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1.
Borroto-Escuela DO Romero-Fernandez W Tarakanov AO Marcellino D Ciruela F Agnati LF Fuxe K 《Biochemical and biophysical research communications》2010,401(4):605-610
In view of the co-distribution of dopamine D2LR and 5-hydroxytryptamine 5-HT2A receptors (D2LR and 5-HT2AR, respectively) within inter alia regions of the dorsal and ventral striatum and their role as a target of antipsychotic drugs; in this study we assessed the potential existence of D2LR-5-HT2AR heteromers in living cells and the functional consequences of this interaction. Thus, by means of a proximity-based bioluminescence resonance energy transfer (BRET) approach we demonstrated that the D2LR and the 5-HT2AR form stable and specific heteromers when expressed in HEK293T mammalian cells. Furthermore, when the D2LR-5-HT2AR heteromeric signaling was analyzed we found that the 5-HT2AR-mediated phospholipase C (PLC) activation was synergistically enhanced by the concomitant activation of the D2LR as shown in a NFAT-luciferase reporter gene assay and a specific and significant rise of the intracellular calcium levels were observed when both receptors were simultaneously activated. Conversely, when the D2LR-mediated adenylyl cyclase (AC) inhibition was assayed we showed that costimulation of D2LR and 5-HT2AR within the heteromer led to inhibition of the D2LR functioning, thus suggesting the existence of a 5-HT2AR-mediated D2LR trans-inhibition phenomenon. Finally, a bioinformatics study reveals that the triplet amino acid homologies LLT (Leu-Leu-Thr) and AIS (Ala-Ile-Ser) in TM1 and TM3, respectively of the D2R-5-HT2AR may be involved in the receptor interface. Overall, the presence of the D2LR-5-HT2AR heteromer in discrete brain regions is postulated based on the existence of D2LR-5-HT2A receptor-receptor interactions in living cells and their codistribution inter alia in striatal regions. Possible novel therapeutic strategies for treatment of schizophrenia should be explored by targeting this heteromer. 相似文献
2.
Daniel Marcellino Gemma Navarro Kristoffer Sahlholm 《Biochemical and biophysical research communications》2010,394(4):988-992
Adenosine A2A receptors (A2ARs) and dopamine D2 receptors (D2Rs) form constitutive heteromers in living cells and exhibit a strong functional antagonistic interaction. Recent findings give neurochemical evidence that extended cocaine self-administration in the rat give rise to an up-regulation of functional A2ARs in the nucleus accumbens that return to baseline expression levels during cocaine withdrawal. In the present work, the acute in vitro effects of a concentration of cocaine known to fully block the dopamine (DA) transporter without exerting any toxic actions were investigated on A2AR and D2LR formed heteromers in transiently co-transfected HEK-293T cells. In vitro treatment of cocaine was found to produce changes in D2R homodimers and in A2AR-D2R heterodimers detected through bioluminescent energy transfer (BRET). Cocaine was found to produce a time- and concentration-dependent reduction in the BRETmax between A2AR-D2LR heterodimers and D2LR homodimers, but not A2AR homodimers, indicating its effect on D2R. Cocaine was evaluated with regard to D2R binding using a human D2LR stable expressing CHO cell line and was found to produce an increase in the affinity of hD2LR for DA. At the level of G protein-coupling, cocaine produced a small, but significant increase in DA-stimulated binding of GTPγS. However, cocaine failed to modulate D2R agonist-induced inhibition of cAMP in stable hD2LR CHO cells or the gating of GIRK channels in oocytes. Taken together, these results indicate a direct and specific effect of a moderate concentration of cocaine on the DA D2LR, that results in enhanced agonist recognition, G protein-coupling and an altered conformational state of D2R homodimers and A2AR-D2R heterodimers. 相似文献
3.
