Nerve Growth Factor (NGF): Physiological Functions and Regulation of Its Synthesis
The physiological role of NGF as a neurotrophic factor in the peripheral nervous system is well established. NGF is essential for the development and maintenance of specific functions of peripheral sympathetic and neural-crest derived sensory neurons. NGF acts as a retrograde messenger between the target organs and the innervating neurons. The regionally different quantities of NGF in target tissues reflect the density of innervation by NGF-responsive neurons, which transport NGF in membrane-confined compartments to the perikaryon after NGF is bound via specific membrane receptors. Although the physiological function of NGF is well documented and a large number of NGF-specific effects on target neurons have been identified, there are two main questions which remain to be elucidated, namely the nature of the second messenger(s) evolving from the binding of NGF to its receptor and the mode of regulation of NGF synthesis in the target tissues. A better understanding of this regulation would provide the prerequisite for a rational approach to the pharmacological modification of NGF synthesis. This is of particular interest because it has recently become apparent that NGF is essential for the preservation of the function of the cholinergic neurons of the basal forebrain nuclei. These neurons are consistently affected in Alzheimers’s disease and their impaired function seems to be largely responsible for the cognitive deficits of this disease.
KeywordsNerve Growth Factor Cholinergic Neuron Nerve Growth Factor Receptor Nerve Growth Factor Level Retrograde Axonal Transport
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