NGF

Nerve growth factor (NGF) was the first neurotrophin to be characterised — discovered by Rita Levi-Montalcini and Stanley Cohen in the 1950s — and remains the prototype member of the neurotrophin family that also includes BDNF, NT-3, and NT-4. NGF is a homodimeric secreted protein that binds the high-affinity tyrosine-kinase receptor TrkA and the low-affinity p75NTR, supporting survival, differentiation, and axonal growth of sympathetic neurons, sensory neurons of the dorsal root ganglia, and central cholinergic neurons of the basal forebrain. NGF is critical for the maintenance of basal forebrain cholinergic neurons, whose progressive loss is a feature of Alzheimer's disease, and for the integrity of small sensory fibres whose dysfunction underlies several chronic neuropathies. In ophthalmology, recombinant human NGF (cenegermin) is licensed for neurotrophic keratitis. In peptide research, NGF is a downstream readout for cognitive-nootropic peptides; cerebrolysin (a porcine-brain-derived peptide preparation studied for stroke and dementia indications) is reported to support endogenous neurotrophin expression including NGF. NGF biology is also relevant to chronic pain research, where the same TrkA signalling that supports sensory-neuron health drives sensitisation in inflammatory pain — generating clinical anti-NGF antibody programmes (tanezumab) targeting osteoarthritic pain.