Evaluation of cellular purine transport and metabolism in the Caco-2 cell using comprehensive high-performance liquid chromatography method for analysis of purines

ABSTRACT

Using Caco-2 cells and our previously developed high-performance liquid chromatography method for quantification of purine bases, nucleosides, and nucleotides, we evaluated cellular purine transport and uptake. The analytes were separated using YMC-Triart C18 column with gradient elution. We used Caco-2 cells as intestinal model cells and monitored purine transport across a monolayer for 2 h. The degree of change of purine concentrations in the permeate was very slight; however, it was possible to simultaneously determine these parameters for all purines because of our method's high sensitivity. In the present study, the purine bases (adenine, guanine, hypoxanthine, and xanthine) showed a relatively high permeability as compared with the nucleosides (adenosine, guanosine, inosine, and xanthosine). Increased concentration of metabolites in the permeate was also observed following the addition of purines. In a cell uptake assay, both the cell culture medium (extracellular) and the cells extracted from Caco-2 with acetonitrile:water (7:3) (intracellular) were measured. The additional nucleoside did not increase significantly within the cells. On the other hand, we observed that nucleotide, such as ATP, increased in the cell in a time-dependent manner following the addition of nucleoside. The additional nucleosides were considered to be rather recycled via the salvage pathway than metabolized to purine bases and/or uric acid in the cell. Such differences might have affected the increase in the serum uric acid levels depending on purine form.     

Genetic influence on variation in serum uric acid in American Indians: the strong heart family study

Hyperuricemia is associated with the metabolic syndrome, gout, renal and cardiovascular disease (CVD). American Indians have high rates of CVD and 25% of individuals in the strong heart family study (SHFS) have high serum uric acid levels. The aim of this study was to investigate the genetic determinants of serum uric acid variation in American Indian participants of the SHFS. A variance component decomposition approach (implemented in SOLAR) was used to conduct univariate genetic analyses in each of three study centers and the combined sample. Serum uric acid was adjusted for age, sex, age × sex, BMI, estimated glomerular filtration rate, alcohol intake, diabetic status and medications. Overall mean ± SD serum uric acid for all individuals was 5.14 ± 1.5 mg/dl. Serum uric acid was found to be significantly heritable (0.46 ± 0.03 in all centers, and 0.39 ± 0.07, 0.51 ± 0.05, 0.44 ± 0.06 in Arizona, Dakotas and Oklahoma, respectively). Multipoint linkage analysis showed significant evidence of linkage for serum uric acid on chromosome 11 in the Dakotas center [logarithm of odds score (LOD) = 3.02] and in the combined sample (LOD = 3.56) and on chromosome 1 (LOD = 3.51) in the combined sample. A strong positional candidate gene in the chromosome 11 region is solute carrier family22, member 12 (SLC22A12) that encodes a major uric acid transporter URAT1. These results show a significant genetic influence and a possible role for one or more genes on chromosomes 1 and 11 on the variation in serum uric acid in American Indian populations.     

Identification of uric acid as the redox molecule secreted by the yeast Arxula adeninivorans

The yeast Arxula adeninivorans has been previously shown to secrete a large amount of an electro-active molecule. The molecule was produced by cells that had been cultivated in a rich medium, harvested, washed and then suspended in phosphate-buffered saline (PBS). The molecule was easily detectable after 60 min of incubation in PBS, and the cells continued to produce the molecule in these conditions for up to 3 days. The peak anodic potential of the oxidation peak was 0.42 V, and it was shown to be a solution species rather than a cell-attached species. We have optimised the production of the molecule, identified it by high-pressure liquid chromatography (HPLC) fractionation and high-resolution mass spectrometric analysis and determined the pathway involved in its synthesis. It has a mass/charge ratio that corresponds to uric acid, and this identification was supported by comparing UV spectra and cyclic voltammograms of the samples to those of uric acid. An A. adeninivorans xanthine oxidase gene disruption mutant failed to produce uric acid, which added further validity to this identification. It also demonstrated that the purine catabolism pathway is involved in its production. A transgenic A. adeninivorans strain with a switchable urate oxidase gene (AUOX) accumulated uric acid when the gene was switched off but did not when the gene was switched on. Cultivation of cells on amino acid and purine-free minimal media with an inorganic nitrogen source suggests that the cells synthesise purines from inorganic nitrogen and proceed to degrade them via the normal purine degradation pathway.     

