Benzodiazepine binding sites on PC12 cells: modulation by nerve growth factor and forskolin

PC12 pheochromocytoma cells show increased binding of the peripheral type benzodiazepine Ro 5-4864 after treatment with nerve growth factor (NGF) in membrane preparations. Forskolin, an activator of adenylate cyclase, acts synergistically with NGF to produce further increases in binding, but by itself produces no effect. The increased binding appears to reflect increases in receptor number, since Kd remains unchanged. Binding shows a trend toward increase by day 6 after NGF treatment, and the increase is significant at days 9 and 12. The physiological roles of benzodiazepine binding sites on PC12 cells are unclear. Treatment of the cells with Ro 5-4864 produces no changes in basal or stimulated release of catecholamines, in activity of adenylate cyclase, or in cell proliferation.