• Nutritional Sciences
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• v.5 no.4
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• pp.190-196
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• 2002

Zinc deficiency has been shown to result in poor appetite, causing anorexia. However, the role of zinc in the regulation of food intake is not well understood. In the present study, we hypothesized that zinc deficiency dysregulates circulating leptin level and leptin mRNA gene expression, and that whether these changes were occuring as a direct result of, or as a compensatory effect of zinc deficiency in rats. After an adaptation period of 4 weeks, Sprague Dawley rats were provided with three different level of zinc, as one week of a Zn-adequate (30 mg/kg) diet, then two weeks of a Zn-depletion (1 mg/kg ), and finally by two weeks of a Zn-repletion (50 mg/kg) diet. At the end of each dietary experimental period, one third of the 26 rats were killed. Zinc levels of blood subfractions (plasma, yee blood cells and mononuclear cells) and in the liver were substantially decreased, despite the fact that food intake was not substantially decreased during the Zn-depletion period. Serum leptin concentration was significantly increased during the zinc depletion period. Leptin mRNA in adipose tissue was also shown to be highly expressed during the Zn-depletion period. Presumably, increased leptin level and leptin mRNA induction during Zn-depletion conditions may be the cause of lowered appetite which is the common symptom of Zn-deficiency. In conclusion, These increases in circulating leptin levels and in leptin gene expression would be the direct result of, rather than the compensatory effect of, zinc deficiency.

• IMMUNE NETWORK
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• v.2 no.4
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• pp.202-207
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• 2002

Background: Kawasaki disease is an acute febrile illness with systemic vasculitis which primarily affects children, We examined the production of leptin in plasma and gene expressions of CXC chemokines in peripheral blood mononuclear cells from patients with Kawasaki disease. Methods: Consecutive 39 samples from 13 patients according to the different clinical stages (acute, subacute, convalescent) of Kawasaki disease were collected. The plasma leptin levels according to clinical stages of Kawasaki disease were examined by ELISA and the expression of IP-10, Mig and IL-8 mRNAs in 39 samples (13 samples of each stage) from 13 cases were examined by RT-PCR. Results: There were not significant changes of plasma leptin levels according to the clinical stages of Kawasaki disease. The mean values of plasma leptin concentrations during each of the stages (n=13, p>0.05, pg/ml) were $335.8{\pm}549.0$ in acute, $358{\pm}347.6$ in subacute, and $443.6{\pm}645.9$ in convalescent stage. The mRNAs of IP-10, Mig, and IL-8 were expressed in 13/13 (100%), 2/13 (15%), 9/13 (69%) during acute stage, 13/13 (100%), 6/13 (46%), 13/13 (100%) during subacute stage, and 13/13 (100%), 4/13 (31%), 10/13 (77%) during the convalescent stage, respectively. In three patients, the production of leptin and expression of IP-10 mRNA were dramatically decreased according to the process of the clinical stages. In five patients with prominent cervical lymphadenopathy, the expression of IL-8 mRNA during the subacute stage was more elevated than the acute and convalescent stages. Conclusion: This data suggests that the production of leptin and the gene expressions of IP-10, Mig and IL-8 seem to have no significant correlation to the clinical stages of Kawasaki disease. However, expression patterns of IP-10, Mig and IL-8 mRNA may be related to the specific clinical manifestations, and the expression of IP-10 may also be correlated to leptin levels with pericardial involvement.

• Korean Journal of Veterinary Service
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• v.28 no.2
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• pp.91-98
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• 2005

Green tea was known which regulated adipocyte differentiation metabolism. The mechanism on the lipid decreased contents of TAG in the plasma. In addition, green tea increased the expression leptin mRNA, PPAR $\delta$ mRNA and TGF $\beta$. The tea tested was korean powdered green tea. In this experiment, Sprague-Dawley (SD) rats were fed $3\%$ green tea(powdered) for 3 weeks on the basal diet and obese diet and green tea grouts-fed pork meats. duck meats. The expression of leptin mRNA and PPAR $\delta$ mRNA were up-regulated in the green tea-fed groups compared with those of the not green tea-fed groups. There were no significantly difference on the expression of leptin mRNA and PPAR $\delta$ mRNA in green tea grouts-fed pork meats, duck meats as compared with the not fed green tea grouts meats. TGF $\beta$ mRNA. TNF $\alpha$ mRNA and adipsin mRNA were not expressed in the pork meats, duck meats. The expression of TGF $\beta$ mRNA, TNF $\alpha$ mRNA and adipsin mRNA were observed in the experimental rats but no significantly difference on the contents. Physiologic regulated genes were not expressed In the green tea grout-fed pork meats and duck meats.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.4
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• pp.433-438
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• 1999

