| Objective: To observe the level of oxidative stress and to investigate thereno-protective effect of different dosages of hydrochloride pioglitazone in diabetic rats.Methods: After an overnight fasting,8rats randomly allocated to normal control groupreceived citrate buffer intraperitoneal injection. Type1diabetic model was induced by asingle intraperitoneal injection of streptozotocin at a large dose of65mg/kg of bodyweight to42rats.72hours later, peripheral blood was harvested from vena caudalis toevaluate the blood glucose level. Animals were considered to be type1diabetic rats ifthey had peripheral blood glucose concentrations of16.7mmol/L or greater in additionto polyuria and other diabetic features. After7days of diabetic model establishment,experiment diabetes group were then randomly divided into following four groups:diabetic rats without treatment (DM, diabetic model control group, n=8),10,20and30m/kg/d pioglitazone (PIO) treated diabetic rats (group DR1, DR2and DR3, n=8respectively). The day the drug administration started was defined as week0. Theperipheral blood glucose, urinary albumin, urinary sediment8-OHdG, urinary creatininewere determined at the basal, the4th week and8th week in the five groups during theobservation. To eliminate the impact of urine volume, urinary albumin and urinarysediment8-OHdG were expressed as urinary UAlb/UCr (UACR), U8-OHdG/UCr(U8CR) respectively. Following eight-week observation, all the animals wereanaesthetized by intraperitoneal injection of chloral hydrate (300mg/kg body weight), and then blood sample was collected for measuring HbA1c, lipid profile, serumcreatinine，BUN，SOD and MDA. After the animals were sacrificed, the left kidneywas immediately enucleated and weighed separately and then kidney hypertrophyindex(KI) was calculated. By virtue of electron microscope, the pathological changes ofthe kidney tissue were observed. Moreover, the renal tissue was acquired for measuringMDA level, expression of p22phox mRNA and p47phox mRNA，activities of SOD.Results(1) The blood glucose levels throughout the study period along with FBG and HbA1c atthe8th week in four diabetic groups were significantly higher than those in group NC(P<0.01), whereas no significant differences were found between PIO-treatment groupsand group DM (P>0.05).(2) At the8th week, the parameters including SCr, BUN, TG, LDL-C were significantlyhigher, whereas serum HDL-C was lower compared to those of NC groups (P<0.05orP<0.01). Pioglitazone therapy markedly reduced serum TG concentration. Notably,HDL-C in group DR2and DR3were higher than that of group DM (P<0.05).(3) At the8th week, compared with group NC, the serum MDA level had increased andthe SOD activity had decreased significantly in these all diabetic rats (P<0.05);Compared with model group, the serum MDA level had decreased and SOD activityhad increased significantly both in group DR2and DR3(P<0.01),but not in DR1group.(4)At the baseline, UACR showed no significant difference among the five groups.Since the4nd weeks, the levels of UACR in four diabetic groups were significantlyhigher than that of group NC. At the4th week, UACR in group DR2and DR3weresignificantly lower than that of group DM, whereas UACR in group DR1was slightlylower. At the8th week, the level of UACR in PIO-treatment group were significantlylower compared to that of group DM (P<0.01), while UACR in group DR2and DR3 were significantly lower than that in group DR1(P<0.05).(5) As shown in electronmicrographs, the glomerular basement membrane thickness(GBMT), ultrastructure of the podocyte and mesangial region in group NC were normaland foot process fusion rate (FPFR) was nearly0.03%. However, both the foot processeffacement and GBM incrassation were also observed in group DM. Meanwhile, somefoot processes were completely ruined, even vanished and the architecture of GBMbecame ambiguous. However, through PIO treatment, both FPFR and GBMT werereduced compared to those of group DM (P<0.01). More importantly, the decliningamplitudes of the parameters mentioned above were significantly greater in group DR2and DR3compared with those of group DR1(P<0.01).(6) At the baseline, U8CR showed no significant difference among the five groups.Since the2nd weeks, the level of U8CR in four diabetic groups were significantlyhigher than group NC. At the4nd week and8th week, U8CR in PIO-treatment groupwere significantly lower compared to that of group DM (P<0.01)，in addition, the levelof U8CR in group DR2and DR3were significantly lower than that of group DR1（P<0.05）.(7) At the8th week，compared with group NC, the renal tissue MDA level had increasedand the SOD activity had decreased significantly in these all diabetic rats (DM、DR1group P<0.01, DR2、DR3group P<0.05); Compared with model group, the renal tissueMDA level had decreased and SOD activity had increased significantly inPIO-treatment groups(DR1group P<0.05, DR2、DR3group P<0.01)；Compared withDR1group，the renal tissue MDA level had decreased and SOD activity had increasedsignificantly in DR2、DR3group (P<0.05)。(8) RT-PCR analysis demonstrated that expression of renal p47phox and p22phoxmRNA in group NC was significantly lower than that in these all diabetic rats (DM、DR1group P<0.01, DR2、DR3group P<0.05).8-week PIO treatment decreased glomerular p47phox and p22phox mRNA expression compared with model group(P<0.01)，andgroup DR2and DR3lower than group DR1(P<0.05).(9) UACR was positively correlated with U8CR and the renal tissue MDA levelrespectively (r=0.867, r=0.62, P<0.01). UACR was negatively correlated with the renaltissue SOD activity (r=0.70，P<0.01)Conclusion(1)Pioglitazone has a reno-protenction for diabetic renal injury with a dose-dependentmanner.(2)The oxidative stress of STZ-induced diabetic rats have a great rise, which may play anegative role in their kidney injury。(3)Pioglitazone can inhibit the oxidative stress in Vivo and renal local tissue of diabeticrats with a dose-dependent manner, which may contribute to in some extent itsreno-protenction... |
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