Dissimilar effects of lithium isotopes on motility in rats.

Male Wistar rats were injected twice daily with chlorides of pure lithium isotopes, either Li-6 or Li-7. While both salts decreased mobility, the salt of Li-6 initially produced a more profound effect than the salt of Li-7. This differential effect of the isotopes proved to be time dependent and was most evident on the third day of treatment. Li-6 is likely to become a valuable tool in basic psychopharmacological research. It may possess therapeutic and/or toxic properties that are different from those of lithium salts currently used in treatment of mania.