[The role of Schwann cells in peripheral nerve degeneration and regeneration--NGF-NGF receptor system].

In a wide variety of peripheral neuropathies, Schwann cells are known to be involved. However, it is still obscure whether Schwann cells play a role in the pathogenesis of nerve degeneration or are only secondarily involved in many neuropathies. Since Schwann cell culture technique is introduced, a number of Schwann cell functions have been clarified, and most of these functions are now believed to be related more with the peripheral nerve regeneration rather than degeneration. When Schwann cells are released from axonal contact, they express NGF receptor on the surface and also secrete NGF. These NGF receptor expression and NGF secretion by Schwann cells also extensively occur in the nerves undergoing active degeneration, and subside again when nerve regeneration is completed. NGF is actually a potent modulator for increasing the neurite sprouts from adult rat DRG neuron in culture. Taking account of these evidences, I discussed the role of NGF-NGF receptor system in the peripheral neuropathies.