Abstract 625: Hypoxia-Induced sFlt-1 Production is Enhanced in Placental Villi from Obese MC4R Deficient Rats

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Ana C Palei ◽  
Frank T Spradley ◽  
Joey P Granger
Keyword(s):  
Endothelial Dysfunction ◽  
Normal Pregnancy ◽  
Maternal Circulation ◽  
Pregnant Rats ◽  
Melanocortin 4 Receptor ◽  
Placental Villi ◽  
Obese Rats ◽  
The Face ◽  
Placental Ischemia

Although the etiology of preeclampsia (PE) remains unclear, evidence indicates that impaired cytotrophoblast invasion followed by placental ischemia/hypoxia promotes the release of placental anti-angiogenic factors, such as soluble fms-like tyrosine kinase-1 (sFlt-1), into the maternal circulation. sFlt-1 blocks the pro-angiogenic actions of vascular endothelial growth factor to elicit maternal endothelial dysfunction and ultimately hypertension and proteinuria. Moreover, a leading risk factor for PE is obesity; however, the mechanisms whereby obesity increases the risk for developing PE are unknown. Our aim was to evaluate circulating and placental sFlt-1 levels in a genetic rodent model of obesity, the melanocortin-4 receptor deficient rat (MC4R+/-). Additionally, we examined the effect of obesity on hypoxia-induced sFlt-1 production in placental villous explants. At gestational day 19, body weight (357±5 vs. 331±11 g) and visceral fat weight (15.3±0.4 vs. 9.2±0.4 g) were higher in MC4R+/- obese pregnant rats (N=7) over MC4R+/+ lean pregnant rats (N=7), whereas mean arterial pressure was similar between groups (MC4R+/-: 110±4 vs. MC4R+/+: 102±2 mmHg). The levels of sFlt-1 in plasma (MC4R+/+: 228±75 vs. MC4R+/+: 141±34 pg/mL) and whole placenta (MC4R+/-: 0.86±0.06 vs. MC4R+/+: 0.82±0.04 pg/mg) were comparable between groups. Similarly, there was no difference in sFlt-1 secretion from 48 h cultures of placental villi explanted from MC4R+/- (1969±176 pg/mg) vs. MC4R+/+ (1408±188 pg/mg) under normoxic conditions (6% oxygen). However, in the face of hypoxia (1% oxygen), there was more pronounced sFlt-1 secretion from MC4R+/- obese rats than MC4R+/+ lean counterparts (2160±233 vs. 1311±120 pg/mg, respectively; P<0.05). In conclusion, we found that sFlt-1 levels were not disrupted in obese pregnant rats during normal pregnancy; however, in vitro studies with placental villi from obese rats showed enhanced hypoxia-induced sFlt-1 secretion. Together these findings suggest that placental ischemia-induced endothelial dysfunction and hypertension may be exaggerated by obesity.

Abstract P613: The Effect of Metabolic Factors on Hypoxia-Induced sFlt-1 Secretion in Rat Placental Villi

Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Ana C Palei ◽  
Frank T Spradley ◽  
Joey P Granger
Keyword(s):  
Trophoblast Invasion ◽  
Vascular Endothelial ◽  
Metabolic Factors ◽  
Maternal Circulation ◽  
Pregnant Rats ◽  
Hypoxic Conditions ◽  
Placental Villi ◽  
Endothelial Growth Factor ◽  
Placental Ischemia

Although the etiology of preeclampsia (PE) remains unclear, evidence indicates that impaired trophoblast invasion followed by placental ischemia/hypoxia promotes the release of placental anti-angiogenic factors, such as soluble fms-like tyrosine kinase-1 (sFlt-1), into the maternal circulation. sFlt-1 blocks the pro-angiogenic actions of vascular endothelial growth factor to elicit maternal endothelial dysfunction and ultimately hypertension. Obesity is a major risk factor for PE. In addition, increased circulating metabolic factors, such as leptin and insulin have been associated with PE. However, the mechanisms whereby obesity and its related metabolic factors increase the risk for the development of PE are unknown. The aim of this study was to evaluate whether chronic leptin or insulin exposure exacerbate hypoxia-induced sFlt-1 secretion from rat placental villi. In order to address this question, placental villous explants were isolated from placentas of normal pregnant rats (n=4, 3 placentas per rat) and pregnant rats treated with either leptin (0.5 mg/kg/min i.p.; n=3, 3 placentas per rat) or insulin (1.5 mU/kg/min s.c.) supplemented with 20% glucose in drinking water (n=3, 3 placentas per rat) from gestational day 14 to 19. Placental explants were then incubated for 48 h at 37 °C under normoxia (6% O2) or hypoxia (1% O2) and sFlt-1 secretion in cultured media was measured by ELISA. While hypoxia significantly enhanced sFlt-1 release of explants from normal pregnant rats compared with normoxia (3224±224 vs 4251±236 pg/mg; P<0.05), explants from chronic hyperleptinemic (3197±178 vs. 3762±317 pg/mg) or euglycemic hyperinsulinemic (4066±186 vs. 4251±213 pg/mg) pregnant rats secreted similar sFlt-1 levels under normoxic and hypoxic conditions, respectively. Additionally, chronic leptin or insulin treatments did not exacerbate the effect of hypoxia on sFlt-1 release. In conclusion, our in vitro studies with placental villi from chronic hyperleptinemic or euglycemic hyperinsulinemic pregnant rats showed no exacerbation of hypoxia-induced sFlt-1 secretion.

