Rat Model Of Pregnancy-induced Hypertension Research Articles

To whom it may concern

To whom it may concern

Honokiol inhibits inflammation and endoplasmic reticulum stress in a rat model of pregnancy-induced hypertension

The levels of inflammatory factors in pregnancy-induced hypertension (PIH) are closely correlated with the severity of the disease. The enhanced endoplasmic reticulum (ER) stress response and upregulated iNOS might contribute to the pathophysiology of preeclampsia. Honokiol has been shown to be a potential anti-inflammatory and anti-ER stress agent. However, the effect of honokiol on the inflammation and ER stress has not been investigated in a gestational hypertensive model. The present study aimed to elucidate the role of honokiol in inflammation, ER stress and endothelial/inducible nitric oxide synthase (eNOS/iNOS) in a PIH rat model. Rats with hypoxia-induced PIH were administered honokiol (0, 200, 600, 2000 μg/kg) daily for one week to different groups by intragastric administration. Systolic blood pressure (SBP) and urinary protein concentration were measured via the tail-cuff method and CBB kit. Proinflammatory cytokines and ER-stress markers, VEGF, NO, iNOS and eNOS in the plasma or placental tissue were analyzed by enzyme-linked immunosorbent assay (ELISA), quantitative real time polymerase chain reaction (RT-qPCR), NO assay kit or western blot. The blood pressure and urinary protein level in PIH rats were significantly decreased after honokiol. Honokiol significantly inhibited the elevated levels of proinflammatory cytokines and ER-stress markers, which were accompanied by the upregulation of eNOS, NO and VEGF mRNA in PIH rats. However, the level of iNOS was reduced by honokiol. Our study suggests a beneficial potential of honokiol in PIH rats through inhibition of proinflammatory cytokines and ER stress. Honokiol could be an intriguing therapeutic approach in ER stress related PIH.

Role of B1 and B2 lymphocytes in placental ischemia-induced hypertension.

Preeclampsia is a prevalent pregnancy complication characterized by new-onset maternal hypertension and inflammation, with placental ischemia as the initiating event. Studies of others have provided evidence for the importance of lymphocytes in placental ischemia-induced hypertension; however, the contributions of B1 versus B2 lymphocytes are unknown. We hypothesized that peritoneal B1 lymphocytes are important for placental ischemia-induced hypertension. As an initial test of this hypothesis, the effect of anti-CD20 depletion on both B-cell populations was determined in a reduced utero-placental perfusion pressure (RUPP) model of preeclampsia. Anti-murine CD20 monoclonal antibody (5 mg/kg, Clone 5D2) or corresponding mu IgG2a isotype control was administered intraperitoneally to timed pregnant Sprague-Dawley rats on gestation day (GD)10 and 13. RUPP or sham control surgeries were performed on GD14, and mean arterial pressure (MAP) was measured on GD19 from a carotid catheter. As anticipated, RUPP surgery increased MAP and heart rate and decreased mean fetal and placental weight. However, anti-CD20 treatment did not affect these responses. On GD19, B-cell populations were enumerated in the blood, peritoneal cavity, spleen, and placenta with flow cytometry. B1 and B2 cells were not significantly increased following RUPP. Anti-CD20 depleted B1 and B2 cells in peritoneum and circulation but depleted only B2 lymphocytes in spleen and placenta, with no effect on circulating or peritoneal IgM. Overall, these data do not exclude a role for antibodies produced by B cells before depletion but indicate the presence of B lymphocytes in the last trimester of pregnancy is not critical for placental ischemia-induced hypertension.NEW & NOTEWORTHY The adaptive and innate immune systems are implicated in hypertension, including the pregnancy-specific hypertensive condition preeclampsia. However, the mechanism of immune system dysfunction leading to pregnancy-induced hypertension is unresolved. In contrast to previous reports, this study reveals that the presence of classic B2 lymphocytes and peritoneal and circulating B1 lymphocytes is not required for development of hypertension following third trimester placental ischemia in a rat model of pregnancy-induced hypertension.

Supplementing punicalagin reduces oxidative stress markers and restores angiogenic balance in a rat model of pregnancy-induced hypertension.

