Arginine Vasopressin-Aquaporin-2 Pathway-Mediated Dehydration Effects of Electroacupuncture in Guinea Pig Model of AVP-Induced Eendolymphatic Hydrops / 中国结合医学杂志

OBJECTIVE@#To investigate the effects of electroacupuncture (EA) on endolymphatic hydrops (EH) and the regulation of arginine vasopressin (AVP)-aquaporin-2 (AQP2) pathway in guinea pigs.@*METHODS@#EH was induced in male guinea pigs by an intraperitoneal injection of AVP. For the treatment, EA was delivered to Baihui (GV 20) and Tinggong (SI 19) acupoints, once per day for 10 consecutive days. In histomorphological studies, cochlear hydrops degree was evaluated by hematoxylin-eosin (HE) staining, and then the ratio of scala media (SM) area to SM + scala vestibuli (SV) area (R value) was calculated. In mechanical studies, a comparison of plasma AVP (p-AVP) concentrations, cyclic adenosine monophosphate (cAMP) levels, vasopressin type 2 receptor (V2R) and AQP2 mRNA expressions in the cochlea were compared among groups.@*RESULTS@#EA significantly reduced cochlear hydrops in guinea pigs (P=0.001). EA significantly attenuated the AVPinduced up-regulation of p-AVP concentrations (P=0.006), cochlear cAMP levels (P=0.003) and AQP2 mRNA expression (P=0.016), and up-regulated the expression of V2R mRNA (P=0.004) in the cochlea.@*CONCLUSIONS@#The dehydrating effect of EA might be associated with its inhibition of AVP-AQP2 pathway activation.

Protection of Danggui-Shaoyao-San extract on IMCD3 cells induced by adramycin based on cAMP/PKA pathway / 中国药理学通报

Aim To investigate the Na+,k +-ATPase, cyclc-AMP (cAMP), protein kinase A (PKA), cAMP-responsive element binding protein (CREB) and aquaporin 2 (AQP2) of the inner medullary col-lecting duct cell (IMCD3) induced by adramycin (ADR) , and to study on the protection mechanism of Danggui-Shaoyao-San (DSS) from the perspective of water-liquid balance. Methods IMCD3 cells were used as the research object. The effects of different concentrations of ADR on the proliferation of IMCD3 cells were determined by MIT assay. There were six groups in the cell experiment, namely, control group, model group, low-, medium-, and high-dose DSS extract (concentrations of 0. 8, 1.6, 3.2 g L"1) and H-89 inhibitor group. ELISA was used to detect the content of cAMP in cells. Changes of Na+ , K +-ATPase activity in cells were detected by Na+,k +-ATPase assay kit. The level of PKA, CREB and AQP2 mRNA in cells were detected by real-time PCR. The protein expression of PKA, CREB and AQP2 in IM-CD3 cells was assessed by Western blot. Results 1 x 10~8 mol L"1 ADR was the optimum concentration in IMCD3 cells. Different concentrations of DSS extract could effectively inhibit the injuiy of IMCD3 cells induced by ADR, and increase the activity of Na+,k +-ATPase and the content of cAMP in cell supernatant. DSS (1.6, 3.2 g L"1) extract could up-regulate the expressions of PKA, CREB and AQP2 mRNA and pro-tein expression (P < 0. 05 , P < 0. 01). Conclusion DSS extract can increase Na+,k +-ATPase activity and activate the cAMP-PKA-CREB pathway, thus inhibiting IMCD3 cell contraction mediated by ADR.

