On the pharmacology of the ergot alkaloid elymoclavine

Pharmacological investigations of the ergot alkaloid of the group of clavines, elymoclavine, isolated from Claviceps sp. cp. II showed the following results: The LD50 for mice for 24 h was 350 (228-535) mg/kg and for rats 145 (81-258) mg/kg. Elymoclavine induced a dose-dependent stereotypy (doses of 2 to 10 mg/kg) in rats and mice which was antagonized by haloperidol and pimozide. It prevented the development of haloperidol catalepsy in rats and produced rotations contralateral to the striatal lesions with 6-OHDA which were antagonized by pimozide and partly by cyproheptadine. Elymoclavine, like bromocriptine, decreased the plasma level of prolactin. Furthermore, elymoclavine increased the exploratory activity of rats in open field; this effect was antagonized by haloperidol and was essentially influenced by many substances acting on different transmitter systems (NA, DA, GABA). Elymoclavine inhibited the picrotoxin and electroshock convulsive seizures but potentiated the pentylenetetrazol ones in mice as these effects were differently influenced by pimozide, haloperidol, 5-HTP, atropine and phentolamine. 100 and 250 micrograms/kg of elymoclavine produced a considerable and persisting decrease of the blood pressure in anaesthetized cats. At 1 X 10(-6) M, without producing any per se effect, elyoclavine decreased the contractile effects of acetylcholine, nicotine, BaCl2 and PGE1 as well as the field electrical stimulation-induced contractions in an isolated segment from guinea-pig ileum. The observed effects of elymoclavine are mainly due to its dopaminergic agonist action. It seems, however, that influences on other transmitter receptors also underlie the mechanism of action of this ergot alkaloid.