Effect of dietary antioxidants on puromycin aminonucleoside nephrotic syndrome

Salvianolic acid A as a multifunctional agent ameliorates doxorubicin-induced nephropathy in rats

Nephrotic syndrome (NS) is still a therapeutic challenge. To date there is no ideal treatment. Evidence suggest that multidrug therapy has more effect than monotherapy in amelioration of renal injury. Salvianolic acid A (SAA) is the major active component of Salviae Miltiorrhizae Bunge. Previous studies have demonstrated that SAA is a multi-target agent and has various pharmacological activities. The pleiotropic properties of SAA predict its potential in the treatment of NS. The study investigated the effect of SAA on doxorubicin-induced nephropathy. The kidney function related-biochemical changes, hemorheological parameters and oxidative stress status were determined, and histological examination using light and transmission electron microcopies and western blot analysis were also performed. Results revealed that treatment with SAA alleviated histological damages, relieved proteinuria, hypoalbuminemia and hyperlipidemia, reduced oxidative stress, as well as improving hemorheology. Furthermore, SAA restored podocin expression, down-regulated the expression of NF-κB p65 and p-IκBα while up-regulating IκBα protein expression. Overall, as a multifunctional agent, SAA has a favorable renoprotection in doxorubicin-induced nephropathy. The anti-inflammation, antioxidant, amelioration of podocyte injury, improvement of hemorheology and hypolipidemic properties may constituent an important part of its therapeutic effects. All these indicate that SAA is likely to be a promising agent for NS.

Functional and morphological olfactory bulb modifications in mice after vanadium inhalation

Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases.

Oxidant stress in primary nephrotic syndrome: does it modulate the response to corticosteroids?

In order to assess the oxidative stress in newly diagnosed children with primary nephrotic syndrome (PNS), we serially measured serum total antioxidant capacity (TAC) and malondialdehyde (MDA) in 33 children with PNS and ten healthy matched controls. Patients were classified into two groups: those who had steroid-sensitive nephrotic syndrome (SSNS; n = 26) and those who had steroid-resistant nephrotic syndrome (SRNS; n = 7). Of the patients with SSNS, 15 were non-relapsers and 11 were relapsers. At the proteinuric phase, all patients had significantly higher MDA levels and lower TAC than the controls. These changes were more marked in patients with SRNS than in those with SSNS. During remission and still on corticosteroids, patients had higher TAC and similar MDA levels as in the proteinuric phase, but the TAC and MDA levels still significantly differed from those of the controls. More improvement in TAC and MDA levels occurred in patients following the weaning of corticosteroids, but TAC was still lower in the patients than in the controls. Moreover, TAC was higher in non-relapsers than in relapsers. Using a receiver operating characteristic curve, the initial response to corticosteroids could be predicted at serum TAC level > or =0.73 mM/L (sensitivity 89%, specificity 86%), while serum TAC levels < or = 1.14 mM/L after the weaning of corticosteroids could predict that the patient would not relapse (sensitivity 91%, specificity 80%). In conclusion, based on our results, PNS can be considered to be associated with oxidative stress even during remission. This stress may modulate the response to corticosteroids. Further prospective studies using larger numbers of patients are needed to validate these results.

Functions and oxidative stress status of leukocytes in patients with nephrotic syndrome

This study was conducted to establish the functions and oxidative stress status in leukocytes of adult patients with nephrotic syndrome. Thirty adult patients with nephrotic syndrome and 32 controls were included. Phagocytosis ability, the killing ability of the micro-organism phagosited of polymorphonuclear leukocytes (PMNL) and monocytes, along with oxidative stress parameters of PMNLs were assessed. There was no statistically significant difference in phagocytosis function of PMNLs and monocytes of patients when compared to those of controls. PMNL burst activities of the patient and control groups also showed no difference; however, the monocyte burst activities of patients were significant (p = 0.012). The glutathione peroxidase (GSH-Px) activities in PMNLs of the patients with nephrotic syndrome were significantly higher (p = 0.026) when compared to those of controls. In comparison with those of the control subjects, the patients had also higher selenium levels in their PMNLs (p < 0.001). Although PMNL malonyldialdehyde (MDA) levels of the patients seem to be higher than those of controls, the difference had no statistical significance (p = 0.071). Conclusively, in the patients with nephrotic syndrome, PMNLs appear to be exposed to an oxidative stress as indicated by their increased GSH-Px activities and selenium content. However, PMNLs in nephrotic syndrome patients seem to be coping with the insulting oxidative stress, as suggested by their near-normal MDA productions. Furthermore, these data suggest that nephrotic syndrome appears not to have an influence on phagocytosis and killing abilities of granulocytes and monocytes as long as these cells can overcome the oxidative stress to which they are exposed in this disease.

