Coupling of D2 dopamine receptors to G-proteins in solubilized preparations of bovine caudate nucleus.
Ontology highlight
ABSTRACT:
SUBMITTER: Chazot JA
PROVIDER: S-EPMC1130693 | biostudies-other | 1992 Jan
REPOSITORIES: biostudies-other
Similar Datasets
Project description:The striatum plays important motor, associative and cognitive roles in brain functions. However, the rodent dorsolateral (the primate putamen) and dorsomedial (the primate caudate nucleus) striatum are not anatomically separated, making it difficult to distinguish their functions. By contrast, anatomical separation exists between the caudate nucleus and putamen in primates. Here, we successfully decreased dopamine D1 receptor (D1R) or D2R mRNA expression levels selectively in the marmoset caudate using shRNA knockdown techniques, as determined using positron emission tomography imaging with specific D1R and D2R ligands and postmortem in situ hybridization analysis. We then conducted a voxel-based correlation analysis between binding potential values of PET imaging and visual discrimination learning task performance in these genetically modified marmosets to find a critical role for the caudate D2R but no apparent role for the caudate D1R. This latter finding challenges the current understanding of the mechanisms underlying D1R activation in the caudate.
| S-EPMC5090965 | biostudies-literature
Project description:Dopamine (DA) transmission plays a critical role in processing rewarding and pleasurable stimuli. Increased synaptic DA release in the nucleus accumbens (NAc) is a central component of the physiological effects of drugs of abuse. The essential trace element selenium mitigates methamphetamine-induced neurotoxicity. Selenium can also alter DA production and turnover. However, studies have not directly addressed the role of selenium in DA neurotransmission. Selenoprotein P (SELENOP1) requires selenium for synthesis and transports selenium to the brain, in addition to performing other functions. We investigated whether SELENOP1 directly impacts (1) DA signaling and (2) the dopaminergic response to methamphetamine. We used fast-scan cyclic voltammetry to investigate DA transmission and the response to methamphetamine in NAc slices from C57/BL6J SELENOP1 KO mice. Recordings from SELENOP1 KO mouse slices revealed reduced levels of evoked DA release and slower DA uptake rates. Methamphetamine caused a dramatic increase in vesicular DA release in SELENOP1 KO mice not observed in wild-type controls. This elevated response was attenuated by SELENOP1 application through a selenium-independent mechanism involving SELENOP1-apolipoprotein E receptor 2 (ApoER2) interaction to promote dopamine D2 receptor (D2R) function. In wild-type mice, increased vesicular DA release in response to methamphetamine was revealed by blocking D2R activation, indicating that the receptor suppresses the methamphetamine-induced vesicular increase. Our data provide evidence of a direct physiological role for SELENOP1 in the dopaminergic response to methamphetamine and suggest a signaling role for the protein in DA transmission.
| S-EPMC8076559 | biostudies-literature
Project description:Plasma membrane microcompartments could allow different signaling pathways to operate more efficiently and prevent cross-talk. We utilized a novel in-cell biotin transfer assay to demonstrate that the majority of plasma membrane-expressed D2 dopamine receptor (D2R) is microcompartmentalized within detergent-resistant structures. Conversely, a minority of D2R existed in a detergent-soluble form and interacted in a relatively unrestricted manner with other cellular proteins. The microcompartmentalization of D2R had functional consequences because dopamine-induced internalization of D2R was largely restricted to the compartmentalized receptor. The D2R-containing microcompartments did not correspond to putative detergent-resistant lipid raft structures. First, the detergent-insoluble D2R structures were significantly denser than detergent-resistant membrane fragments containing flotillin, a widely utilized lipid raft marker protein. Second, the detergent solubility of D2R was unaffected by treatment of cells with the cholesterol chelating agent, methyl-β-cyclodextrin, that is thought to disrupt lipid rafts. Finally, the in-cell biotinylation assay did not provide any evidence for the membrane compartmentalization of peptide motifs thought to target to lipid rafts. Thus, our observations form one of the first demonstrations, in living cells, of plasma membrane microcompartments defined by the ability of the compartment structure to broadly restrict the interaction of resident molecules with other cellular proteins.
