CODISTRIBUTION OF CHOLERATOXIN BINDING-SITES AND TYROSINE-HYDROXYLASEFGF-2 IMMUNOREACTIVE NIGRAL NERVE-CELLS

By means of light and confocal laser microscopical analysis of cholera toxin (CT) binding sites indicating the localization of the gangliosid e GM1, evidence has been obtained for the presence of ganglioside GM1 in discrete nerve terminals, some of them identified by synapsin-1 imm unoreactivity (IR), with a focal distribution in the nerve terminal me mbrane. Double immunolabelling studies demonstrate that GM1 positive n erve terminals are associated with tyrosine hydroxylase/fibroblast gro wth factor-2 (TH/FGF-2) immunoreactive dopamine (DA) perikarya in the zona compacta of the rat substantia nigra. It is suggested that GM1 ma y be released from these terminals to become incorporated into the ner ve cell membrane of the FGF-2-containing DA nigral nerve cells, where they may enhance the activity of neurotrophic factor receptors such as those for FGF-2.