Effect of selenium-deficient diet on tubular epithelium in normal rats

Selenium (Se) deficiency reduces glutathione peroxidase (GPx) activity, resulting in increased oxidative stress. We examined how Se deficiency induces renal injury via oxidative stress over time during the Se-deficient period. Seventy-two male Wistar rats were divided into two groups and fed either a control or Se-deficient diet. Rats were sacrificed on weeks 1, 2, 4, 6, 9, and 12. Blood and urine samples were collected, and the kidneys were removed. Urinalysis was performed, and creatinine clearance (Ccr) was calculated. Expressions of cellular GPx (cGPx) and phospholipid hydroperoxidase GPx (PHGPx) mRNA and GPx activity were measured. Histology was evaluated by light microscopy with immunohistochemistry for 4-hydroxy-2-nonenal (HNE) and vimentin. The Se-deficient diet caused significant decreases in GPx activity and cGPx mRNA expression but no change in PHGPx mRNA, together with significant proteinuria and glucosuria and slight decline in Ccr. The Se-deficient diet induced calcification in the kidney and increased the distribution of HNE and vimentin immunostaining in proximal tubuli, particularly around the outer medulla stripe. However, the histological damage did not progress after 6 weeks of deficiency. Se deficiency induces proteinuria and glucosuria with renal calcification, which may be primarily induced by injury of proximal tubuli via oxidative stress.

Puromycin aminonucleoside induces oxidant-dependent DNA damage in podocytes in vitro and in vivo

A decline in podocyte number correlates with progression to glomerulosclerosis. A mechanism underlying reduced podocyte number is the podocyte's relative inability to proliferate in response to injury. Injury by the podocyte toxin puromycin aminonucleoside (PA) is mediated via reactive oxygen species (ROS). The precise role of ROS in the pathogenesis of PA-induced glomerulosclerosis remains to be determined. We sought to examine whether PA-induced ROS caused podocyte DNA damage, possibly accounting for the podocyte's inability to proliferate in response to PA. In vitro, podocytes were exposed to PA, with or without the radical scavenger 1,3-dimethyl-2-thiourea (DMTU). In vivo, male Sprague-Dawley rats were divided into experimental groups (n = 6/group/time point): PA, PA with DMTU, and control, killed at days 1.5, 3, or 7. DNA damage was measured by DNA precipitation, apurinic/apyrimidinic site, Comet, and 8-hydroxydeoxyguanosine assays. Cell cycle checkpoint protein upregulation (by immunostaining and Western blotting), histopathology, and biochemical parameters were examined. DNA damage was increased in cultured podocytes that received PA, but not PA with DMTU. PA exposure activated specific cell cycle checkpoint proteins, with attenuation by DMTU. DNA repair enzymes were activated, providing evidence for attempted DNA repair. The PA-treated animals developed worse proteinuria and histopathologic disease and exhibited more DNA damage than the DMTU pretreated group. No significant apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining. A mechanism underlying the lack of podocyte proliferation following PA-induced injury in vitro and in vivo may be ROS-mediated DNA damage, with upregulation of specific cell cycle checkpoints leading to cell cycle arrest.

