Distribution of 109Cd in the nervous system of rats after intravenous injection

The distribution of intravenously injected 109Cd in the nervous system was studied in rats twenty-four hr and one week after the injection. Measurements by gamma scintillation showed a high uptake of cadmium in peripheral sensory and autonomic ganglia whereas the uptake was low in the brain, cerebellum and spinal cord. The accumulation of cadmium in the sciatic nerve was significantly higher than in the brain and spinal nerve roots but lower than in ganglia. Autoradiography confirmed that there was no uptake of cadmium in the major part of the brain parenchyma, but showed an accumulation of the metal in areas outside the blood-brain barrier such as the hypophysis, meninges, choroid plexus and pineal gland. Within the peripheral nervous system, the autoradiography showed a localization of cadmium to dorsal root ganglia and, in addition, an uptake was seen in the connective tissue sheaths surrounding the sciatic nerve. The results indicate that the uptake of cadmium is correlated to regional variations in the permeability of blood vessels. The accumulation of cadmium in certain nervous structures may explain some of the neurotoxicological effects which have been demonstrated in animal experiments