• Title, Summary, Keyword: Leptin

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Insulin Resistance of Skeletal Muscle was Recovered by Leptin Injection in vivo, but not in vitro, in High-fat Diet Fed Rats

  • Doh, Kyung-Oh;Park, Jeong-Oak;Jeon, Jeong-Ryne;Kim, Jong-Yeon
    • The Korean Journal of Physiology and Pharmacology
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    • v.9 no.2
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    • pp.125-130
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    • 2005
  • We examined the effect of leptin on the insulin resistance in skeletal muscles by measuring the glucose transport. Male Wistar rats were fed with chow or high-fat diets for 30 days. Three days before sacrifice, high-fat fed rats were subcutaneously injected with leptin (1 mg/kg body weight) for 3 days. The glucose transports in the epitrochlearis and soleus muscle were not different among the experimental groups under basal state, however these were decreased significantly in the high fat-diet rats under insulin-stimulation (p<0.01). Leptin treatment recovered the decreased glucose transport in the epitrochlearis (p<0.05) and soleus (p=0.08). Triglyceride concentration in the soleus muscle was increased significantly in the high fat-fed rats, compared to chow diet rats (p<0.01), and it was decreased significantly by leptin treatment (p<0.01). The glucose transport was measured under basal and $60{\mu}u/ml$ of insulin with or without 50 ng/ml of leptin. Leptin had no direct stimulatory effect on glucose transport under both basal and insulin-stimulated conditions in vitro. These results demonstrate that leptin injection to high fat diet fed rats recovered impaired insulin responsiveness of the skeletal muscles and muscle triglyceride concentration. However, there was no direct stimulatory effect of leptin on insulin sensitivity of the skeletal muscle in vitro.

The Role of Leptin in the Association between Obesity and Psoriasis

  • Hwang, Jaehyeon;Yoo, Ju Ah;Yoon, Hyungkee;Han, Taekyung;Yoon, Jongchan;An, Seoljun;Cho, Jae Youl;Lee, Jongsung
    • Biomolecules & Therapeutics
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    • v.29 no.1
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    • pp.11-21
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    • 2021
  • Adipose tissue secretes many adipokines which contribute to various metabolic processes, such as blood pressure, glucose homeostasis, inflammation and angiogenesis. The biology of adipose tissue in an obese individual is abnormally altered in a manner that increases the body's vulnerability to immune diseases, such as psoriasis. Psoriasis is considered a chronic inflammatory skin disease which is closely associated with being overweight and obese. Additionally, secretion of leptin, a type of adipokine, increases dependently on adipose cell size and adipose accumulation. Likewise, high leptin levels also aggravate obesity via development of leptin resistance, suggesting that leptin and obesity are closely related. Leptin induction in psoriatic patients is mainly driven by the interleukin (IL)-23/helper T (Th) 17 axis pathway. Furthermore, leptin can have an effect on various types of immune cells such as T cells and dendritic cells. Here, we discuss the relationship between obesity and leptin expression as well as the linkage between effect of leptin on immune cells and psoriasis progression.

A Study on Serum Leptin Concentrations by Obesity Index in Male College Students in Korea (일부 남자대학생의 비만지수에 따른 혈중 Leptin 농도 연구)

  • 김순경
    • Journal of Nutrition and Health
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    • v.33 no.5
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    • pp.524-531
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    • 2000
  • This study was conducted to investigate the basal leptin concentrations in normal(n=17, BMI 20-25, obesity index 90-110%) and overweight(n=13, BMI > 25, obestity index > 120%) Korea young aldult males, and correlation between leptin concentrations, nutrients intake, anthropometry and other biochemical parameters. Nutritional status, serum leptin and biochemiccal parameters were evaluated based on 24hr-dietary records, anthropometric measurement and blood analysis. Obesity index were 138% and 101% in overweight and normal group, respectively. Serum leptin concentration was higher in overweight group than that in normal group (8.65$\pm$ 9.41 vs 2.06 $\pm$ 1.19, p<0.05). Serum triglyceride, HDL-cholesterol and insulin concentrations were higher in overweight group than in normal group(p<0.05). Nutrients intakes was not different between two group. The leptin concentrations were correlated with body weight(p<0.001), BMI(p<0.05), obesity index(p<0.05), waist circumference(p<0.05), animal lipid intake(p<0.05)in overweight group.

