SPECT imaging of striatal pre- and postsynaptic dopaminergic status in restless legs syndrome with periodic leg movements in sleep.
Restless legs syndrome (RLS) is a common sleep-related disorder principally characterised by leg paresthesia associated with an irresistible urge to move. A majority of RLS patients experience periodic leg movements during sleep (PLMS) and wakefulness. Pharmacological evidence suggests that RLS-PLMS may be caused by a central nervous system dopaminergic (DA) dysfunction. The aim of the present study was to evaluate the striatal pre- and postsynaptic DA status in patients suffering from both RLS and PLMS, by means of [123I] beta-CIT and [123I]IBZM SPECT respectively. Ten drug-naïve patients and ten age-matched controls participated in this study. All participants were recorded for at least one night of polysomnography before the SPECT studies. No difference was seen in DA transporter ([123I] beta-CIT) binding between RLS-PLMS patients (MD=4.89) and controls (MD=4.81; p=0.81). The study of the striatal D2-receptor binding ([123I]IBZM) revealed a significantly lower binding in patients (MD= 1.72) compared with controls (MD=1.85; p=0.006). These results support the hypothesis that a central DA dysfunction is involved in the physiopathology of RLS-PLMS. Several mechanisms may be responsible for the decrease of the D2-receptor binding. However, since [123I] beta-CIT binding is normal, a decreased number of D2-receptors or a decreased affinity of D2-receptors for [123I]IBZM is more likely than an increased level of synaptic DA with attendant downregulation of D2-receptors.
Michaud
Martin
M
Département de Psychiatrie Faculté de Médecine Université de Montréal, Canada.
Soucy
Jean-Paul
JP
Chabli
Allal
A
Lavigne
Gilles
G
Montplaisir
Jacques
J
D000328:Adult; D001549:Benzamides; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D003042:Cocaine / Q000031:analogs & derivatives; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism; D008875:Middle Aged; D017072:Neostriatum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D009419:Nerve Tissue Proteins; D017729:Presynaptic Terminals / Q000000981:diagnostic imaging* / Q000378:metabolism; D011446:Prospective Studies; D011759:Pyrrolidines; D012148:Restless Legs Syndrome / Q000000981:diagnostic imaging* / Q000503:physiopathology; D013570:Synaptic Membranes / Q000000981:diagnostic imaging* / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D015899:Tomography, Emission-Computed, Single-Photon
D001549:Benzamides; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011759:Pyrrolidines; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide; D003042:Cocaine; D004298:Dopamine