Pre-eclampsia (PE) is a pregnancy disorder that is characterised by severe hypertension and increased risks of foetal and maternal mortality. The aetiology of PE not completely understood; however, maternal nutrition and oxidative stress play important roles in the development of hypertension. The treatment options for PE are currently limited to anti-hypertensive drugs. Punicalagin, a polyphenol present in pomegranate juice, has a range of bioactive properties. The effects of supplementation with punicalagin on angiogenesis and oxidative stress in pregnant rats with induced hypertension were investigated. The pregnant rats were randomly divided into five experimental groups (n=12 per group). Hypertension was induced using an oral dose of NG-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg/day) on days 14–19 of pregnancy. Punicalagin (25, 50 or 100 mg/kg) was given orally on days 14–21 of pregnancy. Punicalagin treatment at the tested doses significantly reduced diastolic, systolic, and mean arterial blood pressure in L-NAME treated rats from day 14. Punicalagin also restored angiogenic balance by increasing the expression of vascular endothelial growth factor and downregulating vascular endothelial growth factor receptor-1/fms-like tyrosine kinase-1. Punicalagin, significantly increased the placental nitric oxide levels as compared to PE group. The increased levels of oxidative stress in rats with PE were markedly decreased by treatment with punicalagin. Punicalagin at the tested doses markedly (p<0.05) enhanced the placental antioxidant capacity in L-NAME-treated rats. The raised catalase activity observed following L-NAME induction was significantly (p<0.05) and restored to normal activity levels in punicalagin treatment. Further, 100 mg dose of punicalagin exhibited higher protective effects as compared to lower doses of 25 and 50 mg. This study shows that supplementation with punicalagin decreased blood pressure and oxidative stress and restored angiogenic balance in pregnant rats with induced PE.

Icariin improves acute kidney injury and proteinuria in a rat model of pregnancy‑induced hypertension.

Icariin has previously been demonstrated to attenuate hyperglycemia-induced renal injury, however the renoprotective effects of icariin in a rat model of pregnancy-induced hypertension (PIH) remain to be elucidated. The present study aimed to investigate the effect of icariin on PIH-induced acute kidney injury (AKI) and proteinuria. Following 18 days of icariin treatment between day 1 and day 18 of gestation, which was combined with NG-nitro-L-arginine methyl ester (L-NAME) treatment between day 12 and day 18 of gestation to induce PIH, the 24 h urine protein level, blood urea nitrogen and serum creatinine were measured by using the Coomassie Brilliant Blue method, a commercial enzymatic kit and the picric acid method, respectively. Renal tissues were collected at day 18 of gestation for hematoxylin and eosin staining and immunohistochemistry. The mRNA expression of AGT and protein expression of angiotensin II (Ang II) in the kidneys of control and PIH rats was investigated by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively, to determine the effect of icariin on components of the renin-angiotensin system. The results demonstrated that L-NAME treatment in pregnant rats resulted in significant increases in systolic blood pressure (SBP) and diastolic blood pressure, in addition to the induction of severe proteinuria. The significant increase in SBP and proteinuria in PIH rats was prevented by icariin. L-NAME-induced AKI resulted in profound renal histological alterations, including mesangial expansion and glomerular lesions. L-NAME administration exerted a marked decrease in the mRNA and protein expression levels of nephrin in the kidneys from PIH rats compared with control group. Furthermore, upregulation of circulating and renal Ang II levels in PIH rats was observed. However, icariin treatment significantly reversed the L-NAME-induced downregulation of nephrin and upregulation of circulating and renal Ang II levels in PIH rats. These results demonstrated that icariin administration improved urinary protein excretion levels and renal tissue damage in PIH rats, and the underlying mechanism was mediated in part, via upregulation of nephrin expression and downregulation of Ang II.

Abstract 030: Low-dose Aspirin During Pregnancy Does Not Prevent Augmentation of Arterial Contractions to Thromboxane A 2 in a Rat Model of Pregnancy-Induced Hypertension

