Parkinsonism ergot alkaloids

Pergolide (ergot alkaloid derivative used to treat Parkinson s disease)... 

Lisuride is a dopamine receptor agonist that is used as an alternative drug in the treatment of Parkinson s disease. The pattern of adverse effects is similar to that seen with most of the ergot alkaloids (SEDA-10,118). The adverse effects that occurred after subcutaneous administration were so troublesome that the subcutaneous formulation was eventually unmarketable. 

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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