Renal injury after uninephrectomy in male and female intrauterine growth-restricted aged rats.
ABSTRACT: Epidemiological studies report an inverse association between birth weight and risk for kidney disease that may differ between males and females, but studies investigating this association are limited. This study tested the hypothesis that male intrauterine growth-restricted offspring in a model of low birth weight induced by placental insufficiency in the rat exhibit enhanced renal injury in response to a persistent secondary renal insult while female growth-restricted offspring are protected. For this study, control offspring from sham-operated dams and growth-restricted offspring from reduced uterine perfusion dams underwent uninephrectomy or a sham procedure at 18 months of age. One month later, urinary markers of renal injury, renal function, and histological damage were measured. Results were analyzed using 2-way ANOVA. Male and female offspring were assessed separately. Proteinuria and urinary neutrophil gelatinase-associated lipocalin were significantly elevated in male growth-restricted offspring exposed to uninephrectomy when compared to male uninephrectomized control. Urinary kidney injury marker-1 was elevated in male uninephrectomized growth-restricted offspring relative to male sham growth-restricted but not to male uninephrectomized controls. Likewise, urinary neutrophil gelatinase-associated lipocalin was elevated in female uninephrectomized growth-restricted offspring but only when compared to female sham growth-restricted offspring. Markers of renal function including glomerular filtration rate and serum creatinine were impaired after uninephrectomy in female offspring regardless of birth weight. Histological parameters did not differ between control and growth-restricted offspring. Collectively, these studies suggest that both male and female growth-restricted offspring demonstrate susceptibility to renal injury following uninephrectomy; however, only male growth-restricted offspring exhibited an increase in renal markers of injury in response to uninephrectomy relative to same-sex control counterparts. These findings further suggest that urinary excretion of protein, kidney injury marker-1, and neutrophil gelatinase-associated lipocalin may be early markers of kidney injury in growth-restricted offspring exposed to a secondary renal insult such as reduction in renal mass.
Project description:The molecular mechanism underlying renal hypertrophy and progressive nephron damage remains poorly understood. Here we generated congenic ribosomal protein S6 (rpS6) knock-in mice expressing nonphosphorylatable rpS6 and found that uninephrectomy-induced renal hypertrophy was significantly blunted in these knock-in mice. Uninephrectomy-induced increases in cyclin D1 and decreases in cyclin E in the remaining kidney were attenuated in the knock-in mice compared with their wild-type littermates. Uninephrectomy induced rpS6 phosphorylation in the wild-type mice; however, no rpS6 phosphorylation was detected in uninephrectomized or sham-operated knock-in mice. Nonetheless, uninephrectomy stimulated comparable 4E-BP1 phosphorylation in both knock-in and wild-type mice, indicating that mTORC1 was still activated in the knock-in mice. Moreover, the mTORC1 inhibitor rapamycin prevented both rpS6 and 4E-BP1 phosphorylation, significantly blunted uninephrectomy-induced renal hypertrophy in wild-type mice, but did not prevent residual renal hypertrophy despite inhibiting 4E-BP1 phosphorylation in uninephrectomized knock-in mice. Thus, both genetic and pharmacological approaches unequivocally demonstrate that phosphorylated rpS6 is a downstream effector of the mTORC1-S6K1 signaling pathway mediating renal hypertrophy. Hence, rpS6 phosphorylation facilitates the increase in cyclin D1 and decrease in cyclin E1 that underlie the hypertrophic nature of uninephrectomy-induced kidney growth.
Project description:Numerous experimental studies suggest that oxidative stress contributes to the pathophysiology of hypertension and, importantly, that oxidative stress plays a more definitive role in mediating hypertension in males than in females. Intrauterine growth restriction induced by reduced uterine perfusion initiated at day 14 of gestation in the rat programs hypertension in adult male growth-restricted offspring; yet, female growth-restricted offspring are normotensive. The mechanisms mediating sex differences in blood pressure in adult growth-restricted offspring are not clear. Thus, this study tested the hypothesis that sex-specific differences in renal oxidative stress contribute to the regulation of blood pressure in adult growth-restricted offspring. A significant increase in blood pressure measured by telemetry in male growth-restricted offspring (P<0.05) was associated with a marked increase in renal markers of oxidative stress (P<0.05). Chronic treatment with the antioxidant Tempol had no effect on blood pressure in male control offspring, but it normalized blood pressure (P<0.05) and renal markers of oxidative stress (P<0.05) in male growth-restricted offspring relative to male control offspring. Renal markers of oxidative stress were not elevated in female growth-restricted offspring; however, renal activity of the antioxidant catalase was significantly elevated relative to female control offspring (P<0.05). Chronic treatment with Tempol did not significantly alter oxidative stress or blood pressure measured by telemetry in female offspring. Thus, these data suggest that sex differences in renal oxidative stress and antioxidant activity are present in adult growth-restricted offspring and that oxidative stress may play a more important role in modulating blood pressure in male but not female growth-restricted offspring.
