White adipose tissue leptin

Leptin is a protein, encoded by the ob gene, first identified in obese mice. The ob gene is apparently expressed exclusively in white adipose tissue. Leptin binds to a receptor in the hypothalamus. 

Takahashi, Y. Ide, T. Dietary n-3 fatty acids affect mRNA level of brown adipose tissue uneou-pling protein 1, and white adipose tissue leptin and glucose transporter 4 in the rat. Br J... 

MacEiougald, O. A., Hwang, C.-S., Fan, H., and Lane, M- D. (1995). Regulated expression of the obese gene product (leptin) in white adipose tissue and 3T3-L1 adipocytes. PriTc. Natl- Acad. Sci. U.S.A. 92,9034-9037-... 

Increased expression of ob gene in adipocytes, and increased secretion of leptin by white adipose tissue into the bloodstream. 

The motion of the body-mass set point had led scientists to postulate that there must be a homeostatic signal from the fuel stores of the body to the brain. This has been referred to as a lipostat which can communicate the level of fuel stores to the brain to alter the appetite and metabolic rate control centers in the brain. In 1995, the hormone leptin was discovered. It is secreted by white adipose tissue at a rate that is proportional to the size of the fat reserves. The hypothalamus in the brain influences energy intake and expenditure, and it possesses receptors for leptin. Binding of leptin reduces food intake and increases whole body BMR. 

Hun, C.S., Hasegawa, K., Kawabata,T., Kato, M., Shimokawa, T., and Kagawa, Y. (1999) Increased Uncoupling Protein 2 mRNA in White Adipose Tissue, and Decrease in Leptin, Visceral Fat, Blood Glucose, and Cholesterol in KK-Ay Mice Fed with Eicosapentaenoic and Docosahexaenoic Acids in Addition to Linolenic Acid,Biochem. Biophys. Res. Commun. 259,85-90. 

Fig. 9.7. Effect of dietary CLA isomers on mRNA expressions of adipoqrtokines in perirenal white adipose tissue. Rats were fed the control diet (5% corn oil + 0.5% safflower oil), the 9c,11 t-CLA diet (5% corn oil + 0.5% 9c,1 If-CLA), or the 10f,12c-CLAdiet (5% corn oil + 0.5% 10f,12c-CLA)for 3 weeks. mRNA expressions of ACT, leptin, and glyceraldehyde phosphate dehydrogenase (GAPDH) were measured by semiquantitative RT-PCR. Relative values to GAPDH expression are expressed as mean standard error for 6 rats. Different letters show significant difference at P < 0.05.

Soukas A, Cohen P, Socci ND, Friedman JM. 2000. Leptin-specific patterns of gene expression in white adipose tissue. Genes Dev 14 963-980. 

In addition to maintenance of body temperature, uncoupling proteins are important in overall energy balance and body weight (section 5.2). It was noted in section 1.3.2 that the hormone leptin secreted by (white) adipose tissue increases expression of uncoupling proteins in muscle and adipose tissue, so increasing energy expenditure and the utilization of adipose tissue fat reserves. 

DAG feeding affects the expression of genes related to energy homeostasis, including leptin in white adipose tissue, and acyl-CoA oxidase and acyl-CoA synthase in the liver. 

GLYCERALDEHYDE-DERIVED ADVANCED GLYCATION END PRODUCTS DECREASE WHITE ADIPOSE TISSUE WEIGHT AND DOWNREGULATE LEPTIN, ADIPONECTIN, AND MACROPHAGE MARKER. 

Figure 2. Decrease in leptin and adiponectin mRNA expression in epididymal white adipose tissues. Representative images of agarose gel electrophoresis (A) and leptin (B) and adiponectin (C) mRNA expression normalized to 36B4 mRNA expression. Data are expressed as mean SEM. p < 0.05 V5. BSA.

Detailed review of the role of leptin in body-weight regulation, the control of food intake, and the roles of white and brown adipose tissues in energy expenditure. 

U. Sarmiento, B. Benson, and S. Kaufman, Morphologic and molecular changes induced by recombinant human leptin in the white and brown adipose tissues of C57BL/6 mice, Lab. Invest., 1997, 77, 243-256. 

In Experiment 1 leptin inhibited food intake of chow-fed Sprague Dawley rats (65, 56 , 53 g/4 days for PBS, leptin and pair-fed respectively. Values with different superscripts are different at P<0.05). At the end of the study inguinal, EPI (2.9 , 2.6 , 2.3 g), retroperitoneal and mesenteric white fat depots and intrascapular brown adipose tissue (0.19 , 0.12 , 0.15 g) were smaller in leptin-infused and parr-fed rats than controls. Leptin inhibited EPI cell basal FAS by 55% and prevented an insulin response. There was a non-significant 36% inhibition of FAS in pair-fed rats. FAE was 44% lower in... 

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