Borroto-Escuela DO Romero-Fernandez W Tarakanov AO Gómez-Soler M Corrales F Marcellino D Narvaez M Frankowska M Flajolet M Heintz N Agnati LF Ciruela F Fuxe K 《Biochemical and biophysical research communications》2010,402(4):801-807
A single serine point mutation (S374A) in the adenosine A2A receptor (A2AR) C-terminal tail reduces A2AR-D2R heteromerization and prevents its allosteric modulation of the dopamine D2 receptor (D2R). By means of site directed mutagenesis of the A2AR and synthetic transmembrane (TM) α-helix peptides of the D2R we further explored the role of electrostatic interactions and TM helix interactions of the A2AR-D2R heteromer interface. We found evidence that the TM domains IV and V of the D2R play a major role in the A2AR-D2R heteromer interface since the incubation with peptides corresponding to these domains significantly reduced the ability of A2AR and D2R to heteromerize. In addition, the incubation with TM-IV or TM-V blocked the allosteric modulation normally found in A2AR-D2R heteromers. The mutation of two negatively charged aspartates in the A2AR C-terminal tail (D401A/D402A) in combination with the S374A mutation drastically reduced the physical A2AR-D2R interaction and lost the ability of antagonistic allosteric modulation over the A2AR-D2R interface, suggesting further evidence for the existence of an electrostatic interaction between the C-terminal tail of A2AR and the intracellular loop 3 (IL3) of D2R. On the other hand, molecular dynamic model and bioinformatic analysis propose that specific AAR, AQE, and VLS protriplets as an important motive in the A2AR-D2LR heteromer interface together with D2LR TM segments IV/V interacting with A2AR TM-IV/V or TM-I/VII. 相似文献
4.
We have previously demonstrated that neuropeptide-EI, at high doses, stimulates the production of cAMP, in caudate putamen, through the activation of adenylate cyclase coupled to specific D1 receptors. The aim of the present work was to find evidences for a probable interaction between this neuropeptide and the dopamine D1 receptor in the mammalian central nervous system. The present data show that neuropeptide-EI, at high concentrations, affected both the maximum binding and the apparent affinity of [n-methyl-3H] (R)-(+)-8 chloro-2,3,4,5- tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol hemimaleate to the dopamine D1 receptor in a concentration-dependent manner. 相似文献
5.
Quan W Kim JH Albert PR Choi H Kim KM 《Biochemical and biophysical research communications》2008,377(2):705-709
ERK activation by dopamine D2 receptor (D2R) has been extensively characterized in various cell types including brain tissues. However, the involvement of β-arrestin in the D2R-mediated ERK activation is not clear yet. Three different strategies were employed in this study to determine the roles of G protein or β-arrestin in D2R-mediated ERK activation. The cellular level of β-arrestins was reduced by RNA interference and pertussis toxin-insensitive Gi proteins were used to identify the G protein involved. Finally point mutations of D2R in which coupling with G protein was abolished but the interaction with β-arrestin was increased, were employed to determine whether the affinity between D2R and β-arrestin is a critical factor for β-arrestin-mediated ERK activation. Our results show that Gi2 protein is involved in D2R-mediated ERK activation but β-arrestins are either not involved or play minor role. 相似文献
6.
Trincavelli ML Daniele S Orlandini E Navarro G Casadó V Giacomelli C Nencetti S Nuti E Macchia M Huebner H Gmeiner P Rossello A Lluís C Martini C 《Cellular signalling》2012,24(4):951-960
The structural and functional interaction between D2 dopamine receptor (DR) and A2A adenosine receptor (AR) has suggested these two receptors as a pharmacological target in pathologies associated with dopamine dysfunction, such as Parkinson's disease. In transfected cell lines it has been demonstrated the activation of D2DR induces a significant negative regulation of A2AAR-mediated responses, whereas few data are at now available about the regulation of A2AAR by D2DR agonists at receptor recognition site. In this work we confirmed that in A2AAR/D2DR co-transfected cells, these receptors exist as homo- and hetero-dimers. The classical D2DR agonists were able to negatively modulate both A2AAR affinity and functionality. These effects occurred even if any significant changes in A2AAR/D2DR energy transfer interaction could be detected in BRET experiments.Since the development of new molecules able to target A2A/D2 dimers may represent an attractive tool for innovative pharmacological therapy, we also identified a new small molecule, 3-(3,4-dimethylphenyl)-1-(2-piperidin-1-yl)ethyl)piperidine (compound 1), full agonist of D2DR and modulator of A2A-D2 receptor dimer. This compound was able to negatively modulate A2AAR binding properties and functional responsiveness in a manner comparable to classical D2R agonists. In contrast to classical agonists, compound 1 led to conformational changes in the quaternary structure in D2DR homomers and heteromers and induced A2AAR/D2DR co-internalization. These results suggest that compound 1 exerts a high control of the function of heteromers and could represent a starting point for the development of new drugs targeting A2AAR/D2 DR heteromers. 相似文献
7.
