Effects of asarone and beta-asarone on conditioned responses, fighting behaviour and convulsions.

In the Ayurvedic system of medicine, the roots and rhizomes of an indigenous Indian plant Acorus calamus are used together with the roots of Rauwolfia serpentina for treating many mental ailments. The influence of asarone and beta-asarone (the trans and cis forms of 2,4,5-trimethoxy-1-propenyl benzene), two active principles of Acorus calamus, when given alone and together with either reserpine or chlorpromazine, has been studied on the conditioned avoidance response of trained rats, on the fighting behaviour of paired mice subjected to mild foot shock and on electro-convulsions. Except for electro-convulsions, asarone in small doses potentiates the effects of reserpine and of chlorpromazine; beta-asarone has no such effect. Estimation of the 5-hydroxytryptamine content of rat brain showed that neither acorus oil nor its active principles increase the concentration of 5-hydroxytryptamine; nor do these compounds cause an additional decrease in the 5-hydroxytryptamine content of the brains of animals treated with reserpine. It is concluded that the potentiating effect of these principles is unrelated to 5-hydroxytryptamine concentration. In experiments using electro-convulsions, asarone increased the percentage mortality of animals treated with chlorpromazine but not of those treated with reserpine.