有机阳离子转运体的基因多态性研究进展

人体的肝脏、肾脏和肠道上广泛分布有各种转运蛋白,其中有机阳离子转运体（OCTs）负责转运一些内、外源性的有机阳离子的转运。在此我们主要讨论的是OCTs家族的成员OCT1和OCT2的基因多态性以及其功能意义。同时我们也就OCT对于药物代谢动力学以及药效学的影响进行阐述,以及OCTs在药物相互作用上的意义。     

内源性物质药物生物等效性评价的探讨

内源性物质是体内已有的物质,内源性物质药物生物等效性的评价因为体内自身物质的存在变得复杂化。文中以内源性物质和生物等效性为关键词,检索Pubmed和万方数据库,对常用的内源性物质药物的生物等效性评价方法进行了综述。     

尿苷二磷酸葡萄糖醛酸转移酶与内源性物质的相互作用

尿苷二磷酸葡萄糖醛酸转移酶(UGT)是人体重要的II相代谢酶,代谢药物的同时也代谢许多重要的内源性物质,如胆红素、甲状腺激素、雌激素、雄激素、胆汁酸和5-羟色胺等。该酶对许多内源性物质的代谢是灭活和清除这些内源性物质的关键步骤,能够防止内源性物质累积引发的毒性反应,或及时终止内源性激素的信号防止肿瘤的发生。然而,内源性物质对UGT酶也会产生影响,特别是在一些生理病理条件下,某些内源性物质能够抑制UGT酶活性,影响其参与的代谢反应。将就内源性物质和UGT酶的相互作用做一综述,以引起人们对UGT酶和内源性物质相互作用的关注。关键词:药物代谢;尿苷二磷酸葡萄糖醛酸转移酶;内源性物质     

特殊生物等效性评价方法介绍

本文我们将着重讨论一些特殊的仿制药品的生物等效性试验方法.此类药品包括代谢物具有生物活性类的药物、对映异构体、内源性物质、高变异性药物和局部作用药物等仿制药品.     

降钙素基因相关肽:一种调节预适应的内源性中介物(英文)

心脏遭受短暂缺血或高温处理后均产生早期和延迟保护效应.缺血预适应的心脏保护作用与内源性活性物质有关.辣椒素敏感的感觉神经的主要递质降钙素基因相关肽(CGRP)介导缺血预适应的早期和延迟保护作用.CGRP介导的预适应能保护内皮细胞.热应激的早期和延迟保护也与内源性CGRP释放有关.某些药物如硝酸甘油诱导的预适应可能与其促CGRP释放有关.这些结果表明CGRP可能是一种内源性心肌保护物质,并在预适应的保护效应中起重要作用.     

纳洛酮治疗重型脑外伤的临床观察

国内外研究表明颅脑损伤后血浆、脑脊液和脑区内源性阿片肽明显升高,内源性阿片肽拮抗剂纳洛酮能降低阿片样物质水平,减少继发性脑损伤,促进神经功能恢复并改善预后.我院自2003年4月来对40例重型脑外伤病例采用纳洛酮药物治疗,临床效果良好,现报道如下.     

从代谢角度探讨中药抗药源性肝损伤机制及相关效应物质

药源性肝损伤是临床常见的药物不良反应之一,且时至今日仍然是药物限制使用、研发终止和上市后警告撤市的主要原因。近年来,中药中多种化学成分及代谢产物和二者通过代谢影响的内源性效应物质因具有良好的保肝活性备受关注,但目前中药抗药源性肝损伤的机制复杂、效应物质尚不明确,且其与代谢相关的研究仍比较薄弱。因此本文从代谢的角度对药源性肝损伤的机制以及其中药治疗的机制进行综述,并首次创新性地将中药效应物质分为外源性(中药活性成分及代谢物)和内源性(肠道益生菌、内源性代谢产物)两大类,为减少药源性肝损伤发生,探索并开发有效的中药抗药源性肝损伤效应物质,并进一步研制具有肝保护作用的临床药物提供参考。     