Antioxidant enzymes in hypertensive and hypertriglyceridemic rats: effect of gender

In a model of hypertensive and hypertriglyceridemic rats (HTG), in which oxidative stress is increased, the influence of gender upon activities of catalase (CAT), glutathione peroxidase (GPX), and superoxide dismutase (SOD) was investigated. Statistically significant differences between antioxidant enzyme activities and treatment with relation to gender were analyzed. Weanling Wistar rats were given normal rat chow and either tap water for control group or 30% sucrose solution for HTG group, for 5-6 months. At the end of the experimental period, blood pressure was significantly higher in both male and female HTG groups, but males showed higher values than females. Serum, heart, kidney, and liver were obtained to determine antioxidant enzyme activities. Activities of CAT and GPX tended to be higher in male animals. A larger number of significant changes in enzyme activities associated with gender appears in HTG than in controls, which indicates the harmful effect of the treatment.

Activities of antioxidant enzymes in two stages of pathology development in sucrose-fed rats

The activities of catalase in liver, heart and kidney as well as glutathione peroxidase and superoxide dismutase in liver, heart, kidney, and serum from hypertriglyceridemic and hypertensive female and male rats were measured at 3 and 8 months of daily administration of sucrose in their drinking water. This treatment induces high levels of serum triglycerides, central obesity, moderate hypertension, hyperinsulinemia, and an increase in lipoper oxida tion, among other alterations. The experimental periods were chosen on the basis of previous observations: at 3 months the level of serum triglycerides increases significantly above the normal value and remains without major changes thereafter, but the blood pressure only rises significantly at about 4 months in males and 5 months in females. So, at 8 months the rats have been subjected to abnormal conditions for 3–4 months. The effect of these and the influence of sex on levels of antioxidant enzymes were investigated. Both factors, sucrose treatment and sex, were conducive to significant changes in those variables.Key words: antioxidant enzymes, gender influence, hypertriglyceridemia, hypertension, sucrose-fed rats.

Soy protein diet ameliorates renal nitrotyrosine formation and chronic nephropathy induced by puromycin aminonucleoside

It has been shown that reactive oxygen species are involved in chronic puromycin aminonucleoside (PAN) induced nephrotic syndrome (NS) and that a 20% soy protein diet reduces renal damage in this experimental model. The purpose of the present work was to investigate if a 20% soy protein diet is able to modulate kidney nitrotyrosine formation and the activity of renal antioxidant enzymes (catalase, glutathione peroxidase, Cu,Zn- or Mn-superoxide dismutase) which could explain, at least in part, the protective effect of the soy protein diet in rats with chronic NS induced by PAN. Four groups of rats were studied: (1) Control rats fed 20% casein diet, (2) Nephrotic rats fed 20% casein diet, (3) Control rats fed 20% soy protein diet, and (4) Nephrotic rats fed 20% soy protein diet. Chronic NS was induced by repeated injections of PAN and rats were sacrificed at week nine. The soy protein diet ameliorated proteinuria, hypercholesterolemia, and the increase in serum creatinine and blood urea nitrogen observed in nephrotic rats fed 20% casein diet. Kidney nitrotyrosine formation increased in nephrotic rats fed 20% casein diet and this increase was ameliorated in nephrotic rats fed 20% soy protein diet. However, the soy protein diet was unable to modulate the antioxidant enzymes activities in control and nephrotic rats fed 20% soy protein diet. Food intake was similar in the two diet groups. The protective effect of a 20% soy protein diet on renal damage in chronic nephropathy induced by PAN was associated with the amelioration in the renal nitrotyrosine formation but not with the modulation of antioxidant enzymes.

Protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity in rats: the indispensability of HO-1 preinduction and lack of association with some antioxidant enzymes

