scholarly journals Leptin Signaling in the Hypothalamus during Chronic Central Leptin Infusion

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 3789-3798 ◽  
Author(s):  
Rekha Pal ◽  
Abhiram Sahu
Keyword(s):  
Food Intake ◽  
Leptin Receptor ◽  
Binding Activity ◽  
Janus Kinase ◽  
Male Rats ◽  
Leptin Resistance ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Leptin Signaling ◽  
Initial Decrease

Abstract Using a rat model of chronic central leptin infusion in which neuropeptide Y neurons develop leptin resistance, we examined whether leptin signal transduction mechanism in the hypothalamus is altered during central leptin infusion. Adult male rats were infused chronically into the lateral cerebroventricle with leptin (160 ng/h) or vehicle via Alzet pumps for 16 d. In the leptin-infused group, the initial decrease in food intake was followed by a recovery to their preleptin levels by d 16, although food intake remained significantly lower than in artificial cerebrospinal fluid controls; and body weight gradually decreased reaching a nadir at d 11 and remained stabilized at lower level thereafter. Phosphorylated leptin receptor and phosphorylated signal transducer and activator of transcription-3 (p-STAT3) remained elevated in association with a sustained elevation in DNA-binding activity of STAT3 in the hypothalamus throughout 16-d period of leptin infusion. However, phosphorylated Janus kinase-2 was increased during the early part of leptin infusion but remained unaltered on d 16. Although hypothalamic suppressors of cytokine signaling-3 (SOCS3) mRNA levels were increased throughout leptin infusion, SOCS3 protein levels were increased only on d 16. This study demonstrates a sustained elevation in hypothalamic leptin receptor signaling through Janus kinase-STAT pathway despite an increased expression of SOCS3 during chronic central leptin infusion. We propose that an alteration in leptin signaling in the hypothalamus through pathways other than STAT3 and/or a defect in downstream of STAT3 signaling may be involved in food intake recovery seen after an initial decrease during chronic central leptin infusion.

scholarly journals Leptin Sensitivity in the Developing Rat Hypothalamus

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 6073-6082 ◽  
Author(s):  
A.-S. Carlo ◽  
M. Pyrski ◽  
C. Loudes ◽  
A. Faivre-Baumann ◽  
J. Epelbaum ◽  
...  
Keyword(s):  
Food Intake ◽  
Neuropeptide Y ◽  
Leptin Receptor ◽  
Primary Cultures ◽  
Cytokine Signaling ◽  
Neuronal Cultures ◽  
Mrna Levels ◽  
Leptin Signaling ◽  
Leptin Sensitivity

In adults, the adipocyte-derived hormone, leptin, regulates food intake and body weight principally via the hypothalamic arcuate nucleus (ARC). During early postnatal development, leptin functions to promote the outgrowth of neuronal projections from the ARC, whereas a selective insensitivity to the effects of leptin on food intake appears to exist. To investigate the mechanisms underlying the inability of leptin to regulate food intake during early development, leptin signaling was analyzed both in vitro using primary cultures of rat embryonic ARC neurones and in vivo by challenging early postnatal rats with leptin. In neuronal cultures, despite the presence of key components of the leptin signaling pathway, no detectable activation of either signal transducer and activator of transcription 3 or the MAPK pathways by leptin was detected. However, leptin down-regulated mRNA levels of proopiomelanocortin and neuropeptide Y and decreased somatostatin secretion. Leptin challenge in vivo at postnatal d (P) 7, P14, P21, and P28 revealed that, in contrast to adult and P28 rats, mRNA levels of neuropeptide Y, proopiomelanocortin, agouti-related peptide and cocaine- and amphetamine-regulated transcript were largely unaffected at P7, P14, and P21. Furthermore, leptin stimulation increased the suppressor of cytokine signaling-3 mRNA levels at P14, P21, and P28 in several hypothalamic nuclei but not at P7, indicating that selective leptin insensitivity in the hypothalamus is coupled to developmental shifts in leptin receptor signaling. Thus, the present study defines the onset of leptin sensitivity in the regulation of energy homeostasis in the developing hypothalamus.

scholarly journals Leptin and glucocorticoid signaling pathways in the hypothalamus of female and male fructose-fed rats

