Clinical characteristics and molecular genetics of seven neonates with congenital nephrogenic diabetes insipidus / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical characteristics, genetic basis and clinical treatment of seven neonates with congenital nephrogenic diabetes insipidus (NDI).@*METHODS@#Clinical data of the patients were collected. High-throughput sequencing was carried out to detect potential variants. Sanger sequencing was used to verify the results.@*RESULTS@#The patients were all males, with the age of onset being 10 to 21 days. All patients were admitted to the hospital for intermittent fever as the first symptom during the neonatal period. Additional symptoms had included polydipsia and polyuria. After the treatment, 5 patients had recovered, the remainders still had NDI symptoms and developmental retardation. Five children were found to harbor pathogenic variants of the AVPR2/AQP2 gene, which included one in-frame mutation of c.645_646insGCACCTACCCTGGGTATCGCC, two missense mutations of c.541C>T and c.419C>A, and two hemizygous deletions of the AVPR2/AQP2 gene. Among these, two were unreported previously. Cases 6 and 7 were a pair of twins. Both had carried homozygous missense variants of c.538G>A of the AVPR2/AQP2 gene, which was known to be pathogenic.@*CONCLUSION@#AVPR2/AQP2 is the main pathogenic gene for congenital NDI, for which two novel pathogenic variants have been discovered in this study. Above results have provided a basis for clinical diagnosis and genetic counseling for the affected pedigrees.

Analysis of AVPR2 variant in a neonate with congenital nephrogenic diabetes insipidus / 中华医学遗传学杂志

OBJECTIVE@#To detect potential variant in a male neonate affected with congenital nephrogenic diabetes insipidus (CNDI).@*METHODS@#Clinical data of the patient was collected. Genomic DNA was extracted from peripheral blood samples from the child and his parents. The whole coding regions of the arginine vasopressin V2 receptor (AVPR2) gene were amplified by PCR and subjected to Sanger sequencing.@*RESULTS@#The patient presented recurrent fever and polyuria after birth. Multiple blood gas analyses indicated hypernatremia. Ultrasound showed bilateral hydronephrosis and hydroureter. The patient was partially responsive to hydrochlorothiazide. DNA analysis identified a hemizygous frameshift variant c.890-899delACCCGGAGGC in exon 2 of the AVPR2 gene in the proband. His mother was heterozygous for the same variant.@*CONCLUSION@#The c.890-899delACCCGGAGGC variant of the AVPR2 gene probably underlies the CNDI in the child. Above discovery has enriched to spectrum of CNDI associated variants.

Expression of V2R and AQPs in the renal medulla of high-fat nutritional obesity of rat / Expresión de V2R y AQPs en la médula renal de ratas con obesidad nutricional alta en grasas

Recent evidence has indicated that adipose tissue produces bioactive substances that contribute to obesity-related kidney disease, altering the renal function and structure. Eight of the AQPs are expressed in the kidney, where several of them contribute to water absorption and maintenance of body water balance. In the study, we mainly examined the localization of AQP2, AQP3 and V2R in renal medulla of Normal Diet (ND) and High-fat Diet (HFD) of rats, respectively. In renal medulla of HFD, immunolight microscopy revealed weak expression of AQP2 at the apical plasma membrane and intracellular vesicles of principal cells of the IMCD and OMCD. AQP3 and V2R expression also observed a decrease in immunolabelling in the IMCD and OMCD. It was suggested that excess lipid accumulation may lead to lipotoxicity and may be the major driver of organ dysfunction such as water reabsorption dysfunction, which may be resulted from abnormal response of rphan G-protein-coupled receptors in kidney.