We have shown that the ameliorative effect of stannous chloride (SnCl2) pretreatment on potassium dichromate (K2Cr2O7)-induced renal damage 24 h after K2Cr2O7 injection was associated with the induction of heme oxygenase-1 (HO-1). In this work we evaluated: (a) if the protective effect of SnCl2 (given 12 h before K2Cr2O7) is associated with changes in the renal activity of HO-1, superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and catalase (CAT) 24 and 48 h after K2Cr2O7 injection, and (b) if HO-1 induction is indispensable before K2Cr2O7 injection. It was found that the protective effect of SnCl2 on renal function was observed both at 24 and 48 h reaching its maximum at 24 h when HO-1 expression was higher. Cu,Zn-SOD, Mn-SOD, and GR activities remained unchanged whereas GPx and CAT activities decreased at 48 h in K2Cr2O7-treated rats. The activity of Cu,Zn-SOD, Mn-SOD, GPx, CAT, and GR was unchanged in the SnCl2-treated rats. To fulfill the objective (b) groups of rats treated with K2Cr2O7 and SnCl2 (given at the same time or 12 h after K2Cr2O7) were studied 24 h after K2Cr2O7-injection. The simultaneous injections of SnCl2 and K2Cr2O7 had no protective effect whereas the injection of SnCl2 12 h after K2Cr2O7 exacerbated renal damage. In conclusion, the protective effect of SnCl2 on K2Cr2O7-induced nephrotoxicity is associated with HO-1 induction and not with other antioxidant enzymes (Cu,Zn-SOD, Mn-SOD, GPx, GR, and CAT) and SnCl2 has a preventive and not a therapeutic effect on renal damage induced by K2Cr2O7.

Antioxidant therapy potentiates antihypertensive action of insulin in diabetic rats

BACKGROUND

Poorly controlled longstanding diabetes frequently results in sustained hypertension (HTN) which plays a major role in the pathogenesis of diabetic nephropathy. In addition, hyperglycemia, per se, causes a reversible rise in blood pressure (BP) and increases production of reactive oxygen species (ROS). Increased ROS activity may raise BP by promoting inactivation of nitric oxide (NO) and/or nonenzymatic generation of vasoconstrictive prostaglandins from peroxidation of arachidonic acid. Therefore, we hypothesized that antioxidant therapy may enhance the BP-lowering effect of glycemia control with insulin replacement in diabetes.

METHODS

Male Sprague-Dawley rats were rendered diabetic by streptozotocin administration and randomized to untreated, antioxidant-treated (vitamin E-fortified food, tocopherol 5000 U/kg chow and vitamin C-fortified H2O, 1000 mg/L), insulin-treated and insulin plus antioxidant-treated groups. Normal rats fed a regular diet or antioxidant-fortified diet served as controls and monitored for 4 weeks.

RESULTS

The diabetic animals showed marked hyperglycemia, HTN, proteinuria, depressed tissue glutathione level and elevated plasma lipid peroxidation product, malondialdehyde (MDA) denoting increased ROS activity. Insulin therapy alone resulted in significant, but incomplete reduction in BP and plasma MDA but not proteinuria. Antioxidant therapy alone had no effect on the measured parameters in either the diabetic or control animals. However, combined insulin and antioxidant therapies normalized BP, plasma MDA and urinary protein in the diabetic animals. As expected, uncontrolled diabetes resulted in glomerular hyperfiltration which was partially reversed by insulin therapy, but was unaffected by antioxidant therapy.

CONCLUSION

Uncontrolled hyperglycemia in the early phase of diabetes was associated with elevated plasma MDA, HTN and proteinuria. Insulin therapy alone resulted in significant but incomplete reduction of plasma MDA and BP. Antioxidant therapy which was ineffective when given alone, normalized plasma MDA, BP and reduced urinary protein excretion when combined with insulin treatment.

Selenium-deficient diet induces renal oxidative stress and injury via TGF-beta1 in normal and diabetic rats

BACKGROUND

Oxidative stress has been implicated in the pathogenesis of diabetic nephropathy. Although glucose itself can initiate oxidative stress, deficiency of essential trace elements such as selenium (Se) may exacerbate this oxidative stress in diabetic rats. The mechanism by which Se deficiency causes oxidative stress and renal injury is not completely understood. This study tested the hypothesis that Se deficiency induces renal oxidative stress and renal injury via transforming growth factor-beta1 (TGF-beta1).

