Renal PGE2 Research Articles

Involvement of NOX-4/JAK/STAT pathway in the protective effect of aprepitant against diclofenac-induced renal toxicity

AimsAprepitant, a neurokinin-1 (NK1) receptor antagonist, is a clinically approved anti-emetic drug. Recently, inhibition of the NK1 receptor has been reported as a potential nephroprotective strategy. We aimed to assess the pharmacological mechanisms of aprepitant against diclofenac (DIC)-induced renal toxicity. Main methodsAn in vivo study was conducted using twenty-four male Wistar rats, divided into 4 groups. Aprepitant was administered for 5 days (5 mg/kg/day) with or without DIC which was given on the 4th and 5th days (50 mg/kg, i.p.). At the end of the study, renal function biomarkers, renal oxidative parameters, prostaglandin E (PGE-2), and NADPH oxidase (NOX-4) were measured. Histopathological changes as well as expression of renal inflammatory and apoptotic markers (tumor necrosis factor alpha (TNF-α) and caspase-3) were investigated. Key findingsDIC caused significant renal damage, as evidenced by deterioration of renal functions, oxidative stress, inflammatory and apoptotic markers, and confirmed by histopathological findings. Pretreatment with aprepitant successfully ameliorated and improved all biochemical and molecular parameters induced by DIC. Moreover, aprepitant restored the decrease in renal PGE-2 concentration and inhibited DIC-activated Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling in renal tissues. SignificanceThe protective effect of aprepitant is possibly attributed to its anti-oxidant and anti-inflammatory roles via the NOX-4/JAK/STAT pathway.

Antenatally Administered NSAIDs Improve Renal Cyclooxygenase and Antiangiogenic Profiles in Rats with Preeclampsia

Although cyclooxygenase (COX) inhibitors are often prescribed to relief fever and pain during pregnancy, their possible interaction with perinatal renal injury induced by preeclampsia (PE) remains undecided. Here, functional, and molecular studies were undertaken in the L-NAME model of PE to assess the influence of gestational exposure to selective COX-2 (celecoxib) or nonselective COX-1/COX-2 inhibitors (diclofenac or naproxen) on the developed renal damage. The treatment of rats with L-NAME (50 mg/kg/day) during the last week of pregnancy significantly increased urine protein content, a marker of renal damage, at gestational day 20, an effect that continued till weaning. The proteinuric effect of PE was paradoxically affected by NSAIDS, intensified by celecoxib, and weakened by diclofenac or naproxen. All NSAIDs comparably reduced the heightened COX-2 activity in renal tissues of PE rats, whereas the parallel elevation in renal COX-1 activity was expectedly less affected by celecoxib compared with the nonselective drugs. The dramatic PE-mediated 10-fold rise in renal prostanoids (PGE2, PGF2α, and thromboxane A2) was reduced by naproxen and to a lesser extent by celecoxib. On the other hand, diclofenac had no effect on elevated renal thromboxane A2, and was less effective than other NSAIDs in reducing renal PGE2 and PGF2α. Finally, all 3 NSAIDs dampened down the elevated renal gene expression of the antiangiogenic factors fms-like tyrosine kinase-1 and soluble endoglin, key predisposing factors to PE-associated multisystem organ injury. The data demonstrate that all tested NSAIDs favorably reprogram perinatal renal damage caused by PE and predisposing molecular mechanisms, effects that were most evident with naproxen.

