Abstract 069: β-Catenin Signaling Contributes to Angiotensin II-Induced Hypertension via Activation of Sodium Transporters in the Distal Nephron

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Xiaohan Lu ◽  
Kexin Peng ◽  
Fei Wang ◽  
Tianxin Yang
Keyword(s):  
Protein Expression ◽  
Collecting Duct ◽  
Urine Volume ◽  
Fold Increase ◽  
Control Group ◽  
Protein Abundance ◽  
Distal Nephron ◽  
Induced Hypertension

β-Catenin signaling plays an important role in regulation of development as well as tissue homeostasis. Recently, we have shown that this pathway is involved in regulation of collecting duct (CD) function. Here, we examined the role of β-catenin signaling in AngII-induced hypertension. C57/BL6 mice were administered for 7 d with vehicle, AngII alone (300 ng/kg/min) or in combination with an inhibitor of β-catenin pathway, ICG-001 (50 mg/kg/d) both via an osmotic mini-pump. Radiotelemetry demonstrated that ICG-001 effectively attenuated AngII-induced hypertension (MAP on day 7: 112.5 ± 2.02 in Control group vs. 137±2.07 in AngII group vs. 119.2±2.26 mmHg in AngII/ICG-001 group, n = 7-9, p<0.05) accompanied with a 34% (34 of 100) increase in 24-h urine volume and a 35% (35 of 100) increase in 24-h urinary Na+ excretion. Following AngII treatment, urinary renin activity and renin content both exhibited a more than 10-fold increase which was completely blocked by ICG-001. AngII infusion selectively elevated α-ENaC protein abundance in the renal medulla but not in the renal cortex; the renal medullary upregulation of α-ENaC protein expression was attenuated by ICG-001. Similarly, renal cortical NCC and NKCC2 protein expression was elevated by AngII infusion; this upregulation of NCC and NKCC2 protein expression was again abolished by ICG-001. In contrast, NHE3 protein abundance remained constant. In cultured mpkCCD cells transfected with a β-catenin-driven luciferase construct, AngII treatment at 500 nM for 24 h induced a 10-fold increase in the reporter activity which was sensitive to ICG-001 (1 μM). In these cells, the AngII treatment induced amiloride-sensitive Na + transport as assessed by epithelial volt-ohmmeter, which was completely blocked by ICG-001. Protein expression of α-ENaC exhibited the similar pattern of changes as ENaC activity whereas the expression of β- or γ-ENaC remained constant. ICG-001 was not associated with noticeable toxicity in vivo or in vitro. In summary, these results suggest that β-catenin signaling mediates AngII-induced hypertension at least in part through regulation of intrarenal renin response and the expression of Na+ transporters in the distal nephron.

Abstract 124: Soluble (Pro)Renin Receptor Regulation of ENaC in Angiotensin II Signaling in the Collecting Duct

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Fei Wang ◽  
Xiaohan Lu ◽  
Chuanming Xu ◽  
Kexin Peng ◽  
Tianxin Yang
Keyword(s):  
Jugular Vein ◽  
Collecting Duct ◽  
Neutralizing Antibody ◽  
Fold Increase ◽  
Receptor Regulation ◽  
Protein Abundance ◽  
Reporter Activity ◽  
Angiotensin Ii Signaling ◽  
Induced Hypertension ◽  
Antibody Elisa