METHODS

Fifty-four male Wistar rats were used. Diabetes was induced in 27 rats by streptozotocin, and the other 27 rats received buffer only. Ten weeks after induction of diabetes, both normal and diabetic rats were killed, their kidneys removed, and glomeruli were isolated. Glomeruli from normal and diabetic rats were incubated in the presence of TGF-beta1 alone or its neutralizing antibody. Antioxidant enzyme (Cu-Zn) superoxide dismutase (Cu-Zn SOD), catalase, and glutathione peroxidase (GSH-Px) activities; total glutathione; and lipid peroxidation were determined. For Se studies, 15 normal and 15 diabetic rats were divided into groups of five each and fed either a regular, Se-deficient, or Se-supplemented diet one week after induction of diabetes. Ten weeks after feeding these diets, rats were killed and glomeruli were isolated. Oxidative stress was examined by determining the mRNA expressions for antioxidant enzymes and also for TGF-beta1. Plasma glucose and albuminuria were determined. Histology of the kidney and interlobular artery was evaluated by light microscopy.

RESULTS

In vitro studies showed that TGF-beta1 significantly reduced glomerular catalase and GSH-Px activities as well as total glutathione levels with an increase in lipid peroxidation in both normal and diabetic rats. Antibody to TGF-beta abrogated these changes. There was no effect of TGF-beta1 on Cu-Zn SOD. Like TGF-beta1, a Se-deficient diet caused a significant decrease in glomerular mRNA expression for Cu-Zn SOD, catalase, and GSH-Px, but a significant increase in TGF-beta1 mRNA expression. Also, a Se-deficient diet caused an increase in albuminuria, glomerular sclerosis, and plasma glucose levels in both normal and diabetic rats. The deficient diet caused a decrease in the lumen size of the interlobular artery. Se supplementation to diabetic rats up-regulated mRNA expression for antioxidant enzymes, and significantly reduced but did not normalize that of TGF-beta1. Glomerular sclerosis was normalized and the interlobular artery lumen size was greatly enlarged in diabetic rats by Se supplementation. Also, the tubulointerstitium was preserved by Se supplementation in diabetic rats.

CONCLUSIONS

The data show that TGF-beta1 is a pro-oxidant and Se deficiency increases oxidative stress via this growth factor. In addition, Se deficiency may simulate hyperglycemic conditions. Se supplementation to diabetic rats prevents not only oxidative stress but renal structural injury, as well.

Post-transcriptional control of catalase expression in garlic-treated rats

Regulation of catalase (CAT) expression, a major antioxidant enzyme that detoxifies H2O2, is very complex. Garlic is effective to prevent or ameliorate oxidative stress probably through its intrinsic antioxidant properties and/or to its ability to modify antioxidant enzyme expression. In this paper we studied the effect of a 2% garlic diet on the renal and hepatic CAT expression (mRNA levels, and enzyme activity, content, synthesis, and degradation). The study was made 2 weeks after feeding rats with a 2% garlic diet. CAT activity and content were measured by a spectrophotometric method and Western blot, respectively. CAT mRNA levels and CAT synthesis (k(s)) and degradation (kD) in vivo were measured by Northern blot and kinetic of reappearance of CAT activity after aminotriazole injection, respectively. Garlic-treatment decreased CAT activity and content, and CAT mRNA levels were unchanged in both tissues. k(s) decreased and kD remained unchanged in kidney and liver. The decrease in k(s) without changes in kD and CAT mRNA levels could explain the low CAT expression in garlic-fed rats. In vivo H2O2 generation in kidney and liver was markedly decreased in garlic-fed rats which could be due to a direct antioxidant effect of garlic. This may be the initial event in the garlic-fed rats that leads to the decreased CAT expression. Our data strongly suggest that the diminished renal and hepatic CAT expression in garlic-fed rats is mediated by post-transcriptional changes (mainly low translational efficiency) which could be an adaptation to the low H2O2.