尿苷二磷酸葡醛酸转移酶的研究进展

尿苷二磷酸葡醛酸转移酶(UGT)是体内最重要的Ⅱ相代谢酶,它可以参与许多内源性物质如胆红素、甾体激素、甲状腺激素、胆汁酸和脂溶性维生素等的代谢,在许多药物如阿片类药物、镇痛药、非甾体抗炎药和抗惊厥药等的代谢中也发挥着重要的作用。UGT在药物的吸收、分布、代谢和排泄中发挥重要作用。研究UGT特别是其基因多态性及其介导的药物-药物相互作用不仅可以指导临床用药,也可以揭示内源性物质代谢紊乱的机制。本文就UGT的分类、组织分布、对药物吸收的影响、基因多态性及其所介导的药物-药物相互作用进行综述。     

CYP2C9基因多态性与药物代谢及疾病关系研究进展

细胞色素氧化酶CYP2C9在药物和内源性物质代谢中起重要作用，其基因具有遗传多态性。这种多态性与药物代谢能力的差异和某些疾病发生有相关性。     

微小RNA对核受体调控药物代谢酶和转运体的研究现状

核受体(NRs)是一类配体依赖性转录因子超家族,通过内源性或外源性配体物质激活调控靶基因的转录。核受体在药物代谢酶和转运体的转录调控中发挥着重要的作用。微小RNA(MicroRNA)是一类内源性的具有调控功能的非编码RNA,其对核受体表达的改变可影响药物代谢酶和转运体的表达,进而影响药效、药物不良反应和药物相互作用。本文系统地综述microRNA对几种重要核受体调控药物代谢酶和转运体的影响。     

Organic cation transporters

1.?Organic cation transporters (OCTs) translocate endogenous (e.g. dopamine) and exogenous (e.g. drugs) substances of cationic nature and, therefore, play an important role in the detoxification of exogenous compounds. This review aims to furnish essential information on OCTs, with an emphasis on pharmacological aspects.

2.?Analysis of the literature on OCTs makes clear that there is a species- and organ-specific distribution of the different isoforms, which can also be differentially regulated. OCTs are responsible for the excretion and/or distribution of many drugs and also for serious tissue-specific side-effects such as cisplatin-induced nephrotoxicity. The presence of single nucleotide polymorphisms in these transporters significantly influences the response of patients to medication, as demonstrated for the antidiabetic drug metformin.

3.?A substantial amount of research has to be undertaken to clarify further the OCT structure–function relationships specifically to define the role of oligomerization on their activity and regulation, to identify intracellular interaction partners of OCTs, and to characterize their pharmacogenetic aspects.     

Organic cation transporters

1. Organic cation transporters (OCTs) translocate endogenous (e.g. dopamine) and exogenous (e.g. drugs) substances of cationic nature and, therefore, play an important role in the detoxification of exogenous compounds. This review aims to furnish essential information on OCTs, with an emphasis on pharmacological aspects. 2. Analysis of the literature on OCTs makes clear that there is a species- and organ-specific distribution of the different isoforms, which can also be differentially regulated. OCTs are responsible for the excretion and/or distribution of many drugs and also for serious tissue-specific side-effects such as cisplatin-induced nephrotoxicity. The presence of single nucleotide polymorphisms in these transporters significantly influences the response of patients to medication, as demonstrated for the antidiabetic drug metformin. 3. A substantial amount of research has to be undertaken to clarify further the OCT structure-function relationships specifically to define the role of oligomerization on their activity and regulation, to identify intracellular interaction partners of OCTs, and to characterize their pharmacogenetic aspects.     

