The Concept of CMR

Platelet hyperactivity

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Leptin is mainly produced and secreted by adipose tissue and acts via the hypothalamus to suppress food intake and increase energy expenditure by modulating glucose and fat metabolism and enhancing thermogenesis (7). Most obese people have high circulating leptin concentrations, which is a signal sent by adipose tissue to limit caloric intake and restore energy balance by reducing appetite and increasing energy expenditure (19). It is therefore generally accepted that overweight and obese individuals are resistant to the effects of leptin (20). The leptin receptor is present in many tissues, including platelets (21). Leptin promotes human platelet aggregation by increasing normal platelet response to the agonists adenosine diphosphate and thrombin (Figure). This has recently been suggested as one mechanism responsible for acute thrombotic events in obesity (22).

Reference

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7. Kershaw EE and Flier JS. Adipose tissue as an endocrine organ. J Clin Endocrinol Metab 2004; 89: 2548-56.

19. Montague CT, Farooqi IS, Whitehead JP, et al. Congenital leptin deficiency is associated with severe early-onset obesity in humans. Nature 1997; 387: 903-8.

20. Havel PJ. Control of energy homeostasis and insulin action by adipocyte hormones: leptin, acylation stimulating protein, and adiponectin. Curr Opin Lipidol 2002; 13: 51-9.

21. Nakata M, Yada T, Soejima N, et al. Leptin promotes aggregation of human platelets via the long form of its receptor. Diabetes 1999; 48: 426-9.

22. Konstantinides S, Schafer K, Koschnick S, et al. Leptin-dependent platelet aggregation and arterial thrombosis suggests a mechanism for atherothrombotic disease in obesity. J Clin Invest 2001; 108: 1533-40.

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