Arachidonic acid metabolism by adult human osteoblast-like cells exhibits sexually dimorphic characteristics

The eicosanoids, including prostaglandin E₂ (PGE₂) and other bioactive arachidonic acid metabolites, are important local mediators of bone remodeling. Presumably, the limited or excessive synthesis of the eicosanoids could compromise bone homeostasis. We have noted that the stimulated release of arachidonic acid by adult male donor derived human osteoblast-like (hOB) cells exceeded the stimulated release measured for female-derived hOB cells by 1.5-fold. Assays of PGE₂ biosynthesis by cytokine-stimulated hOB cells also demonstrated a sex-linked difference, such that male hOB cell PGE₂ production exceeded female cell production by 1.6–2.2-fold. The calcium-dependent cytoplasmic phospholipase A₂ activity in subcellular fractions prepared from hOB cell homogenates was higher in both the cytosolic (1.6-fold) and particulate (1.5-fold) fractions from the male cells than in those prepared from female hOB cells, suggesting a molecular basis for the observed sexually dimorphic characteristics related to arachidonic acid metabolism by hOB cells. The relatively limited capacity of the female cells may limit needed intracellular and intercellular signaling during bone remodeling, thereby contributing to the development of bone pathology. J. Cell. Biochem. 71:74–81, 1998. © 1998 Wiley-Liss, Inc.