栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制研究

目的探讨栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制。方法连续7d灌胃给予氧嗪酸钾盐诱导小鼠高尿酸血症,对比各组血清尿酸水平和24h尿酸排泄量,检测肝脏黄嘌呤氧化酶（XOD）的活性和肾脏尿酸转运体（mURAT1、mGLUT9、mOAT1）的mRNA和蛋白表达水平。结果栀子苷可显著降低高尿酸血症小鼠血清尿酸水平并升高24h尿酸排泄量,同时可抑制肝脏XOD活性,调节肾脏尿酸转运体的表达。结论栀子苷对氧嗪酸钾盐致小鼠高尿酸血症具有明显的改善作用,其作用机制可能是通过抑制XOD活性和调节尿酸转运体的表达水平实现。     

萆薢降酸方对高尿酸血症小鼠模型的药效作用及其对肾脏尿酸盐转运体表达的影响

目的 研究萆薢降酸方提取物对高尿酸血症小鼠的抗高尿酸血症药效作用及其对肾脏蛋白的转运机制。方法 采用氧嗪酸钾致高尿酸血症小鼠模型,观察萆薢降酸方提取物对高尿酸血症小鼠的影响。以220、440、880mg/kg的剂量,连续10 d,以别嘌醇(5mg/kg)为阳性对照。采用比色法测定血清、尿酸、肌酐水平。同时用Western blot法分析肾脏尿酸盐转运蛋白1(URAT1)和阴离子转运蛋白1(OAT1)的蛋白质水平。结果 与模型组比较,高剂量萆薢降酸方可抑制血清中黄嘌呤氧化酶(XOD)活性(18.12±1.33u/L)和肝脏活性蛋白(70.15±5.20u/g)(P<0.05),降低血清尿酸(2.04±0.64mg/L)(P<0.05)和血清肌酐(0.35±0.18mol/L)尿素氮(8.83±0.71mmol/L)(P<0.05);升高尿酸(38.34±8.23mg/L)和尿肌酐(34.38±1.98mmol/L)水平,URAT1表达水平下调,OAT1表达水平上调(P<0.05)。结论 萆薢降酸方可能通过上调OAT1蛋白表达促进尿酸排泄、下调URAT1蛋白表达抑制尿酸重吸收的双重调节功能来促进尿酸在肾脏中的排泄。     

苦参及苦参碱对小鼠肝脏和神经行为学的影响

目的 观察苦参及苦参碱对小鼠肝脏毒性及神经行为学功能的影响。方法 50只ICR小鼠随机分为空白组、苦参1.5,15 g·kg^-1剂量组,苦参碱10,40 mg·kg^-1剂量组,每天给药1次,连续灌胃60 d;首次给药前和末次给药后测定小鼠自主活动及爬竿法平衡协调能力,末次给药后,测定小鼠体质量、血清丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)、碱性磷酸酶(AKP)水平及肝组织SOD活性和MDA含量。结果 与空白组相比,给药组小鼠体质量降低、自主活动数减少,平衡协调能力下降;各给药组AST、ALT、AKP活性均有差异,其中苦参1.5 g·kg^-1,苦参碱10,40 mg·kg^-1组AST、ALT、AKP活性有显著性差异(P<0.05或P<0.01);肝组织SOD活性无明显变化,MDA含量显著上升。结论 小鼠连续灌胃苦参及苦参碱可引起肝脏毒性和神经行为学的改变。     

别嘌醇改善果糖诱导的大鼠高尿酸血症与调节肠道葡萄糖转运子表达的关系研究

目的观察别嘌醇和苯溴马隆对高果糖饮水诱导的高尿酸血症(hyperuricemia,HUA)大鼠血尿酸水平、肝脏黄嘌呤氧化酶活性以及肠道果糖转运子(glucose transporter,GLUT)2和5表达的影响。方法 Wistar大鼠连续饮用10%果糖水8周以制备高尿酸血症大鼠模型,其中从第5周开始分别给予大鼠灌胃5 mg·kg~(-1)别嘌醇或10 mg·kg~(-1)苯溴马隆,共4周。磷钨酸法检测大鼠血尿酸水平,比色法检测肝脏XOD活性,Western blot法和免疫组化染色法检测肠道GLUT2和GLUT5的表达。结果别嘌醇明显降低果糖诱导的HUA大鼠血尿酸水平(P<0.01)和肝脏XOD活性(P<0.01),减少了HUA大鼠肠道GLUT5的表达(P<0.01),但对肠道GLUT2的表达无明显影响。与此同时,苯溴马隆也明显降低了果糖诱导的HUA大鼠血尿酸水平(P<0.01),但对HUA大鼠肝脏XOD活性、肠道GLUT2和GLUT5的表达均无明显影响。结论别嘌醇可明显降低果糖诱导的HUA大鼠血尿酸水平,其机制与抑制肝脏XOD活性以减少尿酸产生,抑制GLUT5表达以减少肠道果糖转运吸收,最终减少果糖代谢产生尿酸相关。     

