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1.
The adenosine A 2A receptor (A 2AR) is a G-protein-coupled receptor that plays a key role in transmembrane signalling mediated by the agonist adenosine. The structure of A 2AR was determined recently in an antagonist-bound conformation, which was facilitated by the T4 lysozyme fusion in cytoplasmic loop 3 and the considerable stabilisation conferred on the receptor by the bound inverse agonist ZM241385. Unfortunately, the natural agonist adenosine does not sufficiently stabilise the receptor for the formation of diffraction-quality crystals. As a first step towards determining the structure of A 2AR bound to an agonist, the receptor was thermostabilised by systematic mutagenesis in the presence of the bound agonist [ 3H]5'-N-ethylcarboxamidoadenosine (NECA). Four thermostabilising mutations were identified that when combined to give mutant A 2AR-GL26, conferred a greater than 200-fold decrease in its rate of unfolding compared to the wild-type receptor. Pharmacological analysis suggested that A 2AR-GL26 is stabilised in an agonist-bound conformation because antagonists bind with up to 320-fold decreased affinity. None of the thermostabilising mutations are in the ZM241385 binding pocket, suggesting that the mutations affect ligand binding by altering the conformation of the receptor rather than through direct interactions with ligands. A 2AR-GL26 shows considerable stability in short-chain detergents, which has allowed its purification and crystallisation. 相似文献
2.
The expression of human G protein-coupled receptors (GPCRs) in Saccharomyces cerevisiae containing chimeric yeast/mammalian G α subunits provides a useful tool for the study of GPCR activation. In this study, we used a one-GPCR-one-G protein yeast screening method in combination with molecular modeling and mutagenesis studies to decipher the interaction between GPCRs and the C-terminus of different α-subunits of G proteins. We chose the human adenosine A 2B receptor (hA 2BR) as a paradigm, a typical class A GPCR that shows promiscuous behavior in G protein coupling in this yeast system. The wild-type hA 2BR and five mutant receptors were expressed in 8 yeast strains with different humanized G proteins, covering the four major classes: G αi, G αs, G αq, and G α12. Our experiments showed that a tyrosine residue (Y) at the C-terminus of the G α subunit plays an important role in controlling the activation of GPCRs. Receptor residues R103 3.50 and I107 3.54 are vital too in G protein-coupling and the activation of the hA 2BR, whereas L213 IL3 is more important in G protein inactivation. Substitution of S235 6.36 to alanine provided the most divergent G protein-coupling profile. Finally, L236 6.37 substitution decreased receptor activation in all G protein pathways, although to a different extent. In conclusion, our findings shed light on the selectivity of receptor/G protein coupling, which may help in further understanding GPCR signaling. 相似文献
3.
腺苷作为神经调质,调节多种神经生物学功能.随觉醒时间延长,动物脑内腺苷水平逐渐增高,在睡眠期显著降低.因此,腺苷被认为是调节睡眠的内稳态因子之一.腺苷受体(receptor,R)有A1R、A2AR、A2BR和A3R四种亚型,其中A1R和A2AR与诱导睡眠相关.激活A1R可抑制促觉醒神经元诱导睡眠,也可抑制促眠神经元导致... 相似文献
4.
Adenosine is an important regulatory metabolite and an inhibitor of platelet activation. Adenosine released from different
cells or generated through the activity of cell-surface ectoenzymes exerts its effects through the binding of four different
G-protein-coupled adenosine receptors. In platelets, binding of A 2 subtypes (A 2A or A 2B) leads to consequent elevation of intracellular cyclic adenosine monophosphate, an inhibitor of platelet activation. The
significance of this ligand and its receptors for platelet activation is addressed in this review, including how adenosine
metabolism and its A 2 subtype receptors impact the expression and activity of adenosine diphosphate receptors. The expression of A 2 adenosine receptors is induced by conditions such as oxidative stress, a hallmark of aging. The effect of adenosine receptors
on platelet activation during aging is also discussed, as well as potential therapeutic applications. 相似文献
5.
