甲状旁腺激素与盐交互作用对肾脏结构和功能的影响

Effect of the interaction between parathyroid hormone and salt on renal structure and function

摘要:

目的 探讨甲状旁腺激素（PTH）与盐交互作用对肾脏结构和功能的影响。方法 选取8周龄雄性SD大鼠30只，随机分为假手术组、PTH组、低盐组（0.6%）、高盐组（8.0%）、PTH+低盐组和PTH+高盐组。按分组情况予胶囊渗透压泵持续泵入鼠重组PTH（1-34）2 pmoL/（kg·h）2周。大鼠按分组接受2周不同浓度的盐水灌胃，其中PTH组和假手术组仅用无菌注射用水灌胃。测量各组大鼠干预前后的体重和血压，并采集24 h尿液和血清样本，检测尿总蛋白（UTP）、尿钾离子（UK⁺）、尿钠离子（UNa⁺）、尿肌酐（UCre）、血钾离子（K⁺）、血钠离子（Na⁺）、血清肌酐等指标，计算肾小球滤过率。采用酶联免疫吸附试验检测血清PTH、血管紧张素Ⅱ（Ang Ⅱ）和醛固酮浓度。采用苏木精-伊红（HE）染色观察肾脏组织形态学变化，免疫组织化学法检测肾脏组织中肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、CD68的表达。结果 PTH+高盐组大鼠收缩压、MAP较假手术组升高（P <0.05），且PTH+高盐组大鼠干预后收缩压较干预前升高（P <0.05）。各组大鼠干预后舒张压比较，差异无统计学意义（P >0.05）。各组大鼠血清Na⁺/K⁺比较，差异无统计学意义（P >0.05）。高盐组、PTH+高盐组较假手术组升高（P <0.05），高盐组、PTH组、PTH+低盐组、PTH+高盐组较低盐组升高（P <0.05）。各组大鼠24 h UK⁺/Cre、24 h UTP/Cre比较，差异均无统计学意义（P >0.05）。PTH+高盐组的24 h UNa⁺/Cre、24 h UNa⁺/K⁺水平较假手组升高，肾小球滤过率较假手术组降低（P <0.05），PTH+高盐组的24 h UNa⁺/Cre、24 h UNa⁺/K⁺水平较低盐组升高，肾小球滤过率较低盐组降低（P <0.05）。高盐组、PTH组、PTH+低盐组、PTH+高盐组大鼠的肾小球体积增大，肾小管扩张，可见蛋白管型，肾间质少量炎症细胞浸润。PTH+高盐组大鼠的肾小球体积增大，小球内可见细胞及基质增生，肾小管扩张，可见蛋白管型，肾间质炎症细胞浸润。各组大鼠CD68、TNF-α、IL-1β阳性表达面积比较，差异均有统计学意义（P <0.05）。结论 高盐、PTH可通过激活肾素-血管紧张素系统促进肾脏炎症的发生，两者可协同加重肾脏组织的炎症损伤，导致肾功能受损。

Abstract:

Objective To investigate the effects of the interaction between parathyroid hormone (PTH) and salt on renal structure and function.Methods Thirty 8-week-old male SD rats were selected and randomly divided into sham group, PTH group, low-salt group (0.6%), high-salt group (8%), PTH + low-salt group, and PTH + high-salt group. Rats were given recombinant PTH (1-34) [2 pmol/(kg?h) ] via capsule osmotic pump for 2 weeks according to the grouping situation. In addition, rats in each group were given different concentrations of saline by gavage for 2 weeks, except for the PTH group and the sham group, which were given sterile injection water only by gavage. The body weight and blood pressure of each group of rats were measured before and after intervention. The 24-hour urine and serum samples were collected to detect indicators such as urine total protein, urine potassium, urine sodium, urine creatinine, blood potassium, blood sodium, and serum creatinine, and to calculate the glomerular filtration rate. The concentrations of serum PTH, angiotensin Ⅱ (Ang Ⅱ), and aldosterone were detected by enzyme-linked immunosorbent assay. The renal morphology was observed by hematoxylin-eosin (HE) staining, and the expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and CD68 in renal tissues were detected by immunohistochemistry.Results The systolic pressure and MAP in the PTH + high-salt group were higher than those in the sham group (P < 0.05), and the systolic pressure after intervention was higher than that before intervention in the PTH + high-salt group (P < 0.05). There was no difference in the diastolic pressure among the groups (P > 0.05). The serum Na⁺/K⁺ ratio was not different among the groups (P > 0.05). The 24-hour UK⁺/Cre and UTP / Cre ratios were not different among the groups (P > 0.05). The levels of PTH, Ang Ⅱ and ALD in the high-salt group and the PTH + high-salt group were higher than those in the sham group (P <0.05), and those in the high-salt group, PTH group, PTH + low-salt group, and PTH + high-salt group were higher compared to those in the low-salt group (P <0.05).The 24-hour UNa⁺/Cre and UNa⁺/K⁺ ratios were higher and the glomerular filtration rate was lower in the PTH + high-salt group than in the sham group (P < 0.05). The 24-hour UNa⁺/Cre and UNa⁺/K⁺ ratios were higher and the glomerular filtration rate was lower in the PTH + high-salt group than in the low-salt group (P < 0.05). Increased glomerular volume, renal tubule dilation, protein casts and mild inflammatory cell infiltration in the renal interstitium were observed in rats of the high-salt group, the PTH group, the PTH + low-salt group, and the PTH + high-salt group. For rats in the PTH + high-salt group, there were increases in the glomerular volume, glomerular mesangial cell and stromal hyperplasia, renal tubule dilation, protein casts and inflammatory cell infiltration in the renal interstitium. The CD68-, TNF-α-, and IL-1β-positive areas were different among the groups (P < 0.05).Conclusion High salt and PTH promote renal inflammation by activating the renin-angiotensin system, and they synergistically aggravate the inflammatory injury of renal tissues and lead to renal dysfunction.