We have shown that activation of (pro)renin receptor (PRR) and local renin response in the collecting duct (CD) contributes to AngII-induced hypertension. Moreover, the 28 kDa soluble (pro)renin receptor (sPRR) derived from cleavage of the extracellular domain of PRR is elevated by AngII and stimulated AQP2 expression via activation of frizzled-8/β-catenin pathway. Here we examined sPRR regulation of ENaC and further explored its implication in AngII signaling. In cultured mpkCCD cells, a recombinant histidine-tagged rat sPRR, sPRR-His, at 10 nM for 24 h induced a 3-fold increase in α-ENaC protein abundance. The native sPRR generated by immunoprecipitation with anti-sPRR antibody from either mouse or human urine exhibited a similar stimulatory effect on α-ENaC expression. The sPRR-His-induced α-ENaC expression was nearly completely abolished by a frizzled-8 inhibitor OMP54F03 (OMP). Similarly, amiloride-sensitive Na + transport as assessed by epithelial volt-ohmmeter was elevated by exposure to sPRR-His within minutes, which was abolished by OMP. In mpkCCD cells expressing a β-catenin-driven luciferase construct, the reporter activity was increased by 2.5-fold which was sensitive to OMP. In these cells, ENaC activity was transiently stimulated by exposure to 100 nM AngII within minutes, which was abolished by a sPRR neutralizing antibody. ELISA demonstrated that 24-h AngII treatment induced a 7-fold increase in medium sPRR concentrations. In floxed mice, urinary sPRR excretion was increased by AngII infusion whereas CD-specific PRR KO mice exhibited a reduced bassline level of urinary sPRR excretion which was not responsive to AngII infusion (300 ng/kg/min). Radiotelemetry demonstrated that the null mice were largely resistant to AngII-induced hypertension (MAP: Floxed/CTR: 105.9±1.6; Floxed/AngII: 136.3±3.1; KO/CTR:106.3±3.6; KO/AngII: 118.7±3.1 mmHg) which was fully restored after sPRR-His infusion via catheterization of jugular vein at 30 μg/kg/d (MAP: KO/AngII+sPRR-His: 135±7.5 mmHg). The MAP returned to normal when sPRR-His was terminated. Together, the present study reveals frizzled-8/β-catenin-dependent activation of α-ENaC in response to sPRR that at least in part contributes to AngII-induced hypertension.

scholarly journals Hydroxytyrosol Plays Antiatherosclerotic Effects through Regulating Lipid Metabolism via Inhibiting the p38 Signal Pathway

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xinxin Zhang ◽  
Yating Qin ◽  
Xiaoning Wan ◽  
Hao Liu ◽  
Chao Iv ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Molecular Mechanisms ◽  
Cholesterol Metabolism ◽  
Fold Increase ◽  
Heart Tissue ◽  
Control Group ◽  
Atherosclerotic Lesions ◽  
Serum Crp

Purpose. Hydroxytyrosol (HT) processes multiaspect pharmacological properties such as antithrombosis and antidiabetes. The aim of this study was to explore the antistherosclerotic roles and relevant mechanisms of HT. Methods. Male apoE-/- mice were randomly divided into 2 groups: the control group and the HT group (10 mg/kg/day orally). After 16 weeks, blood tissue, heart tissue, and liver tissue were obtained to detect the atherosclerotic lesions, histological analysis, lipid parameters, and inflammation. And the underlying molecular mechanisms of HT were also studied in vivo and in vitro. Results. HT administration significantly reduced the extent of atherosclerotic lesions in the aorta of apoE-/- mice. We found that HT markedly lowered the levels of serum TG, TC, and LDL-C approximately by 17.4% (p=0.004), 15.2% (p=0.003), and 17.9% (p=0.009), respectively, as well as hepatic TG and TC by 15.0% (p<0.001) and 12.3% (p=0.003), respectively, while inducing a 26.9% (p=0.033) increase in serum HDL-C. Besides, HT improved hepatic steatosis and lipid deposition. Then, we discovered that HT could regulate the signal flow of AMPK/SREBP2 and increase the expression of ABCA1, apoAI, and SRBI. In addition, HT reduced the levels of serum CRP, TNF-α, IL-1β, and IL-6 approximately by 23.5% (p<0.001), 27.8% (p<0.001), 18.4% (p<0.001), and 19.1% (p<0.001), respectively, and induced a 1.4-fold increase in IL-10 level (p=0.014). Further, we found that HT might regulate cholesterol metabolism via decreasing phosphorylation of p38, followed by activation of AMPK and inactivation of NF-κB, which in turn triggered the blockade of SREBP2/PCSK9 and upregulation of LDLR, apoAI, and ABCA1, finally leading to a reduction of LDL-C and increase of HDL-C in the circulation. Conclusion. Our results provide the first evidence that HT displays antiatherosclerotic actions via mediating lipid metabolism-related pathways through regulating the activities of inflammatory signaling molecules.

335 CYTOPLASMIC MICROINJECTION OF EXOGENOUS DNA IN IN VITRO AND IN VIVO DERIVED SHEEP EMBRYOS

2011 ◽  
Vol 23 (1) ◽  
pp. 263
Author(s):  
F. Pereyra-Bonnet ◽  
A. Gibbons ◽  
M. Cueto ◽  
R. Bevacqua ◽  
L. Escobar ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Genetically Modified ◽  
Fold Increase ◽  
Egfp Expression ◽  
Control Group ◽  
Corpora Lutea ◽  
Exogenous Dna ◽  
Frozen Semen