Clinico-genetic specifications of Bartter and Gitelman syndrome in children

Molecular genetic research has led to the discovery of new genes encoding proteins – transporters, cotransporters and exchangers involved in the transport of sodium, potassium and chlorine in the thick ascending part of the Henle loop and in the distal convoluted tubule. The article presents modern literature data on the genetic types of tubulopathy with the leading syndrome of hypokalemia and alkalosis – Bartter and Gitelman syndromes in children. The clinical and genetic features of the six types of Bartter syndrome with autosomal recessive and X-linked inheritance, classification approaches, diagnosis, and modern treatment methods are described. Since the first description of Bartter syndrome, 6 clinical genetic options have been known, including antenatal I, II, IVa, IVb, V types, which are potentially life-threatening diseases. Bartter type III syndrome is characterized by the manifestation of hypokalemic alkalosis in children at an early and preschool age. Treatment of Bartter syndrome in children includes the correction of water – electrolyte disturbances, the use of non-steroidal anti-inflammatory drugs (NSAIDs) to inhibit the excessive formation of renal prostaglandin PgE 2. Gitelman syndrome with an autosomal recessive type of inheritance manifests itself in children at school age, later on in adolescents and adults there is an increase in clinical manifestations (with severe hypomagnesemic seizures of the upper and lower extremities, arterial hypertension) requiring correction. The review presents the clinical and genetic features of the rare, atypical form of the autosomal recessive Gitelman syndrome with a manifestation in school age, which is characterized by progressive bilateral calcifications of the subcortical parts of the cerebral hemispheres, calcifications in the basal ganglia and subcortical cerebellum. Unlike Bartter syndrome, with more severe clinical manifestations in newborns, infants and young children, Gitelman syndrome tends to increase clinical manifestations in adolescents and adults. Treatment of Gitelman syndrome in children and adolescents includes the correction of water – electrolyte disturbances, the use of magnesium preparations and salt subsidy.

Protective effect of royal jelly against diclofenac-induced hepato-renal damage and gastrointestinal ulcerations in rats

ObjectiveEvaluation of traditionally used royal jelly (RJ) for the management of hepato-renal damage and gastrointestinal ulcerations caused by diclofenac. MethodsForty adult male Wistar rats were allocated into four groups. Rats of the 1st group received only saline and served as normal group. The remaining 3 groups received diclofenac (50 mg/kg/day, I.P.) for 7 days. Group 2 served as diclofenac-control group. Groups 3 and 4 received RJ (150 and 300 mg/kg/day, P.O.) respectively for 30 days. Twenty-four hours after the last treatment, blood samples were collected, rats were sacrificed, and livers, kidneys, stomachs & intestines were harvested. Stomachs and intestines were tested for ulcer counts. Serum levels of AST, ALT, creatinine and urea were investigated. Hepatic, renal, gastric and intestinal tissue contents of myeloperoxidase (MPO) and prostaglandin-E2 (PGE2) were measured. Histopathological examinations were also performed followed by immunohistochemical determination of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression. ResultsDiclofenac administration caused significant deterioration of all the above mentioned parameters. RJ improved hepatic and renal functions. Gastric and intestinal ulcer counts were significantly ameliorated. Hepatic, renal, gastric and intestinal tissue PGE-2 contents and COX-2 expression were significantly elevated. RJ also significantly reduced MPO content and iNOS expression as compared to diclofenac-control group. Improvements of the histopathological pictures of hepatic, renal, gastric and intestinal tissues were also apparent. ConclusionThe study demonstrates promising protective effects of RJ against diclofenac-induced hepato-renal damage and gastrointestinal ulceration in rats.

NSAIDs and heart failure: A dangerous relationship.

One of the potential cardiotoxic action of anti-inflammatory drugs is the occurrence of heart failure (HF), due to their effects on fluid retention and blood pressure. The risk of hospitalization for HF is roughly doubled for both Coxibs, cyclooxygenase-1 (COX-1) and cyclooxygenase- 2 (COX-2) inhibitors, and all the conventional nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs are also associated with a risk of vascular thrombosis, which for NSAIDs is different in relation to their different ability to inhibit COX-1 and COX-2. The cardiovascular toxicity of these drugs in the direction of HF follow different pathways respect to their related vascular thrombosis toxicity and involves, in particular, the renal prostaglandins, PGE2 and prostacyclin, mostly synthesized by COX-2. In the kidneys the PGs perform a direct vasodilatory action, e.g. by means of non-contrasting angiotensin mechanisms, and for this reason nimesulide effects on renal microcirculation are independent from the prevalence of intrarenal renin angiotensin aldosterone system (RAAS) activity. Conversely, nimesulide reduces sodium tubular urinary flow only in presence of intrarenal RAAS.

