Immunohistochemical Localization of Metallothionein in Organs of Rats Treated with either Cadmium, Inorganic or Organic Mercurials
Metallothionein (MT) is a low, molecular, mass protein inducible by heavy metals such as cadmium (Cd), zinc and copper and having high affinity for these metals. In the present study, we have investigated immunohistological localization of metallothionein in the kidney and brain of rats treated with either Cd, inorganic mercury (Hg) or organic Hg.
Kidneys from rats treated with a single dose of Cd showed the presence of MT mainly in the proximal tubular epithelium whereas those from rats treated with Cd for 6 weeks demonstrated very strong MT immunostaining in the proximal and distal tubular epithelium, and the latter showed much stronger staining than the former. In the kidneys from inorganic Hg-treated rats, MT was detected not only in the proximal tubular epithelium but also in the distal tubular epithelium.
When adult rats were administered with either inorganic Hg or organic Hg, MT was induced in ependymal cells, pia mater, arachnoid, vascular endothelial cells and some glial cells. The present results suggest that MT is induced in the distal tubular epithelial cells and that the protein may take part in the blood-brain and cerebrospinal fluid-brain barriers to prevent toxic heavy metals from penetrating into the parenchyma of the brain.
KeywordsTotal Mercury Immunohistochemical Localization Inorganic Mercury Tubular Epithelium Proximal Tubular Epithelium
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