Background: Daily intake of low dose aspirin after 12 weeks of gestation is currently recommended as a preventative intervention in pregnancies at high risk of developing preeclampsia. We previously showed that treating pregnant rats with a synthetic ligand of Toll-like receptor 9 (TLR9; ODN2395) activated the innate immune system causing preeclampsia-like characteristics such as maternal hypertension, vascular oxidative stress, and augmented vascular responses to thromboxane A 2 (TxA 2 ). Hypothesis: Low-dose aspirin treatment would ameliorate ODN2395-induced augmented responses to TxA 2 in maternal arteries. Methods: Pregnant rats were treated with ODN2395 (300 μg) or vehicle on gestational day (GD) 14, 16, 18. Daily low-dose aspirin treatment (1.5 mg/kgBW) started on GD10 and continued throughout gestation. Systolic blood pressure was measured using the tail-cuff method on GD19. On GD21, uterine (UTA) and mesenteric resistance artery (MES) responses to a TxA 2 mimetic (U46619, 10 -9 -10 -6 M) was measured with a wire myograph. Results: Uterine arteries from the ODN2395+Aspirin-treated group had greater contractile responses to U46619 compared to all other groups [Emax, %KCl: Control (n=6): 109.2±8.8; ODN2395 (n=5): 124.4±20.2; Aspirin (n=5): 76.08±11.2; ODN2395+Aspirin (n=5): 134.7±4.5, p&lt;0.05]. Aspirin alone reduced MES responses to U46619 compared to control and MES from ODN2395 and ODN2395+Aspirin groups had greater contractile responses to U46619 compared to Aspirin alone [Emax, %KCl: Control (n=8): 109.8±5.2; ODN2395 (n=6): 111.1±4.3; Aspirin (n=7): 89.4±3.6; ODN2395+Aspirin (n=8): 121.7±6.3, p&lt;0.05]. Rats treated with ODN2395 and ODN+Aspirin had greater systolic blood pressure compared to control rats [control (n=8): 97.3±3.2 mmHg, ODN2395 (n=6): 121.3±4.3 mmHg, Aspirin (n=8): 100.3±2.9 mmHg, ODN2395+Aspirin (n=7): 127.5 ±6.7 mmHg, p&lt;0.05]. Conclusion: Exposure to a TLR9 agonist during pregnancy resulted in augmented contractile responses to a TxA 2 mimetic in maternal arteries when rats were in a regime of low-dose aspirin. This was shown in arteries from both reproductive and non-reproductive vascular beds.

Inhibition of the JAK2/STAT3/SOSC1 Signaling Pathway Improves Secretion Function of Vascular Endothelial Cells in a Rat Model of Pregnancy-Induced Hypertension

Background/Aims: The present study aimed to investigate the effects of the JAK2/STAT3/SOSC1 signaling pathway on the secretion function of vascular endothelial cells (VECs) in a rat model of pregnancy-induced hypertension (PIH). Methods: A PIH rat model was established. Forty-eight pregnant Sprague-Dawley female rats were selected and assigned into four groups: the normal group (normal non-pregnant rats), the non-PIH group (pregnant rats without PIH), the PIH group (pregnant rats with PIH) and the AG490 group (pregnant rats with PIH treated with AG490). Systolic blood pressure (SBP) and urinary protein (UP) were measured. The expressions of JAK2/STAT3/SOSC1 signaling pathway-related proteins in placenta tissues were detect by Western blotting. Radioimmunoassay was applied to detect serum levels of nitric oxide (NO), super oxide dismutase (SOD), placental growth factor (PGF), thromboxane B2 (TXB2) and endothelin (ET). Enzyme-linked immunosorbent assay (ELISA) was used to determine serum levels of interleukin-6 (IL-6), interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α). Results: Compared with the normal and non-PIH groups, the PIH and AG490 groups had higher SBP and UP levels at 17^th and 25^th day of pregnancy. The expressions of p/t-JAK2, p/t-STAT3 and SOSC1 in the PIH and AG490 groups were higher than those in the non-PIH group, while the expressions of p/t-JAK2, p/t-STAT3 and SOSC1 in the AG490 group were lower than those in the PIH group. Compared with the non-PIH group, serum levels of ET, TXB2, IL-6 and TNF-α were increased in the PIH and AG490 groups, while serum levels of NO, SOD, 6-keto-PGF1a and IL-10 levels were reduced. Furthermore, the AG490 had lower serum levels of ET, TXB2, IL-6 and TNF-α and higher serum levels of NO, SOD, 6-keto-PGF1a and IL-10 than those in the PIH group. Conclusion: Our study provides evidence that inhibition of the JAK2/STAT3/SOSC1 signaling pathway could improve the secretion function of VECs in PIH rats.