Garlic ameliorates gentamicin nephrotoxicity: relation to antioxidant enzymes

Reactive oxygen species are involved in gentamicin (GM) nephrotoxicity, and garlic is effective in preventing or ameliorating oxidative stress. Therefore, the effect of garlic on GM nephrotoxicity was investigated in this work. Four groups of rats were studied: (i) fed normal diet (CT), (ii) treated with GM (GM), (iii) fed 2% garlic diet (GA), and (iv) treated with GM and 2% garlic diet (GM + GA). Rats were placed in metabolic cages and GM nephrotoxicity was induced by injections of GM (75 mg/kg every 12 h) for 6 d. Lipoperoxidation and enzyme determinations were made in renal cortex on day 7. GM nephrotoxicity was made evident on day 7 by (i) tubular histological damage, (ii) enhanced BUN and urinary excretion of N-acetyl-beta-D-glucosaminidase, and (iii) decreased creatinine clearance. These alterations were prevented or ameliorated in GM + GA group. The rise in lipoperoxidation and the decrease in Mn-SOD and glutathione peroxidase (GPx) activities observed in the GM group, were prevented in the GM + GA group. Cu, Zn-SOD activity and Mn-SOD and Cu,Zn-SOD content did not change. CAT activity and content decreased in the GM, GA, and GM + GA groups. CAT mRNA levels decreased in the GM group. The protective effect of garlic is associated with the prevention of the decrease of Mn-SOD and GPx activities and with the rise of lipoperoxidation in renal cortex.

Tissue distribution of alpha-tocopherol in nephrotic rats

1. Reactive oxygen species are involved in the pathogenesis of puromycin aminonucleoside (PAN) nephrosis and alpha-tocopherol is one of the major anti-oxidants in the body. 2. In the present study, we measured the levels of alpha-tocopherol by high-performance liquid chromatography in the plasma and in nine tissues of control and nephrotic rats obtained 10 days after either 0.9% saline solution or PAN injection, respectively. 3. In nephrotic rats, alpha-tocopherol levels increased four-fold in plasma; however, the molar ratio of alpha-tocopherol/ cholesterol remained unchanged, suggesting that the increase in alpha-tocopherol content was attributable to an increase in plasma lipid concentration. 4. In nephrotic rats, the alpha-tocopherol/cholesterol ratio increased 1.33-fold in adrenal glands and 1.34-fold in the testis, but remained unchanged in heart, spleen, liver, kidney lung, brain and muscle. 5. These data suggest that, in PAN nephrotic rats, there are alterations in the distribution of alpha-tocopherol and there is no deficiency of alpha-tocopherol in plasma or tissues.

Effect of the in vivo catalase inhibition on aminonucleoside nephrosis

Reactive oxygen species have been involved in the pathophysiology of puromycin aminonucleoside (PAN)-nephrosis. The role of H2O2 in these rats may be studied modulating the amount or activity of catalase, which breakdowns H2O2 to water and oxygen. To explore the role of H2O2 in this experimental model, we studied the effect of the in vivo catalase inhibiton with 3-amino-1,2,4-triazole (ATZ) on the course of PAN-nephrosis. Four groups of rats were studied: control rats (CT group), PAN-injected rats (PAN group), ATZ-injected rats (ATZ group), and ATZ- and PAN-injected rats (ATZPAN group). Rats were placed in metabolic cages to collect 24 h urine along the study, ATZ (1 g/kg) was given 24 h before PAN injection (75 mg/kg), and the proteinuria was measured on days 0, 2, 4, 6, 8, and 10. Proteinuria started before (day 4) and was significantly higher on days 6, 8, and 10 in the ATZPAN group than in the PAN group. On day 10, hypercholesterolemia was significantly higher in the ATZPAN group than in the PAN group. These data indicate that the in vivo catalase inhibition magnifies PAN-nephrosis, suggesting that H2O2 is produced in vivo and involved in the renal damage in this experimental disease.

