The mechanism of the tranquillizing action of asarone from Acorus calamus Linn.

Abstract

Abstract Asarone, the active principle of the indigenous Indian plant Acorus calamus Linn., did not cause any change in the noradrenaline content of whole brain of rats. Unlike tetrabenazine, pretreatment with asarone failed to block the effect of reserpine on the spontaneous motor activity and ptosis of mice, as well as the conditioned avoidance response of trained rats. These findings show that, though in chemical structure asarone resembles a part of the reserpine molecule, its mechanism of action is different from this drug. In animals in which brain noradrenaline has been lowered by pretreatment with α-methyl-l-tyrosine, the effects of asarone, namely, hypothermia, potentiation of barbiturate hypnosis and specific blockade of conditioned avoidance response, were found to be markedly enhanced. It seems that the sedative effect of asarone is dependent on the depression of the ergotropic division of the hypothalamus.