Dasiel O. Borroto-Escuela Daniel Marcellino Francisco Ciruela 《Biochemical and biophysical research communications》2010,394(1):222-227
Evidence exists that the adenosine receptor A2AR and the dopamine receptor D2R form constitutive heteromers in living cells. Mass spectrometry and pull-down data showed that an arginine-rich domain of the D2R third intracellular loop binds via electrostatic interactions to a specific motif of the A2AR C-terminal tail. It has been indicated that the phosphorylated serine 374 might represent an important residue in this motif. In the present study, it was found that a point mutation of serine 374 to alanine reduced the A2AR ability to interact with D2R. Also, this point mutation abolished the A2AR-mediated inhibition of both the D2R high affinity agonist binding and signaling. These results point to a key role of serine 374 in the A2AR-D2R interface. All together these results indicate that by targeting A2AR serine 374 it will be possible to allosterically modulate A2AR-D2R function, thus representing a new approach for therapeutically modulate D2R function. 相似文献
8.
Distinctive and Synergistic Signaling of Human Adenosine A2a and Dopamine D2L Receptors in CHO Cells
YUTING TANG KEITH T. DEMAREST 《Journal of receptor and signal transduction research》2013,33(3):159-179
Adenosine A2a receptor (A2aR) colocalizes with dopamine D2 receptor (D2R) in the basal ganglia and modulates D2R-mediated dopaminergic activities. A2aR and D2R couple to stimulatory and inhibitory G proteins, respectively. Their opposing roles in regulating neuronal activities, such as locomotion and alcohol consumption, are mediated by their opposite actions on adenylate cyclase, which often serves as “co-incidence detector” of various activators. On the other hand, the neural actions of A2aR and D2R are also, at least partially, independent of each other, as indicated by studies using D2R and A2aR knock-out mice. Here we co-expressed human A2aR and human D2LR in CHO cells and examined their signaling characteristics. Human A2aR desensitized rapidly upon agonist stimulation. A2aR activity (80%) was diminished after 2 hr of pretreatment with its agonist CGS21680. In contrast, human D2LR activity was sustained even after 2 hr and 18 hr pretreatment with its agonist quinpirole. Long-term (18 hr) stimulation of human D2LR also increased basal cAMP levels in CHO cells, whereas long-term (18 hr) activation of human A2aR did not affect basal cAMP levels. Furthermore, long-term (18 hr) activation of D2LR dramatically sensitized A2aR-induced stimulation of adenylate cyclase in a pertussis toxin-sensitive way. Forskolin-induced cAMP accumulation was significantly increased after short-term (2 hr) human D2LR stimulation and further elevated after long-term (18 hr) D2LR activation. However, neither short-term (2 hr) nor long-term (18 hr) stimulation of A2aR affected the inhibitory effects of D2LR on adenylate cyclase. Co-stimulation of A2aR and D2LR could not induce desensitization or sensitization of D2LR either. In summary, signaling t hrough A2aR and D2LR is distinctive and synergistic, supporting their unique and yet integrative roles in regulating neuronal functions when both receptors are present. 相似文献
9.
