scholarly journals Endospanin 1 Determines the Balance of Leptin-Regulated Hypothalamic Functions

2018 ◽  
Vol 108 (2) ◽  
pp. 132-141
Author(s):  
Clara Roujeau ◽  
Ralf Jockers ◽  
Julie Dam
Keyword(s):  
Signaling Pathways ◽  
Intracellular Trafficking ◽  
Leptin Receptor ◽  
Leptin Resistance ◽  
Human Obesity ◽  
Leptin Signaling ◽  
Diet Induced Obesity ◽  
Important Regulator ◽  
Neuronal Plasma Membrane ◽  
Underlying Mechanisms

Endospanin 1 (Endo1), a protein encoded in humans by the same gene than the leptin receptor (ObR), and increased by diet-induced obesity, is an important regulator of ObR trafficking and cell surface exposure, determining leptin signaling strength. Defective intracellular trafficking of the leptin receptor to the neuronal plasma membrane has been proposed as a mechanism underlying the development of leptin resistance observed in human obesity. More recently, Endo1 has emerged as a mediator of “selective leptin resistance.” The underlying mechanisms of the latter are not completely understood, but the possibility of differential activation of leptin signaling pathways was suggested among others. In this respect, the expression level of Endo1 is crucial for the appropriate balance between different leptin signaling pathways and leptin functions in the hypothalamus and is likely participating in selective leptin resistance for the control of energy and glucose homeostasis.

scholarly journals Astrocytic leptin-receptor knockout mice show partial rescue of leptin resistance in diet-induced obesity

2013 ◽  
Vol 114 (6) ◽  
pp. 734-741 ◽  
Author(s):  
Bhavaani Jayaram ◽  
Weihong Pan ◽  
Yuping Wang ◽  
Hung Hsuchou ◽  
Aurelien Mace ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Leptin Receptor ◽  
Uncoupling Protein ◽  
Subcutaneous Fat ◽  
Leptin Resistance ◽  
Blood Concentrations ◽  
Leptin Signaling ◽  
Diet Induced Obesity ◽  
Soluble Leptin Receptor ◽  
Similar Body

To determine how astrocytic leptin signaling regulates the physiological response of mice to diet-induced obesity (DIO), we performed metabolic analyses and hypothalamic leptin signaling assays on astrocytic leptin-receptor knockout (ALKO) mice in which astrocytes lack functional leptin receptor (ObR) signaling. ALKO mice and wild-type (WT) littermate controls were studied at different stages of DIO with measurement of body wt, percent fat, metabolic activity, and biochemical parameters. When fed regular chow, the ALKO mice had similar body wt, percent fat, food intake, heat dissipation, respiratory exchange ratio, and activity as their WT littermates. There was no change in blood concentrations of triglyceride, soluble leptin receptor (sObR), mRNA for leptin and uncoupling protein 1 (UCP1) in adipose tissue, and insulin sensitivity. Unexpectedly, in response to a high-fat diet the ALKO mice had attenuated hyperleptinemia and sObR, a lower level of leptin mRNA in subcutaneous fat, and a paradoxical increase in UCP1 mRNA. Thus, ALKO mice did not show the worsening of obesity that occurs with normal WT mice and the neuronal ObR mutation that results in morbid obesity. The findings are consistent with a competing, counterregulatory model between neuronal and astrocytic leptin signaling.

scholarly journals Signaling through Tyr985 of Leptin Receptor as an Age/Diet-Dependent Switch in the Regulation of Energy Balance

2009 ◽  
Vol 30 (7) ◽  
pp. 1650-1659 ◽  
Author(s):  
Jia You ◽  
Yue Yu ◽  
Lei Jiang ◽  
Wenxia Li ◽  
Xinxin Yu ◽  
...  
Keyword(s):  
Energy Balance ◽  
Energy Homeostasis ◽  
Leptin Receptor ◽  
Negative Regulator ◽  
Leptin Resistance ◽  
Leptin Signaling ◽  
Diet Induced Obesity ◽  
Long Form ◽  
Elevated Expression ◽  
Multiple Signaling

ABSTRACT Leptin regulates energy homeostasis through central activation of multiple signaling pathways mediated by Ob-Rb, the long form of leptin receptor. Leptin resistance underlies the pathogenic development of obesity, which is closely associated with environmental factors. To further understand the physiological function of leptin signaling mechanisms, we generated a knock-in line of mice (Y985F) expressing a mutant Ob-Rb with a phenylalanine substitution for Tyr985, one of the three intracellular tyrosines that mediate leptin's signaling actions. Surprisingly, whereas young homozygous Y985F animals were slightly leaner, they exhibit adult-onset or diet-induced obesity. Importantly, both age-dependent and diet-induced deterioration of energy balance was paralleled with pronounced leptin resistance, which was largely attributable to attenuation of leptin-responsive hypothalamic STAT3 activation as well as prominently elevated expression of hypothalamic SOCS3, a key negative regulator of leptin signaling. Thus, these results unmask distinct binary roles for Try985-mediated signaling in energy metabolism, acting as an age/diet-dependent regulatory switch to counteract age-associated or diet-induced obesity.

