Ergot is a group of alkaloids produced by a fungus prevalent in northern Europe and other damp climates. The fungus, known as Claviceps purpurea can contaminate certain grains, particularly rye, barley, and other grasses. Classically, victims of ergot poisoning suffer three major side effects:
Intense vasoconstriction.in the arms and legs
In the older medical literature this was referred to as St. Anthony's fire. People suffering from ergot poisoning often complain of an intense burning sensation in their extremities. Today, scientists understand that muscles and other tissues deprived of blood flow and oxygen burn glucose anaerobically, generating large amounts of lactic acid. The hallmark symptoms of lactic acidosis include muscle fatigue accompanied by a painful burning sensation in the oxygen starved tissues. In extreme cases, untreated vasoconstriction can result in gangrene of the hands or lower legs.
Ergot alkaloids induce miscarriage
This effect is also caused by the interruption of blood flow. When the uterus is starved for blood, it tends to undergo powerful muscle contractions, sometimes to the point of continuous muscle spasm (called tetani). As a result, the placenta separates from the uterine wall, and the woman goes into premature labor, resulting in a miscarriage.
CNS effects including hallucinations and seizures.
The basis for these side effects stems from a combination of vasoconstriction and the chemical similarity of ergot to the hallucinogenic drug lysergic acid diethylamide (LSD). The exact basis of LSD induced hallucinations remains obscure. Activation of NMDA and serotonin receptors resulting in altered firing patterns of serotonergic neurons are believed to be involved. Apparently, ergot alkaloids can cross the blood brain barrier and trigger hallucinations by similar mechanisms. CNS hypoxia secondary to decreased blood flow may account for seizures.
Interestingly, the symptoms of ergot poisoning account for much of the witch hysteria that gripped Europe in the late Middle Ages. The most prevalent episodes of witch hunts occurred, not coincidentally, in those parts of Europe that grew large amounts of rye and barley, for example Germany and the British Isles.
The climate pattern from the 14th through the 18th centuries (sometimes referred to as the Little Ice Age) favored the damp, chilly conditions that promote ergot growth. In the minds of a society living in a pre-scientific era, the only explanation for a mysterious epidemic of hallucinations and spontaneous miscarriages was witchcraft. As late as 1692 in New England, ergot poisoning may have fueled the Salem Witchcraft Trials.
Today, ergot alkaloids are mainly used to stop bleeding in women with postpartum hemorrhage. They were also commonly used to treat migraine headaches but have fallen into disuse with the development of newer drugs.