Two components of the neuroendocrine-hormonal response to long-term treatment of acarbose, adipose tissue-derived leptin and central neuropeptide Y (NPY), were investigated in the ICR mice on a high- carbohydrate diet. Acarbose, administered 5 or 50 mg per 100 g diet for four weeks, dose dependently suppressed body weight gain. The body weight gain was reduced along with the amount of daily food intake in 50 mg acarbose-treated group at $7^{th}\;and\;28^{th}$ day. 5 or 50 mg acarbose treatment administered for four weeks reduced leptin mRNA levels to 62% and 77% of the control group, demonstrating that the amount of leptin mRNA in adipocytes correlates with body weight. As dose of acarbose increased, leptin mRNA level also increased, suggesting that potent inhibition of ${\alpha}-glycosidase$ by a higher dose of acarbose furthers the enzyme activity and leptin gene consequently. On the other hand, central expression level of NPY gene was increased significantly compared with the control group at the same amount of acarbose administered, reflecting that leptin and NPY operate in a negative-feedback circuit to regulate body fat stores.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.5
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• pp.487-498
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• 2016

Leptin, an adipokine predominantly produced from adipose tissue, is well known to induce tumor growth. However, underlying molecular mechanisms are not established yet. While p53 has long been well recognized as a potent tumor suppressor gene, accumulating evidence has also indicated its potential role in growth and survival of cancer cells depending on experimental environments. In the present study, we examined if p53 signaling is implicated in leptin-induced growth of cancer cells. Herein, we demonstrated that leptin treatment significantly increased p53 protein expression in both hepatic (HepG2) and breast (MCF-7) cancer cells without significant effect on mRNA expression. Enhanced p53 expression by leptin was mediated via modulation of ubiquitination, in particular ubiquitin specific protease 2 (USP2)-dependent manner. Furthermore, gene silencing of p53 by small interfering RNA (siRNA) suppressed leptin-induced growth of hepatic and breast cancer cells, indicating the role of p53 signaling in tumor growth by leptin. In addition, we also showed that knockdown of p53 restored suppression of caspase-3 activity by leptin through modulating Bax expression and prevented leptin-induced cell cycle progression, implying the involvement of p53 signaling in the regulation of both apoptosis and cell cycle progression in cancer cells treated with leptin. Taken together, the results in the present study demonstrated the potential role of p53 signaling in leptin-induced tumor growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.568-572
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• 2003

This study investigated the effects of polymannuronate feeding on cholesterol levels and leptin in the serum and liver of Sprague-Dawely rats. After one week of basal diet feeding, four week old S.D. male rats were fed with polymannuronate. The feeding efficiency of the polymannuronate fed group averaged around 0.27, which was 0.02-0.03 lower than that of the control group, and liver weight, also had a lower increase. The liver tissue tagging of rats by staining fat drops increased in the cholesterol fed group. RIA and RT-PCR were used to determine the expression of leptin in the serum and liver of rats. The polymannuronate fed group had a larger reduction in the serum and liver leptin than the cholesterol fed group. The RT-PCR results showed that leptin mRNA was expressed in the liver. The polymannuronate fed group had a larger reduction in liver leptin mRNA expression than the cholesterol fed group. The above results suggest that feeding of polymannuronate improves the physiological function of rats by changing serum and liver lipid composition and the expression of leptin was repressed at a molecular level.

• Journal of Community Nutrition
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• v.8 no.2
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• pp.69-75
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• 2006