Enhanced lipoxygenase/LTD4 signaling accounts for the exaggerated hypertensive and nephrotoxic effects of cyclosporine plus indomethacin in rats

The combined use of cyclosporine (CSA) and nonsteroidal antiinflammatory drugs (NSAIDs) causes exaggerated rises in systolic blood pressure (SBP) and nephrotoxicity. We examined whether these influences relate to the arachidonate/5-lipoxygenase (LOX) pathway. Rats were treated with CSA (20 mg kg−1 day−1), indomethacin (5 mg kg−1 day−1), or their combination for 10 days. Changes in SBP and renal biochemical/histopathological characteristics along with leukotriene levels were determined in rats treated with or without LT receptor antagonists. CSA or indomethacin caused: (i) renal tubular atrophy and interstitial fibrosis, (ii) increases in serum creatinine, blood urea nitrogen (BUN), and renal LTD4, LTB4, TNF-α, TGF-β1, and caspase-3, and (iii) decreases in renal PGE2 and total antioxidant capacity (TAC). SBP measured by tail-cuff plethysmography was increased by CSA but not indomethacin. These effects were mostly intensified in rats treated with CSA plus indomethacin. The co-treatment with montelukast (cysteinyl LT receptor blocker), but not ONO-4057 (LTB4 receptor blocker), ameliorated CSA/indomethacin-evoked hypertension, renal structural/biochemical deterioration, and LTD4 levels. Moreover, montelukast exhibited a greater capacity in reversing inflammatory, oxidative, apoptotic, and fibrotic abnormalities induced by CSA/indomethacin. Overall, lipoxygenase/LTD4 upregulation contributes to the exaggerated hypertension and nephrotoxicity caused by CSA/indomethacin. The therapeutic potential of cysteinyl LT receptor antagonism in rectifying CSA/NSAIDs-evoked anomalies is warranted.

Nitrooleic acid protects against cisplatin nephropathy: role of COX-2/mPGES-1/PGE2 cascade.

Nitrooleic acid (OA-NO2) is an endogenous lipid product which has novel signaling properties, particularly the activation of peroxisome proliferator-activated receptors. The current study aimed to evaluate the protective effects of OA-NO2 against cisplatin-induced kidney injury in mice. Mice were pretreated with OA-NO2 for 48 h before cisplatin administration, and the cisplatin-caused nephrotoxicity was evaluated. After the cisplatin treatment (72 h), the vehicle-treated mice displayed renal dysfunction, as evidenced by the elevated plasma urea and creatinine, which was consistent with the histological damage, such as tubular necrosis, dilation, protein cast, and desquamation of epithelial cells. In contrast, the severity of the renal dysfunction and histological change were reduced in the OA-NO2 pretreated mice. The renal COX-2 and mPGES-1 mRNAs and their respective proteins expression, together with the renal PGE2 amounts, were induced by the cisplatin treatment, but their initiation was reduced by OA-NO2. Moreover, the circulating TNF-α, renal TNF-α, IL-1β, MCP-1, ICAM-1, and VACAM-1 mRNA levels were higher in the cisplatin-treated mice, compared with the controls, but they were attenuated in the OA-NO2 pretreatment group. In summary, the pretreatment with OA-NO2 remarkably ameliorated the cisplatin-induced kidney injury in mice, possibly via the inhibition of the inflammatory response, associated with the COX-2/mPGES-1/PGE2 cascade.