| S-EPMC3642303 | biostudies-literature
Project description:Antisera have been raised against two peptides from the sequence of D2 dopamine receptors: peptide 1 from the predicted second extracellular loop and peptide 2 from the predicted third intracellular loop. The antisera recognize specifically a 95 kDa band in Western blots of several bovine brain regions, which corresponds to the denatured D2 dopamine receptor, whereas in recombinant CHO cells expressing D2 dopamine receptors a 80 kDa band is seen. The antisera immunoprecipitate 10-20% of the D2 dopamine receptors from soluble preparations of bovine brain. The antisera recognize D2 dopamine receptors in immunofluorescence analyses of recombinant CHO cells bearing the receptor gene. The antisera directed against the third intracellular loop, but not those against the second extracellular loop, will interfere with the coupling of D2 dopamine receptors and G-proteins in bovine brain preparations.
| S-EPMC1132245 | biostudies-other
Project description:Dopamine (DA) transmission from the ventral tegmental area (VTA) is critical for controlling both rewarding and aversive behaviors. The transient silencing of DA neurons is one of the responses to aversive stimuli, but its consequences and neural mechanisms regarding aversive responses and learning have largely remained elusive. Here, we report that optogenetic inactivation of VTA DA neurons promptly down-regulated DA levels and induced up-regulation of the neural activity in the nucleus accumbens (NAc) as evaluated by Fos expression. This optogenetic suppression of DA neuron firing immediately evoked aversive responses to the previously preferred dark room and led to aversive learning toward the optogenetically conditioned place. Importantly, this place aversion was abolished by knockdown of dopamine D2 receptors but not by that of D1 receptors in the NAc. Silencing of DA neurons in the VTA was thus indispensable for inducing aversive responses and learning through dopamine D2 receptors in the NAc.
| S-EPMC4036004 | biostudies-literature
Project description:Expected reward impacts behavior and neuronal activity in brain areas involved in sensorimotor processes. However, where and how reward signals affect sensorimotor signals is unclear. Here, we show evidence that reward-dependent modulation of behavior depends on normal dopamine transmission in the striatum. Monkeys performed a visually guided saccade task in which expected reward gain was different depending on the position of the target. Saccadic reaction times were reliably shorter on large-reward trials than on small-reward trials. When position-reward contingency was switched, the reaction time difference changed rapidly. Injecting dopamine D1 antagonist into the caudate significantly attenuated the reward-dependent saccadic reaction time changes. Conversely, injecting D2 antagonist into the same region enhanced the reward-dependent changes. These results suggest that reward-dependent changes in saccadic eye movements depend partly on dopaminergic modulation of neuronal activity in the caudate nucleus.
| S-EPMC6675290 | biostudies-literature
Project description:Brain imaging studies performed in humans have associated low striatal dopamine release and D2R binding with alcohol dependence. Conversely, high striatal D2R binding has been observed in unaffected members of alcoholic families suggesting that high D2R function may protect against alcohol dependence. A possible protective role of increased D2R levels in the striatum is further supported by preclinical studies in non-human primates and rodents. Here, we determined whether there is a causal relationship between D2R levels and alcohol intake. To this end, we upregulated D2R expression levels in the nucleus accumbens of the adult mouse, but selectively restricted the upregulation to the indirect striatal output pathway, which endogenously expresses D2Rs. After overexpression was established, mice were tested in two models of free-choice alcohol drinking: the continuous and intermittent access two-bottle choice models. As anticipated, we found that D2R upregulation leads to hyperactivity in the open field. Contrary to our expectation, D2R upregulation did not reduce alcohol intake during continuous or intermittent access or when alcohol drinking was tested in the context of aversive outcomes. These data argue against a protective role of accumbal indirect pathway D2Rs in alcohol consumption but emphasize their importance in promoting locomotor activity.
