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Objective:To investigate the protective effects of an antioxidant tert-butylhydroquinone (tBHQ) on the morphology and function of retina in early-stage experimental diabetic rats, and to explore the mechanism of its protective effect.Methods:Forty-five healthy SD rats of clean degree were randomized into normal control group, diabetes model group and tBHQ intervention group, with 15 rats in each group according to a random number table.The diabetes model was established via a single intraperitoneal injection of streptozotocin (STZ) in diabetes model group and tBHQ intervention group.Normal control group was intraperitoneally administered with an equal-volume injection of sodium citrate buffer.Rats in the tBHQ intervention group maintained a diet with 1% tBHQ for 2 weeks before the STZ injection, and the other two groups were fed with normal rat food only.Blood from tail vein was collected to assay the blood glucose level at 72 hours, 2 weeks and 4 weeks following modeling.Rat electroretinogram (ERG) was detected at 4 weeks after modeling.Morphological changes of rat retina were observed by hematoxylin and eosin staining.The apoptosis of retinal cells in different layers was detected by TUNEL assay.The expression of protein kinase B (Akt), p-Akt, endothelial nitric oxide synthase (eNOS) and p-eNOS was detected by Western blot.Müller cell line rMC-1 cells cultured in vitro were divided into 5 groups, including normal control group (72-hour culturing in normal medium), mannitol control group (72-hour culturing in medium containing 5.5 mmol/L glucose and 24.5 mmol/L mannitol), high glucose group (72-hour culturing in high-glucose medium), tBHQ intervention group (24-hour culturing in normal-glucose medium containing 5 μmol/L tBHQ, 72-hour culturing in high-glucose medium containing 5 μmol/L tBHQ), and phosphoinositide 3-kinase (PI3K) inhibitor group (6-hour culturing in normal medium containing 5 μmol/L LY294002, 24-hour culturing in normal-glucose medium containing 5 μmol/L LY294002 and 5 μmol/L tBHQ, 72-hour culturing in high-glucose medium containing 5 μmol/L LY294002 and 5 μmol/L tBHQ). The expression of Akt, p-Akt, eNOS and p-eNOS in the cells was detected by western blot.The use and care of animals complied with Regulations for the Administration of Laboratory Animals in Southwest Medical University.The study protocol was approved by the Animal Ethics Committee of Southwest Medical University (No.201711189). Results:The blood glucose level at 72 hours, 2 weeks and 4 weeks after modeling was higher in diabetic model group than tBHQ intervention group and normal control group (all at P<0.01). Four weeks after modeling, the scotopic ERG a-wave and b-wave amplitudes of diabetic model group were lower than those of normal control group and tBHQ intervention group (all at P<0.05). With edema and thickening of inner plexiform layer, thinning of inner nuclear layer and outer nuclear layer, as well as loosely arrangement and disorder of retinal layers, the number of retinal ganglion cells was decreased in diabetic model group in comparison with normal control group, all of which were improved in tBHQ intervention group in comparison with diabetic model group.There were more apoptotic retinal cells in diabetic model group than normal control group and tBHQ intervention group (both at P<0.05), which mainly existed in the outer nuclear layer.The relative expressions of p-Akt/Akt and p-eNOS/eNOS in rat retina of normal control group, diabetic model group and tBHQ intervention group were 0.76±0.11 and 0.83±0.06, 0.52±0.10 and 0.52±0.08, 1.14±0.31 and 1.03±0.13, respectively.The relative expressions of p-Akt/Akt and p-eNOS/eNOS in diabetic model group were lower than those of normal control group and tBHQ intervention group (all at P<0.01). The relative expressions of p-Akt/Akt and p-eNOS/eNOS in normal glucose group, mannitol control group, high glucose group, tBHQ intervention group and PI3K inhibitor group were 0.95±0.38 and 0.86±0.11, 0.94±0.27 and 0.74±0.29, 0.33±0.25 and 0.45±0.29, 1.32±0.37 and 1.28±0.22, 0.24±0.09 and 0.73±0.29, respectively.The relative expressions of p-Akt/Akt and p-eNOS/eNOS were significantly lower in high glucose group than those in normal glucose group and tBHQ intervention group (all at P<0.05), which were significantly lower in PI3K inhibitor group compared with tBHQ intervention group (both at P<0.01). Conclusions:tBHQ has protective effects on the morphology and function of retina in early diabetic rats, and the mechanism may be related to the activation of Akt/eNOS signaling pathway.
