Renal Cortex Of Spontaneously Hypertensive Rats Research Articles

Protective Effects of Combination of Radix Astragali and Radix Salviae Miltiorrhizae on Kidney of Spontaneously Hypertensive Rats and Renal Intrinsic Cells.

To evaluate the effects of combination of Radix Astragali (RA) and Radix Salviae Miltiorrhizae (RS) on kidney of spontaneously hypertensive rats (SHRs) and renal intrinsic cells. SHRs were intragastrically administrated with RA (5.09 g/kg) and RS (2.55 g/kg) either alone or with combination for 4 weeks; valsartan (13.35 mg/kg) was used as a positive control. Blood pressure and renal ultrasonography were monitored periodically. The biomarkers [microalbumin (mALB), cystatin ^C, angiotensin II (Ang II), interleukin-1 beta (IL-1β), and β2-microglobulin (β2-Mg), etc.] in serum and urine were measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions [phosphorylated adenosine 5'-monophosphate-activated protein kinase-α1 (p-AMPKα1), sestrin-β, calcium/calmodulin-dependent protein kinase kinase-β (CaMKK-β), phosphoinositide 3-kinases (PI3K), serine-threonine protein kinase 1 (AKT1), and vascular endothelial growth factor receptor 2 (VEGFR2)] in renal cortex were determined by Western blot. In vitro, the hypertensive cellular model was established by applying 2×10-6 mol/L Ang ^II. The primary human podocytes, human glomerular endothelial cells (HRGECs), and human proximal tubular epithelial cells (HK-2s) were pre-incubated with sulfotanshinone sodium (Tan, 10 μg/mL) and/or calycosin-7-O-β-D-glucoside (Cal, 5 μg/mL). The cellular viability and apoptosis were assayed by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and Annexin V/PI staining, respectively. The level of endothelial nitric oxide synthase (eNOS) in culture supernatant was determined by ELISA. RA+RS signifificantly decreased the diastolic blood pressure, renal vascular resistance index, and parenchymal thickness, increased 24 h urinary volume as well as lowered the levels of urine mALB and serum cystatin ^C, IL-1β and β2-Mg of SHRs (P <0.05 vs. SHRs). The decreased protein levels of p-AMPKα1, sestrinβ and CaMKK-β and the increased protein levels of PI3K, AKT1 and VEGFR2 in renal cortex of SHRs were normalized after RA+RS treatment (P <0.05). In vitro, Tan and Cal attenuated the Ang II-induced abnormal proliferation and increased the apoptosis of HRGECs and HK-2s and improved the level of eNOS in culture supernatant. Whereas, neither of them showed powerful effect on podocyte. The combination of RA and RS had potential effects on alleviating the renal damages of SHRs and the renoprotection was independent of blood pressure level.

BCL6 attenuates renal inflammation via negative regulation of NLRP3 transcription

Renal inflammation contributes to the pathogeneses of hypertension. This study was designed to determine whether B-cell lymphoma 6 (BCL6) attenuates renal NLRP3 inflammasome activation and inflammation and its underlying mechanism. Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were used in the present study. Angiotensin (Ang) II or lipopolysaccharides (LPS) was used to induce inflammation in HK-2 cells, a human renal tubular epithelial (RTE) cell line. NLRP3 inflammasome was activated and BCL6 was downregulated in the kidneys of SHR. Either Ang II or LPS suppressed BCL6 expression in HK-2 cells. BCL6 overexpression in HK-2 cells attenuated Ang II-induced NLRP3 upregulation, inflammation and cell injury. The inhibitory effects of BCL6 overexpression on NLRP3 expression and inflammation were also observed in LPS-treated HK-2 cells. BCL6 inhibited the NLRP3 transcription via binding to the NLRP3 promoter. BCL6 knockdown with shRNA increased NLRP3 and mature IL-1β expression levels in both PBS- or Ang II-treated HK-2 cells but had no significant effects on ASC, pro-caspase-1 and pro-IL-1β expression levels. BCL6 overexpression caused by recombinant lentivirus expressing BCL6 reduced blood pressure in SHR. BCL6 overexpression prevented the upregulation of NLRP3 and mature IL-1β expression levels in the renal cortex of SHR. The results indicate that BCL6 attenuates Ang II- or LPS-induced inflammation in HK-2 cells via negative regulation of NLRP3 transcription. BCL6 overexpression in SHR reduced blood pressure, NLRP3 expression and inflammation in the renal cortex of SHR.