Abstract 301: Testosterone propionate in Ischemia-reperfusion (I/R) induced Acute Kidney Injury (AKI)

Acute kidney injury (AKI) is a leading cause of morbidity and mortality, and men are more prone to AKI than women implicating androgens as a causative factor whereas estrogens have been thought to be protective. These effects are independent of both androgen and estrogen receptors. We showed recently that infusion of testosterone 3 hrs post reperfusion protected rats from renal injury following ischemia/reperfusion (I/R). In the present study, we tested the hypothesis that testosterone works as a renal vasodilator perhaps by increasing nitric oxide. Male SD rats (8-14 wks; n=3-5/grp) were subjected to sham surgery or I/R induced AKI with bilateral clamping of renal vessels for 30 min. Three hrs after reperfusion, rats were given testosterone propionate (20 μg/kg iv over 10 min) or vehicle (0.75%EtOH). Rats were placed in metabolism cages for 24hrs for nitrate/nitrite excretion (UNOxV), and euthanized and blood taken for creatinine (PCr). I/R increased PCr and decreased UNOxV, compared to shams (0.58±0.05 vs. 3.99±0.36 mg/dL, p<0.0001; UNOxV: 8.54±1.7 vs 1.7±0.78 μmol/day/kg BW, p<0.001). Testosterone attenuated the increase in PCr (2.03±0.23 mg/dL, p< 0.01) but had no effect on UNOxV (3.79±0.91 μmol/day/kg). Pretreatment of rats with L-NAME (1mg/kg/day; dose that did not increase BP) for 48 hours prior to I/R abolished the improvement in PCr with testosterone (PCr: 3.73±0.82 mg/dL, p<0.05 vs no LNAME). Infusion of renal vasodilator PGE2 (30μg/kg iv over 10 min 3 hrs after reperfusion) attenuated PCr compared to I/R alone (2.95±0.21mg/dL, p<0.01) but was independent of increased NO (2.61±0.63 μmol/day/kg, p=NS vs I/R alone), and was not as effective in reducing PCr as testosterone (p<0.05). These data show that low dose testosterone infusion 3 hrs post reperfusion improves renal function in AKI perhaps by causing renal vasodilation. When NO synthesis is blocked, testosterone is incapable of improving PCr after I/R. Furthermore, although the known renal vasodilator PGE2 also improves PCr in I/R, although not as effectively as testosterone. These data continue to support the notion that testosterone infusion has therapeutic potential for the treatment of I/R induced AKI in humans. Supported by NIH R01HL66072, P01HL05971 and AHA 14POST18640015.

Urinary concentration does not exclusively rely on plasma vasopressin. A study between genders. Gender and diurnal urine regulation.

We investigated the influence of gender on the diurnal regulation of urine production with special focus on vasopressin, oxytocin and prostaglandin E2. Fifteen young women in mid-follicular phase and 22 young men (20-33years) were included. All participants underwent a 24-h circadian inpatient study under standardized conditions for measurements of plasma vasopressin, oxytocin, sodium and osmolality. Urine was fractionally collected for measurements of electrolytes, aquaporin-2 and prostaglandin E2. Plasma vasopressin expressed a diurnal rhythm with a night-time increase in both genders (P<0.001). The ratio between mean daytime and mean night-time was 1.57 [95% CI: 1.33-1.84] P<0.001 in men and 1.35 [95% CI: 1.11-1.64] P=0.002 in women. P-vasopressin was higher in males during the night (P<0.05). There was no difference in diuresis (P=0.43), urine osmolality (P=0.12) or aquaporin-2 excretion (P=0.80) between genders. We found a trend towards a higher reabsorption of free water in males (P=0.07). The excretion of prostaglandin E2 was higher in males (P<0.001). There was no diurnal rhythm in p-oxytocin (P=0.37) and no correlation to diuresis, urine osmolality or aquaporin-2 excretions. Similar urinary flows and osmolalities are associated with levels of plasma vasopressin and renal PGE2, which are higher in males than in females. Oxytocin does not seem to play a role in the diurnal urine formation, whereas prostaglandin E2 could represent a mediator of the gender difference, not only as a mediator of the vasopressin response, but also as an independent factor. These findings need further elucidation.