Effect of phytic acid on postprandial serum uric acid level in healthy volunteers: a randomized,double-blind,crossover study

Abstract

Phytic acid, a constituent of various plants, has been related to health benefits. Phytic acid has been shown to inhibit purine nucleotide metabolism in vitro and suppress elevation of plasma uric acid levels after purine administration in animal models. This study investigated the effect of phytic acid on postprandial serum uric acid (SUA) in humans. This randomized, double-blind, crossover design study included 48 healthy subjects with normal fasting SUA. Subjects consumed a control drink and a phytic acid drink with purine-rich food, and serum and urine uric acid levels were measured for 360?min after purine loading. Phytic acid lowered the incremental area under the curve (0–360?min) and incremental maximum concentration of SUA after purine loading (p?<?0.05); tended to lower cumulative urinary uric acid excretion (0–360?min) after purine loading (p?<?0.10); and suppressed postprandial SUA in this clinical study. Altogether, our findings suggest that phytic acid may play a beneficial role in controlling postprandial SUA.     

Effects of dietary supplementation of rumen-protected folic acid on rumen fermentation,degradability and excretion of urinary purine derivatives in growing steers

The present experiment was undertaken to determine the effects of dietary addition of rumen-protected folic acid (RPFA) on ruminal fermentation, nutrient degradability, enzyme activity and the relative quantity of ruminal cellulolytic bacteria in growing beef steers. Eight rumen-cannulated Jinnan beef steers averaging 2.5 years of age and 419 ± 1.9 kg body weight were used in a replicated 4 × 4 Latin square design. The four treatments comprised supplementation levels of 0 (Control), 70, 140 and 210 mg RPFA/kg dietary dry matter (DM). On DM basis, the ration consisted of 50% corn silage, 47% concentrate and 3% soybean oil. The DM intake (averaged 8.5 kg/d) was restricted to 95% of ad libitum intake. The intake of DM, crude protein (CP) and net energy for growth was not affected by treatments. In contrast, increasing RPFA supplementation increased average daily gain and the concentration of total volatile fatty acid and reduced ruminal pH linearly. Furthermore, increasing RPFA supplementation enhanced the acetate to propionate ratio and reduced the ruminal ammonia N content linearly. The ruminal effective degradability of neutral detergent fibre from corn silage and CP from concentrate improved linearly and was highest for the highest supplementation levels. The activities of cellobiase, xylanase, pectinase and α-amylase linearly increased, but carboxymethyl-cellulase and protease were not affected by the addition of RPFA. The relative quantities of Butyrivibrio fibrisolvens, Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogenes increased linearly. With increasing RPFA supplementation levels, the excretion of urinary purine derivatives was also increased linearly. The present results indicated that the supplementation of RPFA improved ruminal fermentation, nutrient degradability, activities of microbial enzymes and the relative quantity of the ruminal cellulolytic bacteria in a dose-dependent manner. According to the conditions of this experiment, the optimum supplementation level of RPFA was 140 mg/kg DM.     

