Characterization of the RFamide-like neuropeptides in the nervus terminalis of the goldfish (Carassius auratus)

FMRFamide-immunoreactivity has been demonstrated in the CNS of many vertebrate species. We sought to further characterize this immunoreactivity in nervus terminalis retinal efferents of the goldfish using an antiserum raised against a bovine morphine modulating peptide (A18Famide). This antiserum robustly labels nervus terminalis efferents to the retina, as well as a sub-population of retinal amacrine cells. Under immunocytochemical conditions the antiserum cross-reacted with neuropeptide Y-like as well as A18Famide-like peptides, but under conditions of radioimmunoassay it was highly specific for A18Famide-like peptides. High pressure liquid chromatography, gel permeation chromatography and radioimmunoassay showed that at least two different RFamide-like peptides, approximately the same size as the bovine RFamide-like peptides, are present in the goldfish nervus terminalis.