Effect of fusaric acid on aggression, motor activity, and brain monoamines in mice

The effects of fusaric acid (FA), a dopamine-beta-hydroxylase (D beta H) inhibitor, were determined on aggression, motor activity, and brain monoamines at doses of 3.2 to 60 mg/kg following administration of dietary supplements of L-tyrosine or balanced protein to male albino mice. Compared to saline injected control animals, both aggression and motor activity were reduced by the highest doses of FA. Somewhat more reduction in aggression was observed in animals administered dietary supplements of casein compared to those given the tyrosine supplement. Treatment with FA at doses of 30 to 60 mg/kg decreased brain norepinephrine and dopamine, and decreased brain tyrosine in animals fed the tyrosine supplement. In contrast, FA increased 5-hydroxytryptamine, and caused marked increases in 5-hydroxyindoleacetic acid at the highest doses. The data suggest that the neurochemical effects of FA may not be the same in rats and mice.