Loss of striatal neurons after local microinjection of colchicine.

Intrastriatal injections of colchicine (4 micrograms) produced irreversible striatal damage characterized 30 days later by loss of intrinsic striatal neurons, gliosis and shrinkage but no apparent damage to myelinated bundles of the internal capsule. This neuronal loss was associated with a dramatic reduction of striatal and nigral glutamate-decarboxylase (GAD), the marker of GABA-ergic synapses and of striatal choline-acetyltransferase (CAT), the marker of cholinergic synapses. The levels of dopamine (DA) and serotonin (5HT) in the striatum as well as those of their metabolites were also reduced, indicating that colchicine exerts toxic effects also on terminals of striatal afferent neurons.