Supplementation of maternal omega-3 fatty acids to pregnancy induced hypertension Wistar rats improves IL10 and VEGF levels

ObjectivesOur recent study demonstrates the beneficial effect of a combined supplementation of vitamin B12, folic acid, and docosahexaenoic acid in reducing the severity of pregnancy induced hypertension (PIH). It is also known to be associated with angiogenic imbalance and inflammation. The current study examines whether the individual/combined supplementation of folic acid, vitamin B12 and omega-3 fatty acid during pregnancy can ameliorate the inflammatory markers and restore the angiogenic balance in a rat model of PIH. Materials and methodsThere were total of six groups, control and five treatment groups: PIH Induced; PIH+vitamin B12; PIH+folic acid; PIH+Omega-3 fatty acids and PIH+combined micronutrient supplementation (vitamin B12+folic acid+omega-3 fatty acids). Hypertension during pregnancy was induced using L- Nitroarginine methylester (L-NAME; 50mg/kg body weight/day). Dams were dissected at d20 of gestation and placental tissues were collected for further analysis. ResultsAnimals from the PIH induced group demonstrated lower (p<0.01 for both) IL-10 and VEGF levels as compared to control. However, PIH induction did not alter the protein levels of eNOS, IL-6, Flt and mRNA levels of VEGF and VEGFR-1/ Flt-1. Individual micronutrient supplementation of vitamin B12 and folate did not offer benefit. In contrast individual omega-3 fatty acid as well as combined micronutrient supplementation showed IL-10 and VEGF levels comparable to that of control. ConclusionOmega 3 fatty acid supplementation plays a key role in reducing inflammation in pregnancy induced hypertension.

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Objectives Upregulation of placental soluble fms-like tyrosine kinase 1 (sFlt1) contributes to the pathogenesis of preeclampsia. Our aim was to evaluate novel upstream pathways that regulate placental sFlt1 production. Methods We screened a library of natural compounds ( N = 502) in primary cytotrophoblasts and placental villous cultures and characterized molecules that had biological activity in the nanomolar range. sFlt1 production was assayed by ELISA. Immunoblot analysis, Co-immunoprecipitation, RT-PCR were employed in Characterizing the sFlt1, HIF AND hsp27 proteins and RNA. Pregnancy-induced hypertension rats were used as animal models. Results Here we report three compounds in the cardiac glycoside family, ouabain, gitoxigenin and digitoxin that inhibited placental sFlt1 production at nanomolar concentrations in vitro. We further characterized ouabain and demonstrate that it inhibits sFlt1 mRNA and protein expression in human placental cytotrophoblasts and explant cultures in a dose and time dependent manner. Ouabain down-regulated sFlt1 production by inhibiting hypoxia inducible factor 1 (HIF-1 α ) protein expression in the placenta. Furthermore, we found that phosphorylation of heat shock protein 27 (HSP27) was necessary for ouabain to inhibit HIF-1 α translation. In a rat model of pregnancy-induced hypertension, ouabain reduced mean arterial pressure and enhanced placental HSP27 phosphorylation without any adverse effects on pups. Conclusions Collectively we show that ouabain inhibits placental sFlt1 production through a HIF-1 α / HSP27 dependent pathway. Further studies are needed to explore the usefulness of targeting HIF-1 α /HSP27 pathway in preeclampsia. Disclosures S. Rana: None. A. Rajakumar: None. C. Geahchan: None. S. Salahuddin: None. A. Cerdeira: None. S.D. Burke: None. E. George: None. J. Granger: None. S. Karumanchi: co-inventor on multiple patents for preeclampsia markers and reports service as a consultant to Siemens Diagnostics, and has financial interest in Aggamin LLC.

Ouabain inhibits placental sFlt1 production by repressing HSP27-dependent HIF-1α pathway.

Up-regulation of placental soluble fms-like tyrosine kinase 1 (sFlt1) contributes to the pathogenesis of preeclampsia. To evaluate novel upstream pathways that regulate placental sFlt1 production, we screened a library of natural compounds (n=502) in human placental cell lines. Here, we report 3 compounds in the cardiac glycoside family, ouabain, gitoxigenin, and digitoxin, that inhibit placental sFlt1 production at nanomolar concentrations in vitro. We further characterized ouabain and demonstrated that it inhibits sFlt1 mRNA and protein expression in human placental cytotrophoblasts and explant cultures in a dose- and time-dependent manner. Ouabain down-regulated sFlt1 production by inhibiting hypoxia-inducible factor 1 (HIF-1α) protein expression in the placenta. Furthermore, we found that phosphorylation of heat-shock protein 27 (HSP27) was necessary for ouabain to inhibit HIF-1α translation. In a rat model of pregnancy-induced hypertension, ouabain reduced mean arterial pressure and enhanced placental HSP27 phosphorylation without any adverse effects on pups. Further studies are needed to explore the usefulness of targeting HIF-1α/HSP27 pathway in preeclampsia.