Sahlholm K Marcellino D Nilsson J Fuxe K Arhem P 《Biochemical and biophysical research communications》2008,374(3):496-501
Agonist potency at some neurotransmitter receptors has been shown to be regulated by transmembrane voltage, a mechanism which has been suggested to play a crucial role in the regulation of neurotransmitter release by autoreceptors and in synaptic plasticity. We have recently described the voltage-sensitivity of the dopamine D2L receptor and we now extend our studies to include the other members of the D2-like receptor subfamily; the D2S, D3, and D4 dopamine receptors. Electrophysiological recordings were performed on Xenopus oocytes coexpressing human dopamine D2S, D3, or D4 receptors with G protein-coupled potassium (GIRK) channels. Comparison of concentration-response relationships at −80 mV and at 0 mV for dopamine-mediated GIRK activation revealed significant rightward shifts for both D2S and D4 upon depolarization. In contrast, the concentration-response relationships for D3-mediated GIRK activation were not appreciably different at the two voltages. Our findings provide new insight into the functional differences of these closely related receptors. 相似文献
10.
《Journal of receptor and signal transduction research》2013,33(3):117-130
A substantial body of evidence shows the capacity of the dopamine D3 receptor to couple functionally to G proteins when expressed in an appropriate milieu in heterologous expression systems. In these systems, activation of D3 receptors inhibits adenylate cyclase, modulates ion flow through potassium and calcium channels, and activates kinases, most notably mitogen-activated protein kinase. Coupling to Gi/Go is implicated in many of these effects, but other G proteins may contribute. Studies with chimeric receptors implicate the third intracellular loop in the mediation of agonist-induced signal transduction. Finally, D3-preferring drugs modulate expression of c-fos in neuronal cultures and brain. Signaling mechanisms of the D3 receptor in brain, however, remain to be definitively determined. 相似文献
11.
Yunguo Gong 《Molecular simulation》2013,39(12):970-979
In this study, by homology modelling and molecular dynamics (MD) simulation, models of l-stepholidine (l-SPD) activating the 5-HT1A and D1 receptors were constructed. In 100-ns MD simulations, the D1 and 5-HT1A receptors were activated by the partial agonist l-SPD, conforming with the global toggle switch activation model and the sequential activation model. The residues Y7.53 and Y5.58 swing significantly between different transmembrane (TM) domains after activation. Similarities between D1 and 5-HT1A included (1) the outward motion of TM-5; (2) the ionic lock was independent of the tilt of TM-6 and (3) there was an apparent bending of TM-6, and the ring of l-SPD formed strong π–π interactions with residue W6.48. Differences between the two included the following: (1) in 5-HT1A, l-SPD formed a hydrogen bond with Ala1725.46 of TM-5, and the intracellular end of TM-5 moved outward slowly; that hydrogen bond did not form with the D1 receptor; (2) l-SPD formed stronger interactions with D3.32 and W6.48 in the D1 receptor than in the 5-HT1A receptor and (3) the hydrogen bonding network was somewhat different in SPD-5-HT1A and SPD-D1 receptors. We propose the interaction between l-SPD and D3.32 or/and W6.48 is the original driving force during the whole activation process. 相似文献
12.
β-arrestin mediates the desensitization of GPCRs and acts as an adaptor molecule to recruit the receptor complex to clathrin-rich regions. Class-A GPCRs subsequently dissociate from β-arrestin but class-B GPCRs internalize with β-arrestin in the endocytic vesicles. Here the dopamine D2 and D3 receptors, which have similar structural features but different intracellular trafficking properties, were used in an attempt to better understand the structural requirements for the classification of GPCRs. The C-terminus tail of the vasopressin type-2 receptor was added to the ends of D2R and D3R to increase their affinity to β-arrestin. A point mutation was introduced into the DRY motif to change their basal activation levels. Among a battery of constructs in which the C-terminus tail and/or DRY motif was altered, class-B behavior was observed with the constructs whose affinities for β-arrestin were increased complementarily and their signaling was either maintained or regained. In conclusion, the DRY motif and C-terminal tail of the GPCRs determine complementarily their intracellular trafficking behavior by regulating the affinity to β-arrestin and G protein coupling. 相似文献
13.