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Neurobiology of Leptin : Neuroendocrine Regulation of Food Intake (Leptin의 신경생물학 : 섭식의 신경내분비 조절)

  • Kim, Seung-Hyun;Joe, Sook-Haeng
    • Korean Journal of Psychosomatic Medicine
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    • v.7 no.2
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    • pp.149-157
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    • 1999
  • Food intake and body weight are determined by a complex interaction of regulatory pathways. Leptin, the product of the ob gene, is a recently discovered hormone secreted by adipocytes, that signals the amount of adipose tissue energy stores to the brain and exerts major effects on energy homeostasis and neuroendocrine function. In addition, leptin has recently been shown to affect reproductive function in rodents and humans. The study of leptin and its effectors in the hypothalamus may provide important insights with respect to the interplay of several hypothalamic neuropeptides in regulating feeding as well as the interaction of genetics and environment in the regulation of energy homeostasis. In this review we summarise the action of leptin in the regulation of food intake and highlight a working model of the effects of environmental factors on the leptin system.

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Correlation between Serum Leptin Levels and BMI in Adults Residing in Pohang, Korea

  • Shin, Hyeon-Soo;Crabtree, Jennifer;Rayner, Vernon;Trayhurn, Paul;Do, Myoung-Sool
    • Preventive Nutrition and Food Science
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    • v.10 no.1
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    • pp.64-67
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    • 2005
  • Leptin is a small polypeptide hormone secreted primarily by adipocytes. Leptin regulates energy balance by decreasing food intake and increasing energy expenditure. This study investigated the relationships between serum leptin levels and BMI (body mass index) in 49 adults in Pohang, Korea. The subjects were 25 males and 24 females, aged 21 to 64 years attending an outpatient clinic at Handong University Sunlin Presbyterian Hospital. Values are given +/- the standard error of the mean. Our study shows that the serum leptin levels in these subjects were positively correlated with BMI. The leptin levels were higher in females (2.39+/-1.82 ng/mL) than in males (0.43+/-0.455ng/mL), although lower than previously reported. We therefore compared the serum leptin levels from the male Korean subjects (BMI 24.3+/-0.74㎏/㎡) with serum from six British males with a similar BMI (23.4+/-1.48㎏/㎡). The serum leptin concentrations (1.76+/-0.76 ng/mL) were lower than that of plasma (4.28+/-1.66 ng/mL) in the British subjects. The serum leptin in the British subjects (1.76+/-0.76ng/mL) was higher than that in the Koreans. There was no correlation between leptin levels and BMI in either male (slope 0.018 ± 0.036, p=0.624) or female (slope 0.382±0.433, p=0.417) type 2 diabetic patients in Pohang, Korea. Taken together, our study shows that the serum leptin level in Koreans varies with the BMI, but is lower than that of BMI-matched British subjects.

The Body Weight-related Differences of Leptin and Neuropeptide Y (NPY) Gene Expression in Pigs

  • Shan, Tizhong;Wang, Yizhen;Guo, Jia;Chu, Xiaona;Liu, Jianxin;Xu, Zirong
    • Asian-Australasian Journal of Animal Sciences
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    • v.21 no.2
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    • pp.161-166
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    • 2008
  • To determine if body weight change is directly related to altered leptin and neuropeptide Y (NPY) gene expression, we assessed adipose tissue weight, percent body fat, leptin and NPY mRNA levels and serum leptin concentration in pigs at weights of 1, 20, 40, 60, and 90 kg. The results indicated that the weight of adipose tissues and the percent body fat of pigs significantly increased and correlated with body weight (BW) from 1 to 90 kg (p<0.01). Serum leptin concentrations and leptin mRNA levels in omental adipose tissue (OAT) increased from 1 to 60 kg, and then decreased from 60 to 90 kg. At 60 kg, the serum leptin concentration and leptin mRNA level significantly increased by 33.5% (p<0.01) and 98.2% (p<0.01), respectively, as compared with the levels at 1 kg. At 60 kg, the amount of leptin mRNA in subcutaneous adipose tissue (SAT) was significantly higher than that of 1 and 40 kg animals (p<0.05). NPY gene expression in the hypothalamus also changed with BW and at 60 kg the NPY mRNA level significantly decreased by 54.0% (p< 0.05) as compared with that in 1 kg. Leptin mRNA in OAT was correlated with serum leptin concentrations (r = 0.98, p<0.01), body weight (r = 0.82, p<0.05) and percent body fat (r = 0.81, p<0.05). This is the first report of the developmental expression of leptin in porcine OAT, peritoneal adipose tissue (PAT) and SAT, and proves that the expression of leptin in OAT could reflect the levels of circulating leptin. These results provide some information for nutritional manipulation of leptin secretion which could lead to practical methods of controlling appetite and growth in farm animals, thereby regulating and improving efficiency of lean meat production and meat production quality.