Biochemical bone markers, bone mineral content, and bone mineral density in rats with experimental nephrotic syndrome

The human nephrotic syndrome (NS) is accompanied by important alterations of mineral and bone metabolism. The purpose of the present study was to examine bone metabolism in rats with experimental NS and normal creatinine clearance, and to evaluate the reversibility of this alteration. NS was induced by three injections of puromycin aminonucleoside (PAN) on days 0, 21, and 35 (10, 5, and 5 mg/100 g body weight, respectively). The biochemical markers of bone formation (osteocalcin and alkaline phosphatase) and bone resorption (hydroxyproline and pyridinoline), bone mineral content (BMC), and bone mineral density (BMD), determined by dual-energy x-ray absorptiometry (DEXA), were studied on days 0, 7, 14, 28, 42, 56, 84, and 112. Proteinuria was present throughout the study. Hypoproteinemia was seen on days 7, 28, 42, and 56, returning to control values on days 84 and 112. In serum, osteocalcin (OC) concentration increased (p < 0.001), and alkaline phosphatase (ALP) decreased (p = 0.002). In urine, hydroxyproline increased (p < 0.001), but urinary pyridinoline was not different from the control group throughout the study. Increased serum parathyroid hormone concentration and decreased levels of 25-hydroxy and 1,25-dihydroxyvitamin D were found from day 7. During the intense proteinuria, bone resorption predominates and decreased BMC and BMD ensues in PAN-nephrotic rats. PAN-nephrotic rats showed low BMC and BMD compared to control group (p < 0.001). At the end of the study, when proteinuria persisted but total serum protein returned to control values, the biochemical bone markers, BMC, and BMD returned to normal. In conclusion, PAN-nephrotic rats had reversible bone alterations that were related to the magnitude of proteinuria and the concentration of total serum protein.

Dietary antioxidant inhibits lipoprotein oxidation and renal injury in experimental focal segmental glomerulosclerosis

Lipid peroxidation may be involved in the pathogenesis of focal segmental glomerulosclerosis (FSGS). In the present study we examined whether lipid-soluble antioxidants, probucol and vitamin E, could inhibit renal injury in rats with chronic puromycin aminonucleoside (PA) nephrosis and dietary hypercholesterolemia by protecting lipoproteins from oxidation. Male Sprague-Dawley rats received six intraperitoneal injections of PA over a 10 week period and were fed a high cholesterol (HC) diet (PA-HC) or the same diet supplemented with either 1% probucol or vitamin E (100 IU/kg) for 32 weeks. For comparison, a group of rats received PA injections and a normal diet (PA-normal) with or without probucol or vitamin E. Another group rats received saline injections instead of PA and were fed a HC diet (Sal-HC) with or without probucol or vitamin E. At the end of the experiment, proteinuria, FSGS and tubulointerstitial lesions were present in the untreated rats with PA-HC or PA-normal. The magnitude of these lesions was significantly greater in the PA-HC rats than the PA-normal. In contrast to the PA-HC group with hypercholesterolemia, the PA-normal group did not show hypercholesterolemia from week 16 onwards. The rats with PA-HC alone showed significantly higher renal cortical malondialdehyde (MDA) levels and greater susceptibility of plasma very low density lipoprotein (VLDL) + low density lipoprotein (LDL) to the copper-mediated oxidation than the rats with PA-normal or Sal-HC alone. The administration of probucol or vitamin E in the rats with PA-HC significantly reduced the susceptibility of plasma VLDL + LDL to in vitro oxidation, renal cortical MDA level, proteinuria, mesangial volume density and magnitude of FSGS and interstitial lesions. Immunohistochemical staining of renal tissue showed focal segmental distribution of oxidized LDL (Ox-LDL) in the glomeruli of rats with PA-HC. Administration of probucol or vitamin E reduced the intensity of Ox-LDL staining. The staining with ED1 demonstrated that infiltrating glomerular macrophages were significantly more prevalent in the untreated rats with PA-HC than PA-normal or Sal-HC. Treatment with probucol or vitamin E significantly reduced the number of glomerular macrophages in the rats with PA-HC. These results suggest that alimentary hypercholesterolemia aggravates the renal damage in association with increased renal lipid peroxides in chronic PA nephrosis, and that dietary probucol or vitamin E attenuates renal injury in rats with PA-HC possibly by making lipoproteins resistant to oxidation and by inhibiting intraglomerular macrophage infiltration.