Best Practice & Research Clinical Endocrinology & Metabolism
4Adipocytokines: leptin—the classical, resistin—the controversical, adiponectin—the promising, and more to come
Section snippets
Leptin—the pleiotropic factor
The cloning of the ob gene has furthered our understanding of the mechanisms underlying adiposity, eating disorders and reproduction.
Resistin—the controversial factor
The discovery of resistin as a novel factor secreted by adipocytes with an impact on insulin sensitivity was proposed as a new mechanism to explain the pathogenic sequence of adipocyte-obesity-insulin resistance.56 To date, many aspects of the biology of resistin in terms of its biological effects and regulation remain controversial, and its role as a mediator of insulin resistance, at least in humans, is questionable. However, studies have provided evidence of a role of resistin in
Adiponectin—the protective adipocytokine
The discovery of adiponectin occurred at about the same time as the discovery of leptin (1995/1996), but it did not receive major attention in the scientific community for the next few years until its markedly protective role in the pathogenesis of obesity-related disorders was acknowledged. Compared with the aforementioned factors, adiponectin differs in almost all biological properties and effects. Nevertheless, to date, it is the most promising adipocytokine with a sincere potential for
Visfatin
A ‘new’ adipocytokine was isolated by Fukuhara et al in 2004.160 This adipocytokine, named ‘visfatin’, was found to be highly enriched in the visceral adipose tissue of both humans and rodents. Visfatin was found to be identical to the previously known pre-B cell colony enhancing factor, a cytokine expressed by lymphocytes. Visfatin has a molecular weight of 52 kDa. The coding region of the gene encodes for 491 amino acids. When given to mice, visfatin lowers blood glucose,160 resembling the
Summary and new adipocytokines of interest
In summary, it has been shown that leptin, the initial and classical adipocytokine, is increased in obesity and exerts pleiotropic actions on glucose metabolism, may promote atherosclerosis and proliferation of cancer cells, and stimulates bone formation. Resistin, the controversial factor, has relevance for humans in stimulating the inflammatory cascade leading to atherosclerosis. Contrary to leptin and resistin, adiponectin, the protective factor, is decreased in obesity and has protective
Acknowledgements
This work was supported by grants the Interdisciplinary Center for Clinical Research at the University of Leipzig to A.K. and J.K. (projects B21 and B15).
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