Oglesby, Rosenberg, Winter: Behavioral and biochemical effects of chronic administration of bromide in the rat. Bromide, a sedative in low doses and a psychotogen in high doses in man, was tested for behavioral and biochemical effects in the rat. The kinetics of bromide excretion following chronic administration were studied in the rat to determine drug regimens necessary to achieve stable, non-lethal levels of blood bromide. When administered daily to animals performing on a variable-interval schedule of positive reinforcement (VI 44), a low dose of bromide increased rates of responding while a high dose depressed response rates. Following withdrawal of the drug after six weeks of administration, response rates returned to previously determined control levels. Chlorpromazine failed to antagonize bromide-induced rate depression. No change in the concentration of norepinephrine or 5-hydroxytryptamine was seen with any dose of bromide studied.