Víctor Fernández-Dueñas Maricel Gómez-Soler Xavier Morató Fabiana Núñez Arijit Das T. Santhosh Kumar Serge Jaumà Kenneth A. Jacobson Francisco Ciruela 《Neurochemistry international》2013
The molecular interaction between adenosine A2A and dopamine D2 receptors (A2ARs and D2Rs, respectively) within an oligomeric complex has been postulated to play a pivotal role in the adenosine–dopamine interplay in the central nervous system, in both normal and pathological conditions (e.g. Parkinson’s disease). While the effects of A2AR challenge on D2R functioning have been largely studied, the reverse condition is still unexplored, a fact that might have impact in therapeutics. Here, we aimed to examine in a real-time mode the D2R-mediated allosteric modulation of A2AR binding when an A2AR/D2R oligomer is established. Thus, we synthesized fluorescent A2AR agonists and evaluated, by means of a flow cytometry homogeneous no-wash assay and a real-time fluorescence resonance energy transfer (FRET)-based approach, the effects on A2AR binding of distinct antiparkinsonian drugs in current clinical use (i.e. pramipexole, rotigotine and apomorphine). Our results provided evidence for the existence of a differential D2R-mediated negative allosteric modulation on A2AR agonist binding that was oligomer-formation dependent, and with apomorphine being the best antiparkinsonian drug attenuating A2AR agonist binding. Overall, the here-developed methods were found valid to explore the ability of drugs acting on D2Rs to modulate A2AR binding, thus serving to facilitate the preliminary selection of D2R-like candidate drugs in the management of Parkinson’s disease. 相似文献
14.
J. Taura M. Valle‐León K. Sahlholm M. Watanabe K. Van Craenenbroeck V. Fernández‐Dueñas S. Ferré F. Ciruela 《Genes, Brain & Behavior》2018,17(4)
G protein‐coupled receptors (GPCR) exhibit the ability to form receptor complexes that include molecularly different GPCR (ie, GPCR heteromers), which endow them with singular functional and pharmacological characteristics. The relative expression of GPCR heteromers remains a matter of intense debate. Recent studies support that adenosine A2A receptors (A2AR) and dopamine D2 receptors (D2R) predominantly form A2AR‐D2R heteromers in the striatum. The aim of the present study was evaluating the behavioral effects of pharmacological manipulation and genetic blockade of A2AR and D2R within the frame of such a predominant striatal heteromeric population. First, in order to avoid possible strain‐related differences, a new D2R‐deficient mouse with the same genetic background (CD‐1) than the A2AR knock‐out mouse was generated. Locomotor activity, pre‐pulse inhibition (PPI) and drug‐induced catalepsy were then evaluated in wild‐type, A2AR and D2R knock‐out mice, with and without the concomitant administration of either the D2R agonist sumanirole or the A2AR antagonist SCH442416. SCH442416‐mediated locomotor effects were demonstrated to be dependent on D2R signaling. Similarly, a significant dependence on A2AR signaling was observed for PPI and for haloperidol‐induced catalepsy. The results could be explained by the existence of one main population of striatal postsynaptic A2AR‐D2R heteromers, which may constitute a relevant target for the treatment of Parkinson's disease and other neuropsychiatric disorders. 相似文献
15.
《Journal of receptor and signal transduction research》2013,33(3):107-116
Current understanding of the functional roles of individual dopamine D1-like [D1, D5] and D2-like [D2L/S, D3, D4] receptor subtypes remains incomplete. In particular, the lack of pharmacological agonists and antagonists able to distinguish between D1 and D5 receptors means that any differential roles in the regulation of behavior are poorly understood. Mutant mice with targeted gene deletion (“knockout”) of individual dopamine receptor subtypes offer an important alternative approach to resolving these functional roles. In congenic D1 mutants examined ethologically, progressive increases in specific topographies of behavior over wildtypes were considerably greater than those in D1 mutants on a mixed genetic background; D1 knockout appears to influence the neuronal substrate(s) of habituation to disrupt sculpture of the changing topography of behavior from initial exploration through to quiescence. Similarly, the D1 receptor appears to regulate specific topographies of orofacial movement in the mouse as these are “sculpted” in a time-dependent manner. Although the well-recognized role of the D1-like family in regulating several aspects of behavioral topography has been assumed to involve primarily D1 receptors, this presumption may require modification to accommodate a subtle but not negligible role for their D5 counterparts as evidenced in the phenotype of congenic D5 mutants. 相似文献
16.
