Localization in rat brain of the trace metals, zinc and manganese, after intracerebroventricular injection.

Autoradiographic studies of rat brain, after 65ZnCl2 or 54MnCl2 injection into the lateral ventricle, revealed that 65Zn and 54Mn were transferred freely through the cerebrospinal and extracellular fluid compartments; both tracers appeared in all the ventricles 1 h after injection. At 6 days after injection, 65Zn was concentrated in the hippocampal formation and hypothalamic nuclei but not in the cerebral cortex and superior colliculus of the ipsilateral hemisphere, with a lower uptake into contralateral hemisphere except for the hypothalamic nuclei. 54Mn was concentrated in some brainstem nuclei, such as the red and pontine reticular nuclei, to about the same extent in both hemispheres. These results suggest that both metals were taken up gradually into brain mainly via the cerebrospinal fluid. Relatively high uptake of 65Zn into the cerebral cortex and superior colliculus after intravenous injection suggests uptake in those regions is through two blood/brain barriers.