La evidencia reciente ha indicado que el tejido adiposo produce sustancias bioactivas que contribuyen a la enfermedad renal relacionada con la obesidad, alterando la función y la estructura renal. Ocho de los AQP se expresan en el riñón, donde varios de ellos contribuyen a la absorción de agua y al mantenimiento del equilibrio hídrico corporal. En el estudio, examinamos principalmente la localización de AQP2, AQP3 y V2R en la médula renal de ratas con dieta normal (ND) y ratas con dieta alta en grasas (HFD). En la médula renal del grupo HFD, la microscopía electrónica de barrido reveló una expresión débil de AQP2 en la membrana plasmática apical y las vesículas intracelulares de las células principales de IMCD y OMCD. La expresión de AQP3 y V2R también observó una disminución en el inmunomarcador en IMCD y OMCD. Se sugiere que el exceso de acumulación de lípidos puede conducir a lipotoxicidad y ser el principal impulsor de la disfunción orgánica, como la disfunción de reabsorción de agua, que puede ser el resultado de la respuesta anormal de los receptores acoplados a proteína rphan G en el riñón.

New insights into the transcriptional regulation of aquaporin-2 and the treatment of X-linked hereditary nephrogenic diabetes insipidus

The kidney collecting duct (CD) is a tubular segment of the kidney where the osmolality and final flow rate of urine are established, enabling urine concentration and body water homeostasis. Water reabsorption in the CD depends on the action of arginine vasopressin (AVP) and a transepithelial osmotic gradient between the luminal fluid and surrounding interstitium. AVP induces transcellular water reabsorption across CD principal cells through associated signaling pathways after binding to arginine vasopressin receptor 2 (AVPR2). This signaling cascade regulates the water channel protein aquaporin-2 (AQP2). AQP2 is exclusively localized in kidney connecting tubules and CDs. Specifically, AVP stimulates the intracellular translocation of AQP2-containing vesicles to the apical plasma membrane, increasing the osmotic water permeability of CD cells. Moreover, AVP induces transcription of the Aqp2 gene, increasing AQP2 protein abundance. This review provides new insights into the transcriptional regulation of the Aqp2 gene in the kidney CD with an overview of AVP and AQP2. It summarizes current therapeutic approaches for X-linked nephrogenic diabetes insipidus caused by AVPR2 gene mutations.

Genetic diagnosis for a pedigree affected with hereditary nephrogenic diabetes insipidus / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for pedigree affected with hereditary nephrogenic diabetes insipidus (HNDI).@*METHODS@#Next generation sequencing (NGS) with an osteology system gene panel was carried out for the proband. Suspected mutation was validated by Sanger sequencing of two relatives with similar symptoms and two unaffected relatives from the pedigree.@*RESULTS@#The proband was found to carry a c.856C>T mutation of the AVPR2 gene. The same mutation was detected in the two relatives with similar symptoms and one unaffected healthy relative.@*CONCLUSION@#The HNDI in this pedigree may be attributed to the c.856C>T mutation of the AVPR2 gene.

Effect of Zhenwu Tang on regulating of "AVP-V2R-AQP2" pathway in NRK-52E cells / 中国中药杂志

This study was aimed to investigate the effect and mechanism of Zhenwu Tang on AVP-V2R-AQP2 pathway in NRK-52E cells . Forty eight male SD rats were randomly divided into eight groups with 6 animals in each group. Distilled water or 22.68 g·kg⁻¹·d⁻¹ Zhenwu Tang(calculated by raw drug dosage meter) was given by gavage. Blood samples were collected by cardiac puncture， and the medicated serum was centrifuged from the blood by 3 000 r·min⁻¹. NRK-52E cells were treated with different medicated serum or dDAVP. The condition of cell proliferation was detected by RTCA. The distribution of V2R and AQP2 in cells were detected by immunofluorescence. The expression of V2R， PKA and AQP2 were detected by Western blot and AQP2 mRNA level was detected by real-time PCR. Results showed that the level of AQP2 mRNA(<0.01) and protein expression of V2R， PKA and AQP2(<0.05， <0.01， <0.05) of Z7d group which was treated with Zhenwu Tang medicated serum for 24 h were significantly higher than that of normal rat serum group. And the expression level of V2R， p-AQP2 and AQP2(<0.01， <0.05， <0.01) of Z7d+dDAVP group were significantly increased comparing to normal rat serum group. The results indicate that the applying of Zhenwu Tang medicated serum could increase the expression level of V2R， PKA and AQP2 which exist in AVP-V2R-AQP2 pathway in NRK-52E， and there is synergistic effect between Zhenwu Tang medicated serum and dDAVP. So the pathway of AVP-V2R-AQP2 may be one of the mechanism for which Zhenwu Tang regulate balance of water transportation.