scholarly journals Changes in Expression of the Genes for the Leptin Signaling in Hypothalamic-Pituitary Selected Areas and Endocrine Responses to Long-Term Manipulation in Body Weight and Resistin in Ewes

2020 ◽  
Vol 21 (12) ◽  
pp. 4238
Author(s):  
Dorota Anna Zieba ◽  
Weronika Biernat ◽  
Malgorzata Szczesna ◽  
Katarzyna Kirsz ◽  
Justyna Barć ◽  
...  
Keyword(s):  
Body Weight ◽  
Leptin Receptor ◽  
Fat Body ◽  
Density Lipoprotein ◽  
Reproductive Hormones ◽  
Leptin Resistance ◽  
Nonesterified Fatty Acid ◽  
Cytokine Signaling ◽  
Leptin Signaling

Both long-term undernutrition and overnutrition disturb metabolic balance, which is mediated partially by the action of two adipokines, leptin and resistin (RSTN). In this study, we manipulated the diet of ewes to produce either a thin (lean) or fat (fat) body condition and investigated how RSTN affects endocrine and metabolic status under different leptin concentrations. Twenty ewes were distributed into four groups (n = 5): the lean and fat groups were administered with saline (Lean and Fat), while the Lean-R (Lean-Resistin treated) and Fat-R (Fat-Resistin treated) groups received recombinant bovine resistin. Plasma was assayed for LH, FSH, PRL, RSTN, leptin, GH, glucose, insulin, total cholesterol, nonesterified fatty acid (NEFA), high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Expression levels of a suppressor of cytokine signaling (SOCS-3) and the long form of the leptin receptor (LRb) were determined in selected brain regions, such as the anterior pituitary, hypothalamic arcuate nucleus, preoptic area and ventro- and dorsomedial nuclei. The results indicate long-term alterations in body weight affect RSTN-mediated effects on metabolic and reproductive hormones concentrations and the expression of leptin signaling components: LRb and SOCS-3. This may be an adaptive mechanism to long-term changes in adiposity during the state of long-day leptin resistance.

Obesity-prone rats have normal blood-brain barrier transport but defective central leptin signaling before obesity onset

2004 ◽  
Vol 286 (1) ◽  
pp. R143-R150 ◽  
Author(s):  
Barry E. Levin ◽  
Ambrose A. Dunn-Meynell ◽  
William A. Banks
Keyword(s):  
Blood Brain Barrier ◽  
Leptin Receptor ◽  
Nucleus Tractus Solitarius ◽  
High Energy ◽  
Brain Barrier ◽  
Leptin Signaling ◽  
Caloric Density ◽  
Diet Induced Obesity ◽  
Blood Brain ◽  
Arcuate Nuclei

Rats selectively bred to develop diet-induced obesity (DIO) were compared with those bred to be diet resistant (DR) on a 31% fat high-energy diet with regard to their central leptin signaling and blood-brain barrier (BBB) transport. Peripheral leptin injection (15 mg/kg ip) into lean 4- to 5-wk-old rats produced 54% less anorexia in DIO than DR rats. DIO rats also had 21, 63, and 64% less leptin-induced immunoreactive phosphorylated signal transducer and activator of transcription 3 (pSTAT3) expression in the hypothalamic arcuate, ventromedial, and dorsomedial nuclei, respectively. However, hindbrain leptin-induced nucleus tractus solitarius pSTAT3 and generalized sympathetic (24-h urine norepinephrine) activation were comparable. Reduced central leptin signaling was not due to defective BBB transport since transport did not differ between lean 4- to 5-wk-old DIO and DR rats. Conversely, DIO leptin BBB transport was reduced when they became obese at 23 wk of age on low-fat chow or after 6 wk on high-energy diet. In addition, leptin receptor mRNA expression was 23% lower in the arcuate nuclei of 4- to 5-wk-old DIO compared with DR rats. Thus a preexisting reduction in hypothalamic but not brain stem leptin signaling might contribute to the development of DIO when dietary fat and caloric density are increased. Defects in leptin transport appear to be an acquired defect associated with the development of obesity and possibly age.

scholarly journals Hypothalamic Phosphatidylinositol 3-Kinase Pathway of Leptin Signaling Is Impaired during the Development of Diet-Induced Obesity in FVB/N Mice

