Nerve growth factor (NGF) is one of a family of neurotrophins that induce the survival and proliferation of neurons. In cell culture, NGF induces the formation of neurite projections and, in vivo, may stimulate the innervation of tissues. NGF plays a role in the repair, regeneration, and protection of neurons, and as such could serve as a therapeutic agent in neurodegenerative conditions such as Alzheimer's disease. NGF enhances survival, growth, neurotransmitter biosynthesis of sympathetic and sensory neurons; neurotrophic factor; cutaneous innervation; growth, differentiation and survival of B lymphocytes. It also has a possible role in allergy and tissue repair. NGF is found in the hypothalamus, pituitary, thyroid gland, testes, epididymis, vascular smooth muscle cells, fibroblasts, mast cells and eosinophils. NGF is upregulated by glutamate, vitamin D3, IL6, FGF basic, astrocyte specific IL1, TNF alpha, PDGF and TGF beta. It is downregulated by GABAergic neuronal activity, glucocorticoids and Schwann cell-specific TGF beta.

Secreted.