Specific binding and laterality of human extrastriatal dopamine D2/D3 receptors in late onset type 1 alcoholic patients

Late onset type 1 alcoholism has been suggested to be associated with decreased dopaminergic transmission. Our hypothesis was that late onset type 1 alcoholics have also abnormal extrastriatal dopamine D(2)/D(3) receptor distribution. We performed binding, heterogeneity and laterality analysis of extrastriatal and striatal dopamine D(2)/D(3) receptors in nine late onset male alcoholics and in 12 age-matched healthy males. A radioligand, [(123)I]epidepride was used in high resolution single-photon emission tomography (SPET). Specific binding of epidepride in the left temporal pole was significantly (P<0.05) lower in type 1 alcoholics (0.74+/-0.14 ml/ml) than in controls (0.89+/-0.14 ml/ml). In alcoholics, there was no normal left-to-right asymmetry of the temporal cortical heterogeneity of epidepride distribution observed in control males (0.89+/-0.19 vs. 1.10+/-0.19; P<0.05). The results suggest that the specific binding of dopamine D(2)/D(3) receptors in late type 1 alcoholics is decreased and its laterality in the temporal brain is altered from normal.     

Dopamine transporter and D2-receptor density in late-onset alcoholism

Rationale: Late onset type 1 alcoholism has been suggested to be associated with an underlying dopaminergic defect. Therefore, it is relevant to study both postsynaptic D₂-receptor and presynaptic dopamine transporter (DAT) densities among alcoholics. Objective: We investigated DAT densities, along with striatal and extrastriatal dopamine D₂-receptor densities, in nine non-violent late-onset male alcoholics, who had no major mental disorder nor antisocial personality disorder (ASPD), and nine healthy controls. Methods: [¹²³I]PE2I and [¹²³I]epidepride were used in SPECT imaging. Results: DAT occupancy ratios (striatum/cerebellum) were significantly lower among alcoholics than in controls. Extrastriatal D₂-receptor occupancy ratios (temporal pole/cerebellum) were not significantly different between the groups. Conclusions: Striatal presynaptic DAT densities are decreased among type 1 alcoholics, and this finding is not associated with recent alcohol abuse. Received: 22 March 1999 / Final version: 25 June 1999     

Striatal dopamine transporter density in major depression

Rationale: There are no previous data available regarding [¹²³I]β-CIT binding to the dopamine transporter sites in the basal ganglia in depressed patients. Objective: The present study tested the hypothesis that the brain DAT density in depressed patients is lower than that in matched healthy controls. Methods: Fifteen drug-naive outpatients with major depression and 18 healthy controls were investigated using single photon emission computerized tomography (SPECT) with a high-affinity dopamine transporter specific radioligand, ¹²³I-labeled β-CIT (2β-carbomethoxy-3β-(4-iodophenyl)-tropane). Results: We found a significantly higher [¹²³I]β-CIT uptake in both sides of the basal ganglia in patients with major depression than in the controls (Mann-Whitney U-test, P = 0.002 on the right and P = 0.003 on the left). Conclusions: The radioligand uptake reflecting the DAT density was significantly higher among the patients than in the controls. This finding is unexpected, since it is generally believed that monoaminergic neurotransmission is lower in depression, and therefore it could be assumed that a reduction in dopamine transmission would lead to secondary down-regulation of DAT density. However, it is possible that up-regulation of the DAT may be the primary alteration, which leads to lower intrasynaptic dopamine concentration and to lower dopamine neural transmission. Received: 20 October 1998/Final version: 25 January 1999     

Combined perfusion- and diffusion-weighted MR imaging in acute ischemic stroke during the 1st week: a longitudinal study

PURPOSE: To compare findings with different magnetic resonance (MR) perfusion maps in acute ischemic stroke. MATERIALS AND METHODS: Combined diffusion-weighted (DW) and perfusion-weighted (PW) MR imaging was performed in 49 patients with acute (<24 hours) stroke, on the 1st and 2nd days and 1 week after stroke. Volumes of hypoperfused tissue on maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT) were compared with the volume of infarcted tissue at DW imaging. RESULTS: The mean infarct volume increased from 41 to 65 cm(3) between the 1st and 2nd days (P: <.001; n = 49). On the 1st day, all perfusion maps on average showed hypoperfusion lesions larger than the infarct at DW imaging (P: <.001; n = 49). MTT maps showed significantly (P: <.001) larger hypoperfusion lesions than did rCBF maps, which showed significantly (P: <.001) larger hypoperfusion lesions than did rCBV maps. The sizes of the initial perfusion-diffusion mismatches correlated significantly with the extent of infarct growth (0.479 < r < 0.657; P: 相似文献   

Effects of ageing on serotonin transporters in healthy females

The effect of ageing on brain serotonin transporters was evaluated in 19 healthy female volunteers (age range 22-74 years) using single-photon emission tomography and [123I]nor-beta-CIT. The study subjects were scanned 0.3, 3, 6 and 23 h after injection of 185 MBq of [123I]nor-beta-CIT. The ratio of the distribution volume for tracer in the midbrain to that in the cerebellum minus 1 was used as an index for serotonin transporter binding. An age-related decline of 2% per decade (r=-0.47; P<0.05) was found in the midbrain. The decline in [123I]nor-beta-CIT binding in the serotonin transporter-rich area is much less than that in dopamine transporters in the striatum (6% per decade).     

Elimination of extracranial blood flow during dynamic cerebral perfusion studies using diffusible and non-diffusible radioisotope

The extracranial blood flow seriously complicates the interpretation of dynamic cerebral studies. To eliminate this, we used a blood pressure cuff placed around the head in 50 patients with no evidence of cerebrovascular disease. The pressure in the headband was increased to 30 mmHg above the patient's systolic pressure, and the first 60 sec static scintigram was taken exactly 3 min after the injection of ^99mTc-pertechnetate. A second 60 sec static scintigram was taken without pressure in the headband at 6 min after injection. After correction for diffusion of tracer into extravascular compartments we could still show 13% reduction in counting rates over the hemispheric regions and 30% over the convexity regions during application of the pressure headband. With the Xenon method, the application of the headband appears to have insignificant influence on the results of cerebral perfusion. We thus recommend that a headband should be used for dynamic ^99mTc-isotope cerebral circulation studies.