Project description:Type 2 diabetes (DM2) could be reproduced in rats with alimentary obesity by using low doses of streptozotocin (LD-STZ) as well as STZ in high doses with preliminary nicotinamide (NA) administration. However, STZ could induce tubulotoxicity. <i>Aim</i>. To develop rat model of DN in NA-STZ-induced DM2 and compare it with LD-STZ-model in order to choose the most relevant approach for reproducing renal glomerular and tubular morphofunctional diabetic changes. Starting at 3 weeks after uninephrectomy, adult male Wistar rats were fed five-week high-fat diet and then received intraperitoneally either LD-STZ (40?mg/kg) or NA (230?mg/kg) followed by STZ (65?mg/kg). Control uninephrectomized vehicle-injected rats received normal chow. At weeks 10, 20, and 30 (the end of the study), metabolic parameters, creatinine clearance, albuminuria, and urinary tubular injury markers (NGAL, KIM-1) were evaluated as well as renal ultrastructural and light microscopic changes at weeks 20 and 30. NA-STZ-group showed higher reproducibility and stability of metabolic parameters. By week 10, in NA-STZ-group NGAL level was significantly lower compared to LD-STZ-group. By week 30, diabetic groups showed early features of DN. However, morphofunctional changes in NA-STZ-group appeared to be more pronounced than those in STZ-group despite lower levels of KIM-1 and NGAL. We proposed a new rat model of DM2 with DN characterized by stable metabolic disorders, typical renal lesions, and lower levels of tubular injury markers as compared to LD-STZ-induced diabetes.
Project description:Platelet-rich plasma (PRP) has grown as an attractive biologic instrument in regenerative medicine for its powerful healing properties. It is considered as a source of growth factors that may induce tissue repairing and improve fibrosis. This product has proven its efficacy in multiple studies, but its effect on cisplatin-induced nephrotoxicity has not yet been elucidated. The present investigation was performed to estimate the protective impact of platelet-rich plasma against cisplatin- (CP-) evoked nephrotoxicity in male rats. Nephrotoxicity was induced in male Wistar rats by right uninephrectomy followed by CP administration. Uninephrectomized rats were assigned into four groups: (1) control group, (2) PRP group, (3) CP group, and (4) CP?+?PRP group. PRP was administered by subcapsular renal injection. Renal function, inflammatory cytokines, and growth factor level as well as histopathological investigation were carried out. Treatment with PRP attenuated the severity of CP-induced nephrotoxicity as evidenced by suppressed creatinine, blood urea nitrogen (BUN), and N-acetyl glucosaminidase (NAG) levels. Moreover, PRP depressed intercellular adhesion molecule-1 (ICAM-1), kidney injury molecule-1 (KIM-1), caspase-3, and transforming growth factor-beta 1 (TGF-?1) levels, while enhanced the epidermal growth factor (EGF) level. These biochemical results were reinforced by the histopathological investigation, which revealed restoration of normal renal tissue architectures. These findings highlight evidence for the possible protective effects of PRP in a rat model of CP-induced nephrotoxicity, suggesting a new avenue for using PRP to improve the therapeutic index of cisplatin.