Nora S. Kula Ross J. Baldessarini John W. Kebabian John L. Neumeyer 《Cellular and molecular neurobiology》1994,14(2):185-191
Summary 1. Our aim was to test the hypothesis that selectivity for D3 dopamine (DA) receptors may contribute to limbic anti-DA selectivity ofS-(+)-aporphine DA partial agonists.2. Affinity was tested with3H-emonapride, using human D3 receptors in mouse fibroblasts and D2 receptors in rat striatal tissue.3. D3 receptors showed a picomolar affinity for3H-emonapride, Na+ dependence, and reversible saturability, as well as stereoselectivity. Confirmatory or novel D3/D2 pharmacologic selectivity was found with several benzamides, thioxanthenes, buspirone, GBR-12909, and DA agonists including hydroxyaminotetralins [ADTN, (+)-7-OH-DPAT, (–)-PPHT and its fluorescein derivative], (–)-N-propylnorapomorphine, (–)-3-PPP, (–)-quinpirole, and SDZ-205-502, but neither aminoergoline nor (+)-aporphine partial agonists.4. The results extend pharmacologic characterization of D3-transfected cell membranes but fail to account for the high limbic anti-DA selectivity ofS-(+)-aporphines. 相似文献
17.
Dasiel O. Borroto-Escuela Wilber Romero-Fernandez Manuel Narvaez Julia Oflijan Luigi F. Agnati Kjell Fuxe 《Biochemical and biophysical research communications》2014
Dopamine D2LR-serotonin 5-HT2AR heteromers were demonstrated in HEK293 cells after cotransfection of the two receptors and shown to have bidirectional receptor–receptor interactions. In the current study the existence of D2L-5-HT2A heteroreceptor complexes was demonstrated also in discrete regions of the ventral and dorsal striatum with in situ proximity ligation assays (PLA). The hallucinogenic 5-HT2AR agonists LSD and DOI but not the standard 5-HT2AR agonist TCB2 and 5-HT significantly increased the density of D2like antagonist 3H-raclopride binding sites and significantly reduced the pKiH values of the high affinity D2R agonist binding sites in 3H-raclopride/DA competition experiments. Similar results were obtained in HEK293 cells and in ventral striatum. The effects of the hallucinogenic 5-HT2AR agonists on D2R density and affinity were blocked by the 5-HT2A antagonist ketanserin. In a forskolin-induced CRE-luciferase reporter gene assay using cotransfected but not D2R singly transfected HEK293 cells DOI and LSD but not TCB2 significantly enhanced the D2LR agonist quinpirole induced inhibition of CRE-luciferase activity. Haloperidol blocked the effects of both quinpirole alone and the enhancing actions of DOI and LSD while ketanserin only blocked the enhancing actions of DOI and LSD. The mechanism for the allosteric enhancement of the D2R protomer recognition and signalling observed is likely mediated by a biased agonist action of the hallucinogenic 5-HT2AR agonists at the orthosteric site of the 5-HT2AR protomer. This mechanism may contribute to the psychotic actions of LSD and DOI and the D2-5-HT2A heteroreceptor complex may thus be a target for the psychotic actions of hallunicogenic 5-HT2A agonists. 相似文献
18.
Alfreda Stadlin Heung Ling Choi Karl Wah Keung Tsim David Tsang 《Molecular neurobiology》1995,11(1-3):67-76
It has been reported from this laboratory that prenatal cocaine exposure results in the postnatal transient alterations of
rat striatal dopamine uptake sites examined from postnatal 0–32 wk. The present study aims to examine whether this will result
in a direct/indirect stimulation of dopamine D2 receptors. Pregnant rats were dosed orally with cocaine hydrochloride (60 mg/kg/d) from gestational day (GD) 7–21. Control
animals received an equivalent volume of water. The striatum from the offspring at postnatal 0–32 wk was examined. The radioligand
[3H]sulpiride was used for the Scatchard analysis of the D2 receptors, and the changes in the levels of mRNA for the D2 receptor were studied using Northern blot analysis. Results from the present study revealed that in the control group, there
was an age-dependent increase in the number of D2 receptor sites (B
max:44.00±2.12 to 178.00±45.10 fmol/mg protein) and in the levels of D2 mRNA from PN0–32 wk with the most rapid increase occurring during the first 4 wk of postnatal development. Prenatal cocaine
exposure resulted in only a significant decrease (p<0.001) in the number of D2 receptor sites at PN0 wk and in a 10% increase in mRNA levels at PN3, 4, and 12 wk. It was concluded from this study that
prenatal cocaine exposure resulted in minimal postnatal changes in the dopamine D2 receptor. 相似文献
19.