Adipose tissue has now been recognized as a rich source of metabolically active molecules that include leptin and angiotensinogen (AGT), the precursor of angiotensin II (Ang II). Both of which have been implicated in the pathogenesis of metabolic alteration and hypertension associated with obesity. In this study, we examined the relationship between body mass index (BMI), adipocyte size, leptin, Ang II secretion and mRNA expression in human adipose tissue obtained from female subjects. Leptin and Ang II were analyzed using specific radioimmunoassay kits following a 48hour tissue culture. Leptin and Ang II secretion varied from 1.4 - 72.1ng/g and 0.8 - 57.3pg/g of tissue respectively. These large individual variations limit significant correlation between BMI, leptin and Ang II secretion. Ang II secretion was significantly higher in the obese than the non-obese (p < 0.05) and positively correlated with BMI. However, no difference in leptin secretion between the obese and the non-obese was observed and leptin secretion showed negative correlation with BMI. No difference in leptin and AGT mRNA expression in adipose tissue between the obese and the non-obese was observed. Although several limitations of this study, we found increased Ang II secretion in obese patients compared with non-obese patients, and positive correlation between AGT and BMI. Observed difference in AGT expression between the obese and the non-obese in this study might be of importance in relation with obesity related hypertension. (J Community Nutrition 8(2): 69-75, 2006)

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.8
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• pp.1062-1068
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• 2004

Leptin has a major role in the regulation of food intake and energy homeostasis. In addition, leptin participates in many physiological functions including regulation of lipid metabolism. Bovine recombinant leptin protein was produced in E. coli cells in order to understand function of leptin in the regulation of lipid metabolism. The leptin expression vector was constructed in pGEX-4T-3 vector and transformed into E. coli BL21 cells. Expression of the GST-leptin fusion protein was induced with IPTG. The fusion protein was purified using glutathione sepharose 4B batch method, and the recombinant leptin was eluted after thrombin protease digestion. The effect of leptin on glucose transport was examined in the differentiated adipocytes of 3T3-L1 cells. Leptin had no effect on basal and insulin-stimulated glucose transport in 3T3-L1 cells (p>0.05). Effect of recombinant leptin on glucose and acetate transport was examined in adipose tissues of Korean cattle (Hanwoo). Insulin stimulated glucose transport in both intramuscular and subcutaneous adipose tissues (p<0.05), but leptin did not affect glucose transport in both adipose tissues (p>0.05). Insulin stimulated acetate transport in bovine adipose tissues (p<0.05), but leptin did not affect acetate transport (p>0.05). Northern and RT-PCR analyses showed that mRNA levels of uncoupling protein-2 were increased by leptin treatment in 3T3-L1 cells without statistical difference (p>0.05). In conclusion, bovine recombinant leptin did not affect glucose and acetate transport in both 3T3-L1 adipocytes and bovine adipose tissues, while it stimulates UCP-2 mRNA expression in 3T3-L1 cells.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.372-379
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• 2004

This study evaluated polymanuronates on the differentiation of 3T3-L1 adipocytes. Polymannuronates increased glucose utilization and reduced the accumulation of triglycerides in the cells. The differentiation showed the same results as Oil red O staining. Also, the polymannuronates inhibited GPDH activity as a result of the restrained adipogenesis promotion process in 3T3-L1 adipocytes. The addition of the differentiation promotion factor to 3T3-L1 promoted the differentiation of adipocytes and increased the expression of the leptin level. However the addition of polymannuronates inhibited differentiation of adipocytes and the leptin secretion level in cells by checking the leptin protein level in the culture media. As well as this, it also inhibited the transcriptional mechanism and leptin mRNA expression. These results suggest that the addition of polymannuronates improves the physiological function of 3T3-L1 cells by reducing the accumulation of triglyceride and GPDH activity, and the repressing expression of leptin at a molecular level.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.10
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• pp.1585-1591
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• 2013

The purpose of this study is to examine how to relate with hypothalamus protein BDNF and mRNA leptin expression, and test the effect of exercise training upon anti-obesity in high-fat induced obese rats. Weight and plasma TC of the high-fat diet group (HF) significantly reduced in comparison to those in the high-fat diet and training group (HF-T), high-fat diet and normal diet group (HF-ND), and high-fat diet, training, and normal diet group (HF-ND+T) (P<0.05). Plasm TG of the HF group significantly decreased in comparison to the HF-ND+T group (P< 0.05). The plasma leptin level significantly reduced in the HF-T group in comparison to the HF group, in the HF-ND group compared to the HF-T group, and the HF-ND+T group in comparison to the HF-ND group (P<0.05, respectively). All groups were significantly increased in hypothalamus BDNF protein expression in comparison to the HF group. In hypothalamus leptin mRNA expression, the HF-T and HF-ND groups reduced, but the HF-NF+T group increased in comparison to the HF group. This result suggests that it shows the effect of exercise training upon anti-obesity in high-fat diet induced obese rats and the combined exercise and/or normal diet may affect the optimal obesity improvement and prevention in appetite and weight control.