Lithium effects on rat brain glucose metabolism in long-term lithium-treated rats studied in vivo

The time course of lithium effects on several brain energy metabolites has been investigated in rats. The rats were injected once daily with lithium chloride and killed by freezing in liquid nitrogen 1--8 h after the last injection. The effect of lithium was most marked in the period in which the brain lithium concentration was increasing, whereas the effect was wearing off when the brain lithium concentration had stabilized, even though the lithium concentration was higher. These results led to the hypothesis that the effect of lithium on several parameters depends on the increase in lithium concentration following the administration of lithium, rather than on the absolute concentration of lithium.