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.

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.

Consuming sucrose solution promotes leptin resistance and site specifically modifies hypothalamic leptin signaling in rats

2020 ◽  
Author(s):  
Ruth B.S. Harris
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Sucrose Solution ◽  
Ventromedial Hypothalamus ◽  
Primary Response ◽  
Leptin Resistance ◽  
Sprague Dawley ◽  
Leptin Signaling ◽  
Transient Rise

Rats consuming 30% sucrose solution and a sucrose-free diet (LiqS) become leptin resistant whereas rats consuming sucrose from a formulated diet (HS) remain leptin responsive. This study tested whether leptin resistance in LiqS rats extended beyond a failure to inhibit food intake and examined leptin responsiveness in the hypothalamus and hindbrain of rats offered HS, LiqS or a sucrose free diet (NS). Female LiqS Sprague Dawley rats initially only partially compensated for the calories consumed as sucrose, but energy intake matched that of HS and NS rats when they were transferred to calorimetry cages. There was no effect of diet on energy expenditure, IBAT temperature or fat pad weight. A peripheral injection of 2 mg leptin/kg on Day 23 or 26 inhibited energy intake of HS and NS, but not LiqS rats. Inhibition occurred earlier in HS than NS rats and was associated with a smaller meal size. Leptin had no effect on energy expenditure, but caused a transient rise in IBAT temperature of HS rats. Leptin increased pSTAT3 in the hindbrain and ventromedial hypothalamus of all rats. There was a minimal effect of leptin in the arcuate nucleus and only the dorsomedial hypothalamus showed a correlation between pSTAT3 and leptin responsiveness. These data suggest that the primary response to leptin is inhibition of food intake and that the pattern of sucrose consumption, rather than calories consumed as sucrose causes leptin resistance associated with site specific differences in hypothalamic leptin signaling.

scholarly journals The Anorexigenic Neural Pathways of Oxytocin and Their Clinical Implication

2018 ◽  
Vol 107 (1) ◽  
pp. 91-104 ◽  
Author(s):  
Yuko Maejima ◽  
Shoko Yokota ◽  
Katsuhiko Nishimori ◽  
Kenju Shimomura
Keyword(s):  
Adipose Tissue ◽  
Food Intake ◽  
Fat Mass ◽  
Physiological Role ◽  
Leptin Resistance ◽  
Neural Pathways ◽  
Feeding Regulation ◽  
Food Intake Regulation ◽  
Intake Regulation ◽  
The Brain

Oxytocin was discovered in 1906 as a peptide that promotes delivery and milk ejection; however, its additional physiological functions were determined 100 years later. Many recent articles have reported newly discovered effects of oxytocin on social communication, bonding, reward-related behavior, adipose tissue, and muscle and food intake regulation. Because oxytocin neurons project to various regions in the brain that contribute to both feeding reward (hedonic feeding) and the regulation of energy balance (homeostatic feeding), the mechanisms of oxytocin on food intake regulation are complicated and largely unknown. Oxytocin neurons in the paraventricular nucleus (PVN) receive neural projections from the arcuate nucleus (ARC), which is an important center for feeding regulation. On the other hand, these neurons in the PVN and supraoptic nucleus project to the ARC. PVN oxytocin neurons also project to the brain stem and the reward-related limbic system. In addition to this, oxytocin induces lipolysis and decreases fat mass. However, these effects in feeding and adipose tissue are known to be dependent on body weight (BW). Oxytocin treatment is more effective in food intake regulation and fat mass decline for individuals with leptin resistance and higher BW, but is known to be less effective in individuals with normal BW. In this review, we present in detail the recent findings on the physiological role of oxytocin in feeding regulation and the anorexigenic neural pathway of oxytocin neurons, as well as the advantage of oxytocin usage for anti-obesity treatment.