2014 ◽  
Vol 66 (2) ◽  
pp. 829-839 ◽  
Author(s):  
Danijela Vojnovic-Milutinovic ◽  
Marina Nikolic ◽  
Jovana Dinic ◽  
Ana Djordjevic ◽  
Natasa Velickovic ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Signaling Pathway ◽  
Leptin Receptor ◽  
Female Rats ◽  
Male Rats ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Leptin Sensitivity ◽  
Male And Female Rats ◽  
Glucocorticoid Signaling

Alterations in leptin and glucocorticoid signaling pathways in the hypothalamus of male and female rats subjected to a fructose-enriched diet were studied. The level of expression of the key components of the leptin signaling pathway (neuropeptide Y /NPY/ and suppressor of cytokine signaling 3 /SOCS3/), and the glucocorticoid signaling pathway (glucocorticoid receptor /GR/, 11?-hydroxysteroid dehydrogenase type 1 /11?HSD1/ and hexose-6-phosphate dehydrogenase /H6PDH/) did not differ between fructose-fed rats and control animals of both genders. However, in females, a fructose-enriched diet provoked increases in the adiposity index, plasma leptin and triglyceride concentrations, and displayed a tendency to decrease the leptin receptor (ObRb) protein and mRNA levels. In male rats, the fructose diet caused elevations in plasma non-esterified fatty acids and triglycerides, as well as in both plasma and hypothalamic leptin concentrations. Our results suggest that a fructose-enriched diet can induce hyperleptinemia in both female and male rats, but with a more pronounced effect on hypothalamic leptin sensitivity in females, probably contributing to the observed development of visceral adiposity.

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.

scholarly journals Protein tyrosine phosphatase-1B contributes to LPS-induced leptin resistance in male rats

2015 ◽  
Vol 308 (1) ◽  
pp. E40-E50 ◽  
Author(s):  
Beatriz de Carvalho Borges ◽  
Rodrigo C. Rorato ◽  
Ernane Torres Uchoa ◽  
Paula B. Marangon ◽  
Carol F. Elias ◽  
...  
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Leptin Receptor ◽  
Tyrosine Phosphatase ◽  
Body Weight Loss ◽  
Male Rats ◽  
Leptin Resistance ◽  
Reduce Food Intake ◽  
Low Grade ◽  
Lps Treatment

Leptin resistance is induced by the feedback inhibitors tyrosine phosphatase-1B (PTP1B) and decreased Src homology 2 domain-containing tyrosine phosphatase-2 (SHP-2) signaling. To investigate the participation of PTP1B and SHP-2 in LPS-induced leptin resistance, we injected repeated (6-LPS) intraperitoneal LPS doses (100 μg/kg ip) for comparison with a single (1-LPS) treatment and evaluated the expression of SHP-2, PTP1B, p-ERK1/2, and p-STAT3 in the hypothalamus of male Wistar rats. The single LPS treatment increased the expression of p-STAT3 and PTP1B but not SHP-2. The repeated LPS treatment reduced SHP-2, increased PTP1B, and did not change p-STAT3. We observed that the PTP1B expression induced by the endotoxin was highly colocalized with leptin receptor cells in the hypothalamus of LepRb-IRES-Cre-tdTomato reporter mice. The single, but not the repeated, LPS treatment decreased the food intake and body weight. Leptin had no stimulatory effect on the hypophagia, body weight loss, or pSTAT3 expression in 6-LPS rats, indicating leptin unresponsiveness. Notably, the PTP1B inhibitor (3.0 nmol/rat in 5 μl icv) restored the LPS-induced hypophagia in 6-LPS rats and restored the ability of leptin to reduce food intake and body weight as well as to phosphorylate STAT3 in the arcuate, paraventricular, and ventromedial nuclei of the hypothalamus. The present data suggest that an increased PTP1B expression in the hypothalamus underlies the development of leptin resistance during repeated exposure to LPS. Our findings contribute to understanding the mechanisms involved in leptin resistance during low-grade inflammation as seen in obesity.