Effects of Leptin on Osteoclast Generation and Activity

  • Ko, Seon-Yle;Cho, Sang-Rae;Kim, Se-Won;Kim, Jung-Keun
    • International Journal of Oral Biology
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    • v.30 no.2
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    • pp.47-57
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    • 2005
  • Leptin, the product of the obese gene, is a circulating hormone secreted primarily from adipocytes. Several results suggest that leptin is important mediators of bone metabolism. The present study was undertaken to determine the effects of leptin on anti-osteoclastogenesis using murine precursors cultured on Ca-P coated plates and on the production of osteoprotegerin (OPG) in osteoblastic cells. Additionally, this study examined the possible involvement of prostaglandin $E_2\;(PGE_2)$/protein kinase C (PKC)-mediated signals on the effect of leptin on anti-osteoclastogenesis to various culture systems of osteoclast precursors. Osteoclast generation was determined by counting tartrate-resistant acid phosphatase positive [TRAP (+)] multinucleated cells (MNCs). Osteoclastic activity was determined by measuring area of resorption pits formed by osteoclasts on Ca-P coated plate. The number of 1,25-dihydroxycholecalciferol $(1,25[OH]_2D_3)$- or $PGE_2$-induced TRAP (+) MNCs in the mouse bone marrow cell culture decreased significantly after treatment with leptin. The number of receptor activator of NF-kB ligand (RANKL)-induced TRAP (+) MNCs in M-CSF dependent bone marrow macrophage (MDBM) cell or RAW264.7 cell culture decreased significantly with leptin treatment. Indomethacin inhibited osteoclast generation induced by $1,25[OH]_2D_3$ and dexamethasone, however, no significant differences were found in the leptin treated group when compared to the corresponding indomethacin group. Phorbol 12-myristate 13-acetate (PMA), a PKC activator, inhibited osteoclast generation induced by $1,25[OH]_2D_3$. The number of TRAP (+) MNCs decreased significantly with treatment by PMA at concentrations of 0.01 and $0.1{\mu}M$ in culture. Leptin inhibited PMA-mediated osteoclast generation. Isoquinoline-5-sulfonic 2-methyl-1-piperazide dihydrochloride (H7) had no effect on osteoclast generation induced by $1,25[OH]_2D_3$. Cell culture treatment with leptin resulted in no significant differences in osteoclast generation compared to the corresponding H7 group. Indomethacin showed no significant effect on TRAP (+) MNCs formation from the RAW264.7 cell line. PMA inhibited TRAP (+) MNCs formation induced by RANKL in the RAW264.7 cell culture. H7 had no effect on osteoclast generation from the RAW264.7 cell line. There was no difference compared with the corresponding control group after treatment with leptin. $1,25[OH]_2D_3$- or $PGE_2$-induced osteoclastic activity decreased significantly with leptin treatment at a concentration of 100 ng/ml in mouse bone marrow cell culture. Indomethacin, PMA, and H7 significantly inhibited osteoclastic activity induced by $1,25[OH]_2D_3$ in mouse bone marrow cell culture. No significant differences were found between the leptin treated group and the corresponding control group. The secretion of OPG, a substance known to inhibit osteoclast formation, was detected from the osteoblasts. Treatment by leptin resulted in significant increases in OPG secretion by osteoblastic cells. Taken these results, leptin may be an important regulatory cytokines within the bone marrow microenvironment.

