is a paradoxical effect. Leptin signaling primarily depends on the leptin receptor (Ob-R). The suppressor of cytokine-signaling (SOCS) protein, in particular SOCS-3, was shown as a leptin-regulated inhibitor of proximal leptin signaling, although its role during obesity remains uncertain.
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Affiliation(s)
- Catherine Ribiere
- Department of Biochemistry and Molecular Biology, Faculty of Medecine Paris-Ile deFrance, 45 rue des Saints Pères, 75270 Paris Cedex 06, France.
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26
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Abstract
The hypothalamus is a major site for integration of central and peripheral signals that regulate energy homeostasis. Within the hypothalamus, neurons residing in the ARC (arcuate nucleus)-PVN (paraventricular)-PF/LH (perifornical/lateral hypothalamus) axis communicate among each other and are subjected to the influence of several peripheral factors, including leptin and insulin. Proper signaling in the hypothalamus by leptin, a long-sought peripheral factor that relays the status of fat stores, is critical to normal regulation of food intake and body weight. Leptin action in the hypothalamus is mediated by a large number of orexigenic and anorectic peptide-producing neurons of the ARC-PVN-PF/LH axis. Not only the classical JAK2 (Janus kinase 2)-STAT3 (signal transducer and activator of transcription 3) pathway, but also the phosphatidylinositol-3 kinase-phosphodiesterase 3B-cAMP pathway mediates hypothalamic leptin receptor signaling. It appears that hypothalamic leptin resistance, possibly due to defective nutritional regulation of leptin receptor expression and/or reduced STAT3 signaling in the hypothalamus, contributes to the development of obesity associated with high-fat feeding and aging. Interestingly, hypothalamic neurons may develop leptin resistance despite an intact JAK2-STAT3 signaling path. The role of suppressor of cytokine signaling 3 and other negative regulators of leptin signaling in central leptin resistance needs to be established, an important area of future investigation. Further understanding of the neural circuitry and leptin signaling in the hypothalamus is critical not only for the advancement of our knowledge on the hypothalamic role in energy balance but also for future development of drugs for the attenuation or treatment of obesity and related disorders in humans.
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Affiliation(s)
- Abhiram Sahu
- Ph.D, Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, S-829 Scaife Hall, 3550 Terrace Street, Pittsburgh, Pennsylvania 15262, USA.
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27
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Abstract
Leptin, the long-sought satiety factor of adipocytes origin, has emerged as one of the major signals that relay the status of fat stores to the hypothalamus and plays a significant role in energy homeostasis. Understanding the mechanisms of leptin signaling in the hypothalamus during normal and pathological conditions, such as obesity, has been the subject of intensive research during the last decade. It is now established that leptin action in the hypothalamus in regulation of food intake and body weight is mediated by a neural circuitry comprising of orexigenic and anorectic signals, including NPY, MCH, galanin, orexin, GALP, alpha-MSH, NT, and CRH. In addition to the conventional JAK2-STAT3 pathway, it has become evident that PI3K-PDE3B-cAMP pathway plays a critical role in leptin signaling in the hypothalamus. It is now established that central leptin resistance contributes to the development of diet-induced obesity and ageing associated obesity. Central leptin resistance also occurs due to hyperleptinimia produced by exogenous leptin infusion. A defective nutritional regulation of leptin receptor gene expression and reduced STAT3 signaling may be involved in the development of leptin resistance in DIO. However, leptin resistance in the hypothalamic neurons may occur despite an intact JAK2-STAT3 pathway of leptin signaling. Thus, in addition to defective JAK2-STAT3 pathway, defects in other leptin signaling pathways may be involved in leptin resistance. We hypothesize that defective regulation of PI3K-PDE3B-cAMP pathway may be one of the mechanisms behind the development of central leptin resistance seen in obesity.
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Affiliation(s)
- Abhiram Sahu
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, S829 Scaife Hall, 3550 Terrace Street, Pittsburgh, PA 15261, USA.