车前子醇提物与毛蕊花糖苷对实验性高尿酸血症小鼠的比较研究

目的比较毛蕊花糖苷及含相同量毛蕊花糖苷的车前子醇提物对小鼠急性高尿酸血症血尿酸水平的影响,探讨车前子降尿酸主要物质基础。方法将90只小鼠随机分为空白组、高尿酸血症模型组、别嘌醇(10 mg·kg~(-1))组,车前子低、中、高剂量组,毛蕊花糖苷低、中、高剂量组,每组10只,以不同剂量车前子醇提物(4.2、8.4、16.8 g·kg~(-1))及毛蕊花糖苷(0.05、0.10、0.20 g·kg~(-1))连续灌胃7 d,于最后1次给药前1 h采用氧嗪酸钾盐诱导高尿酸血症模型。检测血清尿酸、肌酐(CRE)和尿素氮(BUN)含量及肝脏黄嘌呤氧化酶(XOD)活性,RT-PCR法测定肾脏尿酸转运体mURAT1、m GLUT9、mOAT1mRNA表达。结果与车前子醇提物相比,相同生药量毛蕊花糖苷降尿酸率达到车前子醇提物的67.8%~85.2%;两者均可抑制肝脏XOD活性(P<0.01或P<0.05),相同生药量毛蕊花糖苷对XOD的抑制等效率达车前子醇提物的66.1%~82.2%;两者均可下调肾脏尿酸mURAT1及m GLUT9 mRNA的表达(P<0.05或P<0.01),相同生药量毛蕊花糖苷对肾mURAT1及m GLUT9 mRNA表达下调等效率分别达车前子醇提物的57.7%~83.2%与56.0%~76.2%;且车前子醇提物可上调肾脏mOAT1 mRNA的表达(P<0.05或P<0.01),但毛蕊花糖苷则对肾脏mOAT1 mRNA不具备上调功能(P>0.05);另外,两者均可降低高尿酸血症小鼠血清CRE及BUN水平(P<0.05或P<0.01),相同生药量毛蕊花糖苷对高尿酸血症小鼠血清CRE及BUN清除等效率分别达车前子醇提物的80.0%~87.5%和59.9%~70.9%。结论毛蕊花糖苷为车前子降尿酸主要物质基础,具有与车前子醇提物相似但不完全相同的降尿酸机制,可做为车前子降尿酸药物开发及质量控制的主要依据。     

黄嘌呤氧化酶抑制剂筛选体系的建立

目的建立黄嘌呤氧化酶(xanthine oxidase, XOD)抑制剂筛选体系。方法应用理化法,测定体外XOD活性、血尿酸、血清XOD活性、组织XOD活性及肝肾功能有关血液指标;病理分析肝脏肾脏的损伤情况。结果选择牛奶来源XOD 3 U·L~(-1),黄嘌呤(Xanthine, XA) 50μmol·L~(-1),37℃,pH 7.4, 20 min为XOD抑制剂体外高通量筛选的最适条件。单次灌胃次黄嘌呤联合皮下注射氧嗪酸钾诱导ICR小鼠,血尿酸水平一过性升高;以血尿酸变化曲线和血尿酸-时间曲线下面积评价急性高尿酸血症小鼠模型。ICR小鼠连续皮下注射氧嗪酸钾血尿酸平稳升高,成模率约70%;以血尿酸水平评价慢性高尿酸血症小鼠模型。上述2种模型动物的血清和组织XOD活性均未见明显变化,肝脏肾脏均未见明显损伤。结论 XOD抑制剂体外筛选方法与急性高尿酸血症小鼠模型、慢性高尿酸血症小鼠模型等体内实验方法相互验证,形成基于分子靶点XOD的抗高尿酸血症药物研发的实验体系。     

