Effects of amantadine on the estrous cycle in rats

Amantadine, administered in single doses of 5-25 mg/kg s.c. to normal cycling rats, induced prolonged estrus, i.e. blocking of ovulation. This result supports the inhibitory role of the dopaminergic mechanisms in the LRF secretion. In larger doses, the drug led to persistent diestrus, too, probably by blocking the dopaminergic mechanisms involved in the PIF secretion. The observed effects agree with the partial dopaminergic agonist character of amantadine.