Dietary administration of nickel: effects on behavior and metallothionein levels

Adult male rats were fed either 0, 10, or 20 mg Ni/kg body weight (as NiCl2) via a 10 g daily food ration. Following 14 days of exposure, animals were trained over a period of 61 days to lever press for food on a VI-2 operant training schedule while continuing to experience the indicated daily doses. Those rats treated with 20 mg/kg Ni lever pressed at a significantly lower rate than controls. Group 10 mg/kg subjects were not significantly different on this behavioral measure than control subjects. Atomic absorption spectrophotometric analysis revealed a dose/response accumulation of Ni in the kidney, but analyses of blood, bone, brain, hair, small intestine, liver, and testes did not show differential agent accumulations. Neither hepatic nor renal metallothionein levels were increased above control levels. These findings were discussed within the framework of other recent behavioral and biochemical studies of heavy metal toxicity.