Immunosuppression Improves Blood Pressure and Endothelial Function in a Rat Model of Pregnancy-Induced Hypertension

Hypertensive disorders of pregnancy, including preeclampsia (PE), affect approximately 7-10% of pregnancies in the US. Clinical and experimental studies strongly suggest that the maternal immune system plays a role in the development of these disorders; however, few therapeutic options exist aside from delivery. Using a deoxycorticosterone acetate (DOCA)/salt-low renin rat model, which exhibits hypertension, proteinuria, endothelial dysfunction, and intrauterine growth restriction (IUGR), we measured serum cytokine levels as an indication of immune system activation. In addition, we suppressed the immune system with either azathioprine (Aza) or mycophenolate mofetil (MMF) during the second half of pregnancy to determine whether the these symptoms could be ameliorated. Our results demonstrate that serum T helper-1 (Th1)-type inflammatory cytokines interleukin (IL)-2, IL-12, interferon-gamma (IFNgamma), and RANTES were significantly elevated in hypertensive pregnant rats while the Th2-type cytokine IL-4 was elevated in normal pregnant animals. Either Aza or MMF significantly attenuated the hypertension, proteinuria, and endothelial dysfunction as well as the increased proinflammatory Th1 cytokine profile in pregnant rats treated with DOCA/salt, and had no effect on these parameters in normal pregnant rats. These data strongly suggest that maternal immune system activation plays a role in the development of pregnancy-induced hypertension (PIH).

Uncoupled Endothelial Nitric Oxide Synthase and Oxidative Stress in a Rat Model of Pregnancy-Induced Hypertension

Preeclampsia is a human pregnancy-associated syndrome associated with hypertension, proteinuria, and endothelial dysfunction. We tested whether increased reactive oxygen species (superoxide and peroxynitrite) production and decreased bioavailability of the endothelial nitric oxide (NO) synthase (eNOS) cofactor tetrahydrobiopterin (BH4) contributes to maternal endothelial dysfunction in rats with pregnancy-induced hypertension and several characteristics of preeclampsia. Nonpregnant (DS) and pregnant (PDS) rats were treated with deoxycorticosterone acetate and 0.9% saline for approximately 3 weeks and nonpregnant (Con) and pregnant (P) rats received tap water. Blood pressure, urinary protein levels, mesenteric vascular reactivity, aortic protein expression, and aortic reactive oxygen species levels were compared between the four groups. The PDS rats had significantly decreased mesenteric endothelium-dependent relaxation responses and aortic NO production compared to Con, DS, and P rats despite increased aortic eNOS expression. Aortic superoxide and peroxynitrite levels were increased in PDS rats compared with Con, DS, and P rats. Scavenging of reactive oxygen species or increasing tetrahydrobiopterin levels normalized mesenteric endothelium-dependent relaxation responses, aortic NO production, and aortic superoxide and peroxynitrite levels in PDS rats. These data suggest that increased superoxide production by NADPH oxidase, peroxynitrite degradation of BH4, and uncoupled eNOS contribute to endothelial dysfunction in a rat model of pregnancy-induced hypertension.

ACE2 and ANG-(1-7) in the rat uterus during early and late gestation

The present study was designed to determine ANG peptide content [ANG I, ANG II, ANG-(1-7)], ACE2 mRNA, and the immunocytochemical distribution of ANG-(1-7) and ACE2 in the uteroembryonic unit during early and late gestation in Sprague-Dawley rats and in a rat model of pregnancy-induced hypertension, the reduced uterine perfusion pressure (RUPP) model. At early pregnancy ANG-(1-7) and ACE2 staining were localized in the primary and secondary decidual zone and luminal and glandular epithelial cells. During late gestation, ANG-(1-7) and ACE2 staining was visualized in the labyrinth placenta and amniotic and yolk sac epithelium. Uterine ANG II concentration at early pregnancy was significantly decreased by 21-55% in the implantation and interimplantation sites compared with virgin rats, whereas ANG-(1-7) levels were maintained at prepregnancy levels. At late gestation, uterine concentrations of ANG I and ANG II were significantly increased (30% and 25%, respectively). In RUPP animals, ANG-(1-7) concentration is significantly reduced in the uterus (181 +/- 16 vs. 372 +/- 74 fmol/g of tissue) and placenta (143 +/- 26 vs. 197 +/- 20 fmol/g of tissue). ACE2 mRNA increased in the uterus of early pregnant compared with virgin rats, yet within the implantation site it was downregulated. At late pregnancy, ACE2 mRNA is elevated by 58% in the uterus and decreased by 59% in RUPP animals. The regulation of ANG-(1-7) and ACE2 in early and late pregnancy supports the hypothesis that ANG-(1-7) and ACE2 may act as a local autocrine/paracrine regulator throughout pregnancy, participating in the early (angiogenesis, apoptosis, and growth) and late (uteroplacental blood flow) events of pregnancy.

