The role of alkaloids in the poisoning of mammals by sclerotia of Claviceps spp.

Abstract

Several alkaloids occurring naturally in the sclerotia of Claviceps spp. have powerful pharmacological properties and ingestion of the sclerotia on infected host plants or in contaminated feedstuffs may result in adverse physiological changes affecting peripheral circulation, fertility, lactation or general behaviour. The relative significance of certain Claviceps spp., parasitic on plant hosts of economic importance, is described. Factors affecting the fungal epidemiology and the availability to the animal of the sclerotial alkaloids are discussed. Recent investigations on the role of C. purpurea sclerotia in animal poisoning are presented. These indicate that many clinical cases in farm animals, previously attributed to ergot poisoning, were probably due to some other agent. Agalactia, caused in pigs by the millet ergot fungus ( C. fusiformis), has in mice been shown to be due to the main alkaloidal component, agroclavine, which is a clavine-type ergot alkaloid previously regarded as having little pharmacological interest. A 2 per cent millet ergot diet fed during the latter part of pregnancy inhibits mammary hypertrophy and prevents lactation. A 5 per cent ergot diet elicits a pronounced central response and is lethal in 5–8 days. Female mice fed on a 2 per cent ergot diet fail to establish a pregnancy. This has also been shown to be due to the alkaloid which, while allowing ovulation and conception, prevents implantation of the blastocysts. Once implantation is complete the same diet has no effect on pregnancy apart from inducing the agalactia syndrome.