基于UHPLC-HRMS血清代谢组学研究黄芪发酵菌质干预高尿酸血症的作用机制

目的 基于UHPLC-HRMS血清代谢组学研究黄芪发酵菌质对高尿酸血症模型大鼠血清内源性代谢产物的影响及机制。方法 将SD大鼠随机分为空白组、模型组、苯溴马隆组(20 mg·kg^-1)和黄芪发酵菌质高剂量组(3.0 g·kg^-1)、低剂量组(1.5 g·kg^-1)。模型组和各给药组均先采用大鼠灌胃300 mg·kg^-1氧嗪酸钾建立高尿酸血症模型,造模后1 h给药组给予相应药物进行干预,14 d后采集大鼠血清。利用UHPLC-HRMS对不同组别大鼠血清中的内源性代谢产物进行分析,并结合多元数据统计分析方法筛选差异代谢物和代谢通路。结果 造模14 d后高尿酸血症大鼠模型建立成功,黄芪发酵菌质显示出良好的降尿酸作用。与空白组相比,模型组发现了17个与高尿酸血症发病相关的潜在生物标志物;黄芪发酵菌质可显著回调其中10个潜在生物标志物,并主要涉及鞘脂代谢、嘧啶代谢、色氨酸代谢、泛酸和辅酶A生物合成、甘氨酸、丝氨酸和苏氨酸代谢等通路发挥降尿酸作用。结论 本研究可为揭示黄芪发酵菌质降尿酸作用机制研究提供依据,并为黄芪的深度开发利用奠定基础。     

短穗兔耳草提取物对高尿酸血症小鼠肾脏保护作用研究

目的 研究短穗兔耳草提取物对高尿酸血症小鼠肾脏有无保护作用。方法 以氧嗪酸钾盐诱导小鼠高尿酸血症模型为实验系统,通过检测血清尿酸和黄嘌呤氧化酶含量和肾脏病理病变等指标,评价短穗兔耳草提取物对高尿酸血症小鼠肾脏的保护作用。结果 短穗兔耳草可显著降低模型大鼠血清、尿酸和黄嘌呤氧化酶含量, 改善了小鼠肾脏结构的变化。结论 短穗兔耳草具有降尿酸活性及肾脏保护作用。     

摄食海参皂苷对小鼠高尿酸血症的影响

目的研究海参皂苷对酵母浸粉诱导的高尿酸血症小鼠的尿酸代谢及相关酶活性的影响。方法将24只♂昆明种小鼠随机分为正常组、模型组、皂苷低、高剂量组。采用口服酵母浸粉进行造模,连续喂饲14 d,分别测定小鼠血清尿酸(uric acid,UA)、肌酐(creatinine,Cr)、尿素氮(blood ureanitrogen,BUN)水平,以及肝脏黄嘌呤氧化酶(xanthine oxi-dase,XOD)、腺苷脱氨酶(adenosine deaminase,ADA)活性。结果喂养14 d后,海参皂苷高、低剂量组血清尿酸水平分别较对照组降低53.1%与55.6%(均P<0.01),肝脏XOD及ADA的活性明显受到抑制,XOD活性分别降低26.3%与28.6%(均P<0.01),ADA活性分别降低24.4%(P<0.05)与34.0%(P<0.01),血清肌酐与尿素氮无变化。结论海参皂苷对酵母浸粉诱导的高尿酸血症有明显的改善作用,其机制与抑制了肝脏XOD和ADA活性有关。     

痛风颗粒各部位对高尿酸血症大鼠尿酸和黄嘌呤氧化酶活性的影响

目的 通过观察痛风颗粒各部位对高尿酸血症大鼠血尿酸、尿尿酸、血黄嘌呤氧化酶活性和肝脏黄嘌呤氧化酶活性的影响,探讨其治疗痛风的物质基础和机制.方法 以腺嘌呤合乙胺丁醇法诱导大鼠高尿酸血症模型,分别用磷钨酸法和酶比色法检测尿酸和黄嘌呤氧化酶的含量.结果 黄酮类成分在降尿酸和抑制黄嘌呤氧化酶活性上均起主要作用;生物碱类成分对尿中尿酸的排泄和血清黄嘌呤氧化酶活性的抑制起较重要作用,有机酸类成分均未表现出明显作用;全方和有效部位组合有明显的降尿酸和抑制黄嘌呤氧化酶活性的作用.结论 黄酮类、生物碱和有机酸类有效部位组合后的药效与处方药一致,是该处方的有效部位群,对高尿酸血症模型大鼠表现出的降尿酸和抑制黄嘌呤氧化酶活性的作用最为显著.     