Organic cation transporters (OCTs, MATEs), in vitro and in vivo evidence for the importance in drug therapy

Organic cation transporters (OCTs) of the solute carrier family (SLC) 22 and multidrug and toxin extrusion (MATE) transporters of the SLC47 family have been identified as uptake and efflux transporters, respectively, for xenobiotics including several clinically used drugs such as the antidiabetic agent metformin, the antiviral agent lamivudine, and the anticancer drug oxaliplatin. Expression of human OCT1 (SLC22A1) and OCT2 (SLC22A2) is highly restricted to the liver and kidney, respectively. By contrast, OCT3 (SLC22A3) is more widely distributed. MATEs (SLC47A1, SLC47A2) are predominantly expressed in human kidney. Data on in vitro studies reporting a large number of substrates and inhibitors of OCTs and MATEs are systematically summarized. Several genetic variants of human OCTs and in part of MATE1 have been reported, and some of them result in reduced in vitro transport activity corroborating data from studies with knockout mice. A comprehensive overview is given on currently known genotype-phenotype correlations for variants in OCTs and MATE1 related to protein expression, pharmacokinetics/-dynamics of transporter substrates, treatment outcome, and disease susceptibility.     

疾病状态下有机阳离子转运体对底物转运影响的研究进展

有机阳离子转运体家族是一类位于细胞膜上的功能性膜蛋白,负责转运内源性、外源性阳离子底物,在底物的吸收、分布和排泄过程中发挥着重要作用,其中肝脏、肾脏和消化道处有机阳离子转运体的作用最明显。在疾病状态下有机阳离子转运体的表达和功能会发生改变,会影响底物的体内处置过程,使底物的动力学行为及其效应发生改变。综述了肝脏疾病、肾脏疾病和消化道疾病状态下有机阳离子转运体表达和功能改变对底物体内转运的影响及其生理、药理学意义。     

The inhibitory effects of five alkaloids on the substrate transport mediated through human organic anion and cation transporters

1.?Human solute carrier transporters (SLCs) are important membrane proteins mediate the cellular transport of many endogenous and exogenous substances. Organic anion/cation transporters (OATs/OCTs) and organic anion transporting polypeptides (OATPs) are essential SLCs involved in drug influx. Drug–drug/herb interactions through competing for specific SLCs often lead to unsatisfied therapeutic outcomes and/or unwanted side effects. In this study, we comprehensively investigated the inhibitory effects of five clinically relevant alkaloids (dendrobine, matrine, oxymatrine, tryptanthrin and chelerythrine) on the substrate transport through several OATs/OCTs and OATPs.

2.?We performed transport functional assay and kinetic analysis on the HEK-293 cells over-expressing each SLC gene.

3.?Our data showed tryptanthrin significantly inhibited the transport activity of OAT3 (IC₅₀?=?0.93?±?0.22?μM, K_i?=?0.43?μM); chelerythrine acted as a potent inhibitor to the substrate transport mediated through OATP1A2 (IC₅₀?=?0.63?±?0.43?μM, K_i?=?0.60?μM), OCT1 (IC₅₀?=?13.60?±?2.81?μM) and OCT2 (IC₅₀?=10.80?±?1.16?μM).

4.?Our study suggested tryptanthrin and chelerythrine could potently impact on the drug transport via specific OATs/OCTs. Therefore, the co-administration of these alkaloids with drugs could have clinical consequences due to drug–drug/herb interactions. Precautions should be warranted in the multi-drug therapies involving these alkaloids.     

Differential pharmacological in vitro properties of organic cation transporters and regional distribution in rat brain

Organic cation transporters (OCTs) are polyspecific carriers implicated in low-affinity, corticosteroid-sensitive extraneuronal catecholamine uptake in peripheral tissues. The three main OCT subtypes, OCT1, OCT2 and OCT3, are also present in the brain, but their central role remains unclear. In the present study, we investigated by comparative in situ hybridization analysis the regional distribution of these transporters in rat brain and compared their functional properties in stably transfected HEK293 cells expressing human or rat OCTs. In rat brain, OCT2 and OCT3 mRNAs are expressed predominantly in regions located at the brain-cerebrospinal fluid border, with OCT3 mRNA expression extending to regions that belong to monoaminergic pathways such as raphe nuclei, striatum and thalamus. After normalization with MPP⁺ uptake, OCT2 and OCT3 subtypes share a similar monoamine preference profile, with higher transport efficacies for epinephrine and histamine than for the other monoamines. Interestingly, a significant level of epinephrine transport, previously only shown for rOCT2, is achieved by most OCTs subtypes. Finally, another novel finding was that OCTs are sensitive to 3,4-methylenedioxymetamphetamine (MDMA), phencyclidine (PCP), MK-801 and ketamine. Altogether, all our results suggest a functional specialization of OCT subtypes, based both on their intrinsic properties and their differential regional expression pattern in the brain.     