Endocrinology ◽  
2007 ◽  
Vol 149 (3) ◽  
pp. 1121-1128 ◽  
Author(s):  
Anantha S. Metlakunta ◽  
Maitrayee Sahu ◽  
Abhiram Sahu
Keyword(s):  
Energy Homeostasis ◽  
Early Period ◽  
Pi3k Pathway ◽  
Leptin Resistance ◽  
Phosphatidylinositol 3 Kinase ◽  
Leptin Signaling ◽  
Diet Induced Obesity ◽  
Pi3k Activity ◽  
Central Leptin Resistance ◽  
Phosphatidylinositol 3

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.

scholarly journals Endothelial leptin receptor mutation provides partial resistance to diet-induced obesity

2012 ◽  
Vol 112 (8) ◽  
pp. 1410-1418 ◽  
Author(s):  
Weihong Pan ◽  
Hung Hsuchou ◽  
Germaine G. Cornelissen-Guillaume ◽  
Bhavvani Jayaram ◽  
Yuping Wang ◽  
...  
Keyword(s):  
Body Weight ◽  
Partial Resistance ◽  
Heat Dissipation ◽  
Leptin Receptor ◽  
Wild Type ◽  
Blood Concentrations ◽  
Leptin Signaling ◽  
Metabolic Chamber ◽  
Diet Induced Obesity ◽  
Obesity And Diabetes

Leptin, a polypeptide hormone produced mainly by adipocytes, has diverse effects in both the brain and peripheral organs, including suppression of feeding. Other than mediating leptin transport across the blood-brain barrier, the role of the endothelial leptin receptor remains unclear. We recently generated a mutant mouse strain lacking endothelial leptin receptor signaling, and showed that there is an increased uptake of leptin by brain parenchyma after its delivery by in situ brain perfusion. Here, we tested the hypothesis that endothelial leptin receptor mutation confers partial resistance to diet-induced obesity. These ELKO mice had similar body weight and percent fat as their wild-type littermates when fed with rodent chow, but blood concentrations of leptin were significantly elevated. In response to a high-fat diet, wild-type mice had a greater gain of body weight and fat than ELKO mice. As shown by metabolic chamber measurement, the ELKO mice had higher oxygen consumption, carbon dioxide production, and heat dissipation, although food intake was similar to that of the wild-type mice and locomotor activity was even reduced. This indicates that the partial resistance to diet-induced obesity was mediated by higher metabolic activity in the ELKO mice. Since neuronal leptin receptor knockout mice show obesity and diabetes, the results suggest that endothelial leptin signaling shows opposite effects from that of neuronal leptin signaling, with a facilitatory role in diet-induced obesity.

scholarly journals Leptin resistance: a prediposing factor for diet-induced obesity

2009 ◽  
Vol 296 (3) ◽  
pp. R493-R500 ◽  
Author(s):  
Philip J. Scarpace ◽  
Yi Zhang
Keyword(s):  
Weight Gain ◽  
Leptin Receptor ◽  
Causative Factor ◽  
Leptin Resistance ◽  
Chow Diet ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Dietary Fructose ◽  
Complex Chronic Disease ◽  
Obesity Syndrome

Obesity is a resilient and complex chronic disease. One potential causative factor in the obesity syndrome is leptin resistance. Leptin behaves as a potent anorexic and energy-enhancing hormone in most young or lean animals, but its effects are diminished or lacking in the obese state associated with a normal genetic background. Emerging evidence suggests that leptin resistance predisposes the animal to exacerbated diet-induced obesity (DIO). Elevation of central leptin in young, lean rats induces a leptin resistance that precludes obesity on a chow diet but accelerates high-fat (HF)-induced obesity. Similarly, chronic dietary fructose consumption evokes a leptin resistance that causes obesity only upon HF exposure. Inherent central leptin insensitivity also contributes to dietary weight gain in certain obesity-prone rats. Conversely, aged, leptin-resistant animals are obese with continuous chow feeding and demonstrate aggravated obesity when challenged with an HF diet. Additionally, a submaximal central blockade with a leptin antagonist leads to obesity on both chow and HF diets, as is the case in rodents with leptin receptor deficiency of genetic origin. Despite the differences in the incidence of obesity on a chow diet, all of these forms of leptin resistance predispose rodents to aggravated HF-mediated obesity. Moreover, once leptin resistance takes hold, it aggravates DIO, and the leptin resistance and obesity compound one another, promoting a vicious cycle of escalating weight gain.

scholarly journals Diet-induced obesity leads to the development of leptin resistance in vagal afferent neurons

