嘌呤P2受体的分子生物学研究进展

嘌呤P2受体家族是目前发现的最复杂的受体家族之一,在体内分布广泛,功能复杂,目前已有7种P2X受体和8种P2Y受体被克隆。P2受体的分类和研究历史非常复杂,随着分子生物技术的发展,P2受体的研究取得了明显的进展,特别是新克隆出的P2Y_(12),P2Y_(13)和P2Y_(14)受体,丰富了P2受体家族,使其结构特征、药理学特性不断被揭示。本文对P2受体的研究历史、分类方法、分子结构特征和药理学特性做一概述,并对最新报道的P2受体的相互作用以及关于P2Y_(15)受体的争论进行综述。     

嘌呤受体P2Y在免疫炎症中的功能研究进展

P2Y受体（P2YRs）是一类由胞外核苷酸活化的G蛋白偶联受体（GPCRs）,从属于嘌呤受体家族。P2Y受体的生理激动剂包括三磷酸腺苷（ATP）、二磷酸腺苷（ADP）、三磷酸尿苷（UTP）、二磷酸尿苷（UDP）,核苷酸糖和二核苷酸等。P2Y受体在机体组织内广泛表达,在免疫应答中发挥着重要作用。近年来随着研究深入,P2Y受体在炎症、癌症、心血管和神经退行性疾病中显示出作为药物靶标的巨大潜力,P2Y受体的研究对新药的进一步开发有着重要的意义。本文就P2Y受体的分类、结构,药理学特性及以P2Y受体为靶点的潜在药物等作一综述。     

嘌呤与嘧啶受体的生理学意义

在脊椎类和无脊椎类动物的多种组织中 ,嘧啶与嘌呤类物质具有广泛的特异性作用。这些化合物的重要生理学作用可归纳为短时程作用与长时程作用两种类型。其中短时程作用涉及神经信号传递、外分泌和内分泌以及免疫细胞功能的调节作用 ;长时程作用涉及个体发育和再生过程中嘧啶与嘌呤类物质对细胞生长、细胞分化、以及细胞增生过程的影响。     

嘌呤与嘧啶受体的生理学意义

在脊椎类和无脊椎类动物的多种组织中,嘧啶与嘌呤类物质具有广泛的特异性作用.这些化合物的重要生理学作用可归纳为短时程作用与长时程作用两种类型.其中短时程作用涉及神经信号传递、外分泌和内分泌以及免疫细胞功能的调节作用;长时程作用涉及个体发育和再生过程中嘧啶与嘌呤类物质对细胞生长、细胞分化、以及细胞增生过程的影响.     

新一代P2T嘌呤受体拮抗剂：ADP在动脉血栓形成中的作用

阿司匹林仅作用于凝血恶烷诱发的血小板凝集，糖蛋白Ⅱｂ／Ⅲａ抗体安全性低，而新一代Ｐ２Ｔ嘌呤受体拮抗剂可能成为更有效的抗栓药，它能有效地、选择性地阻断血小板上Ｐ２Ｔ嘌呤受体，从而消除血栓并抑制ＡＤＰ诱导的血小板凝集，且作用迅速、可逆，但维持时间短，Ｉ期临床研究与动物实验结果一致。鉴于此类药物的特点，作者通过大量体内外研究证明了内源性ＡＤＰ在血栓形成中的作用，并将进行进一步临床研究，评价该类药物的体内     

骨骼肌P2受体的功能与疾病

嘌呤和嘧啶核苷酸作用的P2受体分为G蛋白偶联型的P2Y受体和配体门控离子通道型的P2X受体。研究表明,骨骼肌细胞有多种P2X和P2Y受体亚型表达。嘌呤信号在肌肉萎缩症的肌肉再生中具有重要的作用,与肌肉萎缩症、肌腱炎等骨骼肌疾病有关,并可能为治疗与肌肉有关的疾病提供新的治疗策略。     

神经病理性疼痛的受体机制研究进展

神经病理性疼痛是一类治疗难度非常大的慢性疼痛,由于其发病机制尚未完全阐明,目前尚缺乏理想的治疗药物。以往研究显示,神经病理性疼痛与阿片受体、NMDA受体等有关,现阶段又发现多种受体参与了神经病理性疼痛的病理生理过程。该文综述了嘌呤与嘧啶受体、GABA受体、PAF受体等在神经病理性疼痛发病机制中的作用。     

