NEUROCHEMICAL CHANGES IN RATS CHRONICALLY TREATED WITH A HIGH-CONCENTRATION OF MANGANESE CHLORIDE

Several neurochemical parameters were studied in brain regions of rats chronically treated with a high concentration of manganese chloride (20 mg MnCl2.4H2O per ml. of drinking water) throughout development until adulthood. Large increases in Mn accumulation were found in all brain regions (hypothalamus, + 530%; striatum, + 479%; other regions, + 152 to + 250%) of Mn-treated adult rats. In these animals, Ca levels were decreased (- 20 to - 46%) in cerebellum, hypothalamus, and cerebral cortex but were increased (+ 186%) in midbrain. Mg levels were decreased ( - 12 to - 32%) in pons and medulla, midbrain, and cerebellum. Fe levels were increased (+ 95%) in striatum but were decreased (- 28%) in cerebral cortex. Cu levels were increased (+ 43 to + 100%) in pons and medulla and striatum but Zn levels were decreased ( - 30%) in pons and medulla. Na levels were increased ( + 22%) in striatum but those of K and Cl remained unchanged. Type A monoamine oxidase activities were decreased (- 13 to - 16%) in midbrain, striatum, and cerebral cortex, but type B monoamine oxidase activities decreased ( - 13%) only in hypothalamus. Acetylcholinesterase activities were increased ( + 20 to + 22%) in striatum and cerebellum. The results are consistent with our hypothesis that chronic manganese encephalopathy not only affects brain metabolism of Mn but also that of other metals.