Ergot alkaloids hallucinogen activity

Products of the fungus Claviceps purpurea ergot of rye. Many ergot alkaloids known, with a range of biological activities from vasoconstrictor and oxytocic to hallucinogenic effects used... 

D2-receptor activation gives Gai-mediated inhibition of adenylate cyclase (decreasing cAMP) and these receptors are involved in schizophrenia and Parkinson s disease and in control of motor function, cardiovascular function and behaviour by the CNS. The well-known antipsychotics chlorpromazine and haloperidol are D2-R antagonists. A number of hallucinogenic indole alkaloids from ergot-infected grasses and cereals are D2-R agonists (Table 5.4). 

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