2011 ◽  
Vol 301 (1) ◽  
pp. E187-E195 ◽  
Author(s):  
Guillaume de Lartigue ◽  
Claire Barbier de la Serre ◽  
Elvis Espero ◽  
Jennifer Lee ◽  
Helen E. Raybould
Keyword(s):  
High Fat Diet ◽  
Leptin Resistance ◽  
Afferent Neurons ◽  
High Fat ◽  
Leptin Signaling ◽  
Protein Levels ◽  
Diet Induced Obesity ◽  
Nodose Ganglia ◽  
Vagal Afferent

Ingestion of high-fat, high-calorie diets is associated with hyperphagia, increased body fat, and obesity. The mechanisms responsible are currently unclear; however, altered leptin signaling may be an important factor. Vagal afferent neurons (VAN) integrate signals from the gut in response to ingestion of nutrients and express leptin receptors. Therefore, we tested the hypothesis that leptin resistance occurs in VAN in response to a high-fat diet. Sprague-Dawley rats, which exhibit a bimodal distribution of body weight gain, were used after ingestion of a high-fat diet for 8 wk. Body weight, food intake, and plasma leptin levels were measured. Leptin signaling was determined by immunohistochemical localization of phosphorylated STAT3 (pSTAT3) in cultured VAN and by quantifaction of pSTAT3 protein levels by Western blot analysis in nodose ganglia and arcuate nucleus in vivo. To determine the mechanism of leptin resistance in nodose ganglia, cultured VAN were stimulated with leptin alone or with lipopolysaccharide (LPS) and SOCS-3 expression measured. SOCS-3 protein levels in VAN were measured by Western blot following leptin administration in vivo. Leptin resulted in appearance of pSTAT3 in VAN of low-fat-fed rats and rats resistant to diet-induced obesity but not diet-induced obese (DIO) rats. However, leptin signaling was normal in arcuate neurons. SOCS-3 expression was increased in VAN of DIO rats. In cultured VAN, LPS increased SOCS-3 expression and inhibited leptin-induced pSTAT3 in vivo. We conclude that VAN of diet-induced obese rats become leptin resistant; LPS and SOCS-3 may play a role in the development of leptin resistance.

scholarly journals Endogenous VMH amylin signaling is required for full leptin signaling and protection from diet-induced obesity

2016 ◽  
Vol 310 (4) ◽  
pp. R355-R365 ◽  
Author(s):  
Ambrose A. Dunn-Meynell ◽  
Christelle Le Foll ◽  
Miranda D. Johnson ◽  
Thomas A. Lutz ◽  
Matthew R. Hayes ◽  
...  
Keyword(s):  
Ventromedial Hypothalamus ◽  
Tolerance Test ◽  
Leptin Resistance ◽  
Oral Glucose ◽  
Dorsomedial Nucleus ◽  
Adeno Associated Virus ◽  
Leptin Signaling ◽  
Insulin Resistant ◽  
Diet Induced Obesity ◽  
Hypothalamic Nuclei

Amylin enhances arcuate (ARC) and ventromedial (VMN) hypothalamic nuclei leptin signaling and synergistically reduces food intake and body weight in selectively bred diet-induced obese (DIO) rats. Since DIO 125I-amylin dorsomedial nucleus-dorsomedial VMN binding was reduced, we postulated that this contributed to DIO ventromedial hypothalamus (VMH) leptin resistance, and that impairing VMH (ARC + VMN) calcitonin receptor (CTR)-mediated signaling by injecting adeno-associated virus (AAV) expressing a short hairpin portion of the CTR mRNA would predispose diet-resistant (DR) rats to obesity on high-fat (45%) diet (HFD). Depleting VMH CTR by 80–90% in 4-wk-old male DR rats reduced their ARC and VMN 125I-labeled leptin binding by 57 and 51%, respectively, and VMN leptin-induced phospho-signal transducer and activator of transcription 3-positive neurons by 59% vs. AAV control rats. After 6 wk on chow, VMH CTR-depleted DR rats ate and gained the equivalent amount of food and weight but had 18% heavier fat pads (relative to carcass weight), 144% higher leptin levels, and were insulin resistant compared with control AAV DR rats. After 6 wk more on HFD, VMH CTR-depleted DR rats ate the same amount but gained 28% more weight, had 60% more carcass fat, 254% higher leptin levels, and 132% higher insulin areas under the curve during an oral glucose tolerance test than control DR rats. Therefore, impairing endogenous VMH CTR-mediated signaling reduced leptin signaling and caused DR rats to become more obese and insulin resistant, both on chow and HFD. These results suggest that endogenous VMH amylin signaling is required for full leptin signaling and protection from HFD-induced obesity.

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