A single serine point mutation (S374A) in the adenosine A 2A receptor (A 2AR) C-terminal tail reduces A 2AR-D 2R heteromerization and prevents its allosteric modulation of the dopamine D 2 receptor (D 2R). By means of site directed mutagenesis of the A 2AR and synthetic transmembrane (TM) α-helix peptides of the D 2R we further explored the role of electrostatic interactions and TM helix interactions of the A 2AR-D 2R heteromer interface. We found evidence that the TM domains IV and V of the D 2R play a major role in the A 2AR-D 2R heteromer interface since the incubation with peptides corresponding to these domains significantly reduced the ability of A 2AR and D 2R to heteromerize. In addition, the incubation with TM-IV or TM-V blocked the allosteric modulation normally found in A 2AR-D 2R heteromers. The mutation of two negatively charged aspartates in the A 2AR C-terminal tail (D401A/D402A) in combination with the S374A mutation drastically reduced the physical A 2AR-D 2R interaction and lost the ability of antagonistic allosteric modulation over the A 2AR-D 2R interface, suggesting further evidence for the existence of an electrostatic interaction between the C-terminal tail of A 2AR and the intracellular loop 3 (IL3) of D 2R. On the other hand, molecular dynamic model and bioinformatic analysis propose that specific AAR, AQE, and VLS protriplets as an important motive in the A 2AR-D 2LR heteromer interface together with D 2LR TM segments IV/V interacting with A 2AR TM-IV/V or TM-I/VII. 相似文献
6.
Inflammation is responsible for secondary organ failure after trauma and hemorrhagic shock (T/HS). Adenosine, acting through four G protein-coupled cell surface receptors, A 1, A 2A, A 2B, and A 3, exerts a number of tissue protective and anti-inflammatory effects. The goal of the present study was to test the effect of A 2B adenosine receptor stimulation on T/HS-induced organ injury and inflammation in rats. Rats after T/HS were resuscitated with Ringer’s lactate containing the A 2B receptor agonist BAY 60–6583 or its vehicle. We found that BAY 60–6583 decreased T/HS-induced lung permeability and plasma creatine kinase levels but failed to affect T/HS-induced lung neutrophil infiltration and IκBα expression and plasma alanine aminotransferase levels. Thus, we conclude that stimulation of A 2B receptors protects against T/HS-induced lung and muscle injury. 相似文献
7.
Pro258 in transmembrane domain (TMD) 6 of the bradykinin (BK) B 2 receptor (B 2R) is highly conserved among G-protein coupled receptors (GPCRs). Using mutagenesis, we show that Pro258 is required for normal trafficking of the receptor to the plasma membrane and that mutation of Pro258 to Ala or Leu but not Gly, enhances BK efficacy to induce receptor activation. Furthermore, P258A mutation suppresses the constitutive activity of a constitutively activated N113A-B 2R mutant but preserves the antagonist to agonist efficacy shift previously observed on the N113A single mutant. Our data suggest that Pro258 in TMD6 is required for agonist-independent activation of the B 2R and that straightening of TMD6 at the Pro-kink might favor G-protein coupling. It is also shown that Asn113 is a contact point of BK interaction and it is proposed that the release of a TMD3-TMD6 interaction involving Asn113 is crucial for the efficacy shift from antagonism toward agonism. 相似文献
8.
Angiogenesis is critical to wound repair due to its role in providing oxygen and nutrients that are required to support the growth and function of reparative cells in damaged tissues. Adenosine receptors are claimed to be of paramount importance in driving wound angiogenesis by inducing VEGF. However, the underlying mechanisms for the regulation of adenosine receptors in VEGF as well as eNOS remain poorly understood. In the present study, we found that adenosine and the non-selective adenosine receptor agonists (NECA) induced tube formation in HMEC-1 in a dose-dependent manner. Adenosine or NECA (10 µmol/L) significantly augmented the number and length of the segments in comparison with the control. Simultaneously, VEGF and eNOS were significantly upregulated following the administration of 10 µmol/L NECA, while they were suppressed after A 2B AR genetic silencing and pharmacological inhibition by MRS1754. In addition, VEGF expression and eNOS bioavailability elimination significantly reduced the formation of capillary-like structures. Furthermore, the activation of A 2B AR by NECA significantly increased the intracellular cAMP levels and concomitant CREB phosphorylation, eventually leading to the production of VEGF in HMEC-1. However, the activated PKA-CREB pathway seemed to be invalidated in the induction of eNOS. Moreover, we found that the elicited PI3K/AKT signaling in response to the induction of NECA assisted in regulating eNOS but failed to impact on VEGF generation. In conclusion, the A 2B AR activation-driven angiogenesis via cAMP-PKA-CREB mediated VEGF production and PI3K/AKT-dependent upregulation of eNOS in HMEC-1. 相似文献
9.