Simultaneous quantification by HPLC of purines in umami soup stock and evaluation of their effects on extracellular and intracellular purine metabolism

Ribonucleotide flavor enhancers such as inosine monophosphate (IMP) and guanosine monophosphate (GMP) provide umami taste, similarly to glutamine. Japanese cuisine frequently uses soup stocks containing these nucleotides to enhance umami. We quantified 18 types of purines (nucleotides, nucleosides, and purine bases) in three soup stocks (chicken, consommé, and dried bonito soup). IMP was the most abundant purine in all umami soup stocks, followed by hypoxanthine, inosine, and GMP. The IMP content of dried bonito soup was the highest of the three soup stocks. We also evaluated the effects of these purines on extracellular and intracellular purine metabolism in HepG2 cells after adding each umami soup stock to the cells. An increase in inosine and hypoxanthine was evident 1 h and 4 h after soup stock addition, and a low amount of xanthine and guanosine was observed in the extracellular medium. The addition of chicken soup stock resulted in increased intracellular and extracellular levels of uric acid and guanosine. Purine metabolism may be affected by ingredients present in soups.     

Effects of Losartan/Hydrochlorothiazide on Serum Uric Acid Levels and Blood Pressure in Hypertensive Patients

The effect of a mixed formulation of 50 mg losartan (LOS) and 12.5 mg hydrochlorothiazide (HCTZ) on blood pressure and the uric acid metabolism was analyzed in 73 patients who switched to this formulation from other antihypertensive drugs. Eight patients who switched to the formulation from the regular dose of renin-angiotensin (RA) inhibitor (angiotensin receptor blocker [ARB] or angiotensin-converting enzyme [ACE] inhibitor) only showed a significant decrease in blood pressure, from 156.9 ± 14.1/88.6 ± 9.7 mmHg to 128.3 ± 16.0/76.1 ±10.7 mmHg (p = 0.007), and a significant increase in serum uric acid levels, from 5.2 ± 1.1 mg/dL to 6.8 ± 0.7 mg/dL (p = 0.02). In the other 50 patients who switched from a combination of the regular dose of RA inhibitor and calcium channel blocker (CCB), their blood pressure significantly increased, from 126.0 ± 13.8/72.0 ± 10.0 mmHg to 132.5 ± 16.4/76.5 ± 11.3 mmHg (p = 0.02), and their serum uric acid levels also significantly increased, from 5.6 ± 1.1 mg/dL to 6.1 ± 1.3 mg/dL (p = 0.0002). Considering that guidelines recommend using antihypertensive therapies that do not lead to an increase in serum uric acid levels, we conclude that using the ARB/HCTZ combination is less suitable than the regular dose of the ARB/CCB combination due to its effect on hypertension and serum uric acid levels.     

Protective effect of gallic acid isolated from Peltiphyllum peltatum against sodium fluoride-induced oxidative stress in rat’s kidney

In the present study, the nephroprotective effect of gallic acid isolated from Peltiphyllum peltatum was examined in sodium fluoride (NaF) treated rats. Nephrotoxicity was induced by 1-week intoxication of NaF at 600 ppm through drinking water. The levels of thiobarbituric acid reactive substances, reduced glutathione as well as activities of superoxide dismutase and catalase in renal tissues homogenates were determined. The serum biochemical markers of renal injuries including creatinine, serum urea, blood urea nitrogen, uric acid levels as well as the levels of phosphate and calcium were also assessed. Intoxication with NaF caused a significant increase in the levels of thiobarbituric acid reactive substances (46 % versus to control) and reduced the glutathione concentration (47 %) and the activities of superoxide dismutase (46 %) and catalase (41 %) in renal tissues homogenates. NaF intoxication also induced significant alterations in the kidney biochemical markers increasing the levels of urea, uric acid, blood urea nitrogen, creatinine, and phosphate and decreasing the levels of calcium. Daily administration of gallic acid (20 mg/kg) for 1 week before NaF intoxication brought the antioxidant–oxidant balance similar to the NaF-untreated group. Silymarin, used a standard antioxidant agent, also showed a nephroprotective activity. We concluded that NaF caused nephrotoxicity and oxidative stress in renal tissues and daily administration of gallic acid for 1 week prior to intoxication inhibited toxicity and oxidative stress.     

