ABSTRACT
Recent evidence has implicated the endocannabinoid (eCB) system in nicotine addiction. The eCB system also has an important role in reward mechanisms, and nicotine addiction has been associated with aberrant reward processing. Motivated by this evidence, we tested the hypothesis that eCB modulation of reward processing is altered in subjects with a nicotine addiction (NAD). For this purpose, we compared reward-related activity in NAD with healthy controls (HC) in a pharmacological magnetic resonance imaging (MRI) study using Δ(9)-tetrahydrocannabinol (THC) administration to challenge the eCB system. Eleven HC and 10 NAD participated in a 3-T functional MRI (fMRI) study with a double-blind, cross-over, placebo-controlled design, using a Monetary Incentive Delay (MID) paradigm with three reward levels. Reward activity in the nucleus accumbens (NAcc) and caudate putamen during anticipation and feedback of reward was compared after THC and placebo. fMRI results indicated a significant reduction of reward anticipation activity in the NAcc in NAD after THC administration, which was not present in HC. This is indicated by a significant group by drug by reward interaction. Our data show that THC significantly reduces the NAcc response to monetary reward anticipation in NAD. These results suggest that nicotine addiction is associated with altered eCB modulation of reward processing in the NAcc. This study adds important human data to existing evidence implicating the eCB system in nicotine addiction.
Subject(s)
Dronabinol/pharmacology , Nucleus Accumbens/drug effects , Reaction Time/drug effects , Reward , Tobacco Use Disorder/physiopathology , Adolescent , Adult , Cross-Over Studies , Double-Blind Method , Humans , Image Processing, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Male , Motivation/drug effects , Young AdultABSTRACT
Up to now, various types of particles have been used as labels in immunoassay. Well known examples are erythrocytes and latex particles. More recently, colloidal gold and dye particles have been introduced as a label. Each type of particle offers one (or more) method(s) of detection which depend(s) on the physical properties of the particles. In this paper, the present state-of-the-art regarding particle-labelled immunoassays will be reviewed.
Subject(s)
Immunoassay , Antibodies, Monoclonal/analysis , Colloids , Erythrocyte Membrane/immunology , Erythrocytes/immunology , Hemagglutination Inhibition Tests , Humans , Latex , MicrospheresABSTRACT
An enzyme-immunoassay (EIA) for estimation of human placental lactogen (HPL) in plasma or serum was developed using HPL labelled with horseradish peroxidase (HRP) and anti-HPL sera raised in rabbits. The separation between antiserum-bound and free labelled hormone was accomplished with a double antibody solid phase technique. Interference of substances from the sample with the immunoassay was prevented by dilution of the sample with at least a factor of 20 and measurement of the labelled hormone attached to the solid phase. The peroxidase activity was colorimetrically measured using o-phenyl-enediamine and urea peroxide as substrate. The standard curve of the assay ranged from 3 to 40 ng HPL/ml allowing estimations of HPL in serum or plasma starting from about the 10th week of pregnancy. Normal values were established. Intra- and inter-assay variation coefficients of 6 and 7.5% respectively were found. The EIA showed no cross-reaction with human serum proteins or HCG. The low cross-reaction noted with human growth hormone did not interfere with the assay. An excellent agreement was found with the results of radioimmunoassay (RAI).