Oxytocin produces thermal analgesia via vasopressin-1a receptor by modulating TRPV1 and potassium conductance in the dorsal root ganglion neurons

Recent studies have provided several lines of evidence that peripheral administration of oxytocin induces analgesia in human and rodents. However, the exact underlying mechanism of analgesia still remains elusive. In the present study, we aimed to identify which receptor could mediate the analgesic effect of intraperitoneal injection of oxytocin and its cellular mechanisms in thermal pain behavior. We found that oxytocin-induced analgesia could be reversed by d(CH₂)₅[Tyr(Me)²,Dab⁵] AVP, a vasopressin-1a (V1a) receptor antagonist, but not by desGly-NH₂-d(CH₂)₅[DTyr², Thr⁴]OVT, an oxytocin receptor antagonist. Single cell RT-PCR analysis revealed that V1a receptor, compared to oxytocin, vasopressin-1b and vasopressin-2 receptors, was more profoundly expressed in dorsal root ganglion (DRG) neurons and the expression of V1a receptor was predominant in transient receptor potential vanilloid 1 (TRPV1)-expressing DRG neurons. Fura-2 based calcium imaging experiments showed that capsaicin-induced calcium transient was significantly inhibited by oxytocin and that such inhibition was reversed by V1a receptor antagonist. Additionally, whole cell patch clamp recording demonstrated that oxytocin significantly increased potassium conductance via V1a receptor in DRG neurons. Taken together, our findings suggest that analgesic effects produced by peripheral administration of oxytocin were attributable to the activation of V1a receptor, resulting in reduction of TRPV1 activity and enhancement of potassium conductance in DRG neurons.

Osmotic Demyelination Syndrome Resulting from an Unexpected Response to Tolvaptan in a Patient with Heart Failure / 대한내과학회지

Hyponatremia is commonly encountered in patients with heart failure and has a poor prognosis. Tolvaptan, a novel selective vasopressin V2 receptor blocker, has received attention as an effective drug for treating the syndrome of inappropriate antidiuretic hormone secretion and hypervolemic hyponatremia. However, the safety of tolvaptan in the treatment of hyponatremia is not clear. We experienced a 78-year-old woman with a history of heart failure, atrial fibrillation, and hyponatremia who developed osmotic demyelination syndrome as an unexpected response to treatment with tolvaptan.

Edematous Hyponatremia Treated with Tolvaptan in a Patient with Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) patients rarely present with either syndrome of inappropriate antidiuretic hormone secretion or generalized edema. Tolvaptan is a selective vasopressin V2 receptor antagonist that produces effective aquaresis, and its use in ALS patients has not been previously reported. A 50-year-old male ALS patient was admitted because of both generalized edema and dilutional hyponatremia. These manifestations were refractory to conventional diuretics and fluid therapy, but a very brisk diuresis was induced by tolvaptan administration. Edema and hyponatremia were also improved, and the patient was able to be discharged without tolvaptan. In this case report, we postulate how edema and dilutional hyponatremia developed in the patient, and discuss the mechanism of tolvaptan in treating hypervolemic hyponatremia. Further experience is necessary to evaluate the usefulness of tolvaptan in patients with neurological disorders.