Project description:Prenatal hypoxia is associated with growth restriction and adverse cardiovascular outcomes. Here, we describe renal and cardiovascular outcomes in ageing mouse offspring prenatally exposed to hypoxia (12% O<sub>2</sub>) from embryonic day 14.5 until birth. At 12 months of age, both male and female offspring exposed to prenatal hypoxia had elevated mean arterial pressure. Glomerular number was reduced by 25% in hypoxia-exposed male, but not female, offspring and this was associated with increased urinary albumin excretion, glomerular hypertrophy and renal fibrosis. Hypoxia-exposed offspring of both sexes were more susceptible to salt-induced cardiac fibrosis, however, renal fibrosis was exacerbated by high salt in males only. In male but not female hypoxia-exposed offspring, renal renin mRNA was increased at weaning. By 12 months, renal renin mRNA expression and concentrations were elevated in both sexes. mRNA expression of At <sub>1a</sub> R was also elevated in male hypoxia-exposed offspring at 12 months. These results demonstrate that prenatal hypoxia programs elevated blood pressure and exacerbates salt-induced cardiovascular and renal pathology in a sex specific manner. Given sex differences observed in RAS expression and nephron number, future studies may consider RAS blockade as a therapeutic target in this model.
Project description:Uninephrectomy is not associated with major adverse events in cardiovascular and renal functions of live kidney donors. The effect of high salt diet on the quality of life of live kidney donors is largely unknown. Hence in this study, we aimed to determine the effect of high salt diet on the alterations of renin-angiotensin system and microRNAs leading to CV and renal dysfunction in uninephrectomized rats. In order to mimic clinical scenario, uninephrectomized male Sprague Dawley rats were fed initially with normal pellet diet for 12 weeks and then for 20 weeks with high salt (10% w/w NaCl) diet. At the end of the study, biochemical, functional, histological and molecular parameters were measured. High salt diet feeding resulted in renal dysfunction & fibrosis, decreased baroreflex sensitivity, increased in vivo cardiovascular reactivity to angiotensin II owing to upregulation of angiotensin II type 1 receptors and L-type calcium channels leading to cardiovascular dysfunction in uninephrectomized rats (UNX+HSD) worse than that of normal (binephric) rats fed with high salt diet (HSD). Protein expression of functional and hypertrophic protein markers revealed decreased SERCA, p-AMPK and increased p-AKT. Interestingly, levels of miR-25, miR-451 and miR-155 increased and miR-99 decreased in heart of uninephrectomized rats fed with high salt. However, circulating miR-25 and miR-451 levels decreased and miR-99b increased in these animals. Our study points out that since tissue and circulating levels of miRNAs are not similar, caution must be exercised during the usage of miRs as diagnostic or prognostic biomarkers. To our knowledge, we are the first to show that epigenetic alterations result in cardiac dysfunction in uninephrectomized rats fed with high salt diet.
Project description:Activation of the farnesoid X receptor (FXR) has indicated a therapeutic potential for this nuclear bile acid receptor in the prevention of diabetic nephropathy and obesity-induced renal damage. Here, we investigated the protective role of FXR against kidney damage induced by obesity in mice that had undergone uninephrectomy, a model resembling the clinical situation of kidney donation by obese individuals. Mice fed a high-fat diet developed the core features of metabolic syndrome, with subsequent renal lipid accumulation and renal injury, including glomerulosclerosis, interstitial fibrosis, and albuminuria. The effects were accentuated by uninephrectomy. In human renal biopsies, staining of 4-hydroxynonenal (4-HNE), glucose-regulated protein 78 (Grp78), and C/EBP-homologous protein, markers of endoplasmic reticulum stress, was more prominent in the proximal tubules of 15 obese patients compared with 16 non-obese patients. In mice treated with the FXR agonist obeticholic acid, renal injury, renal lipid accumulation, apoptosis, and changes in lipid peroxidation were attenuated. Moreover, disturbed mitochondrial function was ameliorated and the mitochondrial respiratory chain recovered following obeticholic acid treatment. Culturing renal proximal tubular cells with free fatty acid and FXR agonists showed that FXR activation protected cells from free fatty acid-induced oxidative stress and endoplasmic reticulum stress, as denoted by a reduction in the level of reactive oxygen species staining and Grp78 immunostaining, respectively. Several genes involved in glutathione metabolism were induced by FXR activation in the remnant kidney, which was consistent with a decreased glutathione disulfide/glutathione ratio. In summary, FXR activation maintains endogenous glutathione homeostasis and protects the kidney in uninephrectomized mice from obesity-induced injury.
