scholarly journals Selection of non-competitive leptin antagonists using a random nanobody-based approach

2011 ◽  
Vol 441 (1) ◽  
pp. 425-434 ◽  
Author(s):  
Lennart Zabeau ◽  
Annick Verhee ◽  
Dominiek Catteeuw ◽  
Liesbeth Faes ◽  
Sylvie Seeuws ◽  
...  
Keyword(s):  
Leptin Receptor ◽  
Serum Insulin ◽  
High Energy ◽  
Single Chain ◽  
Liver Size ◽  
Metabolic Switch ◽  
Body Fat Content ◽  
Fibronectin Type Iii ◽  
Energy Consuming ◽  
Study Support

The adipocyte-derived cytokine leptin acts as a metabolic switch, connecting the body's metabolism to high-energy consuming processes such as reproduction and immune responses. Accumulating evidence suggests that leptin plays a role in human pathologies, such as autoimmune diseases and cancer, thus providing a rationale for the development of leptin antagonists. In the present study, we generated and evaluated a panel of neutralizing nanobodies targeting the LR (leptin receptor). A nanobody comprises the variable domain of the naturally occurring single-chain antibodies found in members of the Camelidae family. We identified three classes of neutralizing nanobodies targeting different LR subdomains: i.e. the CRH2 (cytokine receptor homology 2), Ig-like and FNIII (fibronectin type III) domains. Only nanobodies directed against the CRH2 domain inhibited leptin binding. We could show that a nanobody that targets the Ig-like domain potently interfered with leptin-dependent regulation of hypothalamic NPY (neuropeptide Y) expression. As a consequence, daily intraperitoneal injection increased body weight, body fat content, food intake, liver size and serum insulin levels. All of these characteristics resemble the phenotype of leptin and LR-deficient animals. The results of the present study support proposed models of the activated LR complex, and demonstrate that it is possible to block LR signalling without affecting ligand binding. These nanobodies form new tools to study the mechanisms of BBB (blood–brain barrier) leptin transport and the effect of LR inhibition in disease models.

Antagonizing leptin: current status and future directions

2014 ◽  
Vol 395 (5) ◽  
pp. 499-514 ◽  
Author(s):  
Lennart Zabeau ◽  
Frank Peelman ◽  
Jan Tavernier
Keyword(s):  
Nutritional Status ◽  
Immune Responses ◽  
Autoimmune Diseases ◽  
High Energy ◽  
Current Status ◽  
Metabolic Switch ◽  
Future Directions ◽  
Leptin Signaling ◽  
Energy Consuming

Abstract The adipocyte-derived hormone/cytokine leptin acts as a metabolic switch, connecting the body’s nutritional status to high energy consuming processes such as reproduction and immune responses. Inappropriate leptin responses can promote autoimmune diseases and tumorigenesis. In this review we discuss the current strategies to modulate leptin signaling and the possibilities for their use in research and therapy.

scholarly journals Intranasal Leptin Reduces Appetite and Induces Weight Loss in Rats with Diet-Induced Obesity (DIO)

Endocrinology ◽  
2012 ◽  
Vol 153 (1) ◽  
pp. 143-153 ◽  
Author(s):  
Carla Schulz ◽  
Kerstin Paulus ◽  
Olaf Jöhren ◽  
Hendrik Lehnert
Keyword(s):  
Weight Loss ◽  
Leptin Receptor ◽  
Serum Insulin ◽  
Standard Diet ◽  
Altered Expression ◽  
Diet Induced Obesity ◽  
Before And After ◽  
Altered Expression Pattern ◽  
Male Wistar Rats ◽  
Treatment Of Obesity