Decreased Expression of a Novel Prostaglandin Transporter, OAT-PG, Facilitates Renocortical PGE2 Accumulation during Rat Pregnancy

Background: Prostaglandin (PG)-specific organic anion transporter (OAT-PG) is a recently identified renal transporter involved in the local clearance of prostaglandin E₂ (PGE₂). Since the renal biosynthesis of PGE₂ is not increased during pregnancy, this transporter expression would affect the gestational changes in the renal PGE₂ content. Methods: Kidneys from rats at different gestational stages were used to examine gestational changes in the renocortical PGE₂ concentration. The renal expression of OAT-PG and the enzymes for PGE₂ synthesis was also examined sequentially, together with the gestational changes in renal renin production. Results: The renocortical PGE₂ concentration was significantly increased during midterm to late pregnancy, with a maximum increase of 47.6 ± 11.5% from the virgin value. Although the expression of the enzymes, such as cyclooxygenases and PG synthases, was not increased, that of OAT-PG was significantly decreased throughout pregnancy, inversely correlating with changes in the renocortical PGE₂ concentration. Renal renin production was significantly increased during pregnancy. Conclusion: This study demonstrated for the first time that the tissue PGE₂ concentration was increased in pregnant rat kidneys, which may be associated with the gestational rise in glomerular filtration rate. The decreased expression of OAT-PG was thought to be responsible for the increased tissue PGE₂ content.

Effects of Short- and Long-Term Hypercholesterolemia on Contrast-Induced Acute Kidney Injury

Background: Whether hypercholesterolemia is a risk factor for contrast-induced acute kidney injury (CI-AKI) remains unclear. In the present study, the effects of short- and long-term dietary hypercholesterolemia on contrast media-induced nephrotoxicity were evaluated. Methods: Rats were fed either a normal rodent diet (N) or high-cholesterol diet (H). At the end of 2 and 8 weeks, 8 rats from each diet group were given a tail vein injection of either iohexol (group NC and group HC) or vehicle (group N and group H). Blood lipids, renal function and renal hemodynamics were evaluated 1 day after contrast media administration. Renal and urinary prostaglandin E₂ (PGE₂) and thromboxane B₂ (TXB₂) were detected by radioimmunoassay. Renal nitric oxide and malondialdehyde (MDA) were measured by the Griess reaction and thiobarbituric acid method, respectively. Results: Contrast media administration increased serum creatinine levels and induced severe renal tubular necrosis in rats fed the high-cholesterol diet for 8 weeks but not in rats fed the normal diet or high-cholesterol diet for 2 weeks. The renal and urinary PGE₂ and TXB₂ levels increased significantly in rats in group H and group HC at the end of 8 weeks. Renal nitric oxide production decreased, and MDA levels increased markedly in group HC and group H at the end of 8 weeks. Conclusions: We conclude that long-term hypercholesterolemia appeared to be a risk factor for CI-AKI, which might be associated with disorders in intrarenal prostaglandins and abnormalities in renal nitric oxide system induced by lipid peroxidation.

Effects of aspirin, indomethacin, flufenamic acid and paracetamol on prostaglandin output from rat stomach and renal papilla in-vitro and ex-vivo.

The effects of aspirin, indomethacin, flufenamic acid and paracetamol on prostaglandin (PG) biosynthesis were studied in whole cell preparations of rat renal papilla and stomach in-vitro and ex-vivo. In the ex-vivo experiments a low dose aspirin was a potent inhibitor of PGE output from the stomach but not the renal papilla, while in-vitro renal PGE output was inhibited by aspirin to a greater extent than gastric PGE. Indomethacin and flufenamic acid inhibited both renal papillary and gastric PGE outputs in-vitro and ex-vivo. Paracetamol enhanced PGE output from the stomach more than twice ex-vivo, and to a lesser extent in-vitro. It also augmented PGE output from the papilla ex-vivo but not in-vitro. In view of the possible contribution of cellular organization and pharmacokinetic processes to the ultimate effect, it is suggested that studies on the effects of anti-inflammatory and antipyretic agents on PG biosynthesis should not be restricted to fully in-vitro systems.