Mesenteric Vascular Responsiveness in a Rat Model of Pregnancy-Induced Hypertension

Reduced perfusion to the placenta in early pregnancy is believed to be the initiating factor in the development of preeclampsia, triggering local ischemia and systemic vascular hyperresponsiveness. This sequence of events creates a predisposition to the development of altered vascular function and hypertension. This study was designed to determine the influence of placental insufficiency on the responsiveness of mesenteric resistance arteries in an animal model of preeclampsia. Placental insufficiency was induced by reduction in uteroplacental perfusion pressure (RUPP) in experimental Sprague-Dawley rat dams. The uterine branches of the ovarian arteries and the abdominal aortae of pregnant rats were surgically constricted on gestational Day 14. Dams in the control group underwent a sham procedure. Rats were euthanized on gestational Day 20, followed by removal of the small intestine and adjacent mesentery. First-order mesenteric resistance arteries were mounted on a small vessel wire myograph and challenged with incremental concentrations of vasoconstrictors and vasorelaxants. Mesenteric arteries in dams with placental insufficiency demonstrated an increased maximal tension to phenylephrine (7.15 +/- 0.15 vs. 5.4 +/- 0.27 mN/mm, P < 0.001); potassium chloride at 60 mM (3.43 +/- 0.11 vs. 2.77 +/- 0.14 mN/mm, P < 0.01) and 120 mM (3.92 +/- 0.18 vs. 2.97 +/- 0.16 mN/mm, P < 0.01); and angiotensin II (2.59 +/- 0.42 vs. 1.51 +/- 0.22 mN/mm, P < 0.05). Maximal relaxation to endothelium-dependent relaxants acetylcholine and calcium ionophore (A23187) was not significantly reduced. Data suggest that placental insufficiency leads to hyperresponsiveness to vasoconstrictor stimuli in mesenteric arteries.

Adult Hypertension in Intrauterine Growth-Restricted Offspring of Hyperinsulinemic Rats

In humans, intrauterine growth-restricted newborns are prone to develop hypertension as adults. We studied a rat model of pregnancy-induced hypertension associated with intrauterine growth restriction (IUGR) produced by chronic administration of insulin. Fetuses of hyperinsulinemic dams (HDs) were smaller than those of normal dams (5.1+/-0.4 g versus 5.6+/-0.1 g, respectively; P<0.05). At 16 weeks of age, tail-cuff systolic blood pressure was measured, the rats were placed in metabolic cages and euthanized, and the kidneys were examined. Male but not female offspring of HDs (n=9) had higher blood pressure than normal-pregnancy offspring (n=12; 148+/-11 mm Hg versus 118+/-14 mm Hg; P<0.004). In contrast to other models, there was no difference in ours in the number and volume of glomeruli. However, there were significantly greater glomerular, tubulointerstitial, and vascular damage indices in the kidneys of male HD offspring versus controls (2.01+/-0.34 versus 1.08+/-0.16, 1.80+/-0.34 versus 0.76+/-0.12, and 2.13+/-0.81 versus 0.78+/-0.16, respectively; P<0.0001), with similar tubulointerstitial findings in females. Increased expression of collagen type IV, a kidney damage marker indicating fibrosis, was found in the tubulointerstitium. This may be associated with downregulation of bone morphogenetic protein 6, a presumptive antifibrogenic agent, at the end of gestation. In conclusion, male offspring of HDs displayed IUGR and adult hypertension accompanied by several indices of renal fibrosing damage, mainly in the renal tubulointerstitium. Our findings suggest that there is >1 pathway of fetal programming leading from IUGR to development of hypertension in later life.

