[Regulatory mechanisms of nerve growth factor synthesis in vitro]

Astroglial cells and various types of non-neuronal cells in the peripheral nervous system, such as epithelial, Schwann and fibroblast cells synthesize and secrete nerve growth factor (NGF) in culture. NGFmRNA contents are well-correlated with the density of axonal projection from NGF-sensitive neurons, suggesting that NGF synthesis in vivo tissues is regulated by neuronal environments. We investigated neuronal regulations of NGF synthesis using cultured mouse astroglial cells and rat pheochromocytoma PC12 cells. It was found that astroglial NGF synthesis was enhanced by the addition of catecholamine into the cultured medium or the co-culture with differentiated PC12 cells. These results suggest that NGF synthesis in the in vivo tissues is increased by the release of catecholamine as neurotransmitters and/or the contact of NGF-producing cells with differentiated cell bodies and neurites of NGF-sensitive neurons.