目的探讨水通道蛋白2(Aquaporins2,AQP-2)和加压素(anti—diuretic hormone,AVP)在内耳水代谢中的作有机制。方法15只(30耳)成年大鼠,随机分为三组,每组5只(10耳),A组(对照组):腹腔注射生理盐水;B组(AVP组):腹腔注射AVP(0.2U/g);C组(DDAVP组):尾静脉注射V2受体促效剂去精氨酸加压素([deamino--Cys^1,D—Arg^8]-Vasopressin,DDAVP)1ng/只。采用间接免疫荧光法标记内淋巴囊(endolymphaticsac,ES)中AQP-2的表达,ABC法标记肾脏中AQP-2的表达。结果AQP-2-抗在内淋巴囊上皮胞膜胞浆显示荧光染色,B组和C组的内淋巴囊上皮胞膜胞浆AQP-2的表达明显较A组降低(P〈0.01);B组和C组AQP-2的表达则差异无显著统计学意义(P〉0.05)。B组和C组肾脏集合管主细胞胞膜胞浆AQP~2的表达明显较A组增强(P〈0.05)。B组和C组AQP-2表达则差异无显著统计学意义(P〉0.05)。结论AVP促进肾脏表达AQP-2,提高肾脏重吸收的功能,同时抑制内淋巴囊上皮表达AQP-2,从而降低内淋巴囊上皮对水的重吸收;AVP对肾脏和内淋巴囊AQP-2表达的调节可能是通过AVP—V2R—cAMP—AQP2途径实现。
Objective To confirm the expression of Aquaporin2,3,4 (AQP2,3,4, water channel protein) in rats'endolymphatic sacs (ES)and kidneys and to investigate and to compare the effects of anti--diuretic hormone (AVP) and DDAVP( Edeamino-- Cys^1 , D-- Arg^8 ] -- Vasopressin, V2-- receptor agonist ) on the expression of AQP2 in rats' ESs and kidneys. Methods 30 healthy Swards white rats were divided into the negative control, AVP group and dDAVP group respectively. The animals were cardiacally perfused. The temporal bones and kidneys were taken out and sectioned by means of the paraffin--embedded technique. The sections of ESs were labeled with fluorescent antibody by immunohistochemical method, and the kidneys" with avidin- biotin-- peroxidase complex method (ABC). The expressions of AQP--2 were confirmed in the ESs of the rats while the different effects of the AVP and DDAVP on the ESs and the kidneys were observed . The slides used were analyzed by the image--analyzer and the subsequent data were statistically studied. Results In the cytomembrane and cytoplasm of ESs' epithelia ,the constant and clear fluorescent reaction could be observed in the normal control group with the first antibody of AQP2. Significant feeble fluorescent reaction of the first antibody of AQP--2 was revealed in AVP group and DDAVP group. In comparison with the control group, significant stain was found in AVP group and DDAVP group. Noted were also lower gray (P〈0.05), more density(P〈0.05),higher IOD(P〈0.05) and more stained areas (P〈0. 05). There is no difference between the AVP group and DDAVP group in the expression of AQP--2 in two sites. Conclusion AVP promotes the expression of AQP2 in the kidney hut inhibits in ES. AVP controls the expression of AQP--2 in the ES and kidney probably through AVP--V2R--cAMP--AQP2.