离子通道型嘌呤受体P2X4在中枢神经系统中的作用及其作为神经系统疾病干预靶标的前景

ATP除了作为细胞内能量来源物质,也可充当细胞外信号分子激活离子通道型的嘌呤受体P2X受体和G蛋白偶联受体型的P2Y受体。P2X4亚型是一类在中枢神经系统(CNS)广泛表达的P2X受体,通过感受胞外ATP的刺激而参与CNS生理过程,包括慢性痛、乙醇滥用、癫痫、阿尔茨海默病、帕金森病和卒中缺血等。因此,靶向P2X4受体的小分子拮抗剂或增强剂因为其药用前景而受到广泛关注。本文总结了P2X4受体在CNS中相关研究的进展情况,概述了近年来新发现的P2X4受体高选择性拮抗剂。     

功能性P2X1样受体在离体兔动脉的分布

目的:研究功能性P2X_1-like受体在兔6种动脉平滑肌的分布.方法:观察兔离体肾动脉(Re)、股动脉(Fe)、隐动脉(Sa)、肠系膜动脉(Me)、脾动脉(Sp)和耳动脉(Ea)环的收缩反应.结果:NA的最大收缩反应(E_(max·NA))值为Re>Fe>Sa>Me=SP>Ea;经氯化钾最大收缩反应(E_(max·KCl))标准化后,NA的标准化最大收缩反应(E_(max·NA)/E_(max·KCl))值,在 6种血管基本一致.α,β-Methylene ATP最大收缩反应(E_(max·α,β-meATP))值为 Re>Sa=Fe>Ea=Sp=Me;经E_(max·KCL)标准化后,α,β-methylene ATP的标准化最大收缩反应(E_(max·α,β-meATP)/E_(max·KCl))数值各血管仍不同,Fe相似文献   

Characterization and expression of ATP P2X4 receptor from embryonic chick skeletal muscle

Previous pharmacological experiments have indicated the existence of ATP P2X receptors in chick embryonic skeletal muscles. In this study we cloned a P2X₄‐like cDNA encoding a protein of 385 amino acids, which shares 75% and 76% identity with rat and human P2X₄ receptors, respectively. Functional studies of this cP2X₄ receptor expressed in Xenopus oocytes showed that ATP induced a fast inward current, which was partially desensitized upon prolonged application of ATP. The ATP‐induced currents were concentration‐dependent, with an EC₅₀ of 9.5 μM. Adenosine 5′‐O‐(thio)triphosphate and 2‐methylthioATP very weak agonists. α,β‐methyleneATP was almost inactive. In contrast to their potentiating effects on recombinant rat P2X₄ receptors, both suramin and pyridoxalphosphate‐6‐azophenyl‐2′,4′‐disulfonic acid partially blocked ATP‐induced currents. TrinitrophenylATP was able to block ATP‐induced response completely, with an IC₅₀ of 4.7 μM. Northern blot and RT‐PCR analysis showed that cP2X₄ mRNAs were mainly expressed in skeletal muscle, brain, and gizzard of day 10 chick embryos. Lower levels of expression were also detected in liver, heart, and retina. Whole‐mount in situ hybridization showed that cP2X₄ mRNAs were expressed in the brain, spinal cord, notochord, gizzard, and skeletal muscle. The physiological functions of cP2X₄ receptors in embryonic skeletal muscle remain unclear at present. Drug Dev. Res. 53:22–28, 2001. © 2001 Wiley‐Liss, Inc.     

Actions of a series of PPADS analogs at P2X1 and P2X3 receptors

Seven PPADS ( P yridoxal‐5′‐ P hosphate 6‐ A zophenyl 2′,4′‐ D i S ulfonate) analogs were investigated at Group 1 P2X receptors expressed in Xenopus oocytes. All seven analogs potently inhibited P2X₁ (IC₅₀ range, 5–32 nM) and P2X₃ (IC₅₀ range, 22–345 nM), the two Group I P2X receptor subtypes. Analogs showed greater inhibitory activity where the pyridoxal moiety of PPADS contained a 5′‐phosphonate group, rather than a 5′‐phosphate group. Analogs also showed greater potency where disulfonate groups were removed from, or substituted at, the azophenyl moiety. The most active analog was MRS 2257 (pyridoxal‐5′‐phosphonate 6‐azophenyl 3′,5′‐bismethylenephosphonate) at P2X₁ (IC₅₀, 5 nM) and P2X₃ (IC₅₀, 22 nM) receptors, being 14‐fold and 10‐fold more potent than PPADS itself. MRS 2257 produced a nonsurmountable inhibition when tested against a range of ATP concentrations, although blockade was reversed by about 85% after 20 minutes of washout. TNP‐ATP and Ip₅I were equipotent with MRS 2257 at P2X₁ receptors, whereas TNP‐ATP was 64‐fold more potent than MRS 2257 at P2X₃ receptors. In conclusion, the PPADS template can be altered at the pyridoxal and phenyl moieties to produce P2X₁ and P2X₃ receptor antagonists showing higher potency and greater degree of reversibility than the parent compound at these Group I P2X receptors. Drug Dev. Res. 53:281–291, 2001. © 2001 Wiley‐Liss, Inc.     

