The effect of dexamethasone on the in vitro incorporation of precursors of extracellular matrix components in the outflow pathway region of the rabbit eye.

The present study demonstrates that the cells of the outflow pathway region incorporate precursors of the extracellular matrix components during in vitro incubation. Addition of dexamethasone (10(-7) M) to the incubation mixture led to changes in precursor incorporation that were precursor and cell specific. The steroid significantly decreased the incorporation of 3H-glucosamine and increased the incorporation of 3H-proline in the outflow pathway cells and in the fibroblasts of the adjacent sclera. The specificity of the hormone effect was demonstrated by its inability to alter 3H-leucine incorporation. By contrast, in iridial fibroblasts dexamethasone caused a decreased incorporation of 3H-glucosamine while not affecting the incorporation of 3H-proline. Our results suggest that dexamethasone causes an increase in collagen synthesis in the target cells most closely related to the outflow pathway. Further, the decreased incorporation of 3H-glucosamine with dexamethasone suggests decreased synthesis of glycosaminoglycans, glycoproteins or possibly glycolipids in these same cells.