Yuji Odagaki Masakazu Kinoshita Toshio Ota 《Journal of receptor and signal transduction research》2019,39(1):9-17
Although multiple roles of dopamine through D1-like (D1 and D5) and D2-like (D2, D3, and D4) receptors are initiated primarily through stimulation or inhibition of adenylyl cyclase via Gs/olf or Gi/o, respectively, there have been many reports indicating diverse signaling mechanisms that involve alternative G protein coupling. In this study, dopamine-induced Gαq activation in rat brain membranes was investigated. Agonist-induced Gαq activation was assessed by increase in guanosine-5′-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding to Gαq determined by [35S]GTPγS binding/immunoprecipitation assay in rat brain membranes. Dopamine-stimulated Gαq functionality was highest in cortex as compared to hippocampus or striatum. In cerebral cortical membranes, this effect was mimicked by benzazepine derivatives with agonist properties at dopamine D1-like receptors, that is, SKF83959, SKF83822, R(+)-SKF81297, R(+)-SKF38393, and SKF82958, but not by the compounds with dopamine D2-like receptor agonist properties except for aripiprazole. Against expectation, stimulatory effects were also induced by SKF83566, R(+)-SCH23390, and pergolide. The pharmacological profiling by using a series of antagonists indicated that dopamine-induced response was mediated through dopamine D1-like receptor, which was distinct from the receptor involved in 5-HT-induced response (5-HT2A receptor). Conversely, the responses induced by SKF83566, R(+)-SCH23390, and pergolide were most likely mediated by 5-HT2A receptor, but not by dopamine D1-like receptor. Caution should be paid when interpreting the experimental data, especially in behavioral pharmacological research, in which SKF83566 or R(+)-SCH23390 is used as a standard selective dopamine D1-like receptor antagonist. Also, possible clinical implications of the agonistic effects of pergolide on 5-HT2A receptor has been mentioned. 相似文献
20.
Adenylyl Cyclase Interaction with the D2 Dopamine Receptor Family; Differential Coupling to Gi, Gz, and Gs 总被引:1,自引:0,他引:1
Joseph Obadiah Tomer Avidor-Reiss C. Simone Fishburn Shari Carmon Michael Bayewitch Zvi Vogel Sara Fuchs Berta Levavi-Sivan 《Cellular and molecular neurobiology》1999,19(5):653-664
1.The D2-type dopamine receptors are thought to inhibit adenylyl cyclase (AC), via coupling to pertussis toxin (PTX)-sensitive G proteins of the Gi family. We examined whether and to what extent the various D2 receptors (D2S, D2L, D3S, D3L, and D4) couple to the PTX-insensitive G protein Gz, to produce inhibition of AC activity.2.COS-7 cells were transiently transfected with the individual murine dopamine receptors alone, as well as together with the subunit of Gz. PTX treatment was employed to inactivate endogenous i, and coupling to Gi and Gz was estimated by measuring the inhibition of cAMP accumulation induced by quinpirole, in forskolin-stimulated cells.3.D2S or D2L receptors can couple to the same extent to Gi and to Gz. The D4 dopamine receptor couples preferably to Gz, resulting in about 60% quinpirole-induced inhibition of cAMP accumulation. The D3S and D3L receptor isoforms couple slightly to Gz and result in 15 and 30% inhibition of cAMP accumulation, respectively.4.We have demonstrated for the first time that the two D3 receptor isoforms, and not any of the other D2 receptor subtypes, also couple to Gs in both COS-7 and CHO transfected cells, in the presence of PTX.5.Thus, the differential coupling of the D2 dopamine receptor subtypes to various G proteins may add another aspect to the diversity of dopamine receptor function. 相似文献