Differentiation-dependent regulation of the cyclooxygenase cascade during adipogenesis suggests a complex role for prostaglandins

Aim: A thorough understanding of the mechanisms of adipocyte differentiation and metabolism is important for the prevention and/or treatment of obesity and its complications, including type 2 diabetes mellitus. A complex role for prostaglandins (PGs) in adipogenesis is suggested. We examined the expression and cellular localization of enzymes in the cyclooxygenase (COX) cascade that synthesize PGs as well as the PG profile as a function of differentiation status in 3T3‐L1 cells. Methods: Murine 3T3‐L1 preadipocytes were used as a model for studies of adipocyte differentiation induced by a hormone cocktail and compared with the parental fibroblastic line NIH 3T3. Both cell lines were incubated in maintenance medium or differentiation medium. Nine days after differentiation, the expression of enzymes in the COX cascade was evaluated by immunoblot analysis, reverse transcriptase‐polymerase chain reaction (RT‐PCR) and immunocytochemistry, and PG formation was examined using enzyme immunoassay. Results: A differentiation‐dependent diminution of COX‐1 and COX‐2 mRNA and cognate proteins in 3T3‐L1 cells was observed. PG release, including PGE2, 6‐keto PGF1α, PGD2 and 15d‐PGJ2, significantly decreased following differentiation in 3T3‐L1 cells (anova/Tukey, p