Dietary calcium blocks lithium toxicity in hamsters without affecting circadian rhythms

Lithium can be toxic to rodents at plasma concentrations (0.6-1.2 mmol/L) that also phase delay circadian rhythms. In hamsters, raising the concentration of calcium in the diet from 0.1%-3% reduced weight loss and polydipsia caused by 0.4% lithium carbonate. Calcium ingestion did not affect plasma lithium concentration or the phase of the circadian wheel-running rhythm in lithium-treated animals. Calcium ingestion did not alter weight gain, salt or water intake, or circadian rhythms in hamsters not receiving lithium. Dietary calcium supplementation may prevent some toxic effects of lithium without interfering with other central nervous system actions.