Adenosine A 2B receptors of native human and rodent cell lines were investigated using [ 3H]PSB-298 [(8-{4-[2-(2-hydroxyethylamino)-2-oxoethoxy]phenyl}-1-propylxanthine] in radioligand binding studies. [ 3H]PSB-298 showed saturable and reversible binding. It exhibited a K D value of 60 ± 1 nM and limited capacity (B max = 3.511 fmol per milligram protein) at recombinant human adenosine A 2B receptors expressed in human embryonic kidney cells (HEK-293). The addition of sodium chloride (100 mM) led to a threefold increase in the number of binding sites recognized by the radioligand. The curve of the agonist 5′-N-ethylcarboxamidoadenosine (NECA) was shifted to the right in the presence of NaCl, while the curve of the antagonist PSB-298 was shifted to the left, indicating that PSB-298 may be an inverse agonist at A 2B receptors. Adenosine A 2B receptors were shown to be the major adenosine A 2 receptor subtype on the mouse neuroblastoma x rat glioma hybrid cell line NG108-15 cells. Binding studies at rat INS-1 cells (insulin secreting cell line) demonstrated that [ 3H]PSB-298 is a selective radioligand for adenosine A 2B binding sites in this cell line. 相似文献
10.
Caffeine, a stimulant largely consumed around the world, is a non-selective adenosine receptor antagonist, and therefore caffeine actions at synapses usually, but not always, mirror those of adenosine. Importantly, different adenosine receptors with opposing regulatory actions co-exist at synapses. Through both inhibitory and excitatory high-affinity receptors (A1R and A2R, respectively), adenosine affects NMDA receptor (NMDAR) function at the hippocampus, but surprisingly, there is a lack of knowledge on the effects of caffeine upon this ionotropic glutamatergic receptor deeply involved in both positive (plasticity) and negative (excitotoxicity) synaptic actions. We thus aimed to elucidate the effects of caffeine upon NMDAR-mediated excitatory post-synaptic currents (NMDAR-EPSCs), and its implications upon neuronal Ca2+ homeostasis. We found that caffeine (30–200 μM) facilitates NMDAR-EPSCs on pyramidal CA1 neurons from Balbc/ByJ male mice, an action mimicked, as well as occluded, by 1,3-dipropyl-cyclopentylxantine (DPCPX, 50 nM), thus likely mediated by blockade of inhibitory A1Rs. This action of caffeine cannot be attributed to a pre-synaptic facilitation of transmission because caffeine even increased paired-pulse facilitation of NMDA-EPSCs, indicative of an inhibition of neurotransmitter release. Adenosine A2ARs are involved in this likely pre-synaptic action since the effect of caffeine was mimicked by the A2AR antagonist, SCH58261 (50 nM). Furthermore, caffeine increased the frequency of Ca2+ transients in neuronal cell culture, an action mimicked by the A1R antagonist, DPCPX, and prevented by NMDAR blockade with AP5 (50 μM). Altogether, these results show for the first time an influence of caffeine on NMDA receptor activity at the hippocampus, with impact in neuronal Ca2+ homeostasis. 相似文献
11.
A 2A adenosine receptor (A 2AR), P2Y 1 receptor (P2Y 1R) and P2Y 12 receptor (P2Y 12R) are predominantly expressed on human platelets. The individual role of each of these receptors in platelet aggregation has been actively reported. Previously, hetero-oligomerization between these three receptors has been shown to occur. Here, we show that Ca 2+ signaling evoked by the P2Y 1R agonist, 2-methylthioladenosine 5’ diphosphate (2MeSADP) was significantly inhibited by the A 2AR antagonist (ZM241385 and SCH442416) and the P2Y 12R antagonist (ARC69931MX) using HEK293T cells expressing the three receptors. It was confirmed that inhibition of P2Y 1R signaling by A 2AR and P2Y 12R antagonists was indeed mediated through A 2AR and P2Y 12R using 1321N1 human astrocytoma cells which do not express P2Y receptors. We expect that intermolecular signal transduction and specific conformational changes occur among components of hetero-oligomers formed by these three receptors. 相似文献
12.
