Leonurine, an alkaloid from Leonurus artemesia, induces contraction in mouse uterine smooth muscle but relaxation in vascular smooth muscle of rat portal vein

In this work, we studied the in vitro effects of the plant alkaloid, leonurine, which is the active component of the uterotonic medicinal herb Leonurus artemesia, on two types of phasic smooth muscle preparations. We have demonstrated an interesting dual effect of leonurine on the the contractile function of these smooth muscles; i.e. stimulation and inhibition of the contraction in uterine smooth muscle and vascular smooth muscle, respectively. The uterine-stimulating effect may attribute to the restoration of uterus to its normal size after birth whereas the vasorelaxant effect may remove the circulatory stagnation and relieve the uterine pain. This dual effect of leonurine conceivably provides a cellular basis for a rational explanation concerning the effectiveness of the medicinal herb Leonurus in the treatment of pain associated with dysmenorrhea or menopause.