Effects of NGF and glucocorticoid on NGF receptor immunolabeling of cultured rhesus adrenal chromaffin cells

Abstract

Nerve growth factor (NGF) promotes the outgrowth of neurites from cultured adrenal chromaffin cells from adult rhesus monkeys [8], but little is known about the distribution, at the cellular level, of the NGF receptors (NGFR) responsible for this response. We examined changes in immunostaining for NGFR in chromaffin cells cultured for 4 weeks in the presence or absence of NGF, with or without dexamethasone (DEX), which inhibits neuritic outgrowth from these cells. Purified cultures of adrenal chromaffin cells from adult rhesus monkeys were grown for up to 9 weeks in NGF, DEX, NGF plus DEX, or control medium. Cells were immunolabeled with three different monoclonal antibodies directed against different epitopes of the human NGFR. Although the distribution of immunolabeling was not uniform from cell to cell, the overall intensity of NGFR immunolabeling varied dramatically between different growth conditions. Of greatest interest, DEX-treated cells stained the most intensely at all time points, while the intensity of immunolabeling was much fainter in NGF-treated cells and decreased with time in culture. In contrast to the intensity of labeling, the proportion of chromaffin cells with immunoreactivity increased with time in all treatment groups. Thus, GCs do not appear to antagonize the effects of NGF merely by decreasing the total number of immunoreactive NGFR on the surface of these cells.