Manganese concentration in rat brain: manganese transport from the peripheral tissues.

54Mn distribution in the brain and peripheral tissues was studied with the course of time after intravenous injection of 54MnCl2 to see manganese (Mn) transport from the peripheral tissues, i.e. the liver, to the brain. One hour after injection, 54Mn concentrations in the brain were 0.15-0.25% dose/g, and 54Mn was largely concentrated in the choroid plexus. One day after injection, 54Mn in the choroid plexus decreased remarkably. 54Mn in other brain regions increased gradually after then, and reached 0.30-0.40% dose/g 6 days after injection. This increase of 54Mn was due to the redistribution from the peripheral tissues such as liver and pancreas, in which 54Mn was maintained at high levels (2.0-4.0% dose/g). The increment of 54Mn 1 h to 6 days after injection was the largest in the hippocampus, but not in the striatum. These results suggest that the delivery of Mn from the liver to the brain is not involved in preferential Mn accumulation in the basal nuclei under physiological condition. This delivery may be important for brain function.