The Relationships of Plasma Leptin, Backfat Thickness and TDN Intake across Finishing Stage of Holstein Steers

  • Vega, R.A.;Hidari, H.;Kuwayama, H.;Suzuki, M.;Manalo, D.D.
    • Asian-Australasian Journal of Animal Sciences
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    • v.17 no.3
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    • pp.330-336
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    • 2004
  • Six 16 months old Holstein steers were offered ad libitum feed for 7 months, to determine the (1) relationships of backfat thickness (BFT) to plasma leptin, and insulin; and (2) associations of TDN intake/kg body weight (BW) to plasma leptin, BFT and insulin. Feed intake, body weight and BFT were measured on selected monthly ages from day 1 to 8, day 1 and 8, and day 8, respectively. Blood was sampled on day 8 and the plasma was analyzed for leptin, insulin, glucose, NEFA, total cholesterol and triglyceride. Body weight and BFT increased, while TDN intake per kg BW decreased from 16 to 23 months old. Plasma leptin increased and mimicked the level of insulin, resulting to significant correlation (r=0.54; p<0.002). TDN intake was negatively related to plasma leptin (r=0.49; p<0.004), insulin (r=0.41; p<0.02) and BFT at 12 to 13th rib (r=0.48; p<0.005). Backfat thickness at 12 to 13th rib was positively related to plasma leptin (r=0.45; p<0.01). Negative associations of TDN intake with plasma leptin and BFT during finishing period suggest long-term involvement of adipose tissues in the feed intake regulation of steers fed high concentrate diet.

Induction of IL-6 and IL-8 Expression by Leptin Treatment in Periodontal Ligament Cells and Gingival Fibroblasts

  • Park, Hong-Gyu;Kim, Ji-Hye;Cha, Jeong-Heon;Bak, Eun-Jung;Yoo, Yun-Jung
    • International Journal of Oral Biology
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    • v.38 no.2
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    • pp.73-80
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    • 2013
  • Leptin is one of the adipocytokines produced from adipose tissue but its functions in periodontal tissue have not previously been investigated. In our current study, we examined the effects of leptin on the expression of interleukin (IL)-6 and IL-8 in periodontal ligament (PDL) cells and gingival fibroblasts. Leptin receptor expression was evaluated by RT-PCR and the production of cytokines was measured by ELISA. The phosphorylation of Akt and Erk1/2 was assessed by western blotting. mRNA of long and short form leptin receptors were detected in both PDL cells and gingival fibroblasts. Leptin was found to increase the production of IL-6 and IL-8 in both of these cell types, an effect which was not blocked by polymyxin B, an inhibitor of lipopolysaccharide (LPS). Leptin did not alter the production of IL-6 and IL-8 induced by LPS in PDL cells but increased Akt and Erk1/2 phosphorylation in these cells. These results suggest that leptin acts as an inducer of IL-6 and IL-8 in PDL cells and gingival fibroblasts.

Association between Microsatellite DNA Marker of Leptin Gene and Carcass Traits in Korean Cattle

  • Chung Eui-Ryong;Chung Ku-Young
    • Food Science of Animal Resources
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    • v.25 no.1
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    • pp.26-31
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    • 2005
  • Leptin, the product of the obesity (ob) gene, is synthesized in adipocytes or fat cells and has been implicated in the regulation of food intake, energy balance and body composition in mammals. Therefore, the leptin gene could be a candidate gene controlling fat deposition, meat quality and carcass traits in cattle. In this study the microsatellite genotypes for leptin gene were determined and their effects on carcass traits and meat quality were estimated in Korean cattle. Six different microsatellite alleles within leptin gene were identified and gene frequencies of 173, 177, 184, 186, 190 and 192 bp alleles were 0.012, 0.308, 0.067, 0.260, 0.342 and 0.016, respectively. The microsatellite marker of the leptin gene showed a significant association with the carcass percentage (CP) and marbling score (MS). Animals with genotypes 192/192 and 177/184 had higher CP than animals with other genotypes. Animals with genotypes 184/192 and 177/184 had higher MS compared with animals with other genotypes. Thus, the results suggest that the 177, 184 and 192 bp alleles may be associated with increased carcass percentage and intramuscular fat levels. No associations were found between the microsatellite genotypes of the leptin gene and other carcass traits such as carcass weight (CW), backfat thickness (BF) and M. longissimus dorsi area (LDA). In conclusion, the microsatellite markers of the leptin gene may be useful for marker-assisted selection of carcass traits and meat quality in Korean cattle.