NGF function has long been recognized as a crucial function in development and maintenance of the peripheral nervous system. Without NGF, these neurons undergo apoptosis. Promoting axonal growth is also one of NGF function. Studies have shown that it causes axonal branching and a bit of elongation. NGF binds with at least two classes of receptors: the p75 and TrkA. NGF binds to high-affinity tyrosine kinase receptor TrkA. TrkA dimerizes and autophosphorylates its tyrosine kinase segment, which leads to the activation of PI 3-kinase, ras, and PLC signaling pathways. Alternatively, the p75 receptor can form a heterodimer with TrkA which has higher affinity and specificity for NGF.
One of NGF function for Clinical significance is that NGF prevents or reduces neuronal degeneration in animal models of neurodegenerative diseases and these encouraging results in animals have led to several clinical trials in humans. NGF function has also been shown to promote peripheral nerve regeneration in rats. The expression of NGF is increased in inflammatory diseases where it suppresses inflammation. NGF function has also appeared to promote myelin repair. Hence NGF may be useful for the treatment of multiple sclerosis. NGF could also be involved in various psychiatric disorders, such as dementia, depression, schizophrenia, autism, Rett syndrome, anorexia nervosa, and bulimia nervosa. Dysregulation of NGF signaling has also been linked to Alzheimer's disease.