Food intake regulation in late pregnancy and early lactation

1999 ◽  
Vol 24 ◽  
pp. 37-54 ◽  
Author(s):  
K. L. Ingvartsen ◽  
N. C. Friggens ◽  
P. Faverdin
Keyword(s):  
Food Intake ◽  
Late Pregnancy ◽  
Reproductive Hormones ◽  
Early Lactation ◽  
Physical Constraints ◽  
Body Reserves ◽  
Food Intake Regulation ◽  
Periparturient Cows ◽  
Intake Regulation

AbstractThe dip in food intake, which starts in late pregnancy and continues into early lactation, has traditionally been interpreted as a depression in intake due to physical constraints. However, the rôle of physical constraints on intake has been overemphasized, particularly in early lactation. There is mounting evidence that the presence and mobilization of body reserves in early lactation play an important rôle in regulating intake at this time.Conceptually, the dip in intake in early lactation observed when cows have access to non-limiting foods can be accounted for by assuming that the cow has a desired level of body reserves. When the cow is not compromised, the changes with time in body reserves and the dip in intake represent the normal case and provide the basis against which to assess true depressions in intake which may occur when the cow is compromised by limiting nutrition or environment.The regulation of body reserves and intake in the periparturient cow is orchestrated through nervous and hormonal signals. Likely factors that are involved in intake regulation are reproductive hormones, neuropeptides, adrenergic signals, insulin and insulin resistance and leptin. Furthermore, oxidation of NEFA in the liver may result in feedback signals that reduce intake. The relative importance of these is discussed. A better understanding of the physiological signals involved in intake regulation and their interrelations with body weight regulation may provide important indicators of the degree of compromise that periparturient cows may experience.

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 Increased Hypothalamic Protein Tyrosine Phosphatase 1B Contributes to Leptin Resistance with Age

Endocrinology ◽  
2007 ◽  
Vol 148 (1) ◽  
pp. 433-440 ◽  
Author(s):  
Christopher D. Morrison ◽  
Christy L. White ◽  
Zhong Wang ◽  
Seung-Yub Lee ◽  
David S. Lawrence ◽  
...  
Keyword(s):  
Food Intake ◽  
Protein Tyrosine Phosphatase ◽  
Middle Age ◽  
Tyrosine Phosphatase ◽  
Leptin Resistance ◽  
Protein Tyrosine Phosphatase 1B ◽  
Sprague Dawley ◽  
Protein Tyrosine ◽  
Leptin Sensitivity ◽  
Old Rats

Animals at advanced ages exhibit a reduction in central leptin sensitivity. However, changes in growth, metabolism, and obesity risk occur much earlier in life, particularly during the transition from youth to middle age. To determine when initial decreases in central leptin sensitivity occur, leptin-dependent suppression of food intake was tested in 8-, 12-, and 20-wk-old male, chow-fed Sprague Dawley rats. Intracerebroventricular leptin injection (3 μg) suppressed 24-h food intake in 8- and 12-wk-old rats (P < 0.05) but not 20-wk-old rats. To identify potential cellular mediators of this resistance, we focused on protein tyrosine phosphatase 1B (PTP1B), a recently described inhibitor of leptin signaling. PTP1B protein levels, as determined by Western blot, were significantly higher in mediobasal hypothalamic punches collected from 20-wk-old rats, compared with 8-wk-old rats (P < 0.05). When 20-wk-old rats were fasted for 24 h, levels of hypothalamic PTP1B decreased (P < 0.05), coincident with a restoration of leptin sensitivity. To directly test whether inhibition of PTP1B restores leptin sensitivity, 20-wk-old chow-fed rats were pretreated with a pharmacological PTP1B inhibitor 1 h before leptin, and 24-h food intake was recorded. As expected, leptin alone produced a small but nonsignificant reduction in food intake. However, pretreatment with the PTP1B inhibitor resulted in a marked improvement in leptin-dependent suppression of food intake (P < 0.05). These data are consistent with the hypothesis that increases in PTP1B contribute to hypothalamic leptin resistance as rats transition into middle age.

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 Selective Inactivation of Socs3 in SF1 Neurons Improves Glucose Homeostasis without Affecting Body Weight

Endocrinology ◽  
2008 ◽  
Vol 149 (11) ◽  
pp. 5654-5661 ◽  
Author(s):  
Ren Zhang ◽  
Harveen Dhillon ◽  
Huali Yin ◽  
Akihiko Yoshimura ◽  
Bradford B. Lowell ◽  
...  
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Energy Expenditure ◽  
Glucose Homeostasis ◽  
Leptin Resistance ◽  
High Fat ◽  
Leptin Signaling ◽  
Leptin Sensitivity ◽  
High Fat Diets ◽  
Fat Diets