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[Objective] To investigate the effects and mechanisms of Nrf2-ARE (nuclear factor erythroid-2 related factor-anti-oxidant response element) pathway on uremic serum-mediated endothelial dysfunction in human aortic endothelial ceils.[Methods] Human aortic endothelial cells were incubated in endothelial cell medium containing 10％ normal serum,10％ non-diabetic nuremic serum or 10％ diabetic uremic serum respectively,and 20 μmol/L tertiary butyl hydroquinone (tBHQ) were pretreated with cells to active Nrf2-ARE pathway.The cells apoptosis rate were measured by flow cytometry,and the synthesis of NO was detected by flow cytometry and immune fluorescent confocal,while the expression of P-eNOSer1177/eNOS,and quinone oxidoreductase-1 (NQO1) were measured by western blotting.The levels of malondialdehyde,superoxide dismutase,eatalase,and glutathione in these cells were also measured with kits.[Results] Aortic endothelial cells incubated with uremic serum had a higher level of apoptosis rate and MDA (P ＜ 0.05),and a lower level of NO systhesis,P-eNOSSer1177/eNOS expression,CAT,SOD,GSH (P ＜ 0.05).Pretreated with tBHQ can reduce the apoptosis rate and MDA level (P ＜ 0.05),improve the amount of NO systhesis,the expression of P-eNOSSer1177/eNOS,the levels of CAT,SOD,and GSH in these cells (P ＜ 0.05).[Conclusion] Activation of Nrf2-ARE pathway can improve endothelial dysfunction in aortic endothelial cells induced by uremic serum,and its mechanism might be related with enhancement of the antioxidant stress.
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Objective To explore the effect of tert?butylhydroquinone(tBHQ)on ultraviolet B(UVB)?induced oxidative damages in human im?mortalized keratinocytes(HaCaT),and discuss its mechanism. Methods The cultured HaCaT cells were randomly divided into 4 groups:control group(G1),ultraviolet irradiation group(G2),25μmol/L tBHQ pretreatment before ultraviolet irradiation group(G3),and 50μmol/L tBHQ pre?treatment before ultraviolet irradiation group(G4). The content of reactive oxygen species was detected by DCFH?DA method,and the cell prolifera?tion was evaluated by MTT. Western blot was used to measure the protein expression of nuclear factor E2?related factor 2(Nrf2)in both nuclear fac?tions and whole?cell of HaCaT. The mRNA expressions of CAT and SRX were determined by real?time RT?PCR. Results The content of reactive oxygen species in HaCaT cells was increased,and the cell proliferation rate was decreased significantly after ultraviolet irradiation. The pretreatment of 25 and 50μmol/L tBHQ can inhibit the UVB?induced oxidative damage in a dose?dependent manner in HaCaT cells. Compared with G2 group, tBHQ pretreatment could dose?dependently increase the level of Nrf2 protein in nuclear factions and whole?cell of HaCaT,and also the mRNA ex?pressions of CAT and SRX. Conclusion UVB irradiation can induce oxidative stress damages of HaCaT cells. tBHQ may inhibit the UVB?induced oxidative damages through enhancing Nrf2 expressions and nuclear translocation,then activating the transcription of the downstream antioxidant en?zymes CAT and SRX.
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AIM:To investigate the effect of tert-butylhydroquinone ( tBHQ) on the replicative senescence of bone marrow mesenchymal stem cells (BMSCs).METHODS: Late stage BMSCs were continuously treated with tBHQ at concentration of 30 μmol/L for 4 weeks and the cells were used for the following assays immediately .The proteasomal ac-tivity was determined by chemiluminescence method .The samples were subjected to CCK-8 assay and BrdU incorporation as well as flow cytometry analysis for analyzing the cell vitality and proliferation .Percentage of senescent cells was detected by senescence-associatedβ-galactosidase ( SA-β-Gal) staining.The expression of P53 was measured by Western blot .RE-SULTS:After the continuous treatment of tBHQ (30 μmol/L) for 4 weeks, the proteasomal activity of late stage BMSCs increased by 21.96%±1.98%(P<0.05).The cell vitality and survival were significantly increased with the increases in tBHQ doses till 40 μmol/L, and no cytotoxicity reaction with the increased dose of tBHQ till 120 μmol/L was observed . BrdU-positive cells, which represented the cell proliferation , were significantly increased (P<0.05).The proliferation in-dex was also significantly increased by flow cytometry analysis (P<0.05).The SA-β-Gal positive cells and the expression of P53 were decreased (P<0.05).CONCLUSION:tBHQ delays the proteasome dysfunction associated senescence pro-gress of BMSCs by increasing the proteasomal activity .