拟黑多刺蚁乙醇提取物中降低小鼠血清尿酸水平活性部位的筛选与化学成分分析

目的研究拟黑多刺蚁乙醇提取物(EEPR)中降低高尿酸血症模型小鼠血清尿酸水平的活性部位及其主要化学成分。方法昆明小鼠分别ig给予别嘌醇0.04 g.kg-1(阳性对照),EEPR 0.128,0.256和0.512 g.kg-1,EEPR的石油醚部位0.079和0.158 g.kg-1,乙酸乙酯部位0.051和0.102 g.kg-1,正丁醇部位0.052和0.104 g.kg-1和水部位0.042和0.084 g.kg-1,每天1次,连续12 d。正常对照组和模型对照组ig给予等体积含0.3%吐温-80的水溶液。末次给药1 h后除正常对照组外,其余各组小鼠均ip给予次黄嘌呤0.6 g.kg-1。1 h后眼眶静脉丛取血,用磷钨酸比色法测定血清尿酸水平,酶比色法测定黄嘌呤氧化酶活性。对降低血清尿酸水平的活性部位进行GC-MS分析,鉴定其主要化学成分。结果高尿酸血症模型小鼠血清尿酸水平与正常对照组比较明显升高(P<0.01),别嘌醇0.04 g.kg-1,EEPR 0.256和0.512 g.kg-1可明显降低该模型小鼠血清尿酸水平(P<0.05),分别由模型组的(464±143)μmol.L-1下降到273±80,346±85和(302±72)μmo.l L-1(P<0.05)。EEPR中石油醚部位0.079和0.158 g.kg-1可显著降低该模型小鼠血清尿酸水平,分别由模型组的(446±139)μmo.lL-1下降到328±100和(314±112)μmol.L-1(P<0.05),其他部位各剂量组对血清尿酸水平均无明显影响。石油醚部位0.158 g.kg-1可明显抑制黄嘌呤氧化酶活性,由模型对照组的(18±8)U.L-1下降到(11±5)U.L-1(P<0.05)。GC-MS分析结果表明,石油醚部位的脂肪酸中,反式十八碳烯酸甲酯占60.77%,十六烷酸甲酯占18.99%,十六碳烯酸甲酯占9.31%。结论 EEPR中石油醚部位可降低高尿酸血症模型小鼠血清尿酸水平,不饱和脂肪酸为石油醚部位脂肪酸的主要成分。     

Mulberroside a possesses potent uricosuric and nephroprotective effects in hyperuricemic mice

Mulberroside A is a major stilbene glycoside of MORUS ALBA L. (Moraceae), which is effectively used for the treatment of hyperuricemia and gout in traditional Chinese medicine. We examined whether mulberroside A had effects on renal urate underexcretion and dysfunction in oxonate-induced hyperuricemic mice and investigated the potential uricosuric and nephroprotective mechanisms involved. Mulberroside A at 10, 20, and 40 mg/kg decreased serum uric acid levels and increased urinary urate excretion and fractional excretion of uric acid in hyperuricemic mice. Simultaneously, it reduced serum levels of creatinine and urea nitrogen (10-40 mg/kg), urinary N-acetyl- β-D-glucosaminidase activity (10-40 mg/kg), β?-microglobulin (10-40 mg/kg) and albumin (20-40 mg/kg), and increased creatinine clearance (10-40 mg/kg) in hyperuricemic mice. Furthermore, mulberroside A downregulated mRNA and protein levels of renal glucose transporter 9 (mGLUT9) and urate transporter 1 (mURAT1), and upregulated mRNA and protein levels of renal organic anion transporter 1 (mOAT1) and organic cation and carnitine transporters (mOCT1, mOCT2, mOCTN1, and mOCTN2) in hyperuricemic mice. This is the first study demonstrating that mulberroside A exhibits uricosuric and nephroprotective effects mediated in part by cooperative attenuation of the expression alterations of renal organic ion transporters in hyperuricemic mice. These data suggest that mulberroside A may be a new drug candidate for the treatment of hyperuricemia with renal dysfunction.     