The renoprotective effect of shichimotsukokato on hypertension-induced renal dysfunction in spontaneously hypertensive rats

Antihypertensive treatment is highly important to prevent the progression of chronic kidney disease. Shichimotsukokato (SKT), a traditional Japanese medicine (i.e., Kampo formula), lowered systolic blood pressure (SBP) in experimental animal models of hypertension. However, its mechanism of action has not been fully elucidated. We investigated the potential renoprotective mechanism of SKT in spontaneously hypertensive rats (SHRs). Ten-week-old SHRs were randomly divided into four groups (six rats per group). In the SHR control group, the SBP increased remarkably during the 8-week experimental period. In the SHRs, SKT extract administered orally at a daily dose of 0.45 or 0.15 g/kg significantly suppressed the increase in SBP to the same extent as telmisartan administered orally at a daily dose of 0.01 g/kg. At the end of the experiment, blood, urine, and kidney cortex tissue samples were examined. The SKT treatment significantly decreased urinary albumin excretion to nearly the same level as the telmisartan treatment. A notable loss of chloride channel 5 (ClC-5), a chloride channel in the proximal renal tubules, occurred in the SHR control group. Thus, we concluded that SKT administration significantly ameliorated this decrease. The mechanism of SKT in reducing urinary albumin excretion is mediated, at least partly, by prevention of the loss of ClC-5 in the renal cortex of SHRs.

Incidence and risk factors of acute kidney injury after thoracic endovascular aortic repair for type B aortic dissection

It has been demonstrated that the Angiotensin II (Ang II) contents and its receptor density in the kidney of young spontaneously hypertensive rats (SHRs) were significantly higher than in age-matched Wistar-Kyoto rats (WKYs). Ang II has been proved to induce Epithelial-Mesenchymal Transition (EMT). The present study was aimed at testing the role of miRNA-29b (miR-29b) in Ang II-induced EMT. Differential expression of miR-29b in renal cortex between 15-weeks SHRs and age-matched WKYs was determined by real-time quantitative polymerase chain reaction (RT-qPCR). The effect of miR-29b on EMT-associated genes such as transforming growth factor (TGF-b), a-smooth muscle actin (aSMA), CollagenI (ColI) was examined after transfecting miR-29b mimics (24 h before treatment with 10M Ang II) and miR-29b inhibitor into cultured renal tubular epithelial cells line_NRK-52E cells. Analysis of these genes expression was confirmed by RT-qPCR, western blot and immunofluorescence staining. Downregulation of miR-29b in renal cortex of SHRs was demonstrated by RT-qPCR compared with that of WKYs. Transfection of miR-29b inhibitor significantly increased the expression of TGF-b, a-SMA and ColI, while transfection of miR-29b mimics inhibited Ang II-induced upregulation of these genes expression. Expression of miR-29b in renal cortex of SHRs was decreased. The miR-29b may play a crucial role in EMT. Downregulation of miR-29b may exert a similar effect on NRK-52E cells as those seen in treatment of Ang II, while upregulation of miR-29b may protect NRK-52E cells from EMT induced by Ang II.