Enhanced thromboxane synthesis during chronic reductions in uterine perfusion pressure in pregnant rats

Background The purpose of this study was to determine the role of thromboxane A 2 (TXA 2) in a conscious, chronically instrumented rat model of pregnancy-induced hypertension (PIH) produced by chronic reductions in uterine perfusion pressure (RUPP). Methods Mean arterial pressure (MAP), glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and 24-h urinary excretion of TXB 2 (metabolite of TXA 2) were determined in normal pregnant rats and RUPP pregnant rats. Results At day 20 of pregnancy, RUPP rats showed a significantly ( P < .05) higher MAP (125 ± 3 mm Hg v 100 ± 2 mm Hg) as compared with normal pregnant controls. The elevation in arterial pressure in RUPP group was associated with a marked increase ( P < .05) in the urinary concentration of TXB 2 compared with normal pregnant group (3663 ± 488 v 2646 ± 257 pg/24 h). Baseline GFR (1.74 ± 0.13 v 2.40 ± 0.20 mL/min, respectively, P < .05) and ERPF (5.13 ± 0.44 v 6.44 ± 0.58 mL/min, respectively) were decreased in RUPP rats relative to pregnant controls. Infusion of a TX receptor antagonist, SQ 29,548 (2 mg/kg bolus plus 2 mg/kg per h infusion) had no significant effect on increased MAP in RUPP pregnant rats. Similarly, ERPF and GFR did not change during acute blockade of TXA 2 receptors in this group. Conclusion These findings suggest that enhanced production of TXA 2 does not play a major role in mediating the hypertension and renal vasoconstriction produced by chronic RUPP in pregnant rats.

Reduced uterine perfusion pressure during pregnancy in the rat is associated with increases in arterial pressure and changes in renal nitric oxide.

A reduction in nitric oxide (NO) synthesis has been suggested to play a role in pregnancy-induced hypertension. We have recently reported that normal pregnancy in the rat is associated with significant increases in whole-body NO production and renal protein expression of neuronal and inducible NO synthase. The purpose of this study was to determine whether whole-body and renal NO production is reduced in a rat model of pregnancy-induced hypertension produced by chronically reducing uterine perfusion pressure starting at day 14 of gestation. Chronic reductions in uterine perfusion pressure resulted in increases in arterial pressure of 20 to 25 mm Hg, decreases in renal plasma flow (<23%) and glomerular filtration rate (<40%), but no difference in urinary nitrite/nitrate excretion relative to control pregnant rats. In contrast, reductions in uterine perfusion pressure in virgin rats resulted in no significant effects on arterial pressure. Renal endothelial (<4%) and inducible (<11%) NO synthase protein expression did not decrease significantly in the chronically reduced uterine perfusion pressure rats relative to normal pregnant rats; however, significant reductions in neuronal NO synthase were observed (<30%). The results of this study indicate that the reduction in renal hemodynamics and the increase in arterial pressure observed in response to chronic decreases in uterine perfusion pressure in pregnant rats are associated with no change in whole-body NO production and a decrease in renal protein expression of neuronal NO synthase.

Endothelin-a Receptor Blockade Attenuates the Hypertension in a Rat Model of Pregnancy-Induced Hypertension.

6 A rat model of pregnancy-induced hypertension (PIH) produced by chronic reductions in uterine perfusion pressure (RUPP) is associated with a significant elevation in mean arterial pressure and as previously reported by our laboratory, proteinuria and reductions in kidney function. The purpose of this study was to examine the role of endothelin in mediating the hypertension in response to chronic reductions in uterine perfusion pressure in conscious, chronically-instrumented pregnant rats. Mean arterial pressure in RUPP rats (n=7) was significantly higher (123.0 ± 0.8 vs 101.3 ± 1.5 mmHg) than control pregnant rats (n=8). Renal expression of preproendothelin was also significantly elevated (>45%, P 20%, 37.7 ± 2.4 vs 29.9 ± 2.8 densitometric units, respectively) of the RUPP animals as compared to normal pregnant animals. Chronic administration of the selective endothelin-A receptor antagonist (ABT-627, 5mg/kg/day for 10 days, n=9) markedly attenuated the increase in MAP observed in the RUPP animals (123.0 ± 0.8 mmHg in the RUPP animals vs. 103.3 ± 2.3 mmHg in RUPP animals with ET-A antagonist, P

Endothelin-a Receptor Blockade Attenuates the Hypertension in a Rat Model of Pregnancy-Induced Hypertension.