松叶提取物对“过食膏粱厚味”型高尿酸血症大鼠尿酸生成排泄、肝功能及血脂水平的影响

目的 研究松叶提取物对“过食膏粱厚味”型高尿酸血症大鼠尿酸生成排泄、肝功能及血脂水平的影响。方法 将60只♂SD大鼠,随机分为正常对照组、模型对照组、别嘌醇（0.01 g·kg^-1）阳性对照组、松叶提取物3个剂量组（10.0,5.0,2.5 g·kg^-1）,每组10只。除正常对照组给予等体积蒸馏水,其余各组每天上午灌胃给予脂肪乳剂造模,下午灌胃给药,连续9周。观察大鼠一般行为学、摄食量、体质量,分别检测大鼠血清SUA、SCR、BUN、ALT、AST、TC、LDL-c含量;收集24 h尿液,记录UV,检测大鼠尿UUA、UCR含量,计算24 h UUA、FEUA、CUr、CCr,末次给药后测定血清和肝脏XOD、ADA、HGPRT活性。结果 模型对照组大鼠体质量明显降低,血清SUA、SCR、BUN、ALT、TC、LDL-c水平以及血清和肝组织XOD、ADA活性显著升高,肝组织HGPRT活性显著降低,同时UUA、UCR、UV、24 h UUA、FEUA、CUr、CCr显著降低。松叶提取物能显著降低高尿酸血症大鼠血清SUA、SCR、BUN、ALT、TC、LDL-c水平,降低血清和肝组织XOD、ADA活性,升高肝组织HGPRT活性,并且升高UUA、UCR、UV、24 h UUA、FEUA、CUr、CCr。结论 松叶提取物能有效降低HUA大鼠尿酸的生成并促进其排泄,且具有保肝、调血脂的功能。     

Astilbin attenuates hyperuricemia and ameliorates nephropathy in fructose-induced hyperuricemic rats

Astilbin is a flavonoid compound isolated from the rhizome of Smilax china L. The effects and possible mechanisms of astilbin on hyperuricemia and nephropathy rats were elucidated in this study. Different dosages of astilbin (1.25, 2.5, and 5.0 mg/kg) were administered to 10?% fructose-induced hyperuricemic rats. The results demonstrated that astilbin significantly decreased the serum uric acid (Sur) level by increasing the urinary uric acid (Uur) level and fractional excretion of urate (FEUA) but not inhibiting the xanthine oxidase (XOD) activity. In addition, kidney function parameters such as serum creatinine (Scr) and blood urea nitrogen (BUN) were recovered in astilbin-treated hyperuricemic rats. Further investigation indicated that astilbin prevented the renal damage against the expression of transforming growth factor- β1 (TGF-β1) and connective tissue growth factor (CTGF) and also exerted a renal protective role by inhibiting formation of monosodium urate (MSU) and production of prostaglandin E? (PGE?) and interleukin-1 (IL-1). These findings provide potent evidence for astilbin as a safe and promising lead compound in the development of a disease-modifying drug to prevent hyperuricemia and nephropathy.     

Decreased activity of basolateral organic ion transports in hyperuricemic rat kidney: roles of organic ion transporters,rOAT1, rOAT3 and rOCT2

We investigated organic anion and cation transport activity and the expression of several organic ion transporters in hyperuricemic rat kidney. Feeding oxonic acid, an inhibitor of uric acid metabolism, and uric acid for 10 days significantly increased plasma uric acid level. Plasma creatinine and blood urea nitrogen concentrations also increased in hyperuricemic rats, indicating impaired renal function. The accumulation of organic anions, p-aminohippurate (PAH) and methotrexate, and cations, tetraethylammonium (TEA) and cimetidine, into renal slices was markedly decreased, suggesting decreased transport activity for organic anions and cations at the basolateral membrane in the kidney. The expression levels of basolateral organic anion transporters rOAT1 and rOAT3, and organic cation transporter, rOCT2, significantly decreased in hyperuricemic rat kidney as assessed by mRNA and protein levels. In contrast, the expression of rOCT1 was unaltered by hyperuricemia at both mRNA and protein levels. Moreover, the mRNA expression of kidney-specific organic anion transporters, OAT-K1 and OAT-K2, and organic anion transporting polypeptide (oatp) 1, which localize at the brush-border membrane in the kidney, was unchanged in hyperuricemic rats. In conclusion, we showed decreased basolateral organic anion and cation transport activity, accompanied by a specific decrease in rOAT1, rOAT3 and rOCT2 expression in hyperuricemic rat kidney. These phenomena partly contribute to the changed renal disposition of organic anions and cations in hyperuricemia.     