Resistance to brain-mediated effects of leptin is a characteristic feature of obesity, resulting from alterations in leptin receptor signaling in hypothalamic neurons and/or transport across the blood-brain-barrier. We have shown previously, that the latter can be circumvented by intranasal (i.n.) application of leptin in lean rats. This prompted us to test i.n. leptin in animals with diet-induced obesity (DIO) as a basis for future human administration. DIO was induced in male Wistar rats by feeding a cafeteria diet for 25 or 32 wk, respectively. Consecutively, these DIO animals (seven to eight per treatment) and standard diet rats (lean) (14–15 per treatment, matched for age and diet duration) were treated with 0.1, 0.2 mg/kg leptin, or control solution i.n. daily for 4 wk before onset of dark period. Energy intake and body weight were measured daily; blood glucose, serum insulin, and leptin were measured before and after treatment. Expression of hypothalamic neuropeptides was assessed by quantitative real-time PCR. We demonstrate, for the first time, that i.n. leptin reduces appetite and induces weight loss in DIO to the same extent as in lean rats. Our findings are supported accordingly by an altered expression pattern of anorexigenic and orexigenic neuropeptides in the hypothalamus, e.g. proopiomelanocortin, cocaine and amphetamine-related transcript, neuropeptide Y, agouti-related protein. It now appears clear that i.n. leptin is effectively acting in obese animals in the same fashion as in their lean counterparts. These findings now clearly warrant studies in humans and may open new perspectives in the treatment of obesity.

scholarly journals Three weeks of postweaning exercise in DIO rats produces prolonged increases in central leptin sensitivity and signaling

2009 ◽  
Vol 296 (3) ◽  
pp. R537-R548 ◽  
Author(s):  
Christa M. Patterson ◽  
Sebastien G. Bouret ◽  
Ambrose A. Dunn-Meynell ◽  
Barry E. Levin
Keyword(s):  
Food Intake ◽  
Receptor Binding ◽  
Arcuate Nucleus ◽  
Leptin Receptor ◽  
High Energy ◽  
Decrease Food Intake ◽  
Diet Induced Obesity ◽  
Leptin Sensitivity

In rats selectively bred to develop diet-induced obesity (DIO) 3 wk of postweaning exercise reduces weight and adipose regain for 10 wk after exercise cessation, despite intake of 31% fat high-energy (HE) diet. To test the hypothesis that this effect is due to increased central leptin sensitivity, 4-wk-old DIO rats were fed the HE diet and left sedentary (Sed), exercised for 3 wk, and then remained sedentary for 10 additional weeks (Ex/Sed) or continued exercise for a full 13 wk (Ex). After 3 wk, leptin (5 mg/kg ip) induced a 36% decrease in 24-h food intake in Ex rats, while Sed rats had no change in 24-h intake. Ex rats also had 23% more leptin-induced phospho-STAT3 (pSTAT3)-expressing neurons in the arcuate nucleus (ARC) and 95% and 68% higher 125I-labeled leptin receptor binding in the ventromedial and dorsomedial nuclei than did Sed rats, respectively. At 7 wk after onset, leptin decreased 24-h intake by 20% in Ex and 24% in Ex/Sed rats without altering Sed intake. After a total of 13 wk, compared with Sed rats, Ex and Ex/Sed rats had 58% and 38% less fat, respectively, but leptin failed to decrease food intake in any group. Nevertheless, Ex, but not Ex/Sed rats, still had 32% more ARC leptin-induced pSTAT3-expressing neurons than Sed rats. These data suggest that brief postweaning exercise in DIO rats that are inherently leptin resistant causes a sustained resistance to obesity on HE diet, which is, in part, due to increased central leptin sensitivity.

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.

Neuronal deletion of Lepr elicits diabesity in mice without affecting cold tolerance or fertility

2005 ◽  
Vol 289 (3) ◽  
pp. E403-E411 ◽  
Author(s):  
Julie E. McMinn ◽  
Shun-Mei Liu ◽  
Hong Liu ◽  
Ioannis Dragatsis ◽  
Paula Dietrich ◽  
...  
Keyword(s):  
Cold Tolerance ◽  
Leptin Receptor ◽  
Serum Insulin ◽  
Tolerance Test ◽  
Serum Leptin ◽  
Leptin Signaling ◽  
Cold Tolerant ◽  
Total Fat ◽  
The Brain ◽  
Specific Deletion

