Expression of Schwann cell-specific proteins and low-molecular-weight neurofilament protein during regeneration of sciatic nerve treated with neurotrophin-4

Neurotrophin-4 acts as a potent survival factor for subpopulations of moton eurons. To investigate its effect on Schwann cell sheath and axonal protein s during peripheral nerve regeneration, sciatic nerves in adult rats were t ransected and repaired, and fibrin glue containing neurotrophin-4 injected around the repair site. At 5, 15, 30 and 60 days after repair, 5-mm nerve s egments distal to the repair were collected, and western blotting was used to measure myelin-associated glycoprotein, myelin basic protein and low-mol ecular-weight neurofilament protein. In control groups these dramatically d eclined at 5 and 15 days then increased from 30 and 60 days. However, in th e neurotrophin-4 group there was a significant increase (to several times b asal values) in myelin-associated glycoprotein and myelin basic protein at 5-15 days. The relatively small increases (<7%) in Schwann cell numbers sug gest that this is mainly due to increased synthesis per cell. The neurotrop hin-4 group also showed a small but significant increase at 15 days in low- molecular-weight neurofilament protein, which however remained much lower t han basal. We conclude that neurotrophin-4 regulates the expression of myelin-associat ed glycoprotein, myelin basic protein, and to a lesser extent low-molecular -weight neurofilament protein, during peripheral nerve regeneration. (C) 20 01 IBRO. Published by Elsevier Science Ltd. All rights reserved.