REGULATION OF METALLOTHIONEIN CONCENTRATIONS IN RAT-BRAIN - EFFECT OFGLUCOCORTICOIDS, ZINC, COPPER, AND ENDOTOXIN

The effects of known inducers of liver metallothionein (MT) synthesis on MT concentrations in the rat brain have been determined using antib odies that are specific for NIT I and II and do not cross-react with M T III. There were substantial differences in the MT concentrations in different areas of the brain. Dexamethasone increased MT levels after 24 h in the frontal cortex, cortex, medulla oblongata plus pons, midbr ain, striatum, hippocampus, and cerebellum but not in the hypothalamus . Corticosterone produced similar results except in the hippocampus. L ong-lasting adrenocorticotropic hormone increased MT concentrations af ter 12 h in midbrain and striatum but not in the liver. Adrenalectomy decreased MT concentrations after 6 days in the medulla oblongata plus pens, striatum, hippocampus, and hypothalamus but increased concentra tions in the liver and kidneys; these effects were reversed by cortico sterone. The role of glucocorticoids in the regulation of MT levels th erefore differs between tissues and within specific areas of the brain . Injection of zinc or copper intracerebroventricularly and the use of a zinc-deficient diet increased and decreased MT levels, respectively , in some but not all brain areas. Endotoxin increased liver MT but no t brain MT I levels after 8 h.