Characterizing Substrate Properties of Purine-Related Compounds with Purine Metabolism Enzymes for Enzymatic Peak-Shift HPLC Method

We have extended peak-shift method for measuring purine bases to make it suitable for other purine-related compounds. We optimized the reactions of the purine metabolism enzymes 5′-nucleotidase (EC 3.1.3.5), purine nucleoside phosphorylase (PNP) (EC 2.4.2.1), xanthine oxidase (XO) (EC 1.17.3.2), urate hydroxylase (EC 1.7.3.3), adenosine deaminase (ADA) (EC 3.5.4.4), and guanine deaminase (EC 3.5.4.3) by determining their substrate specificity and reaction kinetics. These enzymes eliminate the five purine base peaks (adenine, guanine, hypoxanthine, xanthine, and uric acid) and four nucleosides (adenosine, guanosine, inosine, and xanthosine). The bases and nucleosides can be identified and accurately quantified by comparing the chromatograms before and after treatment with the enzymes. Elimination of the individual purine compound peaks was complete in a few minutes. However, when there were multiple substrates, such as for XO, and when the metabolites were purine compounds, such as for PNP and ADA, it took longer to eliminate the peaks. The optimum reaction conditions for the peak-shift assay methods were an assay mixture containing the substrate (10 μL, 0.1 mg/mL), the combined enzyme solution (10 μL each, optimum concentration), and 50 mM sodium phosphate (up to 120 μL, pH 7.4). The mixture was incubated for 60 minutes at 37°C. This method should be suitable for determining the purine content of a variety of samples, without interference from impurities.     

Allantoxanamide: A potent new uricase inhibitor in vivo

Allantoxanamide (2,4-dihydroxy-6-carboxamide-1,3,5-triazine) was studied as a uricase inhibitor in the rat. Uricase activity $\text{in vitro}$ was inhibited 50% by allantoxanamide at 9 × 10- M concentration. A single 250 mg/kg i.p. dose in the rat gave rise to a serum uric acid level of 14 mg/dl 6 hr after dosing; serum uric acid was still elevated (10 mg/dl) after 24 hr. At this dose level, deposition of uric acid in kidney tubules was observed. Studies with [8-¹⁴ C] uric acid indicated that the effect of allantoxanamide on serum uric acid was due to inhibition of uricase. The allantoxanamide-treated rat may serve as a useful animal model for the study of problems related to purine biosynthesis, drug-induced hyperuricemia and hyperuricosuria, and associated nephropathy.     

Effect of purine-free low-malt liquor (happo-shu) on the plasma concentrations and urinary excretion of purine bases and uridine--comparison between purine-free and regular happo-shu.

To determine whether purine-free and regular low-malt liquor beverages (happo-shu) increase the plasma concentration and urinary excretion of purine bases (hypoxanthine, xanthine, uric acid) and uridine, 6 healthy males were given regular (10 ml/kg of body weight) and purine-free happo-shu (10 ml/kg of body weight). Plasma concentration-time curves were plotted, and the areas under the curves for uric acid and total purine bases (the sum of hypoxanthine, xanthine, and uric acid) were greater in the regular than in the purine-free happo-shu ingestion experiment (both p < 0.05). In addition, the total urinary excretion of xanthine, total purine bases, and uridine was greater in the regular than in the purine-free happo-shu ingestion experiment (p < 0.05 in all cases), although the total urinary excretion of hypoxanthine and uric acid was no different between the regular and the purine-free happo-shu ingestion experiments. These results suggest that uridine contained in regular happo-shu might contribute to an increase in the urinary excretion of uridine along with ethanol, and that the purines contained in regular happo-shu may contribute to the increase in plasma concentration of uric acid due to purine degradation.     

