Existence of dopaminergic neurons in the preoptic region of the goldfish.

Three morphofunctional techniques for the detection of biogenic monoamines have been used in order to find evidence for the presence of dopaminergic neurons in the preoptic region of the goldfish. The formaldehyde-induced fluorescence technique and the immunohistochemical demonstration of tyrosine hydroxylase allowed the detection of cell bodies containing catecholamines in the ventral and lateral walls of the preoptic recess of the goldfish. Specific antibodies indicated that at least part of these perikarya contain dopamine. Evidence for the projection of these neurons to the pituitary are given. These results support the assumption that dopamine, originating from the preoptic region, may act as a gonadotrophin release-inhibiting factor in goldfish.