Chondrogenesis of chick limb mesenchyme in vitro. Effects of prostaglandins on cyclic AMP.

The effects of prostaglandin E2 (PGE2) on cyclic AMP (cAMP) levels of chick limb bud cells during various stages of chondrogenesis were studied utilizing high density, micro-mass, cell culture. Concentrations of PGE2 in cell cultures at these same stages were measured by radio-immunoassay. Both basal levels of cAMP, as well as PGE2-stimulated changes in cAMP, increased maximally during the first 3 days of culture; this increase was associated with the formation of cell aggregates. Concentrations of PGE2 were also highest during this period. By 6 days of culture, nodules, containing cartilage matrix components, predominated. Both basal levels of cAMP and PGE2-stimulated cAMP levels were significantly decreased at this stage, relative to cultures at day 3. Concentrations of PGE2 fell dramatically in the 6-day cultures containing differentiated cartilage. These results support a regulatory role for both PGE2 and cAMP in the early events associated with chondrogenesis.