Retrograde axonal transport of bismuth: an autometallographic study

Bismuth subnitrate was injected into the triceps surae muscle of 3-month-old male Wistar rats. Sections of lumbar spinal cord (L4-L6) and corresponding dorsal root ganglia were developed by autometallography (AMG) to trace possible bismuth in neuronal somata resulting from retrograde axonal transport. At 3 days after treatment bismuth clusters could be traced by AMG in spinal cord motor neurons and in dorsal root ganglion cells ipsilateral to the injection site. Retrograde transport of bismuth could be avoided by ligation or intraneuronal injection of cholchicine into the sciatic nerve. At the ultrastructural level bismuth was found to be located exclusively in lysosome-like organelles in motor and sensory neuronal somata projecting to the injection site. The present study shows that bismuth is transported retrogradely in both sensory and motor axons if their terminals are exposed to bismuth ions.