Analysis of AVPR2 gene mutation in a pedigree affected with congenital nephrogenic diabetes insipidus / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutation in a pedigree affected with congenital nephrogenic diabetes insipidus (NDI).</p><p><b>METHODS</b>Clinical data of a male patient affected with NDI was collected. Genomic DNA was extracted from peripheral blood samples from the patient and five family members. The whole coding region of the arginine vasopressin receptor 2 (AVPR2) gene was amplified by PCR and directly sequenced.</p><p><b>RESULTS</b>The patient presented polyuria and polydipsia postnatally. Computerized tomography revealed bilateral hydronephrosis and hydroureter. The patient was responsive to hydrochlorothiazide but not to desmopressin. DNA analysis identified a hemizygous missence mutation c.295 T>C in exon 2 of the AVPR2 gene in the proband. His mother and grandmother were both heterozygous for the same mutation.</p><p><b>CONCLUSION</b>The congenital NDI in the patient was probably due to mutation of the AVPR2 gene.</p>

The Anti-Inflammatory Effect of Arginine-Vasopressin on Lipopolysaccharide-Induced IkappaBalpha/Nuclear Factor-kappaB Cascade / 대한중환자의학회지

BACKGROUND: Arginine vasopressin (AVP) is widely used as a vasopressor agent. Some recent studies have suggested that AVP may exert an immunomodulatory effect. However, the mechanism about the anti-inflammatory effect of AVP is not well known. We investigated the effect of AVP on the ihibitor of kappa B (IkappaBalpha)/nuclear factor-kappa B (NF-kappaB) pathway in RAW 264.7 cells. METHODS: Cultured RAW 264.7 cells were pretreated with AVP and stimulated with lipopolysaccharide (LPS). To evaluate the effect of AVP on inflammatory cytokines, the concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by an enzyme-linked immunosorbent assay technique. The expression of IkappaBalpha and nuclear translocation of NF-kappaB p65 were measured by Western blotting, and IkappaB kinase (IKK) activity was analyzed by an in vitro immune complex kinase assay. To confirm the AVP effect on IkappaBalpha/NF-kappaB cascade and via V2 receptor, we added tolvaptan (V2 receptor antagonist) after AVP pretreatment. RESULTS: The increase of IL-6 and TNF-alpha in LPS-stimulated RAW 264.7 cells was suppressed by a treatment with AVP. Pretreatment of AVP inhibited increasing of IKK activity and IkappaBalpha degradation induced by LPS in RAW 264.7 cells. Furthermore, LPS induced and NF-kappaB transcription was inhibited by AVP pretreatment. The observed changes in IKK activity, IkappaBalpha degradation and NF-kappaB transcription by AVP was abolished by tolvaptan treatment. CONCLUSIONS: Our results suggest that AVP showed anti-inflammatory effect on LPS-induced IkappaBalpha/NF-kappaB cascade in mouse macrophages via V2 receptors.

Recent Advances in the Management of Autosomal Dominant Polycystic Kidney Disease / 대한내과학회지

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. It is characterized by the dysregulated growth of kidney cysts, resulting in end-stage kidney failure. By identifying the genes involved in ADPKD and detailing the molecular pathology of the disease, putative therapeutic agents have been developed. However, clinical trials of vasopressin receptor antagonists and somatostatin analogues have raised several concerns among researchers and clinicians. Questions regarding when and who to treat and what surrogate marker to use for describing endpoints have been raised. This review focuses on the current methods for managing ADPKD and describes recent findings from clinical trials. The main difficulties associated with implementing therapeutic agents in patients with ADPKD and considerations for clinical settings will also be discussed.

Congenital nephrogenic diabetes insipidus with end-stage renal disease

No abstract available.

