Effect of dietary lithium levels on tissue lithium concentrations, growth rate, and reproduction in the rat

Weanling rats were fed a low-lithium diet (0.005-0.015 ppm) and the same diet supplemented with 0.5 ppm lithium. They were carried through three generations and observations made on growth rate, reproductive performance, and lithium concentration of tissues. Analyses were performed by flame emission using a nitrous oxide-acetylene flame. Tissues and fluids analyzed included whole blood, plasma, milk, adrenal gland, pituitary, salivary gland, thymus, brain, liver, kidney, spleen, heart, lung, skin, testis, ovary, uterus, and femur. The results are only suggestive of a physiological role for trace quantities of lithium. The fertility of second- and third-generation females [10] was inferior to that of the lithium supplemented group, but lithium had no effect on growth rate. Most significantly, the lithium concentrations in the pituitary and adrenal glands were relatively high and maintained constant through two generations regardless of dietary lithium. The lithium concentrations in other tissues were lowered by low dietary intake and in at least two cases, heart and kidney, continued to decrease with successive generations.