Ergot alkaloids like dihydroergotamine (DHE) act as potent serotonin receptor agonists, primarily targeting 5-HT1B and 5-HT1D receptors in cerebral vasculature, which leads to vasoconstriction and reduction of neurogenic inflammation. These medications effectively interrupt pain signaling pathways and decrease vascular permeability, providing rapid symptomatic relief for acute cluster headache episodes by modulating neurotransmitter activity and vascular tone.