Leptin levels

Leptin is a cytokine produced and secreted by adipose tissue in proportion to the body fat content [3]. Mice and humans lacking leptin or its receptor develop a severe hyperphagia and a dramatic degree of obesity which is considerably more pronounced than that of the NDRKO mouse. Thus, leptin is the key adiposity signal in rodents and humans. Leptin secretion appears to reflect the metabolic status of the adipocyte rather than the sheer size of triglyceride deposits, and leptin levels may transiently be dissociated from total body fat. Nonetheless, over the course of a day with unrestricted food supply, plasma leptin levels reliably reflect the amount of total body fat. Local administration of leptin into the brain results in reduced food intake. The vast majority of patients with obesity have elevated serum levels of leptin. Thus, it is believed that the polygenic obesity is due to leptin resistance rather than to inadequate leptin secretion, or to a reduced blood/brain transport of the cytokine. 

Leptin has been shown to markedly reduce appetite and weight in the extremely rare individuals who lack leptin. In contrast, in the first clinical study of patients with polygenic obesity and elevated leptin levels, weight loss was variable and relatively small. This disappointing result may be explained by the leptin resistance consistently observed in obese humans and rodents. However, it cannot be excluded that a small... 

Spiegel, K., Tasali, E., Penev, P. 8r Van, C. E. (2004). Brief communication Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann. Intern. Med. 141, 846-50. 

The role of leptin in human physiology is not restricted to body weight control throngh regulation of food intake and energy expenditure. In addition, leptin levels are also known to affect bone metabolism, the immune system, and reproduction. 

The leptin status of individuals with BN has been less examined. To date, one study has found that serum leptin concentrations in ill bulimics are similar to those of normal control women and are correlated with body mass (Perron et ah, 1997). Recent studies from our group (Gendell et al., 1999) show that plasma and CSF leptin levels are normal in long-term recovered AN and BN subjects. Taken together, these data on AN and BN suggest that, as in normal individuals, leptin is correlated with body weight and is not involved in the etiology of these disorders. However, leptin may still play a role in the development of symptoms when patients are ill with these disorders. 

Grinspoon, S., Gulick, T, Askari, H., Landt, M., Lee, K., Anderson, E., Ma, Z., Vignati, L., Bowsher, R., and Herzog, D. (1996) Serum leptin levels in women with anorexia nervosa. J Clin Endocrinol Metab 81 3861-3864. 

Bromel, T., Blum, W.F., Ziegler, A., Schulz, E., Bender, M., Fleis-chhaker, C., Remschmidt, H., Krleg, J.C., and Hebebrand, J. (1998) Serum leptin levels increase rapidly after initiation of clozapine therapy. Mol Psychiatry 3 76-80. 

The amount of leptin released by adipose tissue depends on both the number and the size of adipocytes. When weight loss decreases the mass of lipid tissue, leptin levels in the blood decrease, the production of NPY is diminished, and the processes in adipose tissue shown in Figure 23-32 are reversed. Uncoupling is diminished,... 

Thrailkill KM, Fowlkes JL, Hyde JF, Litton JC. The effects of co-therapy with recombinant human insulin-like growth factor I and insulin on serum leptin levels in adolescents with type 1 diabetes mellitus. Pediatr Diabetes 2001 2(l) 25-9. 

Franchimont D, Roland S, Gustot T, Quertinmont E, Toubouti Y, Gervy MC, Deviere J, Van Gossum A. Impact of infliximab on serum leptin levels in patients with Crohn s disease. J Clin Endocrinol Metab 2005 90(6) 3510-6. 

Atmaca M, Kuloglu M, Tezcan E, Ustundag B. Weight gain and serum leptin levels in patients on lithium treatment. Neuropsychobiology 2002 46(2) 67-9. 

Pylvanen V, Knip M, Pakarinen A, Kotila M, Turkka J, Isojarvi JI. Serum insulin and leptin levels in valproate-associated obesity. Epilepsia 2002 43(5) 514—7. 

Leptin is a peptide hormone secreted by adipocytes. Recombinant human leptin has been investigated for its potential as an antiobesity agent [105,106]. Women with hypothalamic amenorrhea display reduced levels of leptin. Leptin administration to these women improves reproductive and neuroendocrine function [107], Nasal administration of leptin to rats in the presence of either TDM (1) or LPC [108] caused a significant increase in serum leptin levels. Increased serum leptin levels were associated with reduced food consumption [108], The development of an effective nasal formulation of leptin containing an absorption enhancer may allow more frequent dosing with leptin and thereby overcome the limited efficacy observed following subcutaneous injections of large doses of this hormone. 

Maffei M, Halaas J, Ravussin E, et al. Leptin levels in human and rodent Measurement of plasma leptin and of RNA in obese and weight-reduced subjects. Nat Med 1995 1 1155-1161. 

Meirhaeghe, A., Fajas, L., Helbecque, N., Cottel, D., Lebel, R, Dallongeville, J., Deeb, S., Auwerx, J., and Amouyel, R (1998). A Genetic Polymorphism of the Peroxisome Proliferator-Activated Receptor y Gene Influences Plasma Leptin Levels in Obese Humans. Hum. Mol. Genet. 7, 435-440. 

Guagnano, M. T., Manigrasso, M. R., Ballone, E., Della, V. R., Riccioni, G., Marinopiccoli, M., Nutini, M., Sensi, S., and Davi, G. 2003. Association between serum leptin levels and 24-hour blood pressure in obese women. Obes. Res. 11 549-555. 

Henriksen, J. H., Holst, J. J., Moller, S., Andersen, U. B., Bendtsen, F., and Jensen, G. 2000. Elevated circulating leptin levels in arterial hypertension relationship to arteriovenous overflow and extraction of leptin. Clin. Sci. (London) 99 527-534. 

Livshits, G., Pantsulaia, I., and Gerber, L. M. 2005. Association of leptin levels with obesity and blood pressure possible common genetic variation. Int. J. Obes. (London) 29 85-92. 

Sweeney, G., Keen, J., Somwar, R., Konrad, D., Garg, R., and Klip, A. 2001. High leptin levels acutely inhibit insulin-stimulated glucose uptake without affecting glucose transporter 4 translocation in 16 rat skeletal muscle cells. Endocrinology 142 4806-4812. 

Serum leptin levels increase rapidly after initiation of clozapine therapy. Mol Psychiatry 1998 3(l) 76-80. 

Piche, T., Vandenbos, F., Abakar-Mahamat, A., Vanbiervllet, G., Bar-joan, E.M., Calle, G., Giudicelli, J., Ferrua, B., Laffont, C., Benzaken, S., Tran, A. The severity of Uver fibrosis is associated with high leptin levels in chronic hepatitis C. J. Viral Hepat. 2004 11 91-96... 

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