Co-expression of GAP-43 with dopamine-beta-hydroxylase in adult rat spinal cord.

Dual colour immunofluorescence was used to compare the distribution of dopamine-beta-hydroxylase (DBH) and GAP-43 in the spinal cord of the adult rat. GAP-43 immunostaining was observed in all spinal cord regions containing DBH immunoreactivity. DBH and GAP-43 double-labelled fibres and varicosities were present in the lateral and ventral funiculi of the white matter and in the ventral horn where they were most prominent around motoneurones. In the dorsal horn and around the central canal, GAP-43 immunoreactivity was too abundant to determine whether DBH immunoreactive fibres were double labelled. We conclude that the noradrenergic system is one of a small number of spinal cord systems that express high basal levels of GAP-43 in the adult.