The effects of nerve growth factor (NGF) on crushed sciatic nerve regeneration were studied in 30 rats, with 60 bilateral nerves. The nerves were crushed at a site 6 mm distal to the sciatic notch by the standard technique and 3 mm wide crush injuries were created. Then 2.1 μl of normal saline in the control groups and an equal volume of NGF solution (containing 1 μg of NGF) in the NGF-treated groups was injected into the crush sites and followed for 12, 28, and 56 days, respectively. At the end of the observation, electrophysiological evaluation was carried out; then samples 10 mm distal to the crush site were removed and prepared for histological and morphometric studies. Evoked muscle action potential (MAP) was recorded in 50% of the NGF-treated group at 12 days but not in the control group; the difference was statistically significant (P<0.05). The motor nerve conduction velocity (MNCV) was increased in NGF-treated groups compared with control groups at 28 and 56 days (P<0.05). Morphometrically, significantly more regenerated myelinated fibers (RMFs) were seen at 12 days, and larger diameter RMFs were found at 12, 28, and 56 days in NGF-treated groups than in control groups. These results indicate that topically applied NGF stimulates nerve regeneration and promotes function recovery in crushed rat sciatic nerves. © 1995 Wiley-Liss, Inc.
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