NORADRENALINE TRANSPORT AND TRANSPORTER MESSENGER-RNA OF RAT CHROMAFFIN CELLS ARE CONTROLLED BY DEXAMETHASONE AND NERVE GROWTH-FACTOR

1. The biochemical basis for differences in noradrenaline (NA) transpo rter function between chromaffin cells in the adrenal medulla and thos e maintained in primary culture was investigated. 2. Intact adrenal me dullae of neonatal rats accumulated small amounts of [H-3]NA. In contr ast, dissociated chromaffin cells placed in culture for 2-6 days accum ulated 100-1000 times more [H-3]NA. 3. Nerve growth factor (NGF) stimu lated, whereas glucocorticoids dose dependently and reversibly inhibit ed, [H-3]NA transport in chromaffin cells maintained in culture up to 6 days. During this period, no change in the morphological or biochemi cal characteristics of either NGF-treated or -untreated chromaffin cel ls was evident. 4. A rat NA transporter cDNA clone was isolated for us e in the quantification of NA transporter mRNA. Intact adrenal medulla e contained 40% less NA transporter mRNA than an equivalent number of chromaffin cells in culture. Furthermore, dexamethasone produced nearl y 90% loss and NGF elicited similar to 60% increase in NA transporter mRNA levels in cultured cells. 5. In cultured cells, and possibly in v ivo: glucocorticoids inhibit NA transporter function of chromaffin cel ls at least in part through a decrease in NA transporter mRNA.