Project description:It is well established that inadequate nutrition during fetal life followed by postnatal overabundance programs adiposity and glucose intolerance. Studies addressing sexual dimorphism in developmental responses to a dietary mismatch are limited; the effect on blood pressure and renal function is understudied. Therefore, this study tested the hypothesis that a mismatch of prenatal and postnatal nutrition heightens cardiorenal and metabolic risk, outcomes that may vary by sex. Male and female offspring from sham-operated (control) or reduced uterine perfusion dams (growth restricted) were fed regular chow or a diet high in fat and sugar (enriched diet) from weaning until 6 months of age. Male and female offspring were assessed separately; 2-way ANOVA was used to investigate interactions between intrauterine growth-restricted and enriched-diet. Blood pressure was increased in all enriched-diet groups but did not differ in enriched-diet male or female growth-restricted versus same-sex control counterparts. Glomerular filtration rate was reduced in male growth-restricted regardless of diet; a decrease exacerbated by the enriched-diet suggesting the pathogenesis of increased blood pressure induced via an enriched-diet differs between male growth-restricted versus male control. An enriched diet was associated with glucose intolerance in male and female control but not male growth-restricted; the enriched diet exacerbated glucose intolerance in female growth-restricted. Thus, these findings indicate male growth-restricted are resistant to impaired glucose homeostasis, whereas female growth-restricted are susceptible to metabolic dysfunction regardless of postnatal diet. Hence, moderation of fat and sugar intake may be warranted in those born low birth weight to ensure minimal risk for chronic disease.
Project description:Perinatal insults program sex differences in blood pressure, with males more susceptible than females. Aging may augment developmental programming of chronic disease, but the mechanisms involved are not clear. We previously reported that female growth-restricted offspring are normotensive after puberty. Therefore, we tested the hypothesis that age increases susceptibility to hypertension in female growth-restricted offspring. Blood pressure remained similar at 6 months of age; however, blood pressure was significantly elevated in female growth-restricted offspring relative to control by 12 months of age (137±3 vs 117±4 mm Hg; P<0.01, respectively). Body weight did not differ at 6 or 12 months of age; however, total fat mass and visceral fat were significantly increased at 12 months in female growth-restricted offspring (P<0.05 vs control). Glomerular filtration rate remained normal, yet renal vascular resistance was increased at 12 months of age in female growth-restricted offspring (P<0.05 vs control). Plasma leptin, which can increase sympathetic nerve activity, did not differ at 6 months but was increased at 12 months of age in female growth-restricted offspring (P<0.05 vs control). Because of the age-dependent increase in leptin, we hypothesized that the renal nerves may contribute to the age-dependent increase in blood pressure. Bilateral renal denervation abolished the elevated blood pressure in female growth-restricted offspring normalizing it relative to denervated female control offspring. Thus, these data indicate that age induces an increase in visceral fat and circulating leptin associated with a significant increase in blood pressure in female growth-restricted offspring, with the renal nerves serving as an underlying mechanism.
Project description:Scavenger receptor A (SR-A) is a key transmembrane receptor in the endocytosis of lipids and contributes to the pathogenesis of atherosclerosis. To assess its role in hyperlipidemic chronic kidney disease, wild-type and SR-A-deficient (knockout) mice underwent uninephrectomy followed by either normal or high-fat diet. After 16 weeks of diet intervention, hyperlipidemic wild-type mice presented characteristic features of progressive nephropathy: albuminuria, renal fibrosis, and overexpression of transforming growth factor (TGF)-?1/Smad. These changes were markedly diminished in hyperlipidemic knockout mice and attributed to reduced renal lipid retention, oxidative stress, and CD11c(+) cell infiltration. In vitro, overexpression of SR-A augmented monocyte chemoattractant protein-1 release and TGF-?1/Smad activation in HK-2 cells exposed to oxidized low-density lipoprotein. SR-A knockdown prevented lipid-induced cell injury. Moreover, wild-type to knockout bone marrow transplantation resulted in renal fibrosis in uninephrectomized mice following 16 weeks of the high-fat diet. In contrast, knockout to wild-type bone marrow transplantation led to markedly reduced albuminuria, CD11c(+) cell infiltration, and renal fibrosis compared to wild-type to SR-A knockout or wild-type to wild-type bone marrow transplanted mice, without difference in plasma lipid levels. Thus, SR-A on circulating leukocytes rather than resident renal cells predominantly mediates lipid-induced kidney injury.