6 A rat model of pregnancy-induced hypertension (PIH) produced by chronic reductions in uterine perfusion pressure (RUPP) is associated with a significant elevation in mean arterial pressure and as previously reported by our laboratory, proteinuria and reductions in kidney function. The purpose of this study was to examine the role of endothelin in mediating the hypertension in response to chronic reductions in uterine perfusion pressure in conscious, chronically-instrumented pregnant rats. Mean arterial pressure in RUPP rats (n=7) was significantly higher (123.0 ± 0.8 vs 101.3 ± 1.5 mmHg) than control pregnant rats (n=8). Renal expression of preproendothelin was also significantly elevated (&gt;45%, P&lt;.05) in the medulla (44.1 ± 6.3 vs 24.0 ± 2.6 densitometric units, respectively) and in the cortex (&gt;20%, 37.7 ± 2.4 vs 29.9 ± 2.8 densitometric units, respectively) of the RUPP animals as compared to normal pregnant animals. Chronic administration of the selective endothelin-A receptor antagonist (ABT-627, 5mg/kg/day for 10 days, n=9) markedly attenuated the increase in MAP observed in the RUPP animals (123.0 ± 0.8 mmHg in the RUPP animals vs. 103.3 ± 2.3 mmHg in RUPP animals with ET-A antagonist, P&lt;.05). Endothelin-A receptor blockade had no significant effect on blood pressure in the normal pregnant animals (101.3 ± 1.5 mmHg in normal pregnant rats vs. 96.0 ± 0.9 mmHg in normal pregnant animals with ET-A antagonist, n=8). In summary, hypertension in the RUPP model of pregnancy-induced hypertension was associated with enhanced renal expression of preproendothelin. In addition, hypertension in the RUPP model of PIH was significantly attenuated by selective endothelin-A receptor blockade. These findings suggest that endothelin plays a major role in mediating the hypertension observed in this animal model of pregnancy-induced hypertension produced by chronic reductions in uterine perfusion pressure.

Ca(2+)-insensitive vascular protein kinase C during pregnancy and NOS inhibition.

Pregnancy-induced hypertension is associated with increased vascular resistance; however, the cellular mechanisms involved are unclear. We have previously found that the relation between Ca(2+) entry and the developed force in vascular smooth muscle is altered during normal pregnancy and in a rat model of pregnancy-induced hypertension produced by long-term treatment with the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). The purpose of this study was to investigate whether the pregnancy-associated changes in the vascular Ca(2+) entry-force relation reflect changes in the amount and/or activity of Ca(2+)-insensitive protein kinase C (PKC) isoforms. Active stress and the amount and activity of PKC were measured in deendothelialized aortic strips from nonpregnant and pregnant rats untreated or treated with L-NAME and incubated in Ca(2+)-free (2 mmol/L EGTA) Krebs solution. In nonpregnant rats, the PKC activator phorbol 12,13-dibutyrate (PDBu, 10(-6) mol/L) and the alpha-adrenergic agonist phenylephrine (Phe, 10(-5) mol/L) caused significant, maintained increases in active stress and PKC activity that were inhibited by the PKC inhibitors staurosporine and calphostin C. Western blots in aortic strips of nonpregnant rats revealed the Ca(2+)-insensitive delta-PKC and zeta-PKC isoforms. Both PDBu and Phe caused translocation of delta-PKC from the cytosolic to the particulate fraction. Compared with nonpregnant rats, the amount of delta-PKC and zeta-PKC and the PDBu-stimulated and Phe-stimulated stress, PKC activity and translocation of delta-PKC were significantly reduced in late pregnant rats but significantly enhanced in pregnant rats treated with L-NAME. The PDBu-induced and Phe-induced responses in nonpregnant rats treated with L-NAME were not significantly different from nonpregnant rats, whereas the responses in pregnant rats treated with L-NAME+L-arginine were not significantly different from pregnant rats. These results provide evidence that a signaling pathway in vascular smooth muscle possibly involving the Ca(2+)-insensitive delta-PKC and zeta-PKC isoforms is reduced in late pregnancy and enhanced during long-term inhibition of nitric oxide synthesis. The changes in the amount and activity of vascular PKC isoforms may, in part, explain the changes in vascular resistance during normal pregnancy and pregnancy-induced hypertension.