Suppressor of cytokine signaling 3 (Socs3) has been identified as a mediator of central leptin resistance, but the identity of specific neurons in which Socs3 acts to suppress leptin signaling remains elusive. The ventromedial hypothalamus (VMH) was recently shown to be an important site for leptin action because deleting leptin receptor within VMH neurons causes obesity. To examine the role of VMH Socs3 in leptin resistance and energy homeostasis, we generated mice lacking Socs3 specifically in neurons positive for steroidogenic factor 1 (SF1), which is expressed abundantly in the VMH. These mice had increased phosphorylation of signal transducer and activator of transcription-3 in VMH neurons, suggesting improved leptin signaling, and consistently, food intake and weight-reducing effects of exogenous leptin were enhanced. Furthermore, on either chow or high-fat diets, these mice had reduced food intake. Unexpectedly, energy expenditure was reduced as well. Mice lacking Socs3 in SF1 neurons, despite no change in body weight, had improved glucose homeostasis and were partially protected from hyperglycemia and hyperinsulinemia induced by high-fat diets. These results suggest that Socs3 in SF1 neurons negatively regulates leptin signaling and plays important roles in mediating leptin sensitivity, glucose homeostasis, and energy expenditure.

Abstract 077: Role of Suppressor of Cytokines Signaling 3 (SOCS3) in POMC Neurons in Regulating Metabolic and Cardiovascular Functions in Dietary-Induced Obesity

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Zhen Wang ◽  
Jussara do Carmo ◽  
Alexandre da Silva ◽  
Nicola Aberdein ◽  
John Hall
Keyword(s):  
Food Intake ◽  
Glucose Tolerance ◽  
Body Weight Gain ◽  
Negative Regulator ◽  
Leptin Resistance ◽  
Cytokine Signaling ◽  
Male And Female ◽  
Air Jet ◽  
Cardiovascular Functions

Suppressor of cytokine signaling 3 (SOCS3), a negative regulator of leptin signaling, may contribute to the development of obesity-induced leptin resistance. Previously, we showed that activation of proopiomelanocortin (POMC) neurons mediates the chronic effects of leptin on blood pressure (BP) and glucose regulation. However, the role of SOCS3 in POMC neurons in regulating metabolic and cardiovascular functions in obesity is still unclear. To address this question, we used male and female mice with SOCS3 deleted only in POMC neurons (SOCS3 flox/flox -POMC/cre) and flox control (SOCS3 flox/flox ) mice. After weaning, mice were fed normal chow until 20 wks of age; then glucose tolerance tests (GTT) were performed and telemetry probes were implanted to measure mean arterial pressure (MAP) 24-hrs/day. We found that at 23 wks of age, both male and female SOCS3 flox/flox -POMC/cre mice weighed less than control mice (32±1 vs 37±2 g in male and 25±1 vs 27±1 g in female, n=9-11, p <0.05), but had similar daily food intake (3.5±0.2 g in male and 3.3±0.1 g in female) and MAP (114±1 vs 115±2 mmHg). Only male SOCS3 flox/flox -POMC/cre mice exhibited improved glucose tolerance (AUC: 1059±52 vs 1283±54 mg/dL x 120 min, n=7-10, p <0.05) compared to controls. From 23 wks, mice were switched to a high fat diet (45%, HFD) for 6 wks. After HFD feeding, both male and female SOCS3 flox/flox -POMC/cre mice had slightly reduced food intake (3.2±0.1 vs 3.5±0.2 g in male and 2.7±0.1 vs 3.0±0.2 g in female) and a trend toward lower body weight gain (10±1 vs 12±1 g in male and 4±1 vs 6±1 g in female), although the differences were not significant compared to controls. However, male and female SOCS3 flox/flox -POMC/cre mice fed a HFD had significantly greater MAP increase (7±1 vs 1±1 mmHg, n=13-16, p <0.05) and an enhanced BP response to acute air-jet stress (AUC: 109±9 vs 74±12 mmHg x 5min, n=8-13, p <0.05). After HFD, glucose tolerance was impaired in all groups of mice compared to the baseline at 20 wks, but there were no differences between SOCS3 flox/flox -POMC/cre and controls. These results suggest that deletion of SOCS3 in POMC neurons amplifies the BP response to a HFD and to acute stress, but has minimal effects on metabolic functions to HFD. (NHLBI PO1HL51971, NIGMS P20GM104357, AHA 14POST18160019)

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.

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