Release of PAI-1 by human preadipocytes and adipocytes independent of insulin and IGF-1

The effect of insulin and insulin-like growth factor-1 (IGF-1) on plasminog en activator inhibitor-1 (PAI-1) release from primary cultures of human pre adipocytes and adipocytes has been investigated, Initial experiments measur ing basal PAI-1 release (ng/ml) indicated variability between individual cu ltures. Using a novel technique for adipocyte quantitation, additional expe riments were pet-formed to determine (PAI-1) release per cell, indicating a significant reduction with differentiation. insulin and IGF-1 over a range of concentrations had no effect on PAI-1 release, and RT-PCR of PAI-1 mRNA following treatment with insulin and IGF-1 also indicated similar expressi on between treatments. The cultures did exhibit insulin-stimulated glyceral dehyde-3-phosphate dehydrogenase (GAPDH) expression and leptin synthesis fo llowing differentiation to the adipocyte phenotype. This is the first repor t of PAI-1 secretion by primary cultures of human preadipocytes and adipocy tes, indicating PAI-1 release independent of insulin and IGF-I and implicat ing other factors in the elevated plasma PAI-1 observed with insulin resist ance. (C) 2000 Academic Press.