LITHIUM ATTENUATES HYPOKINESIA INDUCED BY IMMOBILIZATION STRESS IN RATS

1. Hypokinesia following immobilization stress in rats is attenuated b y anti-depressant drugs used in the treatment of unipolar depression. Lithium has anti-depressant effects both clinically and in other anima l models of depression, but the mechanism of its anti-depressant effec t has not been elucidated. 2. To determine if lithium reverses immobil ization-induced hypokinesia, the effects of lithium and immobilization stress were tested in a fully factorial 2 X 2 design. 3. Half the rat s were fed chronic dietary lithium, while the other half ate regular c how. Half of each group were exposed to one hour immobilization, while the other half remained in their home cages until the test. Activity was measured for 20 min in an automated activity meter. 4. Stress sign ificantly reduced activity, but a significant interaction between stre ss and lithium was found, indicating that lithium attenuated the effec t of stress. 5. Lithium-induced attenuation of immobilization stress m ay serve as an animal model for the anti-depressant effects of lithium .