Intracranial injection of Fluoro-Gold results in the degeneration of local but not retrogradely labeled neurons.

Small volumes of either Fluoro-Gold (hydroxy-stilbamidine) or physiological saline were pressure injected into the striatum of adult rats. This paradigm is essentially the same as that used by neuroscientists who inject small quantities of Fluoro-Gold into brain structures to reveal neuronal connections. Using a modified de Olmos' cupric-silver technique, virtually no degeneration could be detected as the result of saline injection at any time point examined. However, comparable injections of Fluoro-Gold resulted in conspicuous cell body and terminal degeneration within the striatum 1-10 days post injection. Terminal degeneration within the substantia nigra pars reticulata could also be seen 2-10 days after injection. Examination of cells of the compacta region revealed conspicuous retrograde uptake of Fluoro-Gold, although none of these cells exhibited any evidence of neuronal degeneration at any postoperative time examined.