Abstract 037: Exaggerated Placental Ischemia-induced Hypertension in Endothelin Receptor Type B (ETB)-deficient Pregnant Rats s Independent of Increased sFlt-1 or ROS Levels

Hypertension ◽  
2017 ◽  
Vol 70 (suppl_1) ◽  
Author(s):  
Frank T Spradley
Keyword(s):  
Blood Pressure ◽  
Acute Hypoxia ◽  
Pressure Control ◽  
Normal Pregnancy ◽  
Endothelin Receptor ◽  
Maternal Circulation ◽  
Pregnant Rats ◽  
Uterine Perfusion ◽  
Placental Ischemia ◽  
In Pregnancy

While the pathogenesis of preeclampsia is not fully understood, studies implicate placental ischemia. Reduced uterine perfusion pressure (RUPP)-induced placental ischemia/hypoxia in animal models stimulates release of factors like antiangiogenic sFlt-1 into the maternal circulation increasing vascular-renal ET-1. ET-1 promotes hypertension via reactive oxygen species (ROS). Blockade of vasoconstrictive ETA abolishes RUPP hypertension. Deficiency of vasodilatory ETB in rats leads to increased blood pressure in pregnancy. While ETB deficiency markedly enhances RUPP hypertension, it is unknown if there is exaggerated RUPP-induced sFlt-1, ET-1 or ROS levels in ETB-def rats. The hypothesis was tested that placental ischemia/hypoxia-induced release of sFlt-1 and circulating ET-1 and ROS are greater in ETB-def rats. Eighteen-week-old ETB-def and transgenic (Tg) control pregnant rats were generated with Wistar Hannover males. RUPP or Sham surgeries were on gestational day 14 and assessment of plasmas and placentas at day 19. RUPP increased placental sFlt-1 (pg/mg) similarly in RUPP ETB-def (781±113, N=5) vs Sham ETB-def (573±54, N=12) and RUPP Tg (631±62, N=5) vs Sham Tg (547±31, N=12) (P<0.05). In placental explant cultures, acute hypoxia (48 h 1% O2 vs normoxia 6% O2) stimulated a comparable release of sFlt-1 (pg/mg) in Sham ETB-def (2577±135 vs 2070±78) and Sham Tg (3208±318 vs 2553±107) (P<0.05). Unexpectedly, plasma sFlt-1 (pg/mL) was lower in RUPP ETB-def (153±48) vs Sham ETB-def (476±125) and RUPP Tg (238±32) vs Sham Tg (463±102) (P<0.05). Plasma ET-1 (fmol/L) was exaggerated in RUPP ETB-def (954±70) and greater in Sham ETB-def (735±43) vs RUPP Tg (122±14) or Sham Tg (142±41) (P<0.05). Plasma H2O2 (umol/L) was not exaggerated in RUPP ETB-def (5.4±1.2) or RUPP Tg (4.0±0.5) but was greater (P<0.05) in Sham ETB-def (6.2±0.3) vs Sham Tg (3.6±0.3). In conclusion, these data suggest in 1) normal pregnancy, ETB is crucial for blood pressure control by regulating bioavailable ET-1 to prevent ROS production and 2) placental ischemia, ETB reduces excess ET-1 to buffer hypertension independently of sFlt-1 or ROS. These data support ETB physiology as important in controlling blood pressure in pregnancy and its loss in mediating hypertension in preeclampsia.

scholarly journals Increased risk for the development of preeclampsia in obese pregnancies: weighing in on the mechanisms

2015 ◽  
Vol 309 (11) ◽  
pp. R1326-R1343 ◽  
Author(s):  
Frank T. Spradley ◽  
Ana C. Palei ◽  
Joey P. Granger
Keyword(s):  
Endothelial Dysfunction ◽  
Vascular Dysfunction ◽  
Clinical Manifestations ◽  
Migration And Invasion ◽  
Metabolic Factors ◽  
Maternal Circulation ◽  
Soluble Factors ◽  
Placental Perfusion ◽  
Increased Risk ◽  
Placental Ischemia