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ObjectiveTo study the protective effects of tert-butylhydroquinone(tBHQ) on sodium arsenite (NaAsO2)-induced cytotoxicity and oxidative injuries. Methods Chang liver cells were pretreated with tBHQ[0(control), 5, 25 μmol/L]for 24 h, and then co-treated with tBHQ(5 μmol/L) together with NaAsO2[0(control),30, 40, 50, 60 μmol/L] for another 24 h, and Alamar blue reduction rates were used to evaluate cell viability,the results were expressed as the relative ratio of Alamar blue reduction rates between the experimental group and the control group. On the other hand, Chang liver cells were pretreated with tBHQ[0(control), 5, 25 μmol/L] for24 h,and then co-treated with tBHQ(5 μmol/L) together with NaAsO2[0(control), 40, 50 μmol/L] for another 24 h,and the levels of cellular reactive oxygen species(ROS) were detected by staining cells with 2',7'-dichlorofluorescin diacetate(DCFH-DA), the results were expressed as the relative ratio of mean fluorescence intensity between the experimental group and the control group. ResultsCell viability decreased dramatically by treatment with NaAsO2(30, 40, 50, 60 μmol/L), while relieved to some extent by pretreatment with 5, 25 μmol/L tBHQ, the main effects of NaAsO2 and tBHQ, as well as their interaction were all statistically significant(F =566.57, 55.09, 14.50,all P ＜ 0.05) ; the cell viability of NaAsO2(30, 40, 50, 60 μmol/L) pretreated with tBHQ(5, 25 mol/L) were 0.75 ±0.02, 0.70 ± 0.04, 0.59 ± 0.03, 0.43 ± 0.03 and 0.75 ± 0.02, 0.73 ± 0.03, 0.65 ± 0.02, 0.50 ± 0.02, respectively,all significantly higher than corresponding NaAsO2 alone groups(0.70 ± 0.03, 0.64 ± 0.03, 0.43 ± 0.03, 0.33 ±0.01, all P ＜ 0.05), the cell viability of NaAsO2(50, 60 μmol/L) pretreated with 25 μmol/L tBHQ was higher than corresponding 5 μmol/L tBHQ pretreatment groups(all P ＜ 0.05). On the other hand, 40, 50 μmol/L of NaAsO2 significantly induced hepatocellular ROS generation, while tBHQ(5, 25 μ mol/L) pretreatment significantly decreased NaAsO2-induced intracellular ROS levels, the main effects of NaAsO2 and tBHQ, as well as their interaction were all statistically significant (F =181.78, 60.55, 4.93, all P ＜ 0.05) ; the ROS levels of NaAsO2(40, 50 μ mol/L) pretreated with tBHQ(5, 25 μmol/L) were 1.87 ± 0.09, 1.80 ± 0.07 and 1.36 ± 0.11, 1.44 ± 0.12,all significantly decreased than corresponding NaAsO2 alone groups(2.30 ± 0.18, 2.18 ± 0.17, all P ＜ 0.05),the ROS levels of NaAsO2(40, 50 μmol/L) pretreated with 25 μmol/L tBHQ decreased than corresponding 5 μmol/L tBHQ pretreatment groups (all P ＜ 0.05). ConclusiontBHQ has a certain antagonism on arsenic induced cytotoxicity and oxidative injuries.
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Effects of oxidized low-density lipoprotein (ox-LDL), l-alpha-stearoyl-lysophosphatidylcholine (LPC), on intracellular Ca2+ concentration were examined in mouse endothelial cells by measuring intracellular Ca2+ concentration ([Ca2+]i) with fura 2-AM and reverse transcription-polymerase chain reaction (RT-PCR). LPC increased [Ca2+]i under the condition of 1.5 mM [Ca2+]o but did not show any effect under the nominally Ca2+-free condition. Even after the store depletion with 30microM 2,5-di-tert- butylhydroquinone (BHQ) or 30microM ATP, LPC could still increase the [Ca2+]i under the condition of 1.5 mM [Ca2+]o. The time required to increase [Ca2+]i (about 1 minute) was longer than that for ATP-induced [Ca2+]i increase (10-30 seconds). LPC-induced [Ca2+]i increase was completely blocked by 1microM La3+. Transient receptor potential channel(trpc) 4 mRNA was detected with RT-PCR. From these results, we suggest that LPC increased [Ca2+]i via the increase of Ca2+ influx through the Ca2+ routes which exist in the plasma membrane.