Immunohistochemical evidence for dopaminergic neurons in the rat superior cervical ganglion.

A double-staining immunoperoxidase technique was used to investigate the distribution of the catecholamine synthesizing enzymes, tyrosine hydroxylase and dopamine-beta-hydroxylase in the rat superior cervical ganglion. It revealed two different populations of sympathetic cells containing the former, but not the latter enzyme. This strongly suggests that the cells were dopaminergic. While one population was made up of small, intensely fluorescent cells, some of which are known to be dopaminergic, the other consisted of small or medium-sized principal sympathetic neurons. I conclude that a small proportion of the catecholaminergic sympathetic neurons use dopamine rather than noradrenaline as their neurotransmitter.