A selective EP4 PGE2 receptor agonist alleviates disease in a new mouse model of X-linked nephrogenic diabetes insipidus

X-linked nephrogenic diabetes insipidus (XNDI) is a severe kidney disease caused by inactivating mutations in the V2 vasopressin receptor (V2R) gene that result in the loss of renal urine-concentrating ability. At present,no specific pharmacological therapy has been developed for XNDI, primarily due to the lack of suitable animal models. To develop what we believe to be the first viable animal model of XNDI, we generated mice in which the V2R gene could be conditionally deleted during adulthood by administration of 4-OH-tamoxifen.Radioligand-binding studies confirmed the lack of V2R-binding sites in kidneys following 4-OH-tamoxifen treatment, and further analysis indicated that upon V2R deletion, adult mice displayed all characteristic symptoms of XNDI, including polyuria, polydipsia, and resistance to the antidiuretic actions of vasopressin. Gene expression analysis suggested that activation of renal EP4 PGE2 receptors might compensate for the lack of renal V2R activity in XNDI mice. Strikingly, both acute and chronic treatment of the mutant mice with a selective EP4 receptor agonist greatly reduced all major manifestations of XNDI, including changes in renal morphology.These physiological improvements were most likely due to a direct action on EP4 receptors expressed on collecting duct cells. These findings illustrate the usefulness of the newly generated V2R mutant mice for elucidating and testing new strategies for the potential treatment of humans with XNDI.

Thyroid Hormone Regulates Renocortical COX-2 and PGE2 Expression in the Late Gestation Fetal Sheep

Cyclooxygenase 2 (COX-2) is important for development of the fetal kidney. Precisely how renal COX-2 expression is regulated in fetal life is unclear. The hypothesis that thyroid hormone positively regulates COX-2 and PGE(2) levels in the late gestation fetal kidney cortex was tested. Sham, thyroidectomized (TX), and TX + thyroid hormone replacement (R) fetal sheep were studied. TX was performed at 120 days gestational age (dGA). TX + R fetuses were continuously infused with thyroxine from 3 days after surgery until study completion. Fetal kidney cortex was obtained at 137 dGA for measurement of renal cyclooxygenase type-2 (COX-2) protein and PGE(2) metabolites. Renocortical COX-2 and PGE(2) levels were significantly lower in TX compared with sham and TX + R fetuses. There were no differences between sham and TX + R fetuses. These findings demonstrate that thyroid hormone positively regulates renal COX-2 and PGE(2) expression in the late gestation fetal sheep kidney.

Physiological Regulation of Prostaglandins in the Kidney

Cyclooxygenase-derived prostanoids exert complex and diverse functions within the kidney. The biological effect of each prostanoid is controlled at multiple levels, including (a) enzymatic reactions catalyzed sequentially by cyclooxygenase and prostanoid synthase for the synthesis of bioactive prostanoid and (b) the interaction with its receptors that mediate its functions. Cyclooxygenase-derived prostanoids act in an autocrine or a paracrine fashion and can serve as physiological buffers, protecting the kidney from excessive functional changes during physiological stress. Through these actions, prostanoids play important roles in maintaining renal function, body fluid homeostasis, and blood pressure. Renal cortical COX2-derived prostanoids, particularly PGI2 and PGE2, play critical roles in maintaining blood pressure and renal function in volume-contracted states. Renal medullary COX2-derived prostanoids appear to have an antihypertensive effect in individuals challenged with a high-salt diet. Loss of EP2 or IP receptor is associated with salt-sensitive hypertension. COX2 also plays a role in maintaining renal medullary interstitial cell viability in the hypertonic environment of the medulla. Cyclooxygenase-derived prostanoids also are involved in certain pathological processes. The cortical COX2-derived PGI2 participates in the pathogenesis of renal vascular hypertension through stimulating renal renin synthesis and release. COX-derived prostanoids also appear to be involved in the pathogenesis of diabetic nephropathy. COXs, prostanoid synthases, and prostanoid receptors should provide fruitful targets for intervention in the pharmacological treatment of renal disease.

