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Abstract
Leptin has been shown to reduce body fat in vivo. Leptin could regulate adipose mass by inhibiting preadipocyte replication, commitment to the adipocyte lineage, and/or lipid accumulation. We determined the effect of leptin, serum from leptin infused rats, and adipose conditioned media from leptin infused rats on preadipocyte proliferation and differentiation in a primary culture of cells from male Sprague-Dawley rat adipose tissue. Leptin (50 ng/ml) stimulated proliferation of preadipocytes, but 250 and 500 ng leptin/ml inhibited proliferation of both preadipocyte and stromal vascular fractions, measured by 3H-thymidine incorporation. Serum (0.25% by volume) from leptin infused rats inhibited proliferation of preadipocyte (p< 0.06) and stromal vascular (p< 0.05) fractions. Conditioned media (30% by volume) had no effect on proliferation of either cell fraction. None of the treatments changed preadipocyte differentiation. These results suggest that leptin could inhibit preadipocyte proliferation by modifying release of a factor from tissue other than adipose tissue.