Search Results for « Dopamine »

Detecting dopamine is of great biological importance because the molecule plays many roles in the human body. For instance, the lack of dopamine release is the cause of Parkinson's disease. Although many researchers have carried out experiments on dopamine detection using carbon nanotubes (CNTs), there are only a few theoretical studies on this topic. We study the adsorption properties of dopamine and its derivatives, L-DOPA and dopamine o-quinone, adsorbed on a semiconducting (10, 0) CNT, using density functional theory calculations. Our computational simulations reveal that localized states originating from dopamine o-quinone appear in the bandgap of the (10, 0) CNT, but those originating from dopamine and L-DOPA do not appear in the gap. Therefore, dopamine o-quinone is expected to be detectable using an external electric field but dopamine and L-DOPA should be difficult to detect.

Dopamine (DA) is an organic chemical that influences several parts of behaviour and physical functions. Fast-scan cyclic voltammetry (FSCV) is a technique used for in vivo phasic dopamine release measurements. The analysis of such measurements, though, requires notable effort. In this paper, we present the use of convolutional neural networks (CNNs) for the identification of phasic dopamine releases.

In order to reveal the effect of nigrostriatal dopamine system on action selection, first a computational model of the cortex-basal ganglia-thalamus loop is proposed and based on this model a simple compound model realizing the Stroop effect is established. Even though Stroop task is mostly used to examine selective attention, the main objective of this work is to investigate the effect of action selection on Stroop task. The computational model of the cortex-basal ganglia-thalamus loop is a non-linear dynamical system which is not only capable of revealing the action selection property of basal ganglia but also capable of modelling the effect of dopamine on action selection. While the interpretation of action selection is based on the solutions of the non-linear dynamical system, the effect of dopamine is modelled by a parameter of the model. The inhibiting effect of dopamine on the habitual behaviour which corresponds to word reading in Stroop task and letting the novel one occur corresponding to colour naming is investigated using the compound computational model established in this work.

The spontaneous oxidation of dopamine in slightly alkaline solutions was investigated on the basis of the work of Lee and others [Science, 318:426-430, 2007], and the reaction product was identified as dopamine-melanin. The ability of melanin to covalently bind amine functional groups was confirmed by quantification of the corresponding binding sites on dopamine-melanin aggregates. Furthermore it is possible to redissolve dopamine-melanin aggregates in strongly alkaline solutions. The obtained small melanin grains were used to build layer-by-layer deposits with poly(diallyldimethylammonium). Different methods of dopamine oxidation to grow melanin films at solid--liquid interfaces were developed. All examined methods lead to continuous dopamine-melanin films with very similar surface morphologies. The dopamine-melanin films become impermeable to electrochemical probes at a thickness in the 10 nm range. In this context a higher permeability for positively charged and neutral probes than for negatively charged ones was confirmed for one preparation method. The adsorption of proteins on dopamine-melanin coatings was explained as combination of electrostatic and strong, most probably covalent, interactions. To obtain this explanation, the zeta-potential of dopamine-melanin deposits has been measured as a function of pH. The formation of melanin by dopamine oxidation in layer-by-layer films of poly(L-lysine) (PLL) and hyaluronate (HA) was studied: Melanin is able to homogeneously fill $(\text{PLL-HA})_n$ films and the obtained polyelectrolyte-melanin composites can be detached from their substrate as free-standing membranes prepared by a biomimetic method in mild conditions.

The dopaminergic system is one of the most important neurotransmitter systems in the central nervous system (CNS). It acts mainly by activation of the D1-like receptor family at the target cell. Additionally, fine-tuning of the signal is achieved via pre-synaptic modulation by the D2-like receptor family. Some dopamine drugs (both agonists and antagonists) bind in addition to DRs also to α2-ARs and 5-HT receptors. Unfortunately, these compounds are often considered subtype(s) specific. Thus, it is important to consider the presence of these receptor subtypes in specific CNS areas as the function virtually elicited by one receptor type could be an effect of other—or the co-effect of multiple receptors. However, there are enough molecules with adequate specificity. In this review, we want to give an overview of the most common off-targets for established dopamine receptor ligands. To give an overall picture, we included a discussion on subtype selectivity. Molecules used as antipsychotic drugs are reviewed too. Therefore, we will summarize reported affinities and give an outline of molecules sufficiently specific for one or more subtypes (i.e., for subfamily), the presence of DR, α2-ARs, and 5-HT receptors in CNS areas, which could help avoid ambiguous results.

The extant versions of many basal ganglia models use a `gating' model of dopamine function which enhances input to D1 receptor units and attenuates input to D2 receptor units. There is evidence that this model is unsatisfactory because (a) there are not sufficient dopaminergic synapses to gate all input and (b) dopamine's main effect is likely to be on the ion-channels contributing to the neuron's membrane potential. Thus, an alternative output function-based model of dopamine's effect is proposed which accounts for the dopamine-mediated changes in ion-channel based currents. Simulation results show that the selection and switching properties of the intrinsic and extended models are retained with the new models. The parameter regimes under which this occurs leads us to predict that an L-type Ca2+ current is likely to be the major determinant of striatal neuron output if the basal ganglia is indeed an action selection mechanism. In addition, the results provide evidence that increasing dopamine can improve a neuron's signal-to-noise ratio.