Selective COX-2 inhibition markedly slows disease progression and attenuates altered prostanoid production in Han:SPRD-cyrats with inherited kidney disease

Selective cyclooxygenase-2 (COX-2) inhibitors appear to have beneficial renoprotective effects in most, but not all, renal disease conditions. The objective of our study was to examine the effects of COX-2 inhibition in a rat model of polycystic kidney disease. Four-week-old Han:SPRD-cy rats were given a standard rodent diet containing NS-398 (3 mg.kg body wt(-1).day(-1)) or a control diet without NS-398 for 7 wk. In diseased rats, selective COX-2 inhibition resulted in 18% and 67% reduction in cystic expansion and interstitial fibrosis, respectively, but no change in renal function. NS-398 also ameliorated disease-associated pathologies, such as renal inflammation, cell proliferation, and oxidant injury (by 33, 38, and 59%, respectively). Kidney disease was associated with elevated renal COX-1 and COX-2 enzyme activities, and NS-398 blunted the increase in COX-2 enzyme activity (as indicated by 21 and 28% lower renal thromboxane B2 and PGE2 levels, respectively). NS-398 reduced urinary excretion of prostanoid metabolites in diseased rats. In summary, COX-2 inhibition attenuated renal injury, reduced the elevated renal COX-2 activity, and ameliorated disease-related alterations in prostanoid production in this rat model of chronic renal disease.

Role of Microsomal Prostaglandin E Synthase 1 in the Kidney

Prostaglandin E(2) (PGE(2)) is one of the most ubiquitous prostanoids in the kidney, where it may influence a wide range of physiologic functions. PGE(2) is generated through enzymatic metabolism of prostanoid endoperoxides by specific PGE synthases (PGES). Several putative PGES have been identified and cloned, including the membrane-associated, inducible microsomal PGES1 (mPGES1), which is expressed in the kidney. To evaluate the physiologic role of mPGES1 in the kidney, mice with targeted disruption of mPges1 gene were studied, with a focus on responses where PGE(2) has been implicated, including urinary concentration, regulation of blood pressure, and response to a loop diuretic. The absence of mPGES1 was associated with a 50% decrease in basal excretion of PGE(2) in urine (P < 0.001). In female but not male mPGES1-deficient mice, there was a reciprocal increase in basal excretion of other prostanoids. Nonetheless, urinary osmolalities were similar in mPges1(+/+) and mPges1(-/-) mice at baseline and after 12 h of water deprivation. Likewise, there were no differences in blood pressure between mPGES1-deficient and wild-type mice on control or high- or low-salt diets. The furosemide-induced increase in urinary PGE(2) excretion that was seen in wild-type mice was attenuated in mPGES1-deficient mice. However, furosemide-associated diuresis was reduced only in male, not female, mPGES1-deficient mice. Stimulation of renin by furosemide was not affected by mPGES1 deficiency. These data suggest that mPGES1 contributes to basal synthesis of PGE(2), but there are other pathways that lead to renal PGE(2) synthesis. Moreover, there are significant gender differences in physiologic contributions of mPGES1 to control kidney function.

Effects of flaxseed derivatives in experimental polycystic kidney disease vary with animal gender

