Abstract
The morphological features and distribution of serotonergic fibers in the spinal cord of 7-and 12-month-old zitter mutant rats which are characterized by abnormal metabolism of superoxides were examined immunohistochemically. In the zitter rat spinal cord, several aberrant serotonergic fibers characterized by swollen varicosities were intermingled with normal serotonergic fibers. These aberrant fibers increased in number by aging. Serotonergic neuron system seem to be vulnerable to superoxide radicals. Thus, these aberrant serotonergic fibers may reflect the degeneration by superoxide radicals. These aberrant fibers were never found in young adult or 12-month-old SD rats. The appearance of these fibers has been reported in the aged (30 months) rat spinal cord. Based on the morphological similarity, the present study indicates the early onset of age-related change in serotonergic fibers in the spinal cord of zitter rats.