Microinjection of DNA into the male pronucleus is a commonly used method to generate transgenic animals. However, it is only moderately efficient in several species because it requires proper male pronuclear visualisation, which occurs only in a narrow window of time in mice. The cytoplasmic microinjection of exogenous DNA (eDNA) is an alternative method that has not been fully investigated. Our objective was to evaluate if cytoplasmic microinjection of eDNA is capable of producing genetically modified embryos. In vitro and in vivo derived sheep embryos were cytoplasmically microinjected with pCX-EGFP previously incubated (5 min in a PVP droplet) with oolemma-cytoplasm fragments obtained from donor oocytes by microsurgery. A control group using microinjected plasmid alone was included in the in vivo procedure. For in vitro microinjection, IVF embryos were microinjected with circular plasmid with promoter (50 or 500 ng μL–1) or without promoter (50 ng μL–1) at 6 h after fertilization. The IVF was performed following (Brackett and Olliphant 1975 Biol. Reprod. 12, 260–274) with 15 × 106 spermatozoa mL–1, and presumptive zygotes were cultured in SOF. The expression of enhance green fluorescent protein (EGFP) was determined under blue light. For in vivo microinjection, embryos from superovulated sheep (by standard procedures) were recovered and microinjected with 50 ng μL–1 of linearized plasmid without promoter at 12 h after laparoscopic insemination with frozen semen (100 × 106 spermatozoa per sheep). Plasmid without promoter was used to avoid any possible cytotoxic effect produced by EGFP expression. The microinjection of IVF embryos with 50 ng μL–1 of plasmid was the best condition to produce embryos expressing eDNA (n = 96; 46.9% cleaved; 12.2% blastocysts; 53.0 and 4.1% of green embryos and blastocysts, respectively). Variables between the groups with or without promoter IVF were not statistically different (Fisher test: P < 0.05); however, when 500 ng μL–1 was microinjected, no blastocysts were obtained. In the in vivo embryo production group, 111 presumptive zygotes were microinjected (n = 37; with plasmid alone) from 16 donor sheep (11.5 ± 4.0 corpora lutea; 8.4 ± 4.8 presumptive zygotes recovered; 74.3% recovery rate). The mean time from injection to cleavage was 18.0 ± 4.5 h, and the percentage of cleavage and damage (due to the embryo injection) were >70% and <10%, respectively. Fifty-eight good quality embryos were transferred into the oviducts of 19 surrogate ewes; 12 of them are pregnant (63.1%). The presence of green IVF embryos demonstrates that eDNA was transported to the nucleus after cytoplasmic injection. We believe that the multi-fold increase (50- to 100-fold) in plasmid concentration compared with that used by others was the key step to our successful cytoplasmic microinjection. Accordingly, the new/old methodology described in this study provides an easy DNA construct delivery system of interest for the implementation of early reprogramming events. In addition, results obtained in the near future using in vivo cytoplasmic microinjection with high concentrations of eDNA could revalidate this technique for producing genetically modified large animals.

scholarly journals In vitro and in vivo immunomodulatory properties of octyl-β-d-galactofuranoside during Leishmania donovani infection

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Hélène Guegan ◽  
Kevin Ory ◽  
Sorya Belaz ◽  
Aurélien Jan ◽  
Sarah Dion ◽  
...  
Keyword(s):  
Immune Response ◽  
Leishmania Donovani ◽  
Parasite Burden ◽  
Human Monocyte ◽  
Fold Increase ◽  
Control Group ◽  
End Of Treatment ◽  
Immunosuppressed Patients

Abstract Background The chemotherapeutic arsenal available to treat visceral leishmaniasis is currently limited, in view of many drawbacks such as high cost, toxicity or emerging resistance. New therapeutic strategies are particularly needed to improve the management and the outcome in immunosuppressed patients. The combination of an immunomodulatory drug to a conventional anti-Leishmania treatment is an emerging concept to reverse the immune bias from Th2 to Th1 response to boost healing and prevent relapses. Methods Here, immunostimulating and leishmanicidal properties of octyl-β-d-galactofuranose (Galf) were assessed in human monocyte-derived macrophages (HM) and in a murine model, after challenge with Leishmania donovani promastigotes. We recorded parasite loads and expression of various cytokines and immune effectors in HM and mouse organs (liver, spleen, bone marrow), following treatment with free (Galf) and liposomal (L-Galf) formulations. Results Both treatments significantly reduced parasite proliferation in HM, as well as liver parasite burden in vivo (Galf, P < 0.05). Consistent with in vitro results, we showed that Galf- and L-Galf-treated mice displayed an enhanced Th1 immune response, particularly in the spleen where pro-inflammatory cytokines TNF-α, IL-1β and IL-12 were significantly overexpressed compared to control group. The hepatic recruitment of myeloid cells was also favored by L-Galf treatment as evidenced by the five-fold increase of myeloperoxidase (MPO) induction, which was associated with a higher number of MPO-positive cells within granulomas. By contrast, the systemic level of various cytokines such as IL-1β, IL-6, IL-17A or IL-27 was drastically reduced at the end of treatment. Conclusions Overall, these results suggest that Galf could be tested as an adjuvant in combination with current anti-parasitic drugs, to restore an efficient immune response against infection in a model of immunosuppressed mice.

