Toxic Effects of Arsenic (III) on Some Hematopoietic and Central Nervous System Variables in Rats and Guinea Pigs

Abstract

Objective: To evaluate the effects of arsenic (III) exposure on porphyrin metabolism and the central nervous system supplemented with data on the effect of hepatic and renal tissues of rats and guinea pigs. Methods: Rats and guinea pigs were exposed to 10 or 25 ppm arsenic in drinking water for 16 weeks. Results: Following chronic arsenic (III) exposure, δ-aminolevulinic acid dehydratase activity in blood showed a significant reduction as did the total cell counts (RBC and WBC) and reduced glutathione with increased urinary δ-aminolevulinic acid. Zinc protoporphyrin, a sensitive indicator of iron deficiency and impairment of heme biosynthesis, showed a significant increase in arsenic exposure. The hepatic δ-aminolevulinic acid dehydratase and δ-aminolevulinic acid synthetase activity increased in chronic arsenic (III) exposure in rats and guinea pigs. Significant changes in the steady-state level of three major neurotransmitters, dopamine, norepinephrine, and 5-hydroxytryptamine, and monoamine oxidase were observed following chronic arsenic (III) exposure. Conclusion: At low doses (10 and 25 ppm in drinking water), the effects of arsenic on hematopoietic indices and whole-brain neurotransmitter concentrations were more prominent in guinea pigs than in rats with some variability in the dose response.