Group IVA phospholipase A2 is associated with the storage of lipids in adipose tissue and liver

Prostaglandin (PG) E2 is considered to participate in the storage of fat in adipocytes and hepatocytes, but roles of group IVA phospholipase A2 (PLA2), a key PLA2 isozyme in the arachidonic acid cascade, remain unclear. The present study examined the possible involvement of the enzyme using group IVA PLA2-deficient mice (C57BL/6 background, 22 weeks of age) fed a normal diet (5.3% fat). The ratio of epididymal fat pad weight to body weight was significantly reduced in group IVA PLA2-deficient mice compared to wild-type mice. Histological analysis revealed that in group IVA PLA2-deficient mice, the adipocytes were smaller, and hepatocytes bearing cytoplasmic vacuolation were scarce. Hepatic triglyceride content and the serum levels of PGE2 in the deficient mice were also lower. However, there was no difference in the serum levels of insulin, glucose, non-esterified free fatty acid, or total cholesterol between the deficient and wild-type mice. Our findings suggest that group IVA PLA2 is involved in the storage of lipids in the adipose tissue and liver and in determining circulating PGE2 levels.