The many functions of nerve growth factor: multiple actions on nociceptors.

Nerve growth factor (NGF) initially interested neurobiologists because of its effects in the developing nervous system. It is now clear that NGF functions throughout the life of the animal with a wide repertoire of actions. In the sensory nervous system it primarily influences the structure and function of nociceptors. Here, we provide a brief review of these actions and raise the overriding biological questions of why these multiple actions occur and how they are carried out.