Effects of Parathyroid Hormone and Cortisol on Prostaglandin Production by Neonatal rat Calvaria in Vitro

Abstract

We have examined the effects of parathyroid hormone (PTH) and cortisol on the production of prostaglandins, particularly PGE₂, by neonatal rat calvaria cultured in a chemically-defined medium. Although there was considerable variability, calvaria produced large amounts of PGE₂ in control cultures, reaching medium concentrations of 40 to 200 nM. PGE₂ release was partially inhibited by cortisol at 10 nM and markedly inhibited at 100 nM. Bovine 1–34 synthetic PTH produced an increase in PGE₂ concentration which was most striking in the presence of a low concentration of cortisol (10 nM). The medium also contained large amounts of 6-keto PGE_1a, the metabolite of prostacyclin, which showed similar changes in response to PTH and cortisol. Thromboxane B₂ concentrations were low and unaffected by these hormones. 1,25-dihydroxyvitamin D did not increase medium PGE₂ concentration. Since PGE₂ is a potent stimulator of bone resorption and formation, some of the effects of PTH as well as cortisol may be mediated by their ability to alter PGE₂ production in skeletal tissue.