Flaxseed derivatives, including both oil and flax lignan, modify progression of renal injury in animal models, including Han:SPRD-cy polycystic kidney disease (PKD). Gender is a significant factor in the rates of progression of many forms of human renal disease, but the role of gender in the response to nutrition intervention in renal disease is unexplored. In this study, male and female Han:SPRD-cy rats or normal littermates were fed either corn oil (CO) or flax oil (FO) diets, with or without 20 mg/kg of the diet flax lignan secoisolaricinoresinol dyglycoside (SDG). Renal injury was assessed morphometrically and biochemically. Renal and hepatic PUFA composition was assessed by GC and renal PGE2 release by ELISA. FO preserved body weight in PKD males, with no effect in females. SDG reduced weight in both normal and PKD females. FO reduced proteinuria in both male and female PKD. FO reduced cystic change and renal inflammation in PKD males but reduced cystic change, fibrosis, renal inflammation, tissue lipid peroxides, and epithelial proliferation in PKD females. SDG reduced renal inflammation in all animals and lipid peroxides in PKD females. A strong interaction between SDG and FO was observed in renal FA composition of female kidneys only, suggesting increased conversion of C18 PUFA to C20 PUFA. FO reduced renal release of PGE2 in both genders. Gender influences the effects of flaxseed derivatives in Han:SPRD-cy rats. Gender-based responses to environmental factors, such as dietary lipid sources and micronutrients, may contribute to gender-based differences in disease progression rates.

Effects of specific COX-2-inhibition on renin release and renal and systemic prostanoid synthesis in healthy volunteers

The renin-angiotensin system plays a critical role in cardiovascular function, but little is known about the effects of specific cyclooxygenase 2 (COX-2) inhibition on this system in healthy humans under physiologic conditions. Twenty-one healthy female volunteers received, in a randomized, double-blind, crossover study, celecoxib 200 mg twice a day, indomethacin 50 mg three times a day, or placebo for 4 days and a single dose, each, on day 5. On day 5 of each treatment, the following parameters were assessed with subjects in an upright position before and after administration of 20 mg furosemide intravenously: plasma renin activity (PRA), plasma aldosterone, serum and urine electrolytes, and creatinine. Index metabolites of prostanoids were analyzed by gas chromatography-tandem mass spectrometry in 24-hour urine on day 4 and in 2-hour urines before and after furosemide administration. Baseline and furosemide-stimulated PRA were reduced to a similar degree by celecoxib and indomethacin. Plasma aldosterone and urinary excretion of potassium showed changes consistent with the alteration of PRA. Urinary excretion rates of prostaglandin E(2), (PGE(2)), 7alpha-hydroxy-5, 11-diketotetranor-prosta-1,16-dioic acid (PGE-M), and 2,3-dinor-thromboxane B(2) (TxB(2)) were not reduced by celecoxib, whereas indomethacin led to a decrease of 40%, 45%, and 80%, respectively. Both active treatments inhibited urinary excretion of 2,3-dinor-6-keto-PGF(1alpha) and 6-keto-PGF(1alpha) by 60% and 40%, respectively. Renin-release in healthy humans with normal salt intake is COX-2 dependent. While COX-1 is critical for renal and systemic PGE(2) production, renal prostacyclin synthesis is apparently COX-2 dependent. Finally, the previously demonstrated shift of the thromboxane-prostacyclin balance toward prothrombotic thromboxane by specific COX-2 inhibition is confirmed.

Perinatal management of a preterm neonate affected by hyperprostaglandin E2 syndrome (HPS)

Neonates affected by hyperprostaglandin E(2) syndrome (HPS) present with severe polyuria. Both urinary losses as well as prostaglandin synthesis inhibitors may precipitate acute renal failure (ARF). Our goal was to maintain euvolaemia by replacement of urinary losses. Our patient was born prematurely with a family history typical of HPS. Urinary salt and water losses and PGE(2) excretion were determined in 2- to 4-h intervals. Salt and water were replaced accordingly. Within the first 48 h, urinary losses and PGE(2) increased continuously to 50 ml/kg/h and 374 ng/h/1.73 m(2), respectively. Following exposure to 0.05-0.5 mg/kg/d indomethacin, urinary output decreased steadily to 10-15/ml/kg/h. In euvolaemic preterm neonates with HPS and the need for excessive replacement of salt and water, inhibition of renal PGE(2) excretion with indomethacin effectively reduces polyuria and natriuresis without acutely compromising renal function.