Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body.
Aripiprazole, sold under the brand names Abilify and Aristada, among others, is an atypical antipsychotic. It is primarily used in the treatment of schizophrenia, obsessive compulsive disorder (OCD), and bipolar disorder; other uses include as an add-on treatment in major depressive disorder, tic disorders, and irritability associated with autism. Aripiprazole is taken by mouth or via injection into a muscle. A Cochrane review found low-quality evidence of effectiveness in treating schizophrenia.
A radioligand is a radioactive biochemical substance, in particular, a ligand that is radiolabeled. Radioligands are used for diagnosis or for research-oriented study of the receptor systems of the body, and for anti-cancer radioligand therapy.
The dopamine hypothesis of schizophrenia or the dopamine hypothesis of psychosis is a model that attributes the positive symptoms of schizophrenia to a disturbed and hyperactive dopaminergic signal transduction. The model draws evidence from the observation that a large number of antipsychotics have dopamine-receptor antagonistic effects. The theory, however, does not posit dopamine overabundance as a complete explanation for schizophrenia. Rather, the overactivation of D2 receptors, specifically, is one effect of the global chemical synaptic dysregulation observed in this disorder.
Glutamate carboxypeptidase II (GCPII), also known as N-acetyl-L-aspartyl-L-glutamate peptidase I, NAAG peptidase, or prostate-specific membrane antigen (PSMA) is an enzyme that in humans is encoded by the FOLH1 gene. Human GCPII contains 750 amino acids and weighs approximately 84 kDa.
(–)-2β-Carboisopropoxy-3β-(4-iodophenyl)tropane is a stimulant drug used in scientific research, which was developed in the early 1990s. RTI-121 is a phenyltropane based, highly selective dopamine reuptake inhibitor and is derived from methylecgonidine. RTI-121 is a potent and long-lasting stimulant, producing stimulant effects for more than 10 hours after a single dose in mice which would limit its potential uses in humans, as it might have significant abuse potential if used outside a medical setting. However RTI-121 occupies the dopamine transporter more slowly than cocaine, and so might have lower abuse potential than cocaine itself.
Dopamine receptor D2, also known as D2R, is a protein that, in humans, is encoded by the DRD2 gene. After work from Paul Greengard's lab had suggested that dopamine receptors were the site of action of antipsychotic drugs, several groups, including those of Solomon Snyder and Philip Seeman used a radiolabeled antipsychotic drug to identify what is now known as the dopamine D2 receptor. The dopamine D2 receptor is the main receptor for most antipsychotic drugs. The structure of DRD2 in complex with the atypical antipsychotic risperidone has been determined.
Dopamine receptor D1, also known as DRD1. It is one of the two types of D1-like receptor family — receptors D1 and D5. It is a protein that in humans is encoded by the DRD1 gene.
Dopamine receptor D3 is a protein that in humans is encoded by the DRD3 gene.
Altanserin is a compound that binds to the 5-HT2A receptor. Labeled with the isotope fluorine-18 it is used as a radioligand in positron emission tomography (PET) studies of the brain, i.e., studies of the 5-HT2A neuroreceptors. Besides human neuroimaging studies altanserin has also been used in the study of rats.
DASB, also known as 3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile, is a compound that binds to the serotonin transporter. Labeled with carbon-11 — a radioactive isotope — it has been used as a radioligand in neuroimaging with positron emission tomography (PET) since around year 2000. In this context it is regarded as one of the superior radioligands for PET study of the serotonin transporter in the brain, since it has high selectivity for the serotonin transporter.
Blonanserin, sold under the brand name Lonasen, is a relatively new atypical antipsychotic commercialized by Dainippon Sumitomo Pharma in Japan and Korea for the treatment of schizophrenia. Relative to many other antipsychotics, blonanserin has an improved tolerability profile, lacking side effects such as extrapyramidal symptoms, excessive sedation, or hypotension. As with many second-generation (atypical) antipsychotics it is significantly more efficacious in the treatment of the negative symptoms of schizophrenia compared to first-generation (typical) antipsychotics such as haloperidol.
Pridopidine is an orally administrated small molecule investigational drug. Pridopidine is a selective and potent Sigma-1 Receptor agonist. It is being developed by Prilenia Therapeutics and is currently in late-stage clinical development for Huntington’s disease (HD) and Amyotrophic Lateral Sclerosis (ALS).
Brain positron emission tomography is a form of positron emission tomography (PET) that is used to measure brain metabolism and the distribution of exogenous radiolabeled chemical agents throughout the brain. PET measures emissions from radioactively labeled metabolically active chemicals that have been injected into the bloodstream. The emission data from brain PET are computer-processed to produce multi-dimensional images of the distribution of the chemicals throughout the brain.
Mefway is a serotonin 5-HT1A receptor antagonist used in medical research, usually in the form of mefway (18F) as a positron emission tomography (PET) radiotracer.
Fallypride is a high affinity dopamine D2/D3 receptor antagonist used in medical research, usually in the form of fallypride (18F) as a positron emission tomography (PET) radiotracer in human studies.
Nifene is a high affinity, selective nicotinic α4β2* receptor partial agonist used in medical research for nicotinic acetylcholine receptors, usually in the form of nifene (18F) as a positron emission tomography (PET) radiotracer.
Metabolic trapping refers to a localization mechanism of synthesized radiocompounds in the human body. It can be defined as the intracellular accumulation of a radioactive tracer based on the relative metabolic activity of the body's tissues. It is a basic principle of the design of radiopharmaceuticals as metabolic probes for functional studies or tumor location.
18F-FMISO or fluoromisonidazole is a radiopharmaceutical used for PET imaging of hypoxia. It consists of a 2-nitroimidazole molecule labelled with the positron-emitter fluorine-18.
Arterial input function (AIF), also known as a plasma input function, refers to the concentration of tracer in blood-plasma in an artery measured over time. The oldest record on PubMed shows that AIF was used by Harvey et al. in 1962 to measure the exchange of materials between red blood cells and blood plasma, and by other researchers in 1983 for positron emission tomography (PET) studies. Nowadays, kinetic analysis is performed in various medical imaging techniques, which requires an AIF as one of the inputs to the mathematical model, for example, in dynamic PET imaging, or perfusion CT, or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).
