Dopaminergic and serotonergic effects of ergometrine

Ergometrine (EGM), 40 mg/kg ip or 100 microgram ivc, produces strong and long-lasting increase of locomotor activity of the rat, completely prevented by pretreatment with spiperone, 0.4 mg/kg, ip, or pimozide, 4 mg/kg ip. Given at a dose of 100 microgram ivc EGM produced a deep hypothermia, resistant to spiperone pretreatment (0.4 mg/kg ip). EGM decelerates cerebral serotonin (5-HT) turnover in mice and rats as measured by accumulation of 5-hydroxyindoleacetic acid after pretreatment with probenecid, and depresses the accumulation of 5-HT in the rat brain stem after pretreatment with pargyline. EGM potentiates the hind limb flexor of spinal rat. This effect is blocked by cyproheptadine (1 mg/kg ip) and danitracen (3 mg/kg ip). The results indicate that EGM stimulates both dopamine and 5-HT receptors in the central nervous system.