Zn localization in rat brain after intracerebroventricular injection of Zn-histidine

Previous studies have shown that ⁶⁵Zn uptake in the brain expressed relative to plasma ⁶⁵Zn level is enhanced by histidine infusion into the blood vessel. To study the effect of histidine on zinc uptake in the brain parenchyma via the CSF, the brains of rats injected intracerebroventricularly with ⁶⁵Zn-His were subjected to autoradiography. Six days after injection, the radioactivity from ⁶⁵Zn-His was distributed in the major part of the brain parenchyma higher than that from ⁶⁵ZnCl₂, and relatively concentrated in the hippocampal formation, globus pallidus and hypothalamus. The radioactivity of the aqueduct was also higher in the ⁶⁵Zn-His group, indicating that CSF clearance of the ⁶⁵Zn-His group may be lower than that of the ⁶⁵ZnCl₂ group. These results suggest an enhancement by histidine on zinc uptake in the brain parenchyma via the CSF.