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DOI: 10.1055/s-2007-982108
Increased growth and elevated IGF-1 serum concentrations in mice with an adipose tissue specific deletion of the Igf-1 receptor
Insulin-like growth factor-1 (IGF-1) and the IGF-1 receptor have been implicated in the regulation of adipocyte differentiation and lipid accumulation in vitro. To investigate the role of IGF-1 receptor in vivo, we created mice with fat-specific disruption of the IGF-1 receptor gene (FIGF-1RKO mice) using the Cre-loxP system. FIGF-1RKO mice have remarkably increased somatic growth most likely as a consequence of elevated IGF-1 serum concentrations. Higher circulating IGF-1 levels could be due to increased IGF-1 expression both in liver and epigonadal adipose tissue, suggesting that adipose tissue plays a role in the regulation of IGF-1 serum concentrations. FIGF-1RKO mice exhibit increased adipose tissue mass with a predominantly increased lipid accumulation in epigonadal fat pads. Insulin-stimulated glucose uptake into adipocytes was unaffected by the deletion of the IGF-1 receptor. Thus, IGF-1 receptor signalling in adipocytes is not crucial for the development and differentiation of adipose tissue, but seems to participate in the regulation of IGF-1 serum concentration.