In view of the co-distribution of dopamine D 2LR and 5-hydroxytryptamine 5-HT 2A receptors (D 2LR and 5-HT 2AR, 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 D 2LR-5-HT 2AR 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 D 2LR and the 5-HT 2AR form stable and specific heteromers when expressed in HEK293T mammalian cells. Furthermore, when the D 2LR-5-HT 2AR heteromeric signaling was analyzed we found that the 5-HT 2AR-mediated phospholipase C (PLC) activation was synergistically enhanced by the concomitant activation of the D 2LR 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 D 2LR-mediated adenylyl cyclase (AC) inhibition was assayed we showed that costimulation of D 2LR and 5-HT 2AR within the heteromer led to inhibition of the D 2LR functioning, thus suggesting the existence of a 5-HT 2AR-mediated D 2LR 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 D 2R-5-HT 2AR may be involved in the receptor interface. Overall, the presence of the D 2LR-5-HT 2AR heteromer in discrete brain regions is postulated based on the existence of D 2LR-5-HT 2A 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
13.
Benign prostatic hypertrophy has been related with glandular ischemia processes and adenosine is a potent vasodilator agent. This study investigates the mechanisms underlying the adenosine-induced vasorelaxation in pig prostatic small arteries. Adenosine receptors expression was determined by Western blot and immunohistochemistry, and rings were mounted in myographs for isometric force recording. A 2A and A 3 receptor expression was observed in the arterial wall and A 2A-immunoreactivity was identified in the adventitia–media junction and endothelium. A 1 and A 2B receptor expression was not obtained. On noradrenaline-precontracted rings, P1 receptor agonists produced concentration-dependent relaxations with the following order of potency: 5′- N-ethylcarboxamidoadenosine (NECA) = {"type":"entrez-protein","attrs":{"text":"CGS21680","term_id":"878113053","term_text":"CGS21680"}}CGS21680 > 2-Cl-IB-MECA = 2-Cl-cyclopentyladenosine = adenosine. Adenosine reuptake inhibition potentiated both NECA and adenosine relaxations. Endothelium removal and ZM241385, an A 2A antagonist, reduced NECA relaxations that were not modified by A 1, A 2B, and A 3 receptor antagonists. Neuronal voltage-gated Ca 2+ channels and nitric oxide (NO) synthase blockade, and adenylyl cyclase activation enhanced these responses, which were reduced by protein kinase A inhibition and by blockade of the intermediate (IK Ca)- and small (SK Ca)-conductance Ca 2+-activated K + channels. Inhibition of cyclooxygenase (COX), large-conductance Ca 2+-activated-, ATP-dependent-, and voltage-gated-K + channel failed to modify these responses. These results suggest that adenosine induces endothelium-dependent relaxations in the pig prostatic arteries via A 2A purinoceptors. The adenosine vasorelaxation, which is prejunctionally modulated, is produced via NO- and COX-independent mechanisms that involve activation of IK Ca and SK Ca channels and stimulation of adenylyl cyclase. Endothelium-derived NO playing a regulatory role under conditions in which EDHF is non-functional is also suggested. Adenosine-induced vasodilatation could be useful to prevent prostatic ischemia. 相似文献
14.
We tested a panel of naturally occurring nucleosides for their affinity towards adenosine receptors. Both N
6-(2-isopentenyl)adenosine (IPA) and racemic zeatin riboside were shown to be selective human adenosine A 3 receptor (hA 3R) ligands with affinities in the high nanomolar range ( K
i values of 159 and 649 nM, respectively). These values were comparable to the observed K
i value of adenosine on hA 3R, which was 847 nM in the same radioligand binding assay. IPA also bound with micromolar affinity to the rat A 3R. In a functional assay in Chinese hamster ovary cells transfected with hA 3R, IPA and zeatin riboside inhibited forskolin-induced cAMP formation at micromolar potencies. The effect of IPA could be
blocked by the A 3R antagonist VUF5574. Both IPA and reference A 3R agonist 2-chloro- N
6-(3-iodobenzyl)adenosine-5′- N-methylcarboxamide (Cl-IB-MECA) have known antitumor effects. We demonstrated strong and highly similar antiproliferative
effects of IPA and Cl-IB-MECA on human and rat tumor cell lines LNCaP and N1S1. Importantly, the antiproliferative effect
of low concentrations of IPA on LNCaP cells could be fully blocked by the selective A 3R antagonist MRS1523. At higher concentrations, IPA appeared to inhibit cell growth by an A 3R-independent mechanism, as was previously reported for other A 3R agonists. We used HPLC to investigate the presence of endogenous IPA in rat muscle tissue, but we could not detect the compound.
