慢性肾功能不全大鼠胫骨生长板甲状旁腺素相关蛋白受体的表达及其对胫骨延长的影响

Effects of parathyroid hormone-related peptide receptor in tibial growth plate on tibial extension in chronic renal insufficiency rats

目的观察慢性肾功能不全大鼠胫骨生长板甲状旁腺素相关蛋白(PTHrp)受体的表达情况及其对胫骨延长的影响。方法雄性2周龄Sprague-Dawley大鼠分为假手术组、模型组和治疗组,每组20只。假手术组只切开暴露左侧输尿管后缝合,术后每天1次生理盐水灌胃;模型组进行左侧输尿管结扎,术后每天1次生理盐水灌胃;治疗组采用左侧输尿管结扎,术后每天1次依那普利灌胃治疗。术后4周收集大鼠24 h尿并测总蛋白含量;处死大鼠,心腔取血检测PTHrp浓度、肌酐、尿素氮。取左侧肾脏制成组织学切片并进行HE染色、Masson染色,观察肾小球、肾小管病理情况。取双侧胫骨测量全长,番红O染色观测胫骨生长板增殖区细胞柱细胞数量,免疫组化技术观测胫骨生长板区PTHrp受体表达情况。结果与假手术组比较,术后4周模型组大鼠24 h尿蛋白、血肌酐、血尿素氮均升高(均P<0.05);治疗组上述肾功能指标均低于模型组(均P<0.05)。模型组和治疗组大鼠血PTHrp浓度均高于假手术组,而治疗组血PTHrp浓度低于模型组(均P<0.05)。HE染色、Masson染色显示模型组肾小球萎缩且存在炎性细胞浸润,肾小管重度扩张,纤维化程度严重;与模型组相比,治疗组肾小球萎缩、炎性细胞浸润、肾小管扩张、纤维化程度减轻。模型组大鼠胫骨全长、生长板增殖区细胞柱细胞数、生长板PTHrp受体表达均低于假手术组(均P<0.05),而治疗组3项指标均高于模型组(均P<0.05)。结论肾功能不全大鼠血液中PTHrp浓度升高,胫骨生长板区PTHrp受体减少,生长板发育缓慢。

Objective To observe the expression of parathyroid hormone-related peptide(PTHrp)receptor in tibial growth plate and its effects on tibial extension in chronic renal insufficiency rats.Methods Two-week-old male Sprague-Dawley rats were randomly divided into sham group,model group and enalapril group,each with 20 rats.In model group and enalapril group rats had chronic renal insufficiency induced by left ureteral obstruction,and rats were respectively given saline and enalapril by gavage after the operation.In sham group,left ureter was only exposed without ligation,and rats were given saline.The urine was collected 4 weeks after the operation and the total protein content was measured.Then all rats were killed.The concentrations of PTHrp,creatinine and urea nitrogen in intracardiac blood were detected.HE staining and Masson staining were performed on the left kidney to observe pathological changes of glomeruli and renal tubules.The total length of bilateral tibia was measured.The number of columnar cells in the growth plate proliferative zone was measured by safranin O staining and the expression of PTHrp receptor in the growth plate was detected by immunohistochemistry.Results The 24 h urine total protein,creatinine and urea nitrogen in model group were higher than those in sham group(all P<0.05),while these 3 renal functional parameters in enalapril group were lower than those in model group(all P<0.05).In model group and enalapril group rats had higher blood concentrations of PTHrp than that in sham group(all P<0.05),but blood PTHrp in enalapril group was lower than that in model group(P<0.05).HE staining and Masson staining showed that in the model group rats had severe tubular dilation,inflammatory cell infiltration and the tissue fibrosis,while in enalapril group renal tubules slightly dilated and had a few inflammatory cell infiltration and tissue fibrosis.Compared with those in the sham group,in model group the tibia length,the chondrocyte number of column structure in the growth plate proliferative zone and the PTHrp receptor decreased(all P<0.05).But in enalapril group those indexes increased than model group(all P<0.05).Conclusions Chronic renal insufficiency rats had increased PTHrp concentration in the blood but decreased PTHrp receptors expression in tibial growth plate,which lead to their limited tibial extension.