| S-EPMC4915247 | biostudies-literature
Project description:Three-dimensional computer models of the rat D2, D3 and D4 dopamine receptor subtypes have been constructed based on the diffraction co-ordinates for bacteriorhodopsin, another membrane-bound protein containing seven transmembrane domains presumed to be arranged in a similar spatial orientation. Models were assembled by aligning the putative transmembrane domains of the dopamine receptors with those of bacteriorhodopsin using sequence similarities, and then superimposing these modelled alpha-helices on to the bacteriorhodopsin-derived co-ordinates. These models explore the potential hydrogen bonding, electrostatic and stacking interactions within the receptor which may be important for maintaining the conformation of these receptors, and thereby provide target sites for agonist binding. Proposed interactions between the catecholamine ligands and these receptors appear to account for the affinity, although not the specificity, of these agonist ligands for the different dopamine receptor subtypes. Such models will be useful for establishing structure-function relationships between ligands and the dopamine receptors, and may ultimately provide a template for the design of receptor-specific drugs.
| S-EPMC1133155 | biostudies-other
Project description:D2 dopamine receptors from bovine brain (caudate nucleus and olfactory tubercle) have been solubilized using sodium cholate/NaCl and their glycoprotein properties studied in terms of their interaction with wheat-germ agglutinin-agarose (WGA-agarose). Under optimal conditions about 65% of the applied D2 dopamine receptors bound to WGA-agarose and could be eluted with N-acetylglucosamine. The ability of receptors to adsorb to the affinity column was shown to be dependent on the cholate and salt concentrations used. Digestion of the membrane bound D2 dopamine receptors with neuraminidase prior to solubilisation reduced the ability of the receptors to bind to WGA-agarose (50% of applied receptors bound) whereas digestion with N-acetylglucosaminidase did not significantly affect binding to WGA-agarose. Digestion with the two enzymes together resulted in a larger decrease in binding to WGA-agarose than was seen with the two enzymes alone (40% of applied receptors bound). Stepwise elution of bound receptors from the WGA-agarose columns using 2.5 mM- and 100-mM-N-acetylglucosamine showed that about 40% of the bound receptors interacted with WGA-agarose in a low-affinity manner, the remainder showing a high-affinity interaction. Neuraminidase treatment reduced the low-affinity population suggesting that the interaction of oligosaccharides bearing sialic acid with WGA-agarose is of lower affinity and that higher-affinity binding is via N-acetylglucosamine. These data are discussed in terms of the heterogeneity of carbohydrate moieties on the D2 dopamine receptors within a brain region. In all the tests applied here, however, receptors from caudate nucleus and olfactory tubercle behaved identically so their glycosylation patterns must be very similar.
| S-EPMC1135323 | biostudies-other
Project description:Influential neurocomputational models emphasize dopamine (DA) as an electrophysiological and neurochemical correlate of reinforcement learning. However, evidence of a specific causal role of DA receptors in learning has been less forthcoming, especially in humans. Here we combine, in a between-subjects design, administration of a high dose of the selective DA D2/3-receptor antagonist sulpiride with genetic analysis of the DA D2 receptor in a behavioral study of reinforcement learning in a sample of 78 healthy male volunteers. In contrast to predictions of prevailing models emphasizing DA's pivotal role in learning via prediction errors, we found that sulpiride did not disrupt learning, but rather induced profound impairments in choice performance. The disruption was selective for stimuli indicating reward, whereas loss avoidance performance was unaffected. Effects were driven by volunteers with higher serum levels of the drug, and in those with genetically determined lower density of striatal DA D2 receptors. This is the clearest demonstration to date for a causal modulatory role of the DA D2 receptor in choice performance that might be distinct from learning. Our findings challenge current reward prediction error models of reinforcement learning, and suggest that classical animal models emphasizing a role of postsynaptic DA D2 receptors in motivational aspects of reinforcement learning may apply to humans as well.
| S-EPMC4138746 | biostudies-literature