草酸降解酶对肠源性高草酸尿症大鼠肾草酸钙结石形成的影响研究

Effects of oxalate-degrading enzyme on the calcium oxalate kidney stones formation in intestinal hyperoxaluria rats

目的 观察草酸降解酶对肠源性高草酸尿症大鼠模型肾草酸钙结石形成的影响.方法 2014年5-6月,以8只健康大鼠为空白对照组（A组）,将24只肠源性高草酸尿症大鼠按完全随机设计随机分为阳性对照组（B组）、低剂量酶灌胃组（C组）和高剂量酶灌胃组（D组）,每组8只.其中A组采用牛理盐水3 ml/d灌胃,B组采用4％草酸铵溶液3 ml/d灌胃,C、D组分别在B组的基础上加用20、40 U/d草酸降解酶灌胃.4组大鼠连续观察28 d,第0、7、14、21、28天测定24 h尿草酸盐浓度,第0及28天检测肾功能及尿Ca^2＋、血Ca^2＋浓度.第28天对A、B、D组大鼠行肾脏能谱CT扫描后,取4组大鼠肾组织切片染色观察草酸钙结晶形成情况.结果 第0天,A、B、C和D组大鼠尿草酸盐浓度分别为（0.61±0.06）、（1.58±0.15）、（1.59±0.10）、（1.64±0.20） mmol/L,后3组组间差异无统计学意义（P＞0.05）,且均高于A组（P＜0.01）.开始灌胃干预后,C、D组大鼠尿草酸盐浓度呈明显下降趋势,且D组下降更明显.第28天,4组大鼠尿草酸盐浓度分别为（0.61±0.11）、（1.64 ±0.12）、（1.17±0.12）、（0.87 ±0.11） mmol/L,C组和D组较B组均明显降低,D组较C组下降更明显,组间差异均有统计学意义（P＜0.01）.各组大鼠肾功能及血Ca^2＋浓度均未明显改变（P＞0.05）.大鼠肾脏影像结果经CT后处理工作站数据分析提示,B组CT值明显高于D组（P＜0.01）,且两组均高于A组（P＜0.01）,3组的差异在低千伏能量条件下更明显.肾切片染色结果显示,B、C、D3组大鼠肾小管内均见草酸钙结晶沉积,B组最多,C组较少,D组更少,A组无明显结晶形成.结论 草酸降解酶能有效减少肠源性高草酸尿症大鼠肾草酸钙结石的形成.

Objective To observe the effects of oxalate-degrading enzyme on the formation of calcium oxalate kidney stones in intestinal hyperoxaluria rats.Methods From May to June,2014,8 healthy rats were selected as the negative control group named Group A.Intestinal hyperoxaluria rats were randomly divided into three groups （n =8）：positive control group （Group B）,low-dose enzyme gavage group （Group C） and high-dose enzyme gavage group （Group D）.Group A were treated with normal salinc by gavage （3 ml/d）.Group B were treated with 4% ammonium oxalate solution by gavage （3 ml/d）.Group C and Group D were treated with 20 U/d or 40 U/d enzyme on the basis of Group B.The intervention lasted for 4 weeks.The oxalate concentrations of 24 hours urine in each group were detected in 0,7th,14th,21th,28th day.The renal function,the serum and urine Ca2＋ in each group were measured in 0 and 28th day.In 28th day,the kidneys of rats in Group A,B,D were examined by spectral CT.The kidneys of 4 groups were examined microscopically for possible calcium oxalate crystals.Results In 0 day,the urinary oxalate concentrations of Group A,B,C and D were （0.61 ±0.06）,（1.58 ±0.15）,（1.59 ±0.10） and （1.64 ±0.20） mmol/ L.There were no significant differences among B,C and D（P 〉 0.05）.Compared with A,the urinary oxalate concentrations of B,C and D were significantly higher （P 〈 0.001）.After the enzyme gavage,the urinary oxalate concentrations of Group C and D were significantly decreased,and Group D dccreased more significantly.In 28th day,the urinary oxalate concentrations of Group A,B,C and D were （0.61 ±0.11）,（1.64 ±0.12）,（1.17 ±0.12） and （0.87 ±0.11） mmol/L.After statistical analysis,the urinary oxalate concentration of Group C and D were significantly lower than Group B （P 〈 0.01）,and Group D decreased more significantly than that in Group C （P 〈 0.01）.The CT post-processing workstation data analysis suggested that the average CT value of Group B were significantly higher than D （P 〈 0.01）,and both of the two groups were higher than Group A （P 〈 0.01）;The differences were more obvious in conditions of lowkilovolt.Renal tubular calcium oxalate crystal deposition were seen the most in Group B,less in Group C and lowest in Group D.Whereas,there was no crystallization in Group A.Conclusion Oxalate-degrading enzymes could inhibit the formation of calcium oxalate kidney stones in intestinal hyperoxaluria rats.