P2 receptor: Subclassification and structure-activity relationships

Structure-activity relationships (SAR) at P2 receptors that support their subclassification into at least five nucleotide receptor subtypes, P_2Z, P_2T, P_2Y, P_2U, and P_2X, are reviewed. The P_2Z receptor is the most sensitive to alterations to ATP. The adenine base, D-ribose sugar, and 5′-triphosphate chain are absolute requirements, but substitutions are tolerated at the C-2 position and replacement by sulphur of an ionized phosphate oxygen leads to enhanced potency. The P_2T receptor, where ADP is the only endogenous agonist, has an absolute requirement for the adenine base, D-ribose sugar, and a 5′-diphosphate chain. C-2 substitution and replacement by sulphur of an ionized oxygen is tolerated. Many analogs of AMP and of ATP are antagonists. The P_2Y receptor requires an adenine base, D-ribose, and a 5′-polyphosphate for maximal potency only. C-2 substitution, and replacement of an ionized oxygen by sulphur, can enhance potency. Methylenephosphonate potencies depend on the position of the methylene group. ADP-β-F is a specific agonist. The P_2X receptor is least sensitive to alterations to ATP. There is no requirement for and adenine base, D-ribose sugar, or triphosphate chain. Methylenephosphonates and some phosphorothioates have enhanced potencies. L-AMP-PCP is a specific agonist. Evidence from SAR for a P_2U subtype is reviewed. SAR studies are complicated by the presence of ectonucleotidases. The overall subclassification of P2 receptors is inadequate and awaits the availability of selective competitive antagonists. © 1993 Wiley-Liss, Inc.     

Molecular physiology of P2 receptors in the central nervous system

Neurons of the central nervous system (CNS) are endowed with ATP-sensitive receptors belonging to the P2X (ligand-gated cationic channels) and P2Y (G protein-coupled receptors) types. Whereas a number of P2X receptors mediate fast synaptic responses to the transmitter ATP, P2Y receptors mediate either slow changes of the membrane potential in response to non-synaptically released ATP or the interaction with receptors for other transmitters. To date seven P2X and seven P2Y receptors of human origin have been molecularly identified and functionally characterized. P2X subunits may occur as homooligomers or as heterooligomeric assemblies of more than one subunit. P2X(7) subunits do not form heterooligomeric assemblies and are unique in mediating apoptosis and necrosis of glial cells and possibly also of neurons. The P2X(2), P2X(4), P2X(4)/P2X(6) and P2Y(1) receptors appear to be the predominant neuronal types. The localisation of these receptors may be at the somato-dendritic region (postsynaptic) or at the nerve terminals (presynaptic). Postsynaptic P2 receptors appear to be mostly excitatory, while presynaptic P2 receptors may be either excitatory (P2X) or inhibitory (P2Y). Since in the CNS the stimulation of a single neuron may activate multiple networks, a concomitant stimulation of facilitatory and inhibitory circuits as a result of ATP release is also possible. Finally, the enzymatic degradation of ATP may lead to the local generation of adenosine which can modulate via A(1) or A(2A) receptor-activation the ATP effect.     

