ABSTRACT
Objective To observe the muscle wasting in diabetic kidney disease (DKD) model of type 2 and non-obese diabetes mellitus in Goto-Kakizaki (GK) rats,and to evaluate the effect of lowprotein diet supplemented with α-keto acids on muscle wasting.Methods Forty-five male 24-weekage GK rats were randomly divided into three groups:normal protein diet group (22％ casein diet,NPD),low protein diet group (6％ casein diet,LPD) and LPD + α-keto group (5％ casein + 1％ α-keto,Keto).Fifteen gender-and age-matched Wistar rats were served as the control group (CTL).The living condition of GK rats was observed and body weight was measured once a week.Urine albumin,serum glucose,lipids,albumin,creatinine and urea nitrogen were measured at the age of 24,32,40,48 weeks.Soleus muscle at the age of 48-week was observed to calculate the muscle size with software.Expressions of atrogin-1,MuRF-1 and MyoD,myogenin were examined by Q-PCR and Western blotting.Results Compared with the CTL group,NPD,LPD,Keto groups had lower body weight [(317.90± 13.81),(330.38±11.96),(390.44±12.25) g vs (429.43± 16.85) g,all P ＜ 0.05],higher urine albumin [(14.36±5.52),(8.12±4.61),(5.58±3.50) mg/24 h vs (0.61±0.16) mg/24 h,all P ＜ 0.05],higher serum creatinine [(81.50±7.88),(66.32±8.36),(63.44±8.21) μmol/L vs (24.43±6.15) μmol/L,all P ＜0.05] and urea nitrogen [(7.53±1.05),(5.63±1.40),(5.54±0.97) mmol/L vs (2.98±0.62) mmol/L,all P ＜0.05].The cross-sectional area of soleus muscle fibers was larger in CTL group.Compared with CTL group,the expression levels of atrogin-1 and MuRF-1 increased significantly (all P ＜ 0.05),and of MyoD and myogenin decreased significantly in NPD,LPD,Keto groups (all P ＜ 0.05).In Keto group after 40 weeks,muscle wasting was improved compared with NPD and LPD group [body weight (381.62± 15.82) g vs (331.50±17.58),(326.60± 13.43) g,all P ＜ 0.05],cross-sectional area of soleus muscle increased,levels of urine albumin,serum creatinine and urea nitrogen decreased (all P ＜ 0.05),the protein expressions of atrogin-1 and MuRF-1 decreased,and myogenin and MyoD were higher as compared to CTL group (all P ＜ 0.05).There were no significant differences between NPD and LPD group.Conclusions In DKD condition,protein degradation in the skeletal muscle is accelerated,the genes which control muscle atrophy are activated,and proliferation and differentiation of the muscle satellite cells are impaired.Low-protein diet supplemented with α-keto acids can improve muscle wasting induced by DKD.
ABSTRACT
ObjectiveTo explore the role of ERK1/2 in the expression of the type-1 plasminogen activator inhibitor(PAI-1) induced by parathonnone (PTH) in human renal tubular epithelial cell line HK-2 cells.MethodsVarious concentrentions of PTH and manifold durations were applied in the test.The expression of PAI-1 mRNA and protein in HK-2 cells was measured by RT-PCR and Western blotting,respectively.Besides,ERK1/2 protein was detected by Western blotting before the ERK1/2 inhibitor incubated with the HK-2 cells or after.Results The expression of PAI-1mRNA and protein was gradually up-regulatad along with the increasing concentrations of PTH(10-12-10-10 mol/L).The maximum level of PAI-1 mRNA and protein was detected in 10-10 mol/L PTH and was 4.01 and 3.81 times of control group.Otherwise,the decreased expression of PAI-1 was found while the concentrations of PTH were beyond 10-10 mol/L.The levels of PAI-1 mRNA and protein were increased in pace withtime from 12 to 72 hour,in time-dependent manner,which was 4.06 (12 h) and 4.03 (72 h) times of 0 hour group.The levels of ERK1/2 and PAI-1 were ascended after 10-10 mol/L PTH incubated with the HK-2 cells (all P＜0.01).Howerver,both of them decended after cells were pretreated by the ERK1/2 inhibitor (all P＜0.01),but were still higher than those of control group(all P＜0.05).ConclusionERK1/2 kinase system partly participates in the regulation of PAI-1 induced by PTH in HK-2 cells.
ABSTRACT
Objective To investigate the influence of uremic serum on the monocyte chemoattractant protein 1 (MCP-1) expression of human umbilical vascular endothelial cells (HUVECs) in vitro and the effect of up-regulation of berne oxygenase 1 (HO-1) on the synthesis of MCP-1 of HUVECs in uremic milieu. Methods HUVECs were incubated to confluence and then preineubated with heroin and/or protoporphyrin zinc IX (ZnPP)for 6 hours.The cultures were subsequently incubated with M199 cell medium containing 10% serum of healthy people or with medium containing 10% serum of maintenance hemodialysis (MHD) patients.HO-1 protein and mRNA expression was detected by immunohistochemistry and semi-quantitative RT-PCR.MCP-1 mRNA expression was measured by semi-quantitative RT-PCR,and MCP-1 protein was quantified by ELISA. Results Up-regulated expression of MCP-1 mRNA and protein was detected in HUVECs incubated with medium containing 10% serum of MHD patients.The protein synthesis was 2.95 folds of the control.Heroin induced expression of HO-1 mRNA and protein,and concurrently inhibited the up-regulated MCP-1 expression induced by uremic serum.Such effects of heroin could be blocked by ZnPP. Conclusions Uremic serum induces the expression of MCP-1 in HUVECs.Up-regulated expresson of endothelial HO-1 induced by heroin inhibits the enhancement of MCP-1 synthesis.HO-1 may be beneficial to the alleviation of endothelial cell injury in uremic milieu.