LOCALIZATION IS RAT-BRAIN OF THE TRACE-METALS, ZINC AND MANGANESE, AFTER INTRACEREBROVENTRICULAR INJECTION

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