Purine metabolites in serum of higher primates,including man

Using a new method for simultaneous quantification of hypoxanthine, xanthine, uric acid, and allantoin by means of high-pressure liquid chromatography, purine metabolites of 18 species of higher primates, including man, have been determined. The data thus produced indicate that the serum concentrations of purine metabolites in primates are influenced by nutrition, sexual hormones, and the procedures used in catching the animals for venipuncture. In the Callitrichidae examined, serum concentrations of purines differ significantly from species to species. The results of a nutritional test show that Callithrix jacchus possesses an efficient system for degradation of dietary purines.     

DIAGNOSIS AND TREATMENT OF GOUTY ARTHRITIS

The characteristic phenomena of acute gouty arthritis are acute arthritis in a middle-aged male, associated with serum uric acid above 6 mg. per 100 cc. and a satisfactory response to colchicine. Roentgenographically observable changes do not occur early.In recent years uric acid metabolism has been studied by means of isotope techniques utilizing labeled substances. Uric acid is excreted in relatively constant amounts by humans and is little affected by variations in dietary intake, except for purine or nucleic acid substances. Persons with gout have a greater total amount of uric acid and a lower turnover than normal persons.In the treatment of acute attacks of gout colchicine is still the most practical single drug, even though its pharmacologic action remains unknown.Benemid (probenecid) is a powerful uricosuric agent of low toxicity which has been subjected to extensive clinical trial for three years. It causes inhibition of the resorption of urate from the glomerular filtrate; the site of action is believed to be the tubular cells. The author''s usual dose is 2 gm. a day. This has caused a lowering of the uric acid in the serum and an increase in the urinary output.     

Hypouricemic Actions of Exopolysaccharide Produced by Cordyceps militaris in Potassium Oxonate-Induced Hyperuricemic Mice

The hypouricemic actions of exopolysaccharide produced by Cordyceps militaris (EPCM) in potassium oxonate-induced hyperuricemia in mice were examined. Hyperuricemic mice were administered intragastrically with EPCM (200, 400 and 800 mg/kg body weight) or allopurinol (5 mg/kg body weight) once daily. Serum uric acid, blood urea nitrogen and liver xanthine oxidase (XOD) activities of each treatment were measured after administration for 7 days. EPCM showed dose-dependent uric acid-lowering actions. EPCM at a dose of 400 mg/kg body weight and allopurinol showed the same effect in serum uric acid, blood urea nitrogen and liver XOD activities in hyperuricemic mice. An increase in liver XOD activities was observed in hyperuricemic mice due to administration of EPCM at a dose of 200 mg/kg body weight. EPCM at a dose of 800 mg/kg body weight did not show significant effects on serum uric acid and XOD activities. We conclude that EPCM has a hypouricemic effect caused by decreases in urate production and the inhibition of XOD activities in hyperuricemic mice, and this natural product exhibited more potential efficacy than allopurinol in renal protection.     

Metabolic Syndrome in Primary Gout

Background and Objectives. Primary gout has traditionally been associated with obesity, arterial hypertension, and abnormal lipid and glucose homeostasis, but we do not know the prevalence of these vascular risk factors in patients with primary gout from a Mediterranean country. Patients and Method. All patients with primary gout and 2 or more acute arthritis episodes documented by a physician were selected for the study. The diagnosis of MS required ≥3 criteria (ATP III). Patients were classified in two groups: decreased (underexcretors) and normal (normoexcretors) uric acid excretion related to serum urate levels. Results. One hundred and four patients (mean age, 59 years; 100 males) with primary gout were included in the study. MS was diagnosed in 38 subjects (37%). The most frequent triad defining MS was an increased waist circumference, blood pressure, and trygliceride levels. The prevalence of type 2 diabetes mellitus (T2D) was significantly higher in patients with the MS (21/38, 55%) as compared with subjects without the MS (3/66, 5%; p < 0.001). Mean serum urate level in patients with and without MS was identical (8.1 mg/dL), but mean 24-hour uric acid excretion was significantly lower in the former than in the latter (444 ± 110 mg/24-hour/1,73 m² versus 546 ± 221 mg/day/1,73 m²; p = 0.009). Conclusions. The condition of the MS occurs in about one-third of the patients with primary gout. Increased waist circumference, blood pressure, and triglycerides levels is the most frequent MS triad. Diminished urinary uric acid excretion is more severe in gout patients with the MS.     