Expression and pharmacological profile of the human organic cation transporters hOCT1, hOCT2 and hOCT3

1. Organic cation transporters (OCTs) are involved in the elimination of monoamines and cationic xenobiotics. To examine whether some cell lines express several different OCTs, we investigated seven human cell lines for the mRNA expression pattern of the human (h) transporters hOCT1, hOCT2 and hOCT3. hOCT1 mRNA was found in all cell lines, six additionally expressed hOCT3 and only two cell lines contained all three hOCTs. 2. Among the three OCTs only for the OCT3 (also designated as 'uptake(2)' or 'extraneuronal monoamine transporter') 'selective' inhibitors are described in the literature. The affinities of the OCT3 inhibitors for the other two OCTs are largely unknown. Therefore, we compared the potencies of eight compounds as inhibitors of hOCT-mediated uptake of the organic cation [(3)H]-1-methyl-4-phenylpyridinium ([(3)H]-MPP(+)) in human embryonic kidney 293 (HEK293) cells stably expressing hOCT1, hOCT2 or hOCT3. Decynium-22 inhibited hOCT3 with 10 fold higher potency than hOCT1 and hOCT2. Corticosterone was about 100 fold more potent as inhibitor of hOCT3 than of hOCT1 or hOCT2, and O-methylisoprenaline (OMI) inhibited almost exclusively hOCT3. Progesterone and beta-Oestradiol preferentially inhibited hOCT3 and hOCT1, whereas prazosin was a potent inhibitor of hOCT1 and hOCT3. Phenoxybenzamine (PbA) inhibited with about equal apparent potency all three hOCTs, whereas the PbA derivative SKF550 ((9-fluorenyl)-N-methyl-beta-chloroethylamine) preferentially inhibited hOCT3 and hOCT2. 3. PbA reversibly inhibited hOCT1 and irreversibly hOCT2 and hOCT3; SKF550 also irreversibly inhibited hOCT3 but hOCT2 in a reversible manner. 4. These compounds enable a functional discrimination of the three hOCTs: hOCT1 is selectively inhibited by prazosin, reversibly inhibited by PbA and it is not sensitive to inhibition by SKF550 and OMI; hOCT2 is reversibly inhibited by SKF550, irreversibly by PbA and not by prazosin, beta-oestradiol and OMI, whereas hOCT3 is selectively inhibited by corticosterone, OMI and decynium22.     

Organic Cation Transporter OCTs (SLC22) and MATEs (SLC47) in the Human Kidney

In the kidney, human organic cation transporters (OCTs) and multidrug and toxin extrusion proteins (MATEs) are the major transporters for the secretion of cationic drugs into the urine. In the human kidney, OCT2 mediates the uptake of drugs from the blood at the basolateral membrane of tubular epithelial cells, and MATE1 and MATE2-K secrete drugs from cells into the lumen of proximal tubules. However, the expression of these transporters depends on the species of the animal. In the rodent kidney, OCT1 and OCT2 are expressed at the basolateral membrane, and MATE1 localizes at the brush-border membrane. Together, these transporters recognize various compounds and have overlapping, but somewhat different, substrate specificities. OCTs and MATEs can transport important drugs, such as metformin and cisplatin. Therefore, functional variation in OCTs and MATEs, including genetic polymorphisms or inter-individual variation, may seriously affect the pharmacokinetics and/or pharmacodynamics of cationic drugs. In this review, we summarize the recent findings and clinical importance of these transporters.