Effect of calcitonin on urine concentration in the rat

1983 ◽  
Vol 244 (4) ◽  
pp. F432-F435 ◽  
Author(s):  
S. Carney ◽  
T. Morgan ◽  
C. Ray ◽  
L. Thompson
Keyword(s):  
Water Permeability ◽  
Partial Agonist ◽  
Collecting Duct ◽  
Free Water ◽  
Urine Concentration ◽  
Distal Nephron ◽  
Free Water Clearance ◽  
Normal Increase

Because mammalian distal nephron segments with both calcitonin- and antidiuretic hormone- (ADH) sensitive adenylate cyclase activity have been described, in vivo and in vitro experiments were performed to study the effect of calcitonin on rat distal nephron water permeability. Calcitonin 1 and 0.1 U/ml, but not 0.01 U/ml, significantly increased the diffusional water permeability in the isolated papillary collecting duct by 15 and 11%, respectively. However, this effect was small when compared with a 68% increase with a supramaximal concentration of ADH (from 4.0 +/- 0.3 to 6.7 +/- 0.9 microns/s; n = 6, P less than 0.01). The normal increase in water permeability with increasing concentration of ADH (0.02 and 0.2 mU/ml) was depressed by the previous addition of calcitonin (1 U/ml) to the bath but was unaltered with the supramaximal ADH concentration (2 mU/ml). Verapamil, a compound that antagonizes cellular calcium entry, did not alter the effect of calcitonin on diffusional water permeability. Calcitonin in concentrations of 0.05, 0.5, and 5 U/ml produced a significant reduction in urine flow and free water clearance. Pretreatment with calcitonin in these concentrations inhibited the antidiuretic action of ADH. These studies suggest that calcitonin acts as a partial agonist to ADH within the distal nephron. It is unclear whether such an action represents a physiological or a pharmacological effect.

scholarly journals In vitro and in vivo tenocyte-protective effectiveness of dehydroepiandrosterone against high glucose-induced oxidative stress

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Shintaro Mukohara ◽  
Yutaka Mifune ◽  
Atsuyuki Inui ◽  
Hanako Nishimoto ◽  
Takashi Kurosawa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Matrix Metalloproteinase ◽  
Protein Expression ◽  
Achilles Tendon ◽  
Mrna Expression ◽  
High Glucose ◽  
Control Group ◽  
Type I

Abstract Background Dehydroepiandrosterone (DHEA), an adrenal steroid, has a protective role against diabetes. This study aimed to investigate the in vitro and in vivo protective effects of DHEA against high glucose-induced oxidative stress in tenocytes and tendons. Methods Tenocytes from normal Sprague-Dawley rats were cultured in low-glucose (LG) or high-glucose (HG) medium with or without DHEA. The experimental groups were: control group (LG without DHEA), LG with DHEA, HG without DHEA, and HG with DHEA. Reactive oxygen species (ROS) production, apoptosis, and messenger RNA (mRNA) expression of NADPH oxidase (NOX) 1 and 4, and interleukin-6 (IL-6) were determined. Further, diabetic rats were divided into a control group and a DHEA-injected group (DHEA group). NOX1 and NOX4 protein expression and mRNA expression of NOX1, NOX4, IL-6, matrix metalloproteinase (MMP)-2, tissue inhibitors of matrix metalloproteinase (TIMP)-2, and type I and III collagens in the Achilles tendon were determined. Results In rat tenocytes, DHEA decreased the expression of NOX1 and IL-6, ROS accumulation, and apoptotic cells. In the diabetic rat Achilles tendon, NOX1 protein expression and mRNA expression of NOX1, IL-6, MMP-2, TIMP-2, and type III collagen were significantly lower while type I collagen expression was significantly higher in the DHEA group than in the control group. Conclusions DHEA showed antioxidant and anti-inflammatory effects both in vitro and in vivo. Moreover, DHEA improved tendon matrix synthesis and turnover, which are affected by hyperglycemic conditions. DHEA is a potential preventive drug for diabetic tendinopathy.

