SUICIDE RETROGRADE TRANSPORT OF VOLKENSIN IN CEREBELLAR AFFERENTS - DIRECT EVIDENCE, NEURONAL LESIONS AND COMPARISON WITH RICIN

Volkensin and ricin, either free or conjugated with colloidal gold, we re injected into the cerebellar cortex of rats. The inferior olive and pontine nuclei were examined to verify the retrograde axonal transpor t of these two toxins, and the consequent neuronal damage. No evidence was obtained of a retrograde axonal transport of ricin in these pathw ays. Injection of gold-conjugated volkensin in the cerebellar cortex r esulted in retrogradely labelled neurones in the inferior olive after 3 h, and in the pontine nuclei after 6 h. Degenerative changes. were v ery severe in the retrogradely labelled neurones 48 h after the gold-c onjugated volkensin injection. In the Nissl-stained material, neuronal degeneration started to be evident in the inferior olive 12 h, and in pontine nuclei 6 h, after volkensin injection. The neuronal degenerat ion in both the inferior olive and pens increased up to 4 days after t he injection. These findings provide direct evidence of the retrograde axonal transport of volkensin in the central nervous system, and of t he time course of the consequent degenerative changes in the afferents to the cerebellar cortex.