Dihydroergotamine: A 9,10alpha-dihydro derivative of ERGOTAMINE. It is used as a vasoconstrictor, specifically for the therapy of MIGRAINE DISORDERS.Ergotamine: A vasoconstrictor found in ergot of Central Europe. It is a serotonin agonist that has been used as an oxytocic agent and in the treatment of MIGRAINE DISORDERS.Sumatriptan: A serotonin agonist that acts selectively at 5HT1 receptors. It is used in the treatment of MIGRAINE DISORDERS.Arteriovenous Anastomosis: A vessel that directly interconnects an artery and a vein, and that acts as a shunt to bypass the capillary bed. Not to be confused with surgical anastomosis, nor with arteriovenous fistula.Dihydroergocornine: A 9,10alpha-dihydro derivative of ERGOTAMINE that contains isopropyl sidechains at the 2' and 5' positions of the molecule.Migraine Disorders: A class of disabling primary headache disorders, characterized by recurrent unilateral pulsatile headaches. The two major subtypes are common migraine (without aura) and classic migraine (with aura or neurological symptoms). (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)Hydroxyzine: A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite CETIRIZINE, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.Ergot Alkaloids: Alkaloids originally isolated from the ergot fungus Claviceps purpurea (Hypocreaceae). They include compounds that are structurally related to ergoline (ERGOLINES) and ergotamine (ERGOTAMINES). Many of the ergot alkaloids act as alpha-adrenergic antagonists.Methiothepin: A serotonin receptor antagonist in the CENTRAL NERVOUS SYSTEM used as an antipsychotic.Serotonin Receptor Agonists: Endogenous compounds and drugs that bind to and activate SEROTONIN RECEPTORS. Many serotonin receptor agonists are used as ANTIDEPRESSANTS; ANXIOLYTICS; and in the treatment of MIGRAINE DISORDERS.Receptor, Serotonin, 5-HT1B: A serotonin receptor subtype found at high levels in the BASAL GANGLIA and the frontal cortex. It plays a role as a terminal autoreceptor that regulates the rate of SEROTONIN release from nerve endings. This serotonin receptor subtype is closely related to and has similar drug binding properties as the 5-HT1D RECEPTOR. It is particularly sensitive to the agonist SUMATRIPTAN and may be involved in mediating the drug's antimigraine effect.Tryptamines: Decarboxylated monoamine derivatives of TRYPTOPHAN.Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Receptors, Serotonin: Cell-surface proteins that bind SEROTONIN and trigger intracellular changes which influence the behavior of cells. Several types of serotonin receptors have been recognized which differ in their pharmacology, molecular biology, and mode of action.