Applying the horseradish perioxidase technique, we studied the effect of the phenol on the peripheral nerve in 39 rats. One side of the sciatic nerve was blocked by 5% or 10% phenol for ten minutes, and irrigated with saline. At intervals of 1, 2, 4, 8 weeks, the spinal cord was removed, and the serial transverse sections were cut at 50μm and stained with diaminobenzidine. The horseradish peroxidase was injected into bilateral tibialis anterior muscles before sacrifice. The number and soma area histogram of the labelled motor neuron were compared with the unblocked side.
Following results were obtained: 1) The labelled motor neuron number that was mostly decreased in two weeks after the phenol block was increased in four weeks (p<0.01), 2) The histological study of the sciatic nerve supported the change of labelled motor neuron number, 3) There was a low correlation between the amplitudes of evoked nerve potential and the labelled motor neuron number, and 4) The selectivity of the damage by the phenol to the peripheral nerve was not clear from the some area histogram.
