Enkephalin-like immunoreactivity levels increase in the motor nucleus after an intramedullar axotomy of motoneurons in the adult cat spinal cord.

Neuropeptide- and serotonin-like immunoreactivities were studied in the lumbar spinal cord of the cat after a longitudinal incision in the ventral funiculus. This lesion, which accomplishes a central axotomy of motoneurons, was accompanied by increased level of Met-enkephalin-like immunoreactivity in nerve endings in those parts of the motor nucleus (lamina IX) which harbored severed motoneurons. This increase, which was evident in the fluorescence microscope, could be verified photometrically by use of a confocal scanning laser microscope.