Rubidium (Rb) treatment of rats: biological effects and implications for psychiatry

Experiments were carried out on rats in order to find out the implications for psychiatry of the basic biological effects of rubidium (Rb). The forced swimming test (FST), used to evaluate the effects on rats of treatment with Rb, was conducted after 1 or 3 mEq/kg Rb was given chronically or subacutely. The weight of rats treated with 1 or 3 mEq/kg Rb, once daily, was observed daily for two weeks. Rb levels in the blood and brain of rats treated with Rb chronically or subacutely were determined by atomic absorption spectrophotometry. The rectal temperature was observed at 30, 60, 90, 120, 180, and 240 min after injections of 1 or 3 mEq/kg Rb. The increase in the mean body weight of treated rats was almost the same as that of the control. The rectal temperature in rats treated with Rb showed a hyperthermic response. With both the 1 and 3 mEq/kg Rb treatments, Rb levels in the brains were significantly higher in the chronic experiments than in the subacute experiments. The experiments conducted to determine the effect of chronic and subacute treatment of Rb are hereafter termed 'chronic experiment' and 'subacute experiment' respectively. Almost the same significant difference was also observed in the Rb levels in the blood. In the FST, a decrease in the mean immobility time was not observed in either the subacute or the chronic experiments. Thus, antidepressant effects, as judged from the FST, were not observed although Rb did actually accumulate in both brain and blood.