Hypothalamic response to leptin changes during a hormonally induced estrous cycle in rats

2006 ◽  
Vol 1 (2) ◽  
pp. 221-234 ◽  
Author(s):  
Kajsa Sjöholm ◽  
Björn Carlsson ◽  
Lena Carlsson
Keyword(s):  
Food Intake ◽  
Estrous Cycle ◽  
Primary Response ◽  
The Body ◽  
Leptin Resistance ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Significant Difference ◽  
Cyclic Feeding

AbstractThe leptin system regulates body fat mass through a feedback loop between adipose tissue and the hypothalamus. To test if leptin responsiveness may be regulated we assayed hypothalamic response to leptin during the estrous cycle; when changes in food intake are known to occur. Immature rats were treated with pregnant mare’s serum gonadotropin (PMSG) to induce synchronized follicular development, ovulation and corpus luteum formation. Leptin response was estimated by measuring the in vitro induction of tis11, a primary response gene activated by STAT3-dependent cytokines in hypothalamic explants after leptin stimulation. In addition, mRNA levels of the suppressor cytokine signaling-3 (SOCS-3), a possible mediator of leptin resistance, were analyzed. Serum leptin levels did not change between days 2 and day 3 (corresponding to proestrus and estrus, respectively) but the response to leptin was higher on day 2 than on day 3 (p=0.05). Food intake displayed a tendency towards downregulation between day 1 and day 2 (p=0.057), and a tendency towards upregulation between day 2 and day 3 (p=0.072), although the body weight increased on day of the study (p<0.0001). There was no significant difference in hypothalamic expression of SOCS-3 between day 2 and day 3. In conclusion, we have shown that leptin responsiveness changes during a hormonally induced estrous cycle in rats. Our data suggest that a change in the hypothalamic response to leptin may cause the cyclic feeding behavior seen in rats.

scholarly journals Region-Specific Leptin Resistance within the Hypothalamus of Diet-Induced Obese Mice

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4880-4889 ◽  
Author(s):  
Heike Münzberg ◽  
Jeffrey S. Flier ◽  
Christian Bjørbæk
Keyword(s):  
High Fat Diet ◽  
Leptin Receptor ◽  
Elevated Serum ◽  
Brain Regions ◽  
Leptin Resistance ◽  
Hypothalamic Nucleus ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
High Fat ◽  
Suppressor Of Cytokine Signaling

Abstract Leptin resistance in diet-induced obese (DIO) mice is characterized by elevated serum leptin and a decreased response to exogenous leptin and is caused by unknown defects in the central nervous system. Leptin normally acts on several brain nuclei, but a detailed description of leptin resistance within individual brain regions has not been reported. We first mapped leptin-responsive cells in brains from DIO mice using phospho-signal transducer and activator of transcription (P-STAT3) immunohistochemistry. After 16 wk of high-fat-diet feeding, leptin-activated P-STAT3 staining within the arcuate nucleus (ARC) was dramatically decreased. In contrast, other hypothalamic and extrahypothalamic nuclei remained leptin sensitive. Reduced leptin-induced P-STAT3 in the ARC could also be detected after 4 wk and as early as 6 d of a high-fat diet. To examine potential mechanisms for leptin-resistant STAT3 activation in the ARC of DIO mice, we measured mRNA levels of candidate signaling molecules in the leptin receptor-STAT3 pathway. We found that the level of suppressor of cytokine signaling 3 (SOCS-3), an inhibitor of leptin signaling, is specifically increased in the ARC of DIO mice. The study suggests that the ARC is selectively leptin resistant in DIO mice and that this may be caused by elevated suppressor of cytokine signaling 3 in this hypothalamic nucleus. Defects in leptin action in the ARC may play a role in the pathogenesis of leptin-resistant obesity.

Topiramate Treatment Improves Hypothalamic Insulin and Leptin Signaling and Action and Reduces Obesity in Mice

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4401-4411 ◽  
Author(s):  
Andrea M. Caricilli ◽  
Erica Penteado ◽  
Lélia L. de Abreu ◽  
Paula G. F. Quaresma ◽  
Andressa C. Santos ◽  
...  
Keyword(s):  
Food Intake ◽  
Molecular Mechanisms ◽  
Janus Kinase ◽  
Mrna Levels ◽  
Obese Mice ◽  
Short Term ◽  
Short Term Treatment ◽  
Peripheral Tissues ◽  
Leptin Signaling ◽  
Brown Adipose