scholarly journals In Vitro and in Vivo Tenocyte-protective Effectiveness of Dehydroepiandrosterone Against High Glucose-induced Oxidative Stress

2021 ◽  
Author(s):  
Shintaro Mukohara ◽  
Yutaka Mifune ◽  
Atsuyuki Inui ◽  
Hanako Nishimoto ◽  
Takashi Kurosawa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Matrix Metalloproteinase ◽  
Protein Expression ◽  
Achilles Tendon ◽  
Mrna Expression ◽  
High Glucose ◽  
Control Group ◽  
Type I

Abstract BackgroundDehydroepiandrosterone (DHEA), an adrenal steroid, has a protective role against diabetes. The aim of this study was to investigate the in vitro and in vivo protective effects of DHEA against high glucose-induced oxidative stress in tenocytes and tendons. Methods In an in vitro study, tenocytes from normal Sprague-Dawley rats were cultured in low-glucose (LG) or high-glucose (HG) medium with or without DHEA. The experimental groups were: control group (LG without DHEA), LG with DHEA, HG without DHEA, and HG with DHEA. Reactive oxygen species (ROS) production, apoptosis, and messenger RNA (mRNA) expression of NADPH oxidase (NOX) 1 and 4, and interleukin-6 (IL-6) were determined. In the in vivo study, diabetic rats were divided into a control group and a DHEA-injected group (DHEA group). NOX1 and NOX4 protein expression and mRNA expression of NOX1, NOX4, IL-6, matrix metalloproteinase (MMP)-2, tissue inhibitors of matrix metalloproteinase (TIMP)-2, and type I and III collagens in the Achilles tendon were determined. Results In rat tenocytes, DHEA decreased the expression of NOX1 and IL-6, ROS accumulation, and apoptotic cells. In the diabetic rat Achilles tendon, NOX1 protein expression and mRNA expression of NOX1, IL-6, MMP-2, TIMP-2, and type III collagen were significantly lower, while type I collagen expression was significantly lower in the DHEA group.Conclusions DHEA showed antioxidant and anti-inflammatory effects both in vitro and in vivo. Moreover, DHEA improved tendon matrix synthesis and turnover which are affected by hyperglycemic conditions. DHEA could be a preventive drug for the diabetic tendinopathy.

Dual effects for lovastatin in anaplastic thyroid cancer: the pivotal effect of transketolase (TKT) on lovastatin and tumor proliferation

2018 ◽  
Vol 66 (5) ◽  
pp. 1.4-9 ◽  
Author(s):  
Chih-Yuan Wang ◽  
Hao-Ai Shui ◽  
Tien-Chun Chang
Keyword(s):  
Thyroid Cancer ◽  
Cell Growth ◽  
Protein Expression ◽  
Tumor Growth ◽  
Anaplastic Thyroid Cancer ◽  
Control Group ◽  
Cancer Cell Growth ◽  
Protein Levels

This study tested the hypothesis that the effects of lovastatin on anaplastic thyroid cancer cell growth are mediated by upregulation of transketolase (TKT) expression. The effects of lovastatin on TKT protein levels in ARO cells were determined using western blot and proteomic analyses. After treatment with lovastatin and oxythiamine, the in vitro and in vivo growth of ARO cells was determined using 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assays and tumor xenografts in nude mice. TKT protein expression in the ARO tumors was assessed using immunohistochemistry analysis. Proteomic analysis revealed that 25 µM lovastatin upregulated TKT expression. Co-treatment of ARO cells with 1 µM lovastatin + 1 µM oxythiamine increased TKT protein expression compared with control levels; however, no differences were observed with 10 µM lovastatin + 1 µM oxythiamine. Furthermore, treatment with either oxythiamine or lovastatin alone reduced ARO tumor expression of TKT, as well as decreased ARO cell proliferation in vitro and tumor growth in vivo. However, mice treated with both lovastatin and oxythiamine at the same time had tumor volumes similar to that of the untreated control group. We conclude that either lovastatin or oxythiamine reduced ARO cell growth; however, the combination of these drugs resulted in antagonism of ARO tumor growth.