In conclusion, the antiproliferative effects of the naturally occurring nucleoside IPA are at least in part mediated by the
A 3R. 相似文献
15.
Adenosine A 2A receptor (A 2AR) is a G protein-coupled receptor enriched in the striatum for which an increased expression has been demonstrated in certain neurological diseases. Interestingly, previous in vitro studies demonstrated that A 2AR expression levels are reduced after treatment with S-adenosyl-L-methionine (SAM), a methyl donor molecule involved in the methylation of important biological structures such as DNA, proteins, and lipids. However, the in vivo effects of SAM treatment on A 2AR expression are still obscure. Here, we demonstrated that 2 weeks of SAM treatment produced a significant reduction in the rat striatal A 2AR messenger RNA (mRNA) and protein content as well as A 2AR-mediated signaling. Furthermore, when the content of 5-methylcytosine levels in the 5′UTR region of ADORA2A was analyzed, this was significantly increased in the striatum of SAM-treated animals; thus, an unambiguous correlation between SAM-mediated methylation and striatal A 2AR expression could be established. Overall, we concluded that striatal A 2AR functionality can be controlled by SAM treatment, an issue that might be relevant for the management of these neurological conditions that course with increased A 2AR expression. 相似文献
16.
Extracellular adenosine activates P1 receptors (A 1, A 2A, A 2B, A 3) on cellular membranes. Here, we investigated the involvement of P1 receptor-mediated signaling in differentiation to regulatory T cells (Treg). Treg were induced in vitro by incubating isolated CD4 +CD62L + naïve murine T cells under Treg-skewing conditions. Antagonists of A 1 and A 2B receptors suppressed the expression of Foxp3, a specific marker of Treg, and the production of IL-10, suggesting the involvement of A 1 and A 2B receptors in differentiation to Treg. We also investigated the effect of these antagonists on T cell activation, which is essential for differentiation to Treg, and found that A 1 antagonist, but not A 2B antagonist, suppressed T cell activation. We conclude that A 1 and A 2B receptors are both involved in differentiation to Treg, but through different mechanisms. Since A 2B antagonist blocked differentiation to Treg without suppressing T cell activation, it is possible that blockade of A 2B receptor would facilitate tumor immunity. 相似文献
17.
Subchronic treatment with MAP (4.6 mg/kg, i.p., once daily for 11 days) significantly decreased the K d, but not B max, values of [ 3H]1,3-dipropyl-8-cyclopentylxanthine ([ 3H]DPCPX) binding to adenosine A 1 receptors in the prefrontal cortex and hippocampus, but not striatum, of rat brain. However, subchronic treatment with PCP (10 mg/kg, i.p., once daily for 11 days) did not alter the K d and B max values of [ 3H]DPCPX binding to adenosine A 1 receptors in these three regions. Subchronic treatment with MAP or PCP did not alter the B max and K d values of [ 3H]2-p-(2-carboxyehyl)phenethylamino-5-N-ethylcarboxyamidoadenosine ([ 3H]CGS21680) binding to adenosine A 2A receptors in the striatum. Furthermore, subchronic treatment with MAP or PCP significantly decreased the specific binding of [ 3H]CGS21680 to adenosine A 2A receptors in the hippocampus, but not in the prefrontal cortex. Thus, these results suggest that MAP and PCP may produce differential effects on the adenosine A 2A receptors, but not adenosine A 1 receptors in rat brain. 相似文献
18.
Endothelin-1 (ET-1) is the most potent vasoconstrictor by binding to endothelin receptors (ET AR) in vascular smooth muscle cells (VSMCs). The complex of angiotensin II (Ang II) and Ang II type one receptor (AT 1R) acts as a transient constrictor of VSMCs. The synergistic effect of ET-1 and Ang II on blood pressure has been observed in rats; however, the underlying mechanism remains unclear. We hypothesize that Ang II leads to enhancing ET-1-mediated vasoconstriction through the activation of endothelin receptor in VSMCs. The ET-1-induced vasoconstriction, ET-1 binding, and endothelin receptor expression were explored in the isolated endothelium-denuded aortae and A-10 VSMCs. Ang II pretreatment enhanced ET-1-induced vasoconstriction and ET-1 binding to the aorta. Ang II enhanced ET AR expression, but not ET BR, in aorta and increased ET-1 binding, mainly to ET AR in A-10 VSMCs. Moreover, Ang II-enhanced ET AR expression was blunted and ET-1 binding was reduced by AT 1R antagonism or by inhibitors of PKC or ERK individually. In conclusion, Ang II enhances ET-1-induced vasoconstriction by upregulating ET AR expression and ET-1/ET AR binding, which may be because of the AngII/Ang II receptor pathways and the activation of PKC or ERK. These findings suggest the synergistic effect of Ang II and ET-1 on the pathogenic development of hypertension. 相似文献
19.
