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Local Administration of Glial Cell Line-derived Neurotrophic Factor Improves Behavioral and Histological Deficit of Neonatal Erb’s Palsy in Rats

OBJECTIVEWe sought to evaluate from a behavioral and histological viewpoint the effect of local administration of glial cell line-derived neurotrophic factor (GDNF) on neonatal preganglionic Erb’s palsy in rats. METHODSThe Erb’s palsy model was produced by transecting the anterior and posterior roots of the left C5–C7 nerves of 7-day-old rats. The rats were divided into GDNF-treated (n = 10) and vehicle-treated groups (n = 11). After we transected the roots, contact in the proximal and distal stumps of the transected nerves was maintained, and the transected point and the entire intraspinal portion of the transected roots were enclosed by Gelfoam soaked with 10 &mgr;g GDNF or saline. The behavioral evaluation consisted of a foot-fault test and a forepaw muscle strength test, all of which were performed from the third to the seventh weeks after the operation. Seven weeks after the operation, all rats were killed, the number of anterior horn cells was counted at C5–C7, and the differences on each side were compared. RESULTSIn the vehicle-treated group, the foot-fault test indicated an abnormality in forelimb function on the root transection side. In the GDNF-treated group, however, significant improvement in forelimb function was observed on the basis of the foot-fault test results obtained in the third to sixth weeks after the operation. In the histological evaluation, the number of anterior horn cells from the side in which the operation took place in the vehicle-treated group was significantly less than that taken from the contralateral side at each segment. In the GDNF-treated group, however, there was no difference in any of the segments, regardless of the side from which they were taken. CONCLUSIONLocal administration of GDNF in a neonatal preganglionic Erb’s palsy model resulted in significant improvement in deficits on the basis of behavioral and histological evaluations.