Topiramate (TPM) treatment has been shown to reduce adiposity in humans and rodents. The reduction in adiposity is related to decreased food intake and increased energy expenditure. However, the molecular mechanisms through which TPM induces weight loss are contradictory and remain to be clarified. Whether TPM treatment alters hypothalamic insulin, or leptin signaling and action, is not well established. Thus, we investigate herein whether short-term TPM treatment alters energy balance by affecting insulin and leptin signaling, action, or neuropeptide expression in the hypothalamus of mice fed with a high-fat diet. As expected, short-term treatment with TPM diminished adiposity in obese mice mainly due to reduced food intake. TPM increased anorexigenic signaling by enhancing the leptin-induced leptin receptor/Janus kinase 2/signal transducer and activator of transcription 3 pathway and the insulin-induced insulin receptor substrate/Akt/forkhead box O1 pathway in parallel to reduced phosphatase protein expression in the hypothalamus of obese mice. These effects were independent of body weight. TPM also raised anorexigenic neuropeptides such as POMC, TRH, and CRH mRNA levels in obese mice. In addition, TPM increased the activation of the hypothalamic MAPK/ERK pathway induced by leptin, accompanied by an increase in peroxisome proliferator-activated receptor-coactivator α and uncoupling protein 1 protein levels in brown adipose tissue. Furthermore, TPM increased AMP-activated protein kinase and acetyl-coenzyme A carboxylase phosphorylation in peripheral tissues, which may help improve energy metabolism in these tissues. Together, these results provide novel insights into the molecular mechanisms through which TPM treatment reduces adiposity.

scholarly journals Hyperphagia and Central Mechanisms for Leptin Resistance during Pregnancy

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1355-1365 ◽  
Author(s):  
M. L Trujillo ◽  
C. Spuch ◽  
E. Carro ◽  
R. Señarís
Keyword(s):  
Food Intake ◽  
Late Pregnancy ◽  
Leptin Resistance ◽  
Cytokine Signaling ◽  
Sprague Dawley ◽  
Leptin Signaling ◽  
Akt Phosphorylation ◽  
Pomc Mrna ◽  
Intake Regulation ◽  
Maternal Hormones

Abstract The purpose of this work was to study the central mechanisms involved in food intake regulation and leptin resistance during gestation in the rat. Sprague Dawley rats of 7, 13, and 18 d of pregnancy [days of gestation (G) 7, G13, and G18] were used and compared with nonpregnant animals in diestrus-1. Food intake was already increased in G7, before hyperleptinemia and central leptin resistance was established in midpregnancy. Leptin resistance was due to a reduction in leptin transport through the blood-brain barrier (BBB) and to alterations in leptin signaling within the hypothalamus based on an increase in suppressor of cytokine signaling 3 levels and a blockade of signal transducer and activator of transcription-3 phosphorylation (G13), followed by a decrease in LepRb and of Akt phosphorylation (G18). In early gestation (G7), no change in hypothalamic neuropeptide Y (NPY), agouti-related peptide (AgRP), or proopiomelanocortin (POMC) expression was shown. Nevertheless, an increase in NPY and AgRP and a decrease in POMC mRNA were observed in G13 and G18 rats, probably reflecting the leptin resistance. To investigate the effect of maternal vs. placental hormones on these mechanisms, we used a model of pseudogestation. Rats of 9 d of pseudogestation were hyperphagic, showing an increase in body and adipose tissue weight, normoleptinemia, and normal responses to iv/intracerebroventricular leptin on hypothalamic leptin signaling, food intake, and body weight. Leptin transport through the BBB, and hypothalamic NPY, AgRP and POMC expression were unchanged. Finally, the transport of leptin through the BBB was assessed using a double-chamber culture system of choroid plexus epithelial cells or brain microvascular endothelial cells. We found that sustained high levels of prolactin significantly reduced leptin translocation through the barrier, whereas progesterone and β-estradiol did not show any effect. Our data demonstrate a dual mechanism of leptin resistance during mid/late-pregnancy, which is not due to maternal hormones and which allows the maintenance of hyperphagia in the presence of hyperleptinemia driven by an increase in NPY and AgRP and a decrease in POMC mRNA. By contrast, in early pregnancy maternal hormones induce hyperphagia without the regulation of hypothalamic NPY, AgRP, or POMC and in the absence of leptin resistance.