Identification of P2X receptors in cultured mouse and rat parasympathetic otic ganglion neurones including P2X knockout studies

We have used patch-clamp recording from cultured neurones, immunohistochemistry and gene deletion techniques to characterize the P2X receptors present in mouse otic ganglion neurones, and demonstrated the presence of similar receptors in rat neurones. All neurones from wild-type (WT) mice responded to ATP (EC(50) 109 microM), but only 38% also responded to alpha beta-meATP (EC(50) 39 microM). The response to alpha beta-meATP was blocked by TNP-ATP with an IC(50) of 38.6 nM. Lowering extracellular pH and co-application of Zn(2+) potentiated responses to ATP and alpha beta-meATP. In P2X(3)(-/-) mouse otic ganglion, all neurones tested responded to 100 microM ATP with a sustained current, but none responded to alpha beta-meATP. In P2X(2)(-/-) mice, no sustained currents were observed, but 36% of neurones responded to both ATP and alpha beta-meATP with transient currents. In P2X(2)/P2X(3)(Dbl-/-) mice, no responses to ATP or alpha beta-meATP were detected, suggesting that other P2X subunits were not involved. In rat otic ganglia, 96% of neurones responded to both ATP and alpha beta-meATP with sustained currents, suggesting a greater proportion of neurones expressing P2X(2/3) receptors. The maximum response to alpha beta-meATP was 40-60% of that evoked by ATP in the same cell. Immunohistochemistry revealed staining for P2X(2) and P2X(3) subunits in WT mouse otic ganglion neurones, which was absent in knockout animals. In conclusion, we have shown for the first time that at least two distinct P2X receptors are present in mouse and rat otic neurones, probably homomeric P2X(2) and heteromeric P2X(2/3) receptors.     

Purinoceptor-mediated contractility of the perfused uterine vasculature of the guinea-pig: influence of oestradiol and pregnancy

1. The effects of ATP, the stable ATP analogues alpha,beta-methylene ATP (alpha,beta-mATP), 2-methylthioATP (2meSATP) and adenosine tetraphosphate (ATP4), the pyrimidine nucleotide uridine 5'-triphosphate (UTP) and the alpha1-adrenoceptor agonist phenylephrine were examined on the isolated perfused uterine vasculature of dioestrous, oestradiol-treated, dexamethasone-treated and late-pregnant guinea-pigs. 2. The alpha1-adrenoceptor agonist phenylephrine elicited concentration-dependent vasoconstriction from preparations of perfused uterine vasculature from dioestrous, estradiol-treated and late-pregnant guinea-pigs. The mean maximal response to phenylephrine was unaffected by treatment of dioestrus guinea-pigs with oestradiol or dexamethasone, but was reduced in preparations from late-pregnant animals. 3. In perfused uterine arteries from dioestrous animals, the pyrimidine UTP, but not ATP4 and ATP, elicited vasoconstrictor responses. In preparations from oestradiol-treated animals, all three agonists elicited vasoconstriction, with a rank order of potency of ATP4 = UTP > ATP, whereas in preparations from late-pregnant animals this order of potency was ATP4 > UTP = ATP. In preparations from dexamethasone-treated animals, the vasoconstriction was similar to that seen in dioestrous animals. Vasoconstrictor responses to ATP4 were significantly greater in preparations of uterine vasculature from oestradiol-treated and pregnant animals than in preparations from dioestrous animals or dexamethasone-treated animals. 4. In preparations from dioestrous, oestradiol-treated, pregnant and dexamethasone-treated animals, alpha,beta-mATP was approximately two to three orders of magnitude more potent than 2meSATP. Compared with preparations from dioestrous animals, the maximal responses to alpha,beta-mATP were significantly greater in tissues from oestradiol-treated and pregnant animals. In preparations from dioestrous animals, the P2 purinoceptor antagonist suramin (100 micro mol/L) inhibited the responses to alpha,beta-mATP, but not those to ATP4. 5. The present study has demonstrated that pregnancy, but not the steroid treatment of dioestrous guinea-pigs with oestradiol or dexamethasone, reduces the sensitivity of the guinea-pig isolated perfused uterine vasculature to phenylephrine. In contrast, preparations from pregnant or oestradiol-treated guinea-pigs respond to ATP4 and to alpha,beta-mATP with significantly greater constrictions than those of dioestrous or dexamethasone-treated animals. These data indicate that the sensitivity of the uterine vasculature to adrenoceptor and purinoceptor agonists is differentially regulated by oestradiol and pregnancy, but not by the synthetic glucocorticoid dexamethasone.     

内吗啡肽研究进展

1997年发现的内吗啡肽 (Endomorphins、EMs) ,结构上属于四肽 ,被认为是 μ阿片受体 (MOR)的内源性配基 ,它通过与G蛋白偶联的MOR受体结合介导许多生理活动 ,本文结合本实验室对内吗啡肽的研究 ,对其神经系统分布、受体结合特性、生理作用、构象及构效关系等方面进行介绍