Uric acid synthesis by rat liver supernatants from purine bases,nucleosides and nucleotides. Effect of allopurinol

The synthesis of uric acid from purine bases, nucleosides and nucleotides has been measured in reaction mixtures containing rat liver supernatant and each one of the following compounds at 1 mM concentration (except xanthine, 0·5 mM and guanosine and guanine, 0·1 mM). The rates of the reaction, expressed as nanomoles of uric acid synthesized g^?1 of wet liver min^?1 were: ATP, 10; ADP, 37; AMP, 62; adenosine, 108; adenine 6; adenylo-succinate, 9; IMP 32; inosine, 112; hypoxanthine, 50; GTP, 19; GDP, 19; GMP, 27; guanosine, 34; guanine, 72; XMP, 10; xanthosine, 24; xanthine, 144. These figures divided by 55 correspond to nanomoles of uric acid synthesized min^?1 per mg^?1 of protein. The rate of synthesis of uric acid obtained with each one of those compounds at 0·1 and 0·05 mM concentrations was also determined. ATP (1 nM) strongly inhibited uric acid synthesis from 0·05 mM AMP (91 per cent) and from 0·05 mM ADP (88 per cent), but not from adenosine. CTP or UTP (1 mM ) also inhibited (by more than 90 per cent) the synthesis of uric acid from 0·05 mM AMP. Xanthine oxidase was inhibited by concentrations of hypoxanthine higher than 0·012 mM. The results favour the view that the level of uric acid in plasma may be an index of the energetic state of the organism. Allopurinol, besides inhibiting uric acid synthesis, reduced the rate of degradation of AMP. The ability of crude extracts to catabolize purine nucleotides to uric acid is an important factor to be considered when some enzymes related to purine nucleotide metabolism, particularly CTP synthase, are measured in crude liver extracts.     

降解尿酸乳酸菌复合菌系的筛选与菌株组合提升降解效果

【背景】高尿酸症由血液中尿酸含量明显升高而导致,利用乳酸菌对人体的益生作用缓解高尿酸血症越来越受到关注。【目的】获得具有降解尿酸能力的乳酸菌复合菌系与纯培养菌株。【方法】以泡菜为样品来源,以尿酸为底物,采用MRS培养基筛选降解尿酸的乳酸菌复合菌系,通过高效液相色谱法测定复合菌系对尿酸的降解能力。【结果】得到一组乳酸菌复合菌系,当培养温度为37 °C、pH值为6.20、静置培养72 h后复合菌系对尿酸的降解率为12.08%;通过优化培养条件,当该菌系在以牛肉膏为单一氮源、初始pH值为5.00、温度为35 °C的条件下培养72 h,尿酸降解率上升至17.19%,降解率比优化前提高了42.3%;从该菌系中分离出两株具有尿酸降解能力的菌株UA-1与UA-2,它们的尿酸降解率分别为10.85%和8.65%;通过形态学观察和16S rRNA基因序列分析,经鉴定两株菌均为布氏乳杆菌(Lactobacillus buchneri)。将两株单菌组合降解尿酸试验发现,UA-1与UA-2比例为2:1的尿酸降解率为20.2%,比原复合菌系的降解能力提高了67.22%。【结论】研究证明了乳酸菌复合菌系对尿酸的降解能力优于单个菌株,为后续利用乳酸菌复合菌系应用提供了数据支持。     

