Glucocorticoid stimulation of dopamine production in PC12 cells on extracellular matrix and plastic

PC12 cells are spherical when cultured on plastic, but flatten and spread extensively when cultured on extracellular matrix (ECM) produced by bovine corneal endothelial cells. We previously demonstrated that cells which have spread on ECM release more dopamine and contain less intracellular dopamine than cells which are rounded on plastic cultureware. Glucocorticoids increase dopamine production in PC12 cells presumably via an increase in tyrosine hydroxylase gene transcription. We questioned whether cell shape as determined by ECM would change the response of PC12 cells to glucocorticoids. Dopamine release and cell content were measured by a radioenzymatic assay in serum-free cultures of PC12 cells on ECM and plastic treated with various glucocorticoids in a dose-response fashion for 24 or 48 h. In addition, the response of cells on both substrata to one dose of dexamethasone was examined from 3-48 h. PC12 cells on ECM and plastic exhibited a dose-related increase in dopamine release and content when treated for 24 h with corticosterone or for 48 h with dexamethasone, corticosterone or cortisol. The ED50s for dexamethasone- and corticosterone-stimulated release and content were similar for cells on ECM and plastic as were the doses at which the first significant increases were detected. The average times at which the first significant increase in release and content occurred were also similar for cells on ECM and plastic. PC12 cells on ECM continue to release more dopamine and store less dopamine than cells on plastic with glucocorticoid treatment. However, glucocorticoid-treated cells on ECM showed a greater percent increase over ECM controls in the cell content of dopamine, whereas glucocorticoid-treated cells on plastic showed a greater percent increase over controls in the release of dopamine. It is hypothesized that glucocorticoids increase dopamine production to a similar extent in cells on ECM and plastic, but that storage is facilitated in cells on ECM.