ABSTRACT
OBJECTIVE To investigate the effect of pachymic acid （PA） on renal function and fibrosis in chronic renal failure （CRF） rats and its potential mechanism based on the Ras homolog gene family member A （RhoA）/Rho-associated coiled-coil forming protein kinase （ROCK） signaling pathway. METHODS Using male SD rats as subjects， the CRF model was established by 5/6 nephrectomy； the successfully modeled rats were divided into model group， PA low-dose， medium-dose and high-dose groups （5， 10， 20 mg/kg PA）， high-dose PA+ROCK pathway activator lysophosphatidic acid （LPA） group （20 mg/kg PA+1 mg/kg LPA）， with 15 rats in each group. Another 15 rats were selected as the sham operation group with only the kidney exposed but not excised. The rats in each drug group were gavaged and/or injected with the corresponding liquid via the caudal vein， once a day， for 12 consecutive weeks. During the experiment， the general condition of rats was observed in each group. After the last administration， the serum renal function indexes （blood urea nitrogen， serum creatinine， uric acid） of rats in each group were detected， the renal histopathological changes were observed； the renal tubule injury score and the area of renal fibrosis were quantified. The levels of oxidative stress indexes [malondialdehyde （MDA）， superoxide dismutase （SOD）] and inflammatory factors （tumor necrosis factor-α， interleukin-1β， interleukin-6）， the positive expression rates of connective tissue growth factor （CTGF） and collagen Ⅰ were detected as well as the expression levels of pathway-related proteins （RhoA， ROCK1） and fibrosis- related proteins （transforming growth factor-β1， bare corneum homologs 2， α-smooth muscle actin） were determined. RESULTS Compared with the sham operation group， the rats in model group had reduced diet， smaller body size， listless spirit and sluggish response， reduced and atrophied glomeruli， dilated renal tubules with chaotic structure， and a large number of inflammatory cells infiltrated interstitium； the serum levels of renal function indexes， renal tubule injury score， renal fibrosis area proportion， the levels of MDA and inflammatory factors， the positive expression rates of CTGF and collagen Ⅰ， and the expression levels of pathway-related proteins and fibrosis-related proteins in renal tissues were significantly increased， while SOD level was significantly decreased （P＜0.05）. Compared with the model group， the general condition and pathological injuries of kidney tissue of rats in PA groups were improved to varying degrees，and the above quantitative indexes were significantly improved in a dose-dependent manner （P＜0.05）. LPA could significantly reverse the improvement effect of PA on the above indicators （P＜0.05）. CONCLUSIONS PA can improve renal function and alleviate renal fibrosis in CRF rats， which may be related to inhibiting the activation of RhoA/ROCK signaling pathway.
ABSTRACT
OBJECTIVE To investigate the effect and mechanism of Astragalus polysaccharide （APS） on peritoneal fibrosis and angiogenesis in rats with peritoneal dialysis （PD）. METHODS Rats were randomly divided into normal control group （Control group）， model group （PD group）， 70 mg/kg APS group （APS-L group）， 140 mg/kg APS group （APS-H group）， and 140 mg/kg APS+40 mg/kg hypoxia-inducible factor-1α （HIF-1α） agonist DMOG group （APS-H+DMOG group）， with 12 rats in each group. PD rat models were constructed in the last four groups of rats. Administration groups were given APS intragastrically and DMOG intraperitoneally. Control group and PD group were given constant volume of normal saline intragastrically， once a day， for 4 consecutive weeks. After the last medication， the peritoneal ultrafiltration （UF）， mass transfer of glucose （MTG）， the levels of serum creatinine （Scr） and blood urea nitrogen （BUN） were detected in rats； peritoneal histomorphology and peritoneal fibrosis （peritoneal thickness and proportion of collagen fiber deposition） were observed； the microvascular density and the expression levels of α-smooth muscle actin （α-SMA）， laminin （LN）， HIF-1α and vascular endothelial growth factor （VEGF） proteins were detected in peritoneal tissue of rats. RESULTS Compared with Control group， the mesothelium of rats in the PD group was loosely arranged and shed， inflammatory cells infiltrated， the peritoneal thickness and proportion of collagen fiber deposition were increased significantly （P＜0.05）. The levels of MTG， Scr and BUN in serum， microvascular density and the expressions of α-SMA， LN， HIF-1α and VEGF proteins were significantly increased， while the level of UF was significantly decreased （P＜ 0.05）； compared with PD group， the levels of above indexes were significantly reversed in APS-L and APS-H groups （P＜0.05）， and the improvement of APS-H group was better than APS-L group （P＜0.05）. Compared with APS-H group， the levels of above indexes in APS-H+DMOG group were all reversed （P＜0.05）. CONCLUSIONS APS inhibits peritoneal fibrosis and angioge-nesis in PD rats by inhibiting HIF-1α/VEGF signaling pathway.