Expression of aquaporin 2, aquaporin 3 and aquaporin 4 in renal medulla of Bactrian camel ( Camelus bactrianus ) / Expresión de acuaporina 2, acuaporina 3 y acuaporina 4 en la médula renal del camello bactriano ( Camelus bactrianus )

SUMMARY: Aquaporins (AQPs) are members of the aquaporin water channel family that play an important role in reabsorption of water from the renal tubular fluid to concentrate urine. Using immunohistochemical staining on paraffin sections, We studied expression of AQP2, AQP3 and AQP4 in renal medulla of Bactrian camel (Camelus bactrianus). The renal medulla of cattle (Bos taurus) acted as the control. Compared with the control, strong expression of AQP2 was observed at the apical plasma membrane and intracellular vesicles, in both the outer medullary collecting duct (OMCD) and the inner medullary collecting duct (IMCD) of camel. Strong expression of AQP3 was observed at the basolateral plasma membrane of the IMCD of camel. Strong AQP4 expression, however, was observed at the basolateral plasma membrane in the OMCD of camel. Moreover, moderate AQP4 expression was detected in endothelium of capillary in medullary region of camels, whereas very weak/absent expression was detected in endothelium of capillary of cattle. We concluded that expression of AQP2, AQP3 and AQP4 in the camel kidney showed some differences from cattle in renal trans-epithelial water transport. It may enhance our better understanding of special water metabolism mechanisms that enable camels to survive in extreme environments.

RESUMEN: Las acuaporinas (AQP) son miembros de las proteínas de transporte que desempeñan un papel importante en la reabsorción de agua del líquido tubular renal para concentrar la orina. Estudiamos la expresión de AQP2, AQP3 y AQP4 en la médula renal del camello bactriano (Camelus bactrianus) usando tinción inmunohistoquímica en secciones de parafina. La médula renal del bovino (Bos taurus) se usó como control. En comparación con el control, se observó una fuerte expresión de AQP2 en la membrana plasmática apical y vesículas intracelulares tanto en el conducto colector medular externo (CCME) como en el conducto colector medular interno (CCMI) del camello. Se observó una fuerte expresión de AQP3 en la membrana plasmática basolateral del CCMI del camello. También se observó una expresión fuerte de AQP4 en la membrana plasmática basolateral en el CCME de camello. Además, se detectó una expresión moderada de AQP4 en el endotelio de los capilares en la región medular de los camellos, mientras que en el endotelio de los capilares del bovino se detectó una expresión muy débil. Concluimos que la expresión de AQP2, AQP3 y AQP4 en el riñón de camello mostró algunas diferencias con el bovino en el transporte trans-epitelial de agua renal. El estudio podría mejorar nuestra comprensión de los mecanismos especiales del metabolismo del agua que permiten a los camellos sobrevivir en ambientes extremos.

Congenital nephrogenic diabetes insipidus：2 cases report of brothers and review / 临床儿科杂志

Objective Congenital nephrogenic diabetes insipidus (CNDI) is a rare disease, the aim of this article is to help better understanding of this disease. Methods The clinical features, genetic analysis and treatments of two siblings with CNDI were retrospectively analyzed, and related literatures were reviewed. Results Both brothers had polydispia, polyuria and low concentrate urine continuously, and they both had a mutation in AQP 2 conifrmmed with Sanger sequencing. This novel frame shift mutation caused arginine of 254 to histidine, and prolonged AQP 2 protein. Conclusions Gene analysis can help diagnosis of CNDI. Amiloride is useful option for treatment.

EXPRESSION OF AQP-2 AND AQP-4 IN MOUSE KIDNEY DURING DEVELOPMENT AND MATURATION / 解剖学报

Objective To observe the sites and relations of AQP-2 and AQP-4 in kidney during development and maturation, and discuss the roles of them. Methods Immunohistochemistry combined with stereological methods were used to observe and measure the expression of AQP-2 and AQP-4. Results AQP-2 was apparently noticed at the apical side and cytoplasm of principle cells in the collecting ducts. The expression of AQP-2 at the apical side increased from 17-fetuses to 1-day neonatal by stereology, but it hardly changed after 1-day neonatal. The expression of AQP-4 was faint at 14-day embryo and enhanced with age to reach a plateau at birth, and was not changed remarkably thereafter. The expression of AQP-4 was less than AQP-2 in every stage of kidney development. It was localized at the basolateral membrane of ureteric buds or collecting ducts.Conclusion We presume that AQPs are very important for balance of water during development and maturation in mice kidney, while AQP-4 is before birth, AQP-2 is after birth.

