糖尿病大鼠肾脏髓质水通道蛋白2的表达和意义

目的 检测链脲佐菌素诱导的糖尿病（DM）大鼠。肾脏髓质集合管水通道蛋白2（AQP-2）的变化。方法 实验大鼠分为正常对照组（Con组）和糖尿病组（DM组）。在成模12周后，分别用光学显微镜、电子显微镜等方法观察。肾脏形态变化，用免疫组织化学、核酸原位杂交和逆转录PCR方法检测DM大鼠肾髓质集合管AQP-2的表达。结果 （1）实验初DM组与Con组之间血糖、体重差异无统计学意义（P〉0．05），但12周时DM组血糖明显升高（P〈0．01），尿量高于Con组（P〈0．01），体重明显低于Con组（P〈0．01），DM组相对。肾重高于Con组（P〈0．01），二组间血肌酐无明显变化（P〉0．05）。（2）DM组尿渗透压低于Con组（P〈0．05），血渗透压高于Con组（P〈0．05）。（3）DM组大鼠血浆加压素水平比Con组明显升高（P〈0．05）。（4）光镜下。肾脏结构未见明显改变，电镜下可见。肾脏髓质集合管亮细胞和暗细胞结构改变。（5）DM大鼠肾脏髓质集合管AQP-2mRNA及蛋白质的表达增加。结论 DM大鼠肾脏髓质AQP-2mRNA及蛋白质的表达增加，并伴有早期。肾脏病理改变。尿AQP-2有望作为糖尿病。肾病早期诊断指标。

Expression of aquaporin-2 in renal medulla of diabetic rats and its significance

Objective To investigate the change of aquaporin-2 (AQP-2) in collecting tubules of renal medulla in rats with diabetes mellitus (DM) induced by streptozotocin (STZ). Methods The rats were assigned to two groups: normal control group and DM group. STZ-induced DM rats were established for 12 weeks, then the tissue structure of the kidneys of both groups was studied under light microscope and transmission electron microscope. The expression of AQP-2 in collecting tubules of renal medulla was assayed by immunohistochemistry, hybridization in situ and RT-PCR. Results (1) There was no difference in blood glucose and body weight between the two groups at beginning (all P>0.05). But after 12 weeks, blood glucose level and urine volume in DM group were higher and greater than those in control group (both P<0.01).BodyweightofratsinDM group was lower than that in control group (P<0.01), and the average weight of kidney in DM group was higher than that in control group (P<0.01). The serum creatinine showed no significant difference between the two groups (both P>0.05). (2) The urine osmolality in DM group was decreased while the plasma osmolality increased (P<0.05). (3) TheplasmavasopressininDMgroupwashigherthanthat of control group (P<0.05). (4) The tissue structure of DM rats did not show significantchange under light microscope. The damage of principal cells and intercalated cells in renal medulla of DM group was observed under transmission electron microscope. (5) The expression of AQP-2 in renal medulla of DM group was increased. Conclusion The expressions of AQP-2 mRNA and protein are increased in renal medulla of DM rats and accompanied by early renal pathological change. Urinary AQP-2 may serve as a parameter in diagnosing diabetic nephropathy at earlier stage.