123I-beta-CIT and 123I-IBZM-SPECT scanning in levodopa-naive Parkinson's disease

Mov Disord. 1998 May;13(3):438-45. doi: 10.1002/mds.870130311.

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.

MeSH terms

  • Aged
  • Benzamides
  • Carrier Proteins / physiology*
  • Cerebellum / diagnostic imaging
  • Cerebellum / physiopathology
  • Cocaine / analogs & derivatives
  • Corpus Striatum / diagnostic imaging
  • Corpus Striatum / physiopathology
  • Dopamine Plasma Membrane Transport Proteins
  • Female
  • Humans
  • Iodine Radioisotopes
  • Male
  • Membrane Glycoproteins*
  • Membrane Transport Proteins*
  • Middle Aged
  • Nerve Tissue Proteins*
  • Parkinson Disease / diagnostic imaging*
  • Parkinson Disease / physiopathology
  • Pyrrolidines
  • Receptors, Dopamine D2 / physiology*
  • Tomography, Emission-Computed, Single-Photon*

Substances

  • Benzamides
  • Carrier Proteins
  • Dopamine Plasma Membrane Transport Proteins
  • Iodine Radioisotopes
  • Membrane Glycoproteins
  • Membrane Transport Proteins
  • Nerve Tissue Proteins
  • Pyrrolidines
  • Receptors, Dopamine D2
  • 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane
  • 3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide
  • Cocaine