Enhancement of apomorphine and l-amphetamine-induced behaviors by magnesium

The behavioral effects of magnesium suggest that this divalent cation has psychomotor stimulant-like properties. Because deficiencies of this cation lead to reductions in drug-induced behaviors dependent on the levels of norepinephrine and dopamine, and numerous in vitro studies have demonstrated a relationship between magnesium and catecholamine activity, the present experiments investigate whether administration of magnesium will lead to increases in stereotyped and locomotor behaviors induced by apomorphine and l-amphetamine. Such changes would suggest that magnesium is increasing the activity of catecholamines in vivo. The results demonstrate that magnesium dose dependently increases the potency of these drugs by producing greater behavioral effects at certain drug doses, by producing shifts to the left in dose-response functions, and by producing decreases in the ED50 as dose of magnesium increases.