The Anti-Inflammatory Effect of Arginine-Vasopressin on Lipopolysaccharide-Induced IkappaBalpha/Nuclear Factor-kappaB Cascade / 대한구급학회지

BACKGROUND: Arginine vasopressin (AVP) is widely used as a vasopressor agent. Some recent studies have suggested that AVP may exert an immunomodulatory effect. However, the mechanism about the anti-inflammatory effect of AVP is not well known. We investigated the effect of AVP on the ihibitor of kappa B (IkappaBalpha)/nuclear factor-kappa B (NF-kappaB) pathway in RAW 264.7 cells. METHODS: Cultured RAW 264.7 cells were pretreated with AVP and stimulated with lipopolysaccharide (LPS). To evaluate the effect of AVP on inflammatory cytokines, the concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were assessed by an enzyme-linked immunosorbent assay technique. The expression of IkappaBalpha and nuclear translocation of NF-kappaB p65 were measured by Western blotting, and IkappaB kinase (IKK) activity was analyzed by an in vitro immune complex kinase assay. To confirm the AVP effect on IkappaBalpha/NF-kappaB cascade and via V2 receptor, we added tolvaptan (V2 receptor antagonist) after AVP pretreatment. RESULTS: The increase of IL-6 and TNF-alpha in LPS-stimulated RAW 264.7 cells was suppressed by a treatment with AVP. Pretreatment of AVP inhibited increasing of IKK activity and IkappaBalpha degradation induced by LPS in RAW 264.7 cells. Furthermore, LPS induced and NF-kappaB transcription was inhibited by AVP pretreatment. The observed changes in IKK activity, IkappaBalpha degradation and NF-kappaB transcription by AVP was abolished by tolvaptan treatment. CONCLUSIONS: Our results suggest that AVP showed anti-inflammatory effect on LPS-induced IkappaBalpha/NF-kappaB cascade in mouse macrophages via V2 receptors.

Genetic analysis of a congenital nephrogenic diabetes insipidus pedigree / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>As an X-linked recessive way, arginine vasopressin receptor 2 (AVPR2) gene mutation resulted in a hereditary disease - congenital nephrogenic diabetes insipidus (CNDI). We found a suspect clinical CNDI pedigree. In order to identify the genetic etiology, we performed the genetic analysis.</p><p><b>METHODS</b>The clinical features of the proband and his family members were recorded. The laboratory tests and imaging inspections were analyzed. The water deprivation and pituitrin loading test were performed in the proband and his brother. The genomic DNA of all the members of the pedigree was extracted and then PCR amplification on AVPR2 gene was carried out. Sequencing in both directions was performed to identify mutation on AVPR2 gene.</p><p><b>RESULTS</b>Both the proband and his brother were diagnosed as CNDI, meanwhile the other members of this pedigree were normal. No severe biochemical abnormality was found in the two CNDI patients. Both the patients had moderate urinary retention, severe megaloureter and hydronephrosis, and mild renal insufficiency. Two mutations of AVPR2 gene were discovered in the 3rd exon in the patients, a silent mutation L309L and a nonsense mutation R337X. The AVPR2 gene R337X mutation was co-segregated with CNDI. R337X mutation was not a reported mutation in the mainland of China.</p><p><b>CONCLUSION</b>The AVPR2 gene R337X mutation was also a genetic etiology of CNDI patients in the mainland of China.</p>

Clinical Application of V2 Receptor Antagonists / 대한내과학회지

Hyponatremia results from a relative excess of total body water compared with the sodium content. Except for primary polydipsia, vasopressin activation plays a major role in pathogenesis of water retention. Consequently, the increase of solute-free water clearance by inactivating vasopressin action would be a more reasonable therapeutic approach than the addition of sodium. The V2 vasopressin receptor is mainly localized to the collecting ducts in the kidney and causes water reabsorption via water channels. Selective V2 receptor antagonists or vaptans were recently introduced to clinical practices and may be useful for correcting dilutional hyponatremia. Clinical trials have shown that vaptans are effective in increasing the serum sodium concentration in patients with syndrome of inappropriate anti-diuresis and congestive heart failure and that they might be safe as long as patients are allowed free accesses to water. However, the indications for using vaptans need to be more refined, and the question of their long-term cost-effectiveness should be answered. In addition, the potential roles of vaptans in ameliorating the growth of cysts in polycystic kidney disease, saving diuretics in edematous disorders, and retarding the progression of chronic kidney disease are being explored.