L-阿拉伯糖对尿酸的调节作用

转录因子是一类在生物生命活动过程中起到调控作用的重要因子,参与了各种信号转导和调控过程,可以直接或间接结合在顺式作用元件上,实现调控目标基因转录效率的抑制或增强,从而使植物在应对逆境胁迫下做出反应。 WRKY转录因子在大多数植物体内都有分布,是一类进化非常保守的转录因子家族,参与植物生长发育以及响应逆境胁迫的生理过程。众多研究表明,WRKY转录因子在植物中能够应答各种生物胁迫,如细菌、病毒和真菌等;多种非生物胁迫,包括高温、冷害、高光和高盐等;以及在各种植物激素,包括茉莉酸( JA)、水杨酸( SA)、脱落酸( ABA)和赤霉素( GA)等,在其信号传递途径中都起着重要作用。 WRKY转录因子家族蛋白至少含有一段60个氨基酸左右的高度保守序列,被称为WRKY结构域,其中WRKYGQK多肽序列是最为保守的,因此而得名。该转录因子的WRKY结构域能与目标基因启动子中的顺式作用元件W￣box( TTGAC序列)特异结合,从而调节目标基因的表达,其调控基因表达主要受病原菌、虫咬、机械损伤、外界胁迫压力和信号分子的诱导。该文介绍了植物WRKY转录因子在植物应对冷害、干旱、高盐等非生物胁迫与病菌、虫害等生物胁迫反应中的重要调控功能,并总结了WRKY转录因子在调控这些逆境胁迫反应过程中的主要生理机制。     

Xanthine Oxidase Inhibition by 1,3-dipropyl-8-sulfophenyl-xanthine (DPSPX), an Antagonist of Adenosine Receptors

Xanthine oxidase (XO), an enzyme involved in purine metabolism, is a source of either oxidants (superoxide radical) or antioxidants (uric acid). Interference with XO activity can lead to oxidative stress, thus contributing to the pathogenesis of cardiovascular diseases. The adenosine receptors antagonist, 1,3-dipropyl-8-sulfophenylxanthine (DPSPX), induces hypertension and cardiovascular injury in rats. Since DPSPX is a xanthine, we aimed at evaluating DPSPX's influence on XO activity to ascertain its contribution to DPSPX-induced hypertension. The activity of isolated XO in the presence of DPSPX was evaluated spectrophotometrically. Serum and urinary uric acid levels of DPSPX-treated rats were measured using a commercial kit. DPSPX inhibited XO activity in a concentration-dependent manner and reduced rat serum and urinary uric acid levels. It can be concluded that: DPSPX is an inhibitor of XO; decreased generation of uric acid may lead to oxidative stress, thus contributing to endothelial dysfunction and vascular morphological changes in DPSPX-treated rats.     

Suitable Concentrations of Uric Acid Can Reduce Cell Death in Models of OGD and Cerebral Ischemia–Reperfusion Injury

Cerebral infarction (CI) is a common clinical cerebrovascular disease, and to explore the pathophysiological mechanisms and seek effective treatment means are the hotspot and difficult point in medical research nowadays. Numerous studies have confirmed that uric acid plays an important role in CI, but the mechanism has not yet been clarified. When treating HT22 and BV-2 cells with different concentrations of uric acid, uric acid below 450 μM does not have significant effect on cell viability, but uric acid more than 500 μM can significantly inhibit cell viability. After establishing models of OGD (oxygen-glucose deprivation) with HT22 and BV-2 cells, uric acid at a low concentration (50 μM) cannot improve cell viability and apoptosis, and Reactive oxygen species (ROS) levels during OGD/reoxygenation; a suitable concentration (300 μM) of uric acid can significantly improve cell viability and apoptosis, and reduce ROS production during OGD/reoxygenation; but a high concentration (1000 μM) of uric acid can further reduce cell viability and enhance ROS production. After establishing middle cerebral artery occlusion of male rats with suture method, damage and increase of ROS production in brain tissue could be seen, and after adding suitable concentration of uric acid, the degree of brain damage and ROS production was reduced. Therefore, different concentrations of uric acid should have different effect, and suitable concentrations of uric acid have neuroprotective effect, and this finding may provide guidance for study on the clinical curative effect of uric acid.