Leptin signaling in the brain regulates energy intake and expenditure. To test the degree of functional neuronal leptin signaling required for the maintenance of body composition, fertility, and cold tolerance, transgenic mice expressing Cre in neurons ( CaMKIIα-Cre) were crossed to mice carrying a floxed leptin receptor ( Lepr) allele to generate mice with neuron-specific deletion of Lepr in ∼50% ( C F/F mice) and ∼75% ( C Δ17/F mice) of hypothalamic neurons. Leptin receptor (LEPR)-deficient mice ( Δ17/Δ17) with heat-shock-Cre-mediated global Lepr deletion served as obese controls. At 16 wk, male C F/F, C Δ17/F, and Δ17/Δ17 mice were 13.2 ( P < 0.05), 45.0, and 55.9% ( P < 0.001) heavier, respectively, than lean controls, whereas females showed 31.6, 68.8, and 160.7% increases in body mass ( P < 0.001). Significant increases in total fat mass ( C F/F: P < 0.01; C Δ17/F and Δ17/Δ17: P < 0.001 vs. sex-matched, lean controls), and serum leptin concentrations ( P < 0.001 vs. controls) were present in proportion to Lepr deletion. Male C Δ17/F mice had significant elevations in basal serum insulin concentrations ( P < 0.001 vs. controls) and were glucose intolerant, as measured by glucose tolerance test (AUC P < 0.01 vs. controls). In contrast with previous observations in mice null for LEPR signaling, C F/F and C Δ17/F mice were fertile and cold tolerant. These findings support the hypothesis that body weight, adiposity, serum leptin concentrations, and glucose intolerance are proportional to hypothalamic LEPR deficiency. However, fertility and cold tolerance remain intact unless hypothalamic LEPR deficiency is complete.

Research on the Energy Saving Potential of Official Cars in China

2011 ◽  
Vol 128-129 ◽  
pp. 1217-1221
Author(s):  
Quan Le Liu ◽  
Wei Chen
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Fuel Efficiency ◽  
High Energy ◽  
Maintenance Cost ◽  
Strategy Method ◽  
Energy Saving Potential ◽  
Energy Consuming

The quantity of official cars increased with the speed exceeding 20% every year which need much more energy be consumed to meet the official car needs. To investigate the energy saving potential of official cars in China, This paper introduced the strategy method with systemic viewpoint to reduce official cars energy consumption through analyzing the reason of high energy consuming of official cars. The resulted showed that only reduce the quantities and maintenance cost, and decline the displacement and using frequency can realize fuel efficiency of official cars.

Ontogeny of diet-induced obesity in selectively bred Sprague-Dawley rats

2003 ◽  
Vol 285 (3) ◽  
pp. R610-R618 ◽  
Author(s):  
Matthew R. Ricci ◽  
Barry E. Levin
Keyword(s):  
Leptin Receptor ◽  
Splice Variants ◽  
Caloric Intake ◽  
High Energy ◽  
Sprague Dawley ◽  
Low Fat Diet ◽  
Diet Induced Obesity ◽  
Leptin Sensitivity ◽  
Sprague Dawley Rats ◽  
Plasma Leptin

Outbred Sprague-Dawley rats selectively bred for their propensity to develop diet-induced obesity (DIO) become heavier on low-fat diet than those bred to be diet resistant (DR) beginning at ∼5 wk of age. Here we assessed the development of metabolic and neural functions for insights into the origins of their greater weight gain. From week 5 to week 10, chow-fed DIO rats gained 15% more body weight and ate ∼14% more calories but had only slightly greater adiposity and plasma leptin than DR rats. From day 3 through week 10, DIO and DR rats had similar mRNA expression of arcuate nucleus neuropeptide Y, proopiomelanocortin, agouti-related peptide, and all splice variants of the leptin receptor (OB-R). When fed a high-energy (HE; 31% fat) diet, 7-wk-old DIO rats had a 240% increase in plasma leptin levels after only 3 days. Despite this early leptin rise, they maintained a persistent hyperphagia and became more obese than chow-fed DIO rats and DR rats fed chow or HE diet. Their failure to reduce caloric intake, despite high levels of leptin, suggests that selectively bred DIO rats might have reduced leptin sensitivity similar to that seen in the outbred DIO parent strain.

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