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Postmortem and positron emission tomography (PET) studies have reported several alterations in serotonin 1A receptor (5-HT1A) binding parameters in patients with schizophrenia. This study examines 5-HT1A availability in vivo in individuals with schizophrenia and schizo-affective disorder. Twenty-two medication-free individuals with schizophrenia or schizo-affective disorder and 18 healthy subjects underwent PET scans with [11C]WAY 100635. Regional distribution volumes ( V T, in milliliters per gram) were derived using a two-tissue compartment kinetic model. Outcome measures for 5-HT1A availability included binding potential (BP) and the specific to nonspecific equilibrium partition coefficient ( V 3″). Eleven brain regions with high density of 5-HT1A were included in the analysis. No significant differences were observed in regional BP or V 3″ between patients and controls. No significant relationships were observed between regional 5-HT1A availability and symptom severity. The postmortem literature reports increased 5-HT1A binding in the prefrontal cortex in schizophrenia. This study did not detect differences in 5-HT1A binding. Whereas in two recently published PET studies, one reports increased binding in the temporal lobe while the other reports decreased binding in the amygdala. These inconsistencies suggest that the alterations demonstrated in postmortem studies cannot be reliably detected at the resolution achieved with PET. This raises the question as to whether major changes in the level of expression of the 5-HT1A receptor play a role in the pathophysiology of schizophrenia. [ABSTRACT FROM AUTHOR]

Objectives: The effect of gender and female menstrual cycle on human striatal dopamine transporters (DATs) was investigated with single-photon emission computed tomography (SPECT) using the ligand 2β-carbomethoxy-3β-(4-[123I]iodophenyl)tropane. Methods: Ten female subjects aged 18-40 years (25.3±7.3 years) were scanned twice during the early follicular and the mid-luteal phases to detect any hormone-mediated changes in DAT availability in the striatum or serotonin transporter (SERT) availability in brainstem-diencephalon. Plasma estradiol and progesterone levels were obtained at the time of SPECT and confirmed the expected increases from the follicular to the luteal phases. Finally, in a post hoc analysis of a previously published healthy-subject sample, striatal DAT availability was compared between 70 male and 52 female subjects who ranged in age from 18 to 88 years. Results: In the ten menstrual cycle subjects, DAT availability (V3″) in striatum and SERT availability in brainstem-diencephalon did not differ between follicular and luteal phases. Moreover, change in V3″ for striatum or brainstem-diencephalon was uncorrelated with change in plasma estradiol or progesterone from the follicular to the luteal phase. In the larger healthy-subject sample, there was no significant effect of gender or the interaction of age and gender on striatal V3″. Conclusions: These findings suggest that in using DAT or SERT ligands in the study of neuropsychiatric disorders, matching of female subjects according to a menstrual cycle phase is unnecessary. Although the present investigation did not confirm previous reports of gender differences in striatal DAT availability, controlling for gender in such studies still seems advisable. [ABSTRACT FROM AUTHOR]

Presents a study which determined the in vivo affinity of [18F]fallypride for striatal and extrastriatal dopamine D2 receptors in nonhuman primates. Measurement of the in vivo affinity of [18F]fallypride for D2 receptors; Comparison between the in vivo affinity of [18F]fallypride in striatal and extrastriatal regions; Evaluation and comparison of several methods for the derivation of regional [18F]fallypride affinities.

Rationale: Although selective serotonin reuptake inhibitors (SSRIs) are widely used in the treatment of anxiety and depressive disorders, the occupancy of the serotonin reuptake transporter (SERT) achieved in humans at typical clinical doses by these agents remains poorly characterized. Objective: The purpose of this study was to determine the occupancy of the SERT achieved in vivo by the SSRI paroxetine in social phobia patients at typical antianxiety doses. Methods: Measures of SERT availability were obtained with positron emission tomography and the SERT radiotracer [[sup 11]C](+)-McN 5652 in five patients with social phobia before and during treatment with paroxetine at usual therapeutic doses (20-40 mg per day). Results: Occupancy of the SERT by paroxetine was high in all subjects and in all regions measured after 3-6 months of continuous treatment. Conclusions: The results of this study in an anxiety disorder sample are consistent with previously reported results in a depressed sample and suggest that paroxetine at therapeutic doses achieves very high occupancy levels of the SERT. [ABSTRACT FROM AUTHOR]