Location of heat shock protein 70 and metallothionein immunoreactivity associated with copper deficiency in the CNS of lambs

Abstract

The localizations of metallothionein I and II (MT), a small molecular weight heavy metal binding proteins, and 70-kDa heat shock protein (Hsp70) were investigated by immunohistochemical techniques in brains of lambs that had been injured by congenital copper deficiency. The results were compared with those obtained from control lambs. The morphological findings of the congenital copper deficiency in the central nervous system (CNS) were recorded. The amount of copper in the brain and liver of the lambs and feed of breeding ewes and soil was also assayed by atomic absorption spectrophotometry. The amount of copper in the brain, liver, soil and feed were low. Immunohistochemically, MT and Hsp70 expressions were found to be markedly increased in the CNS of congenital copper deficient lambs compared with control lambs. MT immunoreactivity was prominently found in the astrocytes while strong Hsp70 labelling was in both astrocytes and neurons in the cerebrum, cerebellum, thalamus/hypothalamus and medulla oblongata. Immunohistochemical labelling for both MT and Hsp70 was also seen in the pia mater, ependymal cells and choroid plexi. Present results suggest that the elevated expressions of MT and Hsp70 in astrocytes and neurons are possibly indicating that they are less susceptible to the consequences of cell stress factors and could be exploited to increase selectively their survival in copper deficiency.