Modification of dopamine D2 receptor activity by pergolide in Parkinson's disease: an in vivo study by PET.
It is well known that chronic administration of pergolide and other dopamine agonists may induce a downregulation of dopamine D2 receptors in the rat model of Parkinson's disease (PD). To our knowledge, this effect has not been demonstrated in vivo in patients with PD. At present, the status of striatal dopamine D2 receptors can be studied with use of positron emission tomographic (PET) technology. Five patients with PD chronically treated with levodopa were studied with use of PET and [11C]-raclopride before and after 6 months of pergolide treatment (dose range = 4.5-7.5 mg/d). We found a slight reduction in the specific striatal [11C]-raclopride uptake index (mean reduction 14% in putamen and 9% in caudate) after pergolide treatment. This reduction appears to be related to downregulation of the receptor, although competitive binding of pergolide at the D2 receptor cannot be excluded.
Linazasoro
G
G
Center for Neurology and Functional Neurosurgery, Clínica Quirón, San Sebastián, Guipúzcoa, Spain.
Obeso
J A
JA
Gómez
J C
JC
Martínez
M
M
Antonini
A
A
Leenders
K L
KL
D000978:Antiparkinson Agents / Q000627:therapeutic use*; D002230:Carbidopa / Q000627:therapeutic use; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism; D018491:Dopamine Agonists / Q000627:therapeutic use*; D018492:Dopamine Antagonists / Q000378:metabolism; D015536:Down-Regulation; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000378:metabolism; D010479:Pergolide / Q000627:therapeutic use*; D020891:Raclopride / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D014055:Tomography, Emission-Computed
D000978:Antiparkinson Agents; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D010479:Pergolide; D020891:Raclopride; D007980:Levodopa; D002230:Carbidopa