Serotonin modulates agonistic and reproductive behavior across vertebrate species. 5HT 1A and 5HT 1B receptors mediate many serotonergic effects on social behavior, but other receptors, including 5HT 2 receptors, may also contribute. We investigated serotonergic regulation of electrocommunication signals in the weakly electric fish Apteronotus leptorhynchus. During social interactions, these fish modulate their electric organ discharges (EODs) to produce signals known as chirps. Males chirp more than females and produce two chirp types. Males produce high-frequency chirps as courtship signals; whereas both sexes produce low-frequency chirps during same-sex interactions. Serotonergic innervation of the prepacemaker nucleus, which controls chirping, is more robust in females than males. Serotonin inhibits chirping and may contribute to sexual dimorphism and individual variation in chirping. We elicited chirps with EOD playbacks and pharmacologically manipulated serotonin receptors to determine which receptors regulated chirping. We also asked whether serotonin receptor activation generally modulated chirping or more specifically targeted particular chirp types. Agonists and antagonists of 5HT 1B/1D receptors (CP-94253 and GR-125743) did not affect chirping. The 5HT 1A receptor agonist 8OH-DPAT specifically increased production of high-frequency chirps. The 5HT 2 receptor agonist DOI decreased chirping. Receptor antagonists (WAY-100635 and MDL-11939) opposed the effects of their corresponding agonists. These results suggest that serotonergic inhibition of chirping may be mediated by 5HT 2 receptors, but that serotonergic activation of 5HT 1A receptors specifically increases the production of high-frequency chirps. The enhancement of chirping by 5HT 1A receptors may result from interactions with cortisol and/or arginine vasotocin, which similarly enhance chirping and are influenced by 5HT 1A activity in other systems. 相似文献
20.
Syntheses and biological activities of imidazo-, pyrimido- and diazepino[2,1- f]purinediones containing N-alkyl substituents (with straight, branched or unsaturated chains) are described. Tricyclic derivatives were synthesized by the cyclization of 8-bromo-substituted 7-(2-bromoethyl)-, 7-(3-chloropropyl)- or 7-(4-bromobutyl)-theophylline with primary amines under various conditions. Compound 22 with an ethenyl substituent was synthesized by dehydrohalogenation of 9-(2-bromoethyl)-1,3-dimethyltetrahydropyrimido[2,1- f]purinedione. The obtained derivatives (5–35) were initially evaluated for their affinity at rat A 1 and A 2A adenosine receptors (AR), showing moderate affinity for both adenosine receptor subtypes. The best ligands were diazepinopurinedione 28 ( Ki = 0.28 μM) with fivefold A 2A selectivity and the non-selective A 1/A 2A AR ligand pyrimidopurinedione 35 ( Ki A 1 = 0.28 μM and Ki A 2A = 0.30 μM). The compounds were also evaluated for their affinity at human A 1, A 2A, A 2B and A 3 ARs. All of the obtained compounds were docked to the A 2A AR X-ray structure in complex with the xanthine-based, potent adenosine receptor antagonist—XAC. The likely interactions of imidazo-, pyrimido- and diazepino[2,1- f]purinediones with the residues forming the A 2A binding pocket were discussed. Furthermore, the new compounds were tested in vivo as anticonvulsants in maximal electroshock, subcutaneous pentylenetetrazole (ScMet) and TOX tests in mice (i.p.). Pyrimidopurinediones showed anticonvulsant activity mainly in the ScMet test. The best derivative was compound 11, showing 100 % protection at a dose of 100 mg/kg without symptoms of neurotoxicity. Compounds 6, 7, 8 and 14 with short substituents showed neurotoxicity and caused death. In rat tests (p.o.), 9 was characterized by a high protection index (>13.3). AR affinity did not apparently correlate with the antiepileptic potency of the compounds. Electronic supplementary materialThe online version of this article (doi:10.1007/s11302-013-9358-3) contains supplementary material, which is available to authorized users. 相似文献
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