Influence of transferrin on manganese uptake in rat brain

✍ Scribed by Atsushi Takeda; Shioji Ishiwatari; Shoji Okada

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 555 KB
• Volume: 59
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/(sici)1097-4547(20000215)59:4<542::aid-jnr10>3.0.co;2-b

✦ Synopsis

To evaluate the influence of transferrin (Tf) on manganese (Mn) uptake in the brain, pH 8.6 buffer-treated 54 MnCl 2 , which has a higher affinity for Tf than untreated 54 MnCl 2 , and Tf-bound 54 Mn were prepared. When pH 8.6 buffertreated 54 MnCl 2 and untreated 54 MnCl 2 were incubated with apo-Tf in Tris (2-amino-2-hydroxymethylpropane-1,3-diol)-HCl buffer, the percentage of the total 54 MnCl 2 bound to Tf was approximately 85% and 10%, respectively. One hour after intravenous (iv) injection of pH 8.6 buffer-treated 54 MnCl 2 and untreated 54 MnCl 2 , both tracers were concentrated similarly in the choroid plexus in the ventricles and distributed in other brain regions. Six days after iv injection, both pH 8.6 buffer-treated 54 MnCl 2 and untreated 54 MnCl 2 tracers were concentrated in the superior olivary complex, inferior colliculi, and red nuclei, although the former radioactivity was lower than the latter. Moreover, Tf-bound 54 Mn was prepared and injected iv into rats. The radioactivity from Tf-bound 54 Mn, which was also concentrated in the same regions, e.g., the superior olivary complex, was the lowest of all three traces. Tf-bound 54 Mn was stable during incubation with serum for 1 hr. It is likely that more Mn is transported into the brain when Mn is not bound to Tf. When Tf-bound 54 Mn and 54 MnCl 2 were unilaterally injected into the lateral ventricle, radioactivity was distributed only around the ipsilateral ventricle in the Tf-bound 54 Mn group 7 days after injection, whereas it was distributed more extensively in the 54 MnCl 2 group. It is likely that Tf-bound Mn in the CSF is less readily transported into the brain parenchymal cells than the non-Tf-bound form. These results suggest that Mn is transported into the brain efficiently via a Tf-independent uptake system.