Effect of Eurycoma longifolia stem extract on uric acid excretion in hyperuricemia mice

OBJECTIVE Eurycoma longifolia is a tropical medicinal plant belonging to Simaroubaceae distributed in South East Asia. The aim of this study is to explore the effect and mechanism of E. longifolia stem 70% ethanol extract(EL) and its active compoundson uric acid excretion. METHODS Potassium oxonate(PO) induced hyperuricemia rats and adenine-PO induced hyperuricemia mouse model were used to evaluate the effects of EL. Ultra Performance Liquid Chromatography was used to determine the levels of plasma or serum uric acid and creatinine. Hematoxylin-eosin staining was applied to observe kidney pathological changes, Western blotting was applied to detect protein expression levels of uric acid transporters. Effects of constituents on urate uptake were tested in h URAT1-expressing HEK293 T cells. RESULTS EL significantly reduced serum and plasma uric acid levels at dosages of 100, 200 and400 mg·kg~(-1) in hyperuricemia rats and mice, and increased the clearance rate of uric acid and creatinine, improved therenal pathological injury. The protein expression levels of urate reabsorption transporter 1(URAT1) and glucose transporter 9 were down-regulated while sodium-dependent phosphate transporter 1 and ATP-binding cassette transporter G2 were up-regulated in the kidney after EL treatment. The diterpenes(50 μmol·L~(-1)) isolated from EL showed inhibitory effects on urate uptake in h URAT1-expressing HEK293 T cells,and the effect of eurycomanol was further confirmed in vivo. CONCLUSION EL significantly reduced blood uric acid levels and prevented pathological changes of kidney in PO induced hyperuricemia animal model, improved renal urate transports. We partly clarified the mechanism was related to suppressing effect of URAT1 by diterpene in EL. This study is the first to demonstrate that EL plays a role in hyperuricemia by promoting renal uric acid excretion.     

复方芪苓配方颗粒治疗大鼠高尿酸血症的作用机制研究

目的 研究复方芪苓配方颗粒对高尿酸血症大鼠的降尿酸作用,并从尿酸排泄途径探讨其作用机制。方法 SD大鼠随机分为正常组、模型组、苯溴马隆组、复方芪苓配方颗粒高、中、低剂量组(9.6,4.8,2.4 g·kg-1),通过腺嘌呤灌胃及氧嗪酸钾皮下注射建立高尿酸血症模型,连续给药14 d。分别测定血清尿酸、肌酐、尿素、尿尿酸水平,计算肾脏尿酸清除率。采用RT-PCR方法分别测定动物肾脏中相关转运体的表达水平;观察肾组织病理改变。结果 与模型组比较,复方芪苓配方颗粒组高尿酸血症大鼠的血清尿酸、肌酐、尿素水平显著降低,其肾脏尿酸清除率显著升高;其肾组织病理改变显示,肾小管内尿酸盐结晶减少,肾小管-间质损伤较轻。复方芪苓配方颗粒可以显著下调肾脏尿酸盐转运体1(URAT1)、葡萄糖转运蛋白9(GLUT9) mRNA的表达,上调有机阴离子转运体1(OAT1) mRNA的表达。结论 复方芪苓配方颗粒能降低高尿酸血症大鼠的血清尿酸水平并减轻肾组织病理损害,其作用机制可能是通过调节尿酸转运体的表达水平,以降低肾脏尿酸盐重吸收能力、增加尿酸盐分泌,从而促进尿酸排泄。     

Pharmacologic inducers of the uric acid exporter ABCG2 as potential drugs for treatment of gouty arthritis

Uric acid is the end product of purine catabolism and its plasma levels are maintained below its maximum solubility in water(6–7 mg/dl).The plasma levels are tightly regulated as the balance between the rate of production and the rate of excretion,the latter occurring in urine(kidney),bile(liver)and feces(intestinal tract).Reabsorption in kidney is also an important component of this process.Both excretion and reabsorption are mediated by specific transporters.Disruption of the balance between production and excretion leads to hyperuricemia,which increases the risk of uric acid crystallization as monosodium urate with subsequent deposition of the crystals in joints causing gouty arthritis.Loss-of-function mutations in the transporters that mediate uric acid excretion are associated with gout.The ATP-Binding Cassette exporter ABCG2 is important in uric acid excretion at all three sites:kidney(urine),liver(bile),and intestine(feces).Mutations in this transporter cause gout and these mutations occur at significant prevalence in general population.However,mutations that are most prevalent result only in partial loss of transport function.Therefore,if the expression of these partially defective transporters could be induced,the increased number of the transporter molecules would compensate for the mutation-associated decrease in transport function and hence increase uric acid excretion.As such,pharmacologic agents with ability to induce the expression of ABCG2 represent potentially a novel class of drugs for treatment of gouty arthritis.