MicroRNA-29b protected renal fibrosis

It has been demonstrated that the Angiotensin II (Ang II) contents and its receptor density in the kidney of young spontaneously hypertensive rats (SHRs) were significantly higher than in age-matched Wistar-Kyoto rats (WKYs). Ang II has been proved to induce Epithelial-Mesenchymal Transition (EMT). The present study was aimed at testing the role of miRNA-29b (miR-29b) in Ang II-induced EMT. Differential expression of miR-29b in renal cortex between 15-weeks SHRs and age-matched WKYs was determined by real-time quantitative polymerase chain reaction (RT-qPCR). The effect of miR-29b on EMT-associated genes such as transforming growth factor (TGF-b), a-smooth muscle actin (aSMA), CollagenI (ColI) was examined after transfecting miR-29b mimics (24 h before treatment with 10M Ang II) and miR-29b inhibitor into cultured renal tubular epithelial cells line_NRK-52E cells. Analysis of these genes expression was confirmed by RT-qPCR, western blot and immunofluorescence staining. Downregulation of miR-29b in renal cortex of SHRs was demonstrated by RT-qPCR compared with that of WKYs. Transfection of miR-29b inhibitor significantly increased the expression of TGF-b, a-SMA and ColI, while transfection of miR-29b mimics inhibited Ang II-induced upregulation of these genes expression. Expression of miR-29b in renal cortex of SHRs was decreased. The miR-29b may play a crucial role in EMT. Downregulation of miR-29b may exert a similar effect on NRK-52E cells as those seen in treatment of Ang II, while upregulation of miR-29b may protect NRK-52E cells from EMT induced by Ang II.

Progression of microalbuminuria in SHR is associated with lower expression of critical components of the apical endocytic machinery in the renal proximal tubule

Cumulative epidemiological evidence indicates that the presence of microalbuminuria predicts a higher frequency of cardiovascular events, peripheral disease, and mortality in essential hypertension. Microalbuminuria may arise from increased glomerular permeability and/or reduced proximal tubular reabsorption of albumin by receptor-mediated endocytosis. This study aimed to evaluate the temporal pattern of urinary protein excretion and to test the hypothesis that progression of microalbuminuria is associated with decreased protein expression of critical components of the endocytic apparatus in the renal proximal tubule of spontaneously hypertensive rats (SHR). We found that urinary albumin excretion increased progressively with blood pressure in SHR from 6 to 21 wk of age. In addition, SDS-PAGE analysis of urinary proteins showed that microalbuminuric SHR virtually excreted proteins of the size of albumin or smaller (<70 kDa), typical of tubular proteinuria. Moreover, the protein abundance of the endocytic receptors megalin and cubilin as well as of the chloride channel ClC-5 progressively decreased in the renal cortex of SHR from 6 to 21 wk of age. Expression of the vacuolar H⁺-ATPase B2 subunit was also reduced in the renal cortex of 21-wk-old compared with both 6- and 14-wk-old SHR. Collectively, our study suggests that enhanced urinary protein excretion, especially of albumin, may be due, at least in part, to lower expression of key components of the apical endocytic apparatus in the renal proximal tubule. Finally, one may speculate that dysfunction of the apical endocytic pathway in the renal proximal tubule may contribute to the development of microalbuminuria in essential hypertension.

Estrogen effects on NOS in the renal cortex of Spontaneously Hypertensive Rats (SHR).

Estrogen has been implicated in renal protection afforded females with hypertension. Nitric oxide (NO) is an important regulator of kidney function, and NO levels have are reported to be higher in females. The hypothesis of this study was that estrogen enhances the NO system in the renal cortex of SHR. 14-week old female SHR were studied (n=3–8): gonad-intact, ovariectomized (OVX), and OVX with estrogen replacement (OVXE, 1.7 mg/pellet). Microalbumin (ualb) excretion was used to assess renal injury. OVXE had greater ualb excretion (1.8±0.2 ug/day/gram) compared to intact and OVX (0.8±0.1, 0.6±0.1 ug/day/gram respectively, p=0.003). Nitrite/nitrate (NOx) excretion and NOS protein expression and activity were examined in the renal cortex. NOx excretion was comparable between groups (pmol/day: intact 6.5±0.7, OVX 7.3±0.8, OVXE 6.2±0.7). NOS3 protein expression and phosphorylation of NOS3 on serine residues 1177 and 633 were comparable in all groups. However, NOS1 expression was greater in the cortex from intact females (2.38±.18 RDU) compared to OVX and OVXE (RDU: OVX 1.19±0.24, OVXE 0.67±0.02; p=0.04 vs intact, OVX vs OVXE p=0.09). There was no difference in total NOS activity between groups (pmol/mg: intact 21.1±4.4, OVX 18.9±1.9, OVXE 25.4±7.4). These data suggest that unopposed estrogen does not protect against renal injury. Furthermore, renal cortical NOS1 is sensitive to a non-estrogen ovarian hormone.