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Plut C, Ribière C, Giudicelli Y, Dausse JP. Hypothalamic leptin receptor and signaling molecule expressions in cafeteria diet-fed rats. J Pharmacol Exp Ther 2003; 307:544-9. [PMID: 12966151 DOI: 10.1124/jpet.103.054726] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although obesity is associated with a state of leptin resistance, it has been suggested that leptin may contribute to the pathogenesis of obesity-related hypertension. In previous studies, we reported that cafeteria diet feeding induces hyperleptinaemia and hyperinsulinemia in both male and female rats, with hypertension occurring only in male rats. However, when female rats were neonatally treated with testosterone (T), these animals develop hypertension when fed the cafeteria diet. These observations led us to investigate leptin signaling and some neuropeptides that are leptin targets in the hypothalamus of male, intact female, and T-treated female cafeteria diet-fed rats. A decrease in the hypothalamic leptin receptors (Ob-Ra and Ob-Rb) and pro-opiomelanocortin (POMC) mRNA was observed only in male hypertensive cafeteria diet-fed rats. Although no alterations in Ob-R occurred in both groups of female cafeteria diet-fed rats, the hyperleptinaemic state of these animals had no influence on POMC mRNA levels. In intact female rats, expression of the suppressors of cytokines signaling SOCS-1, SOCS-2, SOCS-3, and cytokine inhibitor signaling were unaltered, whereas in T-treated females SOCS-3 was overexpressed. Finally SOCS-1 mRNA level was increased only in male rats. Because hyperinsulinemia was reported to counteract the leptin-induced stimulation of the sympathetic tone and because SOCS-1 and -3 are potential inhibitors of insulin signaling, our results suggest that the hypothalamic overexpression of SOCS-1 or SOCS-3 found in male or T-treated female rats after cafeteria diet feeding could block the negative influence of the hyperinsulinemia on the central pressor action of leptin, thereby contributing to their hypertensive state.
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Affiliation(s)
- Charles Plut
- Department of Biochemistry and Molecular Biology, Faculté de Médecine de Paris-Ile de France-Ouest, Université Versailles-St Quentin en Yvelines, 45 rue des Saints-Pères, 75270 Paris Cedex 06, France.
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Scarpace PJ, Matheny M, Zolotukhin S, Tümer N, Zhang Y. Leptin-induced leptin resistant rats exhibit enhanced responses to the melanocortin agonist MT II. Neuropharmacology 2003; 45:211-9. [PMID: 12842127 DOI: 10.1016/s0028-3908(03)00158-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to determine if leptin could induce a leptin resistance in young rats and if leptin-induced leptin resistant rats are responsive to the melanocortin agonist, melanotan II (MT II). Recombinant adeno-associated virus encoding rat leptin cDNA (rAAV-leptin) or control viral vector were administered into young, lean rats for 300 days, and food consumption, body weight, oxygen consumption, serum leptin, and leptin signal transduction were measured. In the rAAV-leptin rats, the anorexic response attenuated by day 140, and the increase in energy expenditure attenuated prior to day 223. At day 300, the rats were challenged with centrally administered recombinant leptin to test leptin responsiveness. Whilst the control responded with a decrease in food intake, the rAAV-leptin rats were unresponsive. The same rats were administered MT II subsequently, and both the leptin-resistant and leptin-responsive groups displayed reduced food intake. Notably, the anorexic response persisted longer in the leptin-resistant group. These data demonstrate that leptin induces leptin resistance in young rats and that these leptin-resistant rats have an enhanced anorexic response to exogenous melanocortin activation. We suggest that defective endogenous melanocortin activation may represent one element of leptin resistance, leading to compensatory hypersensitivity of the melanocortin pathway.
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Affiliation(s)
- Philip J Scarpace
- Geriatric Research, Education and Clinical Center (182), Department of Veterans Affairs Medical Center, Gainesville, FL 32608-1197, USA.
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Han Z, Yan JQ, Luo GG, Liu Y, Wang YL. Leptin receptor expression in the basolateral nucleus of amygdala of conditioned taste aversion rats. World J Gastroenterol 2003; 9:1034-7. [PMID: 12717851 PMCID: PMC4611367 DOI: 10.3748/wjg.v9.i5.1034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIM: To determine whether serum leptin level and the leptin receptor (OB-R) expression in the basolateral amygdala (BLA) change following conditioned taste aversion (CTA) formation.
METHODS: The serum leptin concentration was measured by rat leptin RIA kit, long and short forms of leptin receptor (OB-Rb and OB-Ra) mRNA in the brain sections were examined by in situ hybridization (ISH) and the expression of OB-R was assessed by immunohistochemistry ABC method with a highly specific goat anti-OB-R antibody.
RESULTS: The level of serum leptin didn’t show significant difference between CTA and control group. Comparing with the control group, the CTA group had an increase on count of OB-R immunohistochemistry positive-stained cells in the BLA (127 ± 12 vs 48 ± 9 per 1 mm2). The OB-Rb mRNA expression level enhanced by 11.9% in the BLA, while OB-Ra mRNA level increased by 7.4% on the choroid plexus in CTA group. So BLA was supposed to be a region where interactions between gustatory and vagal signals take place.
CONCLUSION: BLA is one of the sites, which are responsible for CTA formation in the brain. Leptin and OB-R maybe involved in neuronal communication for CTA. So leptin and its receptors probably take part in CTA and integration of autonomic and extroceptive information.
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Affiliation(s)
- Zhen Han
- Department of Physiology, Xi'an Jiaotong University School of Medicine, Shaanxi Province, China
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