Effects of lithium on an amphetamine animal model of bipolar disorder.

1. This study examines the effects of chronic lithium administration on changes induced by amphetamine administration and withdrawal on open field locomotor activity of rats, and considered as an animal model of behaviors displayed in bipolar disorders. 2. For 21 days, rats were administered either single daily intraperitoneal injections (IP) of 0.9% saline, 0.15 mEq/kg, or 1.5 mEq/kg lithium chloride (LiCl). From day 7 to day 16, half of the animals in each group consisting of 12 rats were administered twice daily IP injections of either 1.5 mg/kg d-amphetamine or 0.9% saline. From day 17 to 21, d-amphetamine was withdrawn. 3. Neither dose of LiCl significantly altered the increases in activity levels produced by amphetamine. The withdrawal of amphetamine lead to an immediate return to baseline activity levels which neither dose of LiCl significantly affected. 4. The absence of interactive effects suggests that the influence of lithium and amphetamine on activity are mediated by different neurotransmitter systems.