Beneficial effect of simvastatin and pravastatin treatment on adverse cardiac remodelling and glomeruli loss in spontaneously hypertensive rats

The aim of the present study was to investigate the possibility of different effects of the hydrophobic statin simvastatin and the hydrophilic statin pravastatin on the remodelling process in the overloaded left ventricle and renal cortex of SHRs (spontaneously hypertensive rats). Fifteen SHRs were treated for 40 days with simvastatin, pravastatin or placebo (water) via orogastric administration. Left ventricle and renal cortex were examined by light microscopy and stereology. LV (left ventricular) cardiomyocyte nuclei (N[cmn]) and glomeruli (N[gl]) numbers were estimated by the dissector method. BP (blood pressure) and serum triacylglycerols (triglycerides) were lower in the statin-treated groups than in the untreated control group. The volume density of the interstitial connective tissue was smaller and length density of the intramyocardial arteries, as well as the arteries/cardiomyocyte ratio, was greater in the statin-treated groups than in the control group. No difference was observed between the two statin-treated groups. The cross-sectional cardiomyocyte area was significantly smaller in the simvastatin-treated group than in the control or pravastatin-treated groups, and it was smaller in the pravastatin-treated group than in the control group. N[cmn] and N[gl] were greater in the two statin-treated groups than in the control group, but no significant difference was observed between the two statin-treated groups. In conclusion, administration of the statins simvastatin and pravastatin to SHRs effectively prevented the elevation in BP and serum triaclyglycerols, and also attenuated adverse cardiac and kidney remodelling by preventing LV hypertrophy, enhancing myocardial vascularization with the decrease in interstitial fibrosis and attenuating cardiomyocyte and glomerular loss.

Renal kallikrein activity in rats developing spontaneous hypertension

1. Spontaneously hypertensive rats (SHR) excrete less kallikrein in urine than Wistar-Kyoto rats (WKY) during the developmental phase of hypertension. The present study was designed to examine whether the urinary defect is related to abnormalities in the renal kallikrein content in this hypertensive model. 2. Active and total kallikrein were measured (amidolytic assay) in the renal cortex of newborn and 4-, 8- and 12-week-old SHR and age-matched WKY. Active and total kallikrein were also measured in urine at the same ages, except at birth. 3. Tissue active kallikrein was significantly lower in SHR at birth, representing on average 53% of the values in WKY expressed as content per total cortex weight. Tissue total kallikrein did not differ between newborn SHR and WKY. 4. SHR at 4, 8 and 12 weeks of age had lower urinary active and total kallikrein excretion. Tissue active akllikrein, but not total kallikrein, was higher than in age-matched WKY per g of cortex weight or per mg of protein, whereas both tissue active and total kallikrein were lower in SHR when expressed as content per total cortex weight. At these three ages, active kallikrein represented, on average 86%, while total kallikrein represented 77%, of the values in age-matched WKY. 5. Our results indicate a defect in prokallikrein activation rather than in kallikrein synthesis in the renal cortex of SHR at birth. The reduction in urinary kallikrein excretion during the developmental phase of hypertension in young SHR is similar to the reduction observed in the renal tissue.