Role of hypoleptinemia during cold adaptation in Brandt's voles (Lasiopodomys brandtii)

2009 ◽  
Vol 297 (5) ◽  
pp. R1293-R1301 ◽  
Author(s):  
Gang-Bin Tang ◽  
Jian-Guo Cui ◽  
De-Hua Wang
Keyword(s):  
Food Intake ◽  
Cold Adaptation ◽  
Leptin Receptor ◽  
Uncoupling Protein ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Serum Leptin ◽  
Brown Adipose ◽  
Lasiopodomys Brandtii

Brandt's voles Lasiopodomys brandtii exhibit large increases in nonshivering thermogenesis to cope with chronic cold exposure, resulting in compensatory hyperphagia and fat mobilization. These physiological events are accompanied by a remarkable reduction in serum leptin levels. However, the role of hypoleptinemia in cold adaptation in this species is still unknown. In the present study, we tested the hypothesis that hypoleptinemia contributes to increases in food intake and brown adipose tissue (BAT) thermogenesis by modifying hypothalamic neuropeptides in cold-exposed Brandt's voles. Adult male voles were transferred to 5°C for 28 days. Accompanied by a decrease in serum leptin levels, hypothalamic agouti-related protein (AgRP) mRNA levels were significantly increased, but there were no changes in the long form of leptin receptor (Ob-Rb), suppressor of cytokine signaling 3 (SOCS3), neuropeptide Y (NPY) mRNA, proopiomelanocortin (POMC), and cocaine- and amphetamine-regulated peptide (CART) mRNA levels in the hypothalamus. When cold-exposed voles were returned to warm (23°C) for 28 days, body mass, food intake, serum leptin, and AgRP mRNA were restored to control levels. Leptin administration in cold-exposed voles decreased food intake as well as hypothalamic AgRP mRNA levels. There were no significant effects of leptin administration on hypothalamic Ob-Rb, SOCS3, NPY, POMC, CART mRNA, and uncoupling protein 1 levels under cold conditions. These results suggest that hypoleptinemia partially contributes to cold-induced hyperphagia, which might involve the elevation of hypothalamic AgRP gene expression.

scholarly journals High Intakes of [6S]-5-Methyltetrahydrofolic Acid Compared with Folic Acid during Pregnancy Programs Central and Peripheral Mechanisms Favouring Increased Food Intake and Body Weight of Mature Female Offspring

Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1477
Author(s):  
Emanuela Pannia ◽  
Rola Hammoud ◽  
Ruslan Kubant ◽  
Jong Yup Sa ◽  
Rebecca Simonian ◽  
...  
Keyword(s):  
Body Weight ◽  
Folic Acid ◽  
Food Intake ◽  
Leptin Receptor ◽  
Liver Weight ◽  
Female Offspring ◽  
Mature Female ◽  
Cytokine Signaling ◽  
Light Cycle ◽  
Energy Regulation

Supplementation with [6S]-5-methyltetrahydrofolic acid (MTHF) is recommended as an alternative to folic acid (FA) in prenatal supplements. This study compared equimolar gestational FA and MTHF diets on energy regulation of female offspring. Wistar rats were fed an AIN-93G diet with recommended (2 mg/kg diet) or 5-fold (5X) intakes of MTHF or FA. At weaning, female offspring were fed a 45% fat diet until 19 weeks. The 5X-MTHF offspring had higher body weight (>15%), food intake (8%), light-cycle energy expenditure, and lower activity compared to 5X-FA offspring (p < 0.05). Both the 5X offspring had higher plasma levels of the anorectic hormone leptin at birth (60%) and at 19 weeks (40%), and lower liver weight and total liver lipids compared to the 1X offspring (p < 0.05). Hypothalamic mRNA expression of leptin receptor (ObRb) was lower, and of suppressor of cytokine signaling-3 (Socs3) was higher in the 5X-MTHF offspring (p < 0.05), suggesting central leptin dysregulation. In contrast, the 5X-FA offspring had higher expression of genes encoding for dopamine and GABA- neurotransmitter receptors (p < 0.01), consistent with their phenotype and reduced food intake. When fed folate diets at the requirement level, no differences were found due to form in the offspring. We conclude that MTHF compared to FA consumed at high levels in the gestational diets program central and peripheral mechanisms to favour increased weight gain in the offspring. These pre-clinical findings caution against high gestational intakes of folates of either form and encourage clinical trials examining their long-term health effects when consumed during pregnancy.

Sign in / Sign up

Export Citation Format

Share Document