Molecular analysis of AQP2 promoter. I. cAMP-dependent regulation of mouse AQP2 gene

To determine molecular mechanisms of Aquaporin-CD (AQP2) gene regulation, the promoter region of the AQP2 gene was examined by transiently transfecting a promoter-luciferase reporter fusion gene into mouse renal collecting duct cell lines such as mIMCD-3, mIMCD-K2, and M-1 cells, and NIH3T3 mouse embryo fibroblast cells. PCR-Southern analysis reveals that mIMCD-3 and mIMCD-K2 cells express AQP2, but M-1 and NIH3T3 cells do not, and that the treatment with cpt-cAMP (400 muM) or forskolin/isobutylmethylxanthine (IBMX) increased the AQP2 expression in IMCD cells. In both IMCD and NIH3T3 cells, the constructs containing the promoter of AQP2 gene showed promoter activities, indicating lack of tissue-specific element in the 1.4 kb 5'-flanking region of the mouse AQP2 gene. Luciferase activity in the IMCD cells transfected with the construct containing 5-flanking region showed responsiveness to cpt-cAMP, indicating that the 1.4 kb 5'-flanking region contains the element necessary for the regulatory mechanism by cAMP. The promoter-luciferase constructs which do not have a cAMP-responsible element (CRE) still showed the cAMP responsiveness in IMCD cells, but not in NIH3T3 cells. Increase in medium osmolarity did not affect AQP2 promoter activity in mIMCD-K2 cells. These results demonstrate that AQP2 gene transcription is increased with cAMP treatment through multiple motifs including CRE in the 5'-flanking region of the gene in vitro, and the regulatory mechanism may be important for in vivo regulation of AQP2 expression.

EXPRESSION AND REGULATORY FUNCTION OF INTER RELATED POLYPEPTIDES DURING DEVELOPMENT OF RENAL TUBULES IN CHICK EMBRYO / 解剖学报

Objective To observe the expression of EGFR,TGF-?,AQP-2 and Bax during development of renal tubules in chick embryo,and explore the role and regulating significance of them. Methods The expression of EGFR,TGF-?,AQP-2 and Bax were observed by immunohistochemistry combined with stereological methods in 36 chicks kidney at 10th-46th incubation stages.The expression intensity of them was analyzed by IPP software. Results The epithelial cells of proximal tubules in chick embryo appeared EGFR immunoreactivity at 26th-46th stages;At 26th-37th stages the epithelial cells of proximal tubules and distal tubules of mesonephros appeared TGF-? immunoreactivity,the epithelial cells of proximal tubules and distal tubules of metanephros appeared TGF-? immunoreactivity at 33rd-40th stages,at 40th-46th stages the epithelial cells of proximal tubules of metanephros appeared TGF-? immunoreactivity but the epithelial cells of distal tubules did not appeare TGF-? immunoreactivity;The epithelial cells of collecting tubules in chick embryo appeared AQP-2 immunoreactivity at 26th-46th stages;The epithelial cells of proximal tubules and distal tubules of mesonephros appeared Bax immunoreactivity at 26th-37th stages,the epithelial cells of proximal tubules of metanephros appeared Bax immunoreactivity at 33rd-46th stages.Images showed the expressions of EGFR,TGF-?(?_1,?_2,?_3)and Bax first displayed up then down,but expression of AQP-2 always displayed up during development of chick embryo.Conclusion Mesonephros of chick embryo has the function of excreting.Degeneration of renal tubules of mesonephros might be related with the excessive expression of TGF-? and Bax.Development,differentiation and maturation of renal tubules and collecting tubules of metanephros might be due to the synergetic expression of EGFR,TGF-?,AQP-2 and Bax.AQP-2 relats to the balance of water during development and maturation of renal tubules in chick embryo.