Nerve growth factor: mechanism of action.

Although the detailed mechanism of action of NGF as it occurs in vivo still requires considerable clarification, a model in which NGF is generated by end organs of responsive neurons and interacts with these neurons to provide trophic stimulation and maintenance of viability seems highly plausible. The demonstration of NGF synthesis by these cells, including the details of the process, is required, and information regarding the events following the formation of the hormone-receptor complex at the plasma membrane must be obtained. However, the contribution of internalization and the possible role of the internalized receptor as a second messenger for generating the long-term effects of the hormone are particularly appealing. Any findings with NGF will almost certainly provide additional important insights into other polypeptide growth factors, particularly those substances found in the neurotrophic subset.