Search results for " DOPAMINE"
showing 10 items of 177 documents
Vulnerability to psychotogenic effects of ketamine is associated with elevated D2/3-receptor availability.
2012
Previous positron emission tomography (PET) studies employing competition paradigms have shown either no change or substantial declines in striatal ( 11 C)-raclopride binding after challenge with psychotogenic doses of the N-methyl-D-aspartate antagonist ketamine. We sought to probe the relationship between the severity of ketamine-induced psychotic symptoms and altered dopamine D2/3 receptor availability throughout brain using the high affinity ligand ( 18 F)-fallypride (FP). PET recordings were obtained in a group of 10 healthy, young male volunteers, in a placebo condition, and in the course of an infusion with ketamine at a psychotomimetic dose. Administration of the Positive and Negati…
The striatal and extrastriatal D2/D3 receptor-binding profile of clozapine in patients with schizophrenia.
2005
Positron emission tomography (PET) studies reveal that clozapine at clinically used doses occupies less than 60% of D2/D3 dopamine receptors in human striatum. Here, the occupancy of D2/D3 dopamine receptors by clozapine in patients with schizophrenia was determined to test the hypothesis that clozapine binds preferentially to extrastriatal dopamine receptors. A total of 15 clozapine-treated inpatients with schizophrenia underwent a [18F]fallypride PET scan. Receptor occupancy was calculated as percent reduction in binding potential relative to unblocked values measured in seven normal volunteers. Mean D2/D3 receptor occupancy was statistically significantly higher in cortical (inferior tem…
Prolactin plasma levels and D2-dopamine receptor occupancy measured with IBZM-SPECT
1996
By the application of 123([123I]IBZM), an iodine-labelled dopamine D2-receptor antagonist, brain D2 receptors in humans can be visualized with single photon emission computed tomography (SPECT). The ratio of IBZM binding to striatal regions versus binding to frontal cortex (ST/FC ratio) provided a semiquantitative measurement of D2 receptor binding in the striatum. This study investigated the relationship between receptor occupancy and plasma prolactin levels in 12 male patients treated with haloperidol, benperidol or clozapine. Prolactin levels were positively correlated with D2 receptor occupancy, reflecting at least in part a comparable dopamine receptor antagonism in different dopaminer…
Occupancy of striatal D 2 -like dopamine receptors after treatment with the sigma ligand EMD 57445, a putative atypical antipsychotic
1999
Rationale: EMD 57445 (panamesine) is a high affinity sigma ligand with the profile of an atypical antipsychotic in animal studies. It has been reported recently to have antipsychotic activity in schizophrenia. However, its metabolite, EMD 59983, binds also to D2 and D3 dopamine (DA) receptors. Objectives: The aim of this study was to test, using single photon emission computed tomography (SPECT) and [123I]iodobenzamide (IBZM) as the radiotracer, whether EMD 59983 would pass the blood-brain barrier and to what extent it would contribute to the effects of EMD 57445 in schizophrenia. Methods: Two IBZM SPECT-scans were performed in five neuroleptic-free schizophrenic patients (DSM IV), one befo…
Identification of two novel polymorphisms and a rare deletion variant in the human dopamine D4 receptor gene
1995
We report two novel polymorphisms and a rare deletion variant in the human dopaine D4 receptor gene. The two polymorphisms are characterized by single base pair substitutions, namely a G-->C transversion changing codon 11 from GGG (encoding Gly) to CGG (encoding Arg) and a C-->T transition in position -11 upstream from the start codon. The Arg11 variant occurs at a frequency of about 1% and the C-->T transition at a frequency of about 7% in German control subjects (n = 148). Allele frequencies observed in patients suffering from schizophrenia (n = 256) and bipolar affective disorder (n = 99) were similar. The deletion variant is characterized by a 21 bp deletion affecting codons 36 to 42 co…
Dopamine receptor 2 activation inhibits ovarian vascular endothelial growth factor secretion in vitro: implications for treatment of ovarian hypersti…
2013
Objective To ascertain whether vascular endothelial growth factor (VEGF) secretion by luteinized granulosa cells (GCs) is modulated by the dopaminergic system in a dose-dependent fashion and how this is related to the differential efficacy of dopamine receptor 2 (D2)-agonists (D2-ag) in preventing ovarian hyperstimulation syndrome (OHSS). Design The relationship between the dopaminergic system and VEGF secretion in luteinized GCs was evaluated. Archived human ovaries were immunostained to characterize D2 expression. Setting University affiliated infertility center. Patient(s) Premenopausal women and egg donors. Intervention(s) Luteinized GCs were cultured with the D2-ag cabergoline. Human o…
Pain perception in Parkinson's disease: A systematic review and meta-analysis of experimental studies
2017
While hyperalgesia (increased pain sensitivity) has been suggested to contribute to the increased prevalence of clinical pain in Parkinson's disease (PD), experimental research is equivocal and mechanisms are poorly understood. We conducted a meta-analysis of studies comparing PD patients to healthy controls (HCs) in their response to experimental pain stimuli. Articles were acquired through systematic searches of major databases from inception until 10/2016. Twenty-six studies met inclusion criteria, comprising 1292 participants (PD = 739, HCs = 553). Random effects meta-analysis of standardized mean differences (SMD) revealed lower pain threshold (indicating hyperalgesia) in PD patients d…
Opiate-induced dopamine release is modulated by severity of alcohol dependence: an [(18)F]fallypride positron emission tomography study.
2011
Background Preclinical data implicate the reinforcing effects of alcohol to be mediated by interaction between the opioid and dopamine systems of the brain. Specifically, alcohol-induced release of β-endorphins stimulates μ-opioid receptors (MORs), which is believed to cause dopamine release in the brain reward system. Individual differences in opioid or dopamine neurotransmission have been suggested to be responsible for enhanced liability to abuse alcohol. In the present study, a single dose of the MOR agonist remifentanil was administered in detoxified alcohol-dependent patients and healthy control subjects to mimic the β-endorphin-releasing properties of ethanol and to assess the effect…
Synthesis and Characterization of a Novel Series of Agonist Compounds as Potential Radiopharmaceuticals for Imaging Dopamine D-2/3 Receptors in Their…
2014
Imaging of dopamine D2/3 receptors (D2/3R) can shed light on the nature of several neuropsychiatric disorders in which dysregulation of D2/3R signaling is involved. Agonist D2/3 tracers for PET/SPECT imaging are considered to be superior to antagonists because they are more sensitive to dopamine concentrations and may selectively label the high-affinity receptor state. Carbon-11-labeled D2/3R agonists have been developed, but these short-lived tracers can be used only in centers with a cyclotron. Here, we report the development of a series of novel D2R agonist compounds based on the 2-aminomethylchromane (AMC) scaffold that provides ample opportunities for the introduction of longer-lived […
New dopamine D2 receptor polymorphisms in rats and association with apomorphine-induced stereotypies.
2002
Adult Wistar rats injected with the dopamine receptor agonist apomorphine display different types of motility patterns with respect to oral stereotypes and locomotor activities. It was tested whether phenotypes exhibiting either ‘sniffing’ or ‘non-sniffing’ behaviour differed in gene structures of dopamine receptors D1 or D2. Forty-five Wistar rats of both genders were tested after a single dose of apomorphine (2 mg/kg s.c.) for stereotyped behaviour. Sequence analysis of the 5′ flanking region, the 5′ untranslated region and the coding region of the two genes revealed a new sequence for the 5′ flanking region of the D1 receptor gene and two polymorphisms in the promoter region of the D2 re…