A Case of Hyponatraemic Seizure Following Terlipressin Therapy for a Variceal Hemorrhage in a Patient with Liver Cirrhosis / 대한내과학회지

Terlipressin has splanchnic vasoconstrictive effects, and is generally used for the management of gastroesophageal variceal bleeding secondary to liver cirrhosis. Terlipressin is a synthetic arginine vasopressin (AVP) analog containing a nonapeptide sequence. Terlipressin has increased selectivity for the V1 receptor, compared with AVP; hence, it is considered to be a safe vasoconstrictor. However, side effects such as hyponatremia and seizure, although very rare, have been reported. Hyponatremia related to terlipressin may be caused by the syndrome of inappropriate antidiuresis (SIAD), which is a disorder of sodium and water balance characterized by hypotonic hyponatremia without elevation of the antidiuretic hormone level. Here, we report a case of hyponatremic seizure induced by an infusion of terlipressin in a 52-year-old female who had isolated gastric variceal bleeding secondary to alcoholic liver cirrhosis.

The Role of V2 Receptor Antagonists in the Treatment of Hyponatremia

No abstract available.

The pressor effect of angiotensin-(1-7) in the rat rostral ventrolateral medulla involves multiple peripheral mechanisms

OBJECTIVE: In the present study, the peripheral mechanism that mediates the pressor effect of angiotensin-(1-7) in the rostral ventrolateral medulla was investigated. METHOD: Angiotensin-(1-7) (25 pmol) was bilaterally microinjected in the rostral ventrolateral medulla near the ventral surface in urethane-anesthetized male Wistar rats that were untreated or treated (intravenously) with effective doses of selective autonomic receptor antagonists (atenolol, prazosin, methyl-atropine, and hexamethonium) or a vasopressin V1 receptor antagonist [d(CH2)5 -Tyr(Me)-AVP] given alone or in combination. RESULTS: Unexpectedly, the pressor response produced by angiotensin-(1-7) (16 ± 2 mmHg, n = 12), which was not associated with significant changes in heart rate, was not significantly altered by peripheral treatment with prazosin, the vasopressin V1 receptor antagonist, hexamethonium or methyl-atropine. Similar results were obtained in experiments that tested the association of prazosin and atenolol; methyl-atropine and the vasopressin V1 antagonist or methyl-atropine and prazosin. Peripheral treatment with the combination of prazosin, atenolol and the vasopressin V1 antagonist abolished the pressor effect of glutamate; however, this treatment produced only a small decrease in the pressor effect of angiotensin-(1-7) at the rostral ventrolateral medulla. The combination of hexamethonium with the vasopressin V1 receptor antagonist or the combination of prazosin, atenolol, the vasopressin V1 receptor antagonist and methyl-atropine was effective in blocking the effect of angiotensin-(1-7) at the rostral ventrolateral medulla. CONCLUSION: These results indicate that angiotensin-(1-7) triggers a complex pressor response at the rostral ventrolateral medulla that involves an increase in sympathetic tonus, release of vasopressin and possibly the inhibition of a vasodilatory mechanism.

Efficacy of Vaptans for Management of Ascites in Patients with Liver Cirrhosis / 대한내과학회지

Ascites is the most common complication of liver cirrhosis, but its pharmacological management is unsatisfactory in some patients because of a lack of response to treatment with conventional diuretics. Patients with cirrhosis and ascites generally have increased non-osmotic secretion of vasopressin which participates in the pathogenesis of fluid retention. Vaptans are a new family of orally active drugs that increase urine volume by antagonizing specifically the vasopressin receptors in the principal cells of the collecting ducts that have been shown to correct dilutional hyponatremia effectively. They also seem to be promising in the management of ascites by reducing the increased extracellular fluid volume in conditions associated with water retention including liver cirrhosis. However, there is a paucity of information on whether vaptans might have beneficial effect in enhancing ascites reduction in patients with cirrhosis. This review addresses the pharmacological actions of vaptans, their clinical applications, and future potential roles in managing patients with liver cirrhosis and ascites.