Summary

Relationships between energy intake and fibrinolytic functions have been documented in detail.We evaluated food deprivation (FD) as a means of modulating fibrinolytic activity in genetically obese and diabetic db/db mice and in their lean counterparts. Twelve hours of FD induced considerable gene expression of plasminogen activator inhibitor-1 (PAI-1) in both epididymal (3.8-fold, p<0.05) and intestinal (2.4-fold, p<0.05) adipose tissues without affecting plasma PAI-1 levels in db/db mice, whereas the FD did not affect these parameters in wild-type mice. Importantly, 24 hours of FD increased the plasma PAI-1 content in wild-type (1.9-fold, p<0.01) but not in db/db mice, although adipose PAI-1 mRNA levels were significantly increased in db/db mice.The plasma PAI-1 content significantly correlated with hepatic PAI-1 mRNA levels in wild-type (r=0.84, p<0.01) and in db/db (r=0.63, p<0.01) mice. However, plasma PAI-1 did not correlate with adipose PAI-1 expression in db/db mice, although adipose tissue in general is thought to be the principal site of PAI-1 production in obesity. Hepatic PAI-1 expression was closely correlated with serum levels of free fatty acids in wild-type (r=0.72, p<0.01), but not in db/db mice.Adipose PAI-1 expression significantly correlated with serum corticosterone levels in both genotypes (wild-type, r=0.52, p<0.05; db/db, r=0.51, p<0.01), suggesting that adipose PAI-1 expression is up-regulated by fastinginduced glucocorticoids. The present findings suggested that fasting differentially affects fibrinolytic activity in obese and lean subjects and that PAI-1 expression in the liver as well as in adipose tissues comprises an important determinant of increased risk for cardiovascular disease in obesity.