title: 123I-beta-CIT and 123I-IBZM-SPECT scanning in levodopa-naive Parkinson's disease.
abstract: Striatal dopamine transporter function and dopamine D2 receptor status were evaluated in 15 patients with early untreated Parkinson's disease using single photon emission tomography (SPECT) with 123I-Iodo-2beta-carboxymethoxy-3beta-(4-idiophenyl)tropane (beta-CIT) and 123I-Iodobenzamide (IBZM) as pre- and postsynaptic ligands. Symptoms were unilateral in five patients and bilateral but asymmetric in 10 patients. Patients with bilateral symptoms had significantly lower 18-hour striatal/cerebellar beta-CIT binding ratios (3.59 +/- 0.79) than hemiparkinsonian patients (5.76 +/- 1.48, p < 0.05) reflecting more advanced disease in this subgroup. Patients with bilateral parkinsonism were also found to have a significant side-to-side difference in striatal beta-CIT binding with more marked reduction contralateral to the presenting limb (18-hour striatal/cerebellar ratio: 4.13 +/- 0.78 [ipsilateral] versus 3.59 +/- 0.79 [contralateral], p < 0.05). Dopamine D2 receptor binding as measured by IBZM was significantly elevated contralateral to the affected side in hemiparkinsonian patients (striatal/cerebellar ratio: 2.42 +/- 0.90 [contralateral] versus 2.19 +/- 0.80 [ipsilateral], p < 0.05). This asymmetric upregulation was absent in the patients with bilateral parkinsonism (striatal/cerebellar ratio: 1.85 +/- 0.43 [contralateral to more severely affected side] versus 1.83 +/- 0.34 [ipsilateral], p > 0.05). Our data suggest that postsynaptic dopamine receptor upregulation contralateral to the presenting side occurs in untreated unilateral PD and disappears in untreated bilateral (asymmetric) PD despite a greater loss of dopamine transporter function. Combined beta-CIT and IBZM SPECT studies may be helpful to monitor the progression of nigrostriatal dysfunction in early PD.
authors.affiliation: Department of Neurology, University of Innsbruck, Austria.
authors.forename: G K
authors.initials: GK
authors.lastname: Wenning
authors.forename: E
authors.initials: E
authors.lastname: Donnemiller
authors.forename: R
authors.initials: R
authors.lastname: Granata
authors.forename: G
authors.initials: G
authors.lastname: Riccabona
authors.forename: W
authors.initials: W
authors.lastname: Poewe
mesh_terms: D000368:Aged; D001549:Benzamides; D002352:Carrier Proteins / Q000502:physiology*; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000503:physiopathology; D003042:Cocaine / Q000031:analogs & derivatives; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000503:physiopathology; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D008875:Middle Aged; D009419:Nerve Tissue Proteins; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D001549:Benzamides; D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide; D003042:Cocaine