Cisplatin Nano-Liposomes Promoting Apoptosis of Retinoblastoma Cells Both In Vivo and In Vitro

2020 ◽  
Vol 12 (4) ◽  
pp. 536-542
Author(s):  
Lijuan Zhao ◽  
Fei Wang ◽  
Wei Fan
Keyword(s):  
Protein Expression ◽  
Nude Mice ◽  
Caspase 3 ◽  
Mrna Level ◽  
Control Group ◽  
Mrna Levels ◽  
Bax Protein ◽  
Experimental Group

This study was established to investigate the effects of cisplatin nano-liposomes on the apoptosis of the human retinoblastoma (RB) cell line Y79 in vitro and in vivo. Y79 cells were cultured and then exposed to Annexin V/PI to test their apoptosis, tested with the Caspase-3 activity detection kit to examine the change in activity of Caspase-3, and subjected to western blotting to test Bcl-2 and Bax protein expression. Y79-cell-transplanted tumor model in nude mice was also established and divided into three groups, with five nude mice in each. Cisplatin nano-liposomes were applied to the experimental group, cisplatin was injected into the control group, while saline was administered to the blank group, after which the nude mice were killed and the tumor was removed. Tumor volumes and weights in the three groups were compared. Nucleic acid extraction from magnetic beads was adopted to extract DNA, RT-PCR was employed to test Bcl-2 and Bax mRNA levels in tumor tissues, and in situ cell death assay kit was applied to test apoptotic cells. In comparison to the cisplatin solution and DMSO groups, the cisplatin liposome group showed higher Y79 apoptotic rate, Caspase-3 activity, and Bax protein expression, and lower Bcl-2 protein expression (all P < 0 05). In comparison with the control and blank groups, the experimental group showed lower tumor volume, weight, and Bcl-2 mRNA level of nude mice. In addition, in comparison with the control group, the experimental group showed higher cellular apoptotic rate and Bax mRNA level. In terms of the clinical effects of cisplatin nano-liposomes on a tumor transplant in nude mice with cervical cancer, they were shown to promote tumor apoptosis.

Lithium treatment inhibits renal GSK-3 activity and promotes cyclooxygenase 2-dependent polyuria

2005 ◽  
Vol 288 (4) ◽  
pp. F642-F649 ◽  
Author(s):  
Reena Rao ◽  
Ming-Zhi Zhang ◽  
Min Zhao ◽  
Hui Cai ◽  
Raymond C. Harris ◽  
...  
Keyword(s):  
Protein Expression ◽  
Glycogen Synthase ◽  
Lithium Treatment ◽  
Critical Role ◽  
Urine Volume ◽  
Cyclooxygenase 2 ◽  
Gsk 3Β ◽  
Cox2 Expression

The use of LiCl in clinical psychiatry is routinely complicated by overt nephrogenic diabetes insipidus (NDI), the mechanism of which is incompletely understood. In vitro studies indicate that lithium can induce renal medullary interstitial cell cyclooxygenase 2 (COX2) protein expression via inhibition of glycogen synthase kinase-3β (GSK-3β). Both COX1 and COX2 are expressed in the kidney. Renal prostaglandins have been suggested to play an important role in lithium-induced polyuria. The present studies examined whether induction of the COX2 isoform contributes to LiCl-induced polyuria. Four days after initiation of lithium treatment in C57 BL/6J mice, urine volume increased in LiCl-treated mice by fourfold compared with controls ( P < 0.0001) and was accompanied by decreased urine osmolality. This was temporally associated with increased renal COX2 protein expression and increased urinary PGE2 excretion, whereas COX1 levels remained unchanged. COX2 inhibition significantly blunted lithium-induced polyuria ( P < 0.0001) and reduced urinary PGE2 levels. Lithium-associated polyuria was also seen in COX1−/− mice and was associated with increased urinary PGE2. COX2 inhibition completely prevented polyuria and PGE2 excretion in COX1−/− mice, suggesting that COX2, but not COX1, plays a critical role in lithium-induced polyuria. Lithium also induced renal medullary COX2 protein expression in congenitally polyuric antidiuretic hormone (AHD)-deficient rats, demonstrating that lithium-induced COX2 protein expression is not secondary to altered ADH levels or polyuria. Lithium also decreased renal medullary GSK-3β activity, and this was temporally related to increased COX2 expression in the kidney from lithium-treated mice, consistent with a tonic in vivo suppression of COX2 expression by GSK-3 activity. In conclusion, these findings temporally link decreased GSK-3 activity to enhanced renal COX2 expression and COX2-derived urine PGE2 excretion. Suppression of COX2-derived PGE2 blunts lithium-associated polyuria.

Sign in / Sign up

Export Citation Format

Share Document