Axonal and dendritic transport in Purkinje cells of cerebellar slice cultures studied by microinjection of horseradish peroxidase

Axonal and dendritic transport in single Purkinje neurons of cerebellar sli ce cultures was quantified as single transport distances. Examination of th e cells within a vital tissue was regarded as being an approach to the in s itu condition. The Purkinje cells were organotypically integrated in the in vitro tissues and extended long axonal projections connecting synapses to the target neurons. The tracer horseradish peroxidase (HRP) was applied via microinjection to the somata of the Purkinje cells and the injected neuron s were incubated thereafter for defined time-intervals. The tracer was tran sported anterogradely into the neuron processes. The measurements on both t he axonal and the dendritic transport of microinjected HRP revealed continu ous transportation with increasing times of postincubation. This transport was reduced by the use of microtubule-depolymerizing drugs. The axonal tran sport of the tracer was either retarded in colchicine-treated cells or cont inuously reduced for up to 50% in vinblastine-treated neurons. Thus, a corr elation of axonal transport to the microtubules was demonstrated. The dendr ites were filled with the tracer after 60 min of postincubation. Dendritic transport was reduced by the use of vinblastine, and not significantly by c olchicine. The results strongly support the dependence of neuronal transpor t on microtubules as a component of the cytoskeleton.