Expression of NADPH-diaphorase activity in the facial motoneurons after compression of the facial nerve in the albino rat.

Compression of the rat facial nerve in its bony canal led to increased nitric oxide synthase activity in the facial motoneurons as revealed by NADPH-d histochemistry. The increase occurred steadily from 3 days to 6 weeks, peaking at 4 weeks after compression. Parallel to this was also a gradual return of facial function which reached its maximum at 4-5 weeks after compression.