Influence of prostaglandins on connective tissue cell growth and function.

Prostaglandins (PGs) are synthesized by cultured fibroblasts. PGs regulate specific cellular functions by influencing cyclic nucleotide levels. PGE1 increases cAMP levels, thus enhancing glycosaminoglycan (GAG) synthesis and reducing proliferation. Exogenous cyclic nucleotides, on the other hand, affect PG formation. Glucocorticoids (GCs) decrease cAMP content, GAG synthesis and PG formation in fibroblasts, the latter effect occurring only after prolonged incubations. The decrease in endogenous PG levels causes a sensitization of the cells to exogenous PGE1, thus counteracting the initial inhibitory effect of GCs on cAMP content and GAG synthesis. Cell proliferation shows an inverse relationship to PG-induced changes in cAMP levels.