| Objectives:To investigate the different effects of soy protein and casein on metabolism and renal function in the uninephrectomized rats. Materials and methods:Sixty-four Sprague-Dawley rats were randomly divided into operated group(n=48) and sham-operated group(n=16).A week after the operation,all rats were fed the experimental diet respectively for a sixteen-week experiment.The operated rats were randomly assigned to six diets:HSP(high soy protein)and HCP(high casein protein),consumed a diet containing 36% soy protein,36% casein respectively.NSP(normal soy protein)and NCP(normal casein protein), consumed a diet containing 24% soy protein,24% casein respectively.LSP(low soy protein) and LCP(low casein protein), consumed a diet containing 12% soy protein,12% casein respectively.The sham-operated rats were assigned to two groups:sham(sham-operated)+NSP and sham+NCP, consumed a diet containing 24% soy protein,24% casein respectively. Intake and Body weight(BW) were measured every week.Systolic blood pressure(SBP),diastolic blood pressure(DBP),Serum and urine levels of creatinine, urea nitrogen,uric acid,albumin,plasma lipids and electrolytes were measured every 4 week.16 months later,all the rats were killed and taken kidneys for kidney weight(KW). Results:1.Total intake and Body weight gain:group LSP showed a greater intake and weight gain when compared with group HSP and NSP at the end of the experiment(P<0.05).No difference was found in the groups of casein diet(P>0.05). Compared with group HSP,group NSP respectively,group HCP and group NCP were significantly higher at the end(P<0.05). Compared to group sham+NSP, group sham+NCP showed a greater intake and weight gain(P<0.05). No difference was found between the groups of operated and sham-operated(P>0.05).2.KW/BW: KW/BW of group LSP and group LCP were the lowest in the operated group(P<0.05). The operated groups showed higher kidney weight than the sham-operated groups(P<0.05).There was no difference in the two types of protein throughout the study(P>0.05).3.Blood pressure:Group LSP and LCP showed a significantly lowest SBP in the operated groups from the fourth week to the end(P<0.05).There was no difference between the two types of protein in operated groups(P>0.05).No difference was found between the operated groups and sham-operated groups(P>0.05).There was no difference in DBP among all the groups throughout the study(P>0.05).4.The serum creatinine:No difference was found in the operated groups or in the sham-operated groups(P>0.05).Throughout the study,the operated groups showed a significantly higher serum creatinine when compared with the sham-operated groups(P<0.05).5.The creatinine clearance:Compared with group HSP, group NSP respectively, group HCP and group NCP were significantly higher in the twelfth and sixteenth week(P<0.05).Compared with group NSP, group NCP respectively, group Sham+NSP and group Sham+NCP were significantly higher in the beginning of the study,fourth and eighth week(P<0.05),but these two sham-operated groups decreased after the twelfth week,and no difference was found between the operated groups and sham-operated groups at the end(P>0.05).6.The serum urea nitrogen:Compared with LSP, group HSP showed a significant higher serum urea nitrogen from fourth week to sixteenth week(P<0.05). Compared with NSP, serum urea nitrogen in LSP decreased significantly in the eighth week. Group LCP showed a significantly lowest serum urea nitrogen in the fourth,eighth and sixteenth week when compared with group HCP and NCP(P<0.05).Compared with group HCP,group NCP respectively,group HSP and group NSP were significantly higher in the eighth,twelfth and sixteenth week(P<0.05).Group Sham+NSP showed a significantly higher serum urea nitrogen when compared with group Sham+NCP(P<0.05).Throughout the study, the operated group showed a significantly higher serum urea nitrogen when compared with the sham-operated group(P<0.05).7.The serum uric acid:Compared with group HSP and group NSP respectively, the serum uric acid of group HCP and group NCP were significantly higher in the fourth, twelfth and sixteenth week(P<0.05).Group LCP presented a significantly increased serum uric acid in the fourth and sixteenth week when compared with group LSP(P<0.05).8.The serum triglyceride: group LSP and LCP showed a significantly lowest serum triglyceride in the operated group from the fourth week to the end(P<0.05).In the fourth,twelfth and sixteenth week,groups consumed casein showed a significantly higher serum triglyceride when compared with the groups of soy protein in the operated rats(P<0.05).Compared with the group Sham+NSP,group Sham+NCP presented a significantly higher serum triglyceride from the fourth week to the end(P<0.05).9.The serum cholesterol: Compared with the group HSP,group HCP showed a significantly higher serum cholesterol in the fourth and eighth week(P<0.05). Compared with the group NSP,group NCP showed a significantly higher serum cholesterol in the fourth week(P<0.05).Group LCP showed a significantly higher serum cholesterol in the fourth,eighth and sixteenth week when compared with the group LSP(P<0.05).Group Sham+NCP showed a significantly increased serum cholesterol when compared with group Sham+NSP throughout the study(P<0.05).10.The serum albumin: In the fourth,twelfth and sixteenth week, serum albumin was significantly higher in group HSP, when compared with group HCP(P<0.05). Compared with group NSP and LSP respectively,group NCP and LCP presented a significantly higher serum albumin in the fourth,eighth and twelfth week(P<0.05).Group Sham+NSP showed an increased serum cholesterol when compared with group Sham+NCP throughout the study.11.The excretion of urinary albumin: The excretion of urinary albumin increased with the increasing protein intake. Group HCP presented a significantly increased excretion of urinary albumin from the fourth week to the end, when compared with the group HSP(P<0.05).Compared with group NSP and group LSP respectively, the excretion of urine albumin of group NCP and group LCP were significantly higher in the fourth, eighth and sixteenth week(P<0.05). Conclusions:1.Low nephron number with unilateral nephrectomy can cause reserved renal function decreased significantly.2.Low level protein will not cause malnutrition,early intervention is the key to prevent kidney function decline.3.Soy protein has beneficial effects on SBP.The soybean protein diet can reduce urinary protein excretion when compared with casein,The soybean protein diet protects residual renal function better.4.Compared with casein, soy protein also has more beneficial effects for the regulation of serum uric acid and serum lipids in rat with remnant kidney. |
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