Preeclampsia (PE) is a pregnancy-specific disorder typically presenting as new-onset hypertension and proteinuria. While numerous epidemiological studies have demonstrated that obesity increases the risk of PE, the mechanisms have yet to be fully elucidated. Growing evidence from animal and human studies implicate placental ischemia in the etiology of this maternal syndrome. It is thought that placental ischemia is brought about by dysfunctional cytotrophoblast migration and invasion into the uterus and subsequent lack of spiral arteriole widening and placental perfusion. Placental ischemia/hypoxia stimulates the release of soluble placental factors into the maternal circulation where they cause endothelial dysfunction, particularly in the kidney, to elicit the clinical manifestations of PE. The most recognized of these factors are the anti-angiogenic sFlt-1 and pro-inflammatory TNF-α and AT1-AA, which promote endothelial dysfunction by reducing levels of the provasodilator nitric oxide and stimulating production of the potent vasoconstrictor endothelin-1 and reactive oxygen species. We hypothesize that obesity-related metabolic factors increase the risk for developing PE by impacting various stages in the pathogenesis of PE, namely, 1) cytotrophoblast migration and placental ischemia; 2) release of soluble placental factors into the maternal circulation; and 3) maternal endothelial and vascular dysfunction. This review will summarize the current experimental evidence supporting the concept that obesity and metabolic factors like lipids, insulin, glucose, and leptin affect placental function and increase the risk for developing hypertension in pregnancy by reducing placental perfusion; enhancing placental release of soluble factors; and by increasing the sensitivity of the maternal vasculature to placental ischemia-induced soluble factors.

Possible role of gap junctions in activation of myometrium during parturition

1978 ◽  
Vol 235 (5) ◽  
pp. C168-C179 ◽  
Author(s):  
R. E. Garfield ◽  
S. M. Sims ◽  
M. S. Kannan ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Gap Junctions ◽  
Freeze Fracture ◽  
Normal Pregnancy ◽  
Pregnant Rats ◽  
Junction Formation ◽  
Synchronous Contraction ◽  
Do So

Gap junctions between smooth muscle cells of the myometrium of pregnant rats were found only immediately prior to, during and immediately after parturition by quantitative thin-section and freeze-fracture microscopy. Ovariectomy of 16- to 17-days-pregnant rats resulted in premature termination of pregnancy and the appearance of gap junctions. Methods that prolonged normal pregnancy in rats or maintained pregnancy in ovariectomized animals (progesterone treatment) prevented the appearance of gap junctions. Gap junctions formed in tissues incubated for 24--96 h in vitro without any hormonal influence. We propose that gap junctions are essential for normal labor and delivery for synchronous contraction of the muscle of the uterus. We present a model for control of parturition that may apply to other animals including humans. The model proposes: 1) the possible roles progesterone, prostaglandins, or estrogens may play in initiating gap-junction formation; 2) that the formation of gap junctions is a necessary step in activation of the myometrium leading to labor; and 3) that agents used to stimulate or inhibit labor may do so by affecting gap junctions.

scholarly journals Hormonal control of Luteal 20α-Hydroxy steroid dehydrogenase and Δ5-3β-hydroxy steroid dehydrogenase during luteolysis in the pregnant rat

1975 ◽  
Vol 152 (3) ◽  
pp. 433-443 ◽  
Author(s):  
R G Rodway ◽  
N J Kuhn
Keyword(s):  
Prostaglandin F2α ◽  
Late Pregnancy ◽  
Normal Pregnancy ◽  
Hormonal Control ◽  
Placental Lactogen ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

Treatment of pregnant rats with human chorionic gonadotrophin, luteotrophin (luteinizing hormone), luteotrophin-releasing hormone, prostaglandin F2α, aminoglutethimide, or by foetoplacental removal or hysterectomy achieved a common multiple-response pattern, namely increased activity of luteal 20α-hydroxy steroid dehydrogenase with decreased activity of delta5-3β-hydroxy steriod dehydrogenase and release of delta4-3-oxo steroids in vitro. 2. Similar effects of foetoplacental removal are noted in pregnant mice. 3. Gonadotrophin induced lower activities of 20α-hydroxy steroid dehydrogenase, except at the very end of pregnancy, and partly inhibited the induction caused by foetoplacental removal. 4. The results suggest that existence of a placental factor that restrains these changes until the end of normal pregnancy, which is produced in amounts proportional to the number of placentae and is conveyed to the ovary via the blood. 5. This factor was not replaced by prolactin. 6. It is argued that neither placental lactogen nor pituitary luteotrophin participate in the induction of 20α-hydroxy steroid dehydrogenase at late pregnancy in the rat. 7. Aminoglutethimide induced 20α-hydroxy steroid dehydrogenase only in late pregnancy. This was partly reversed by progesterone, wholly reversed by progesterone plus oestrogen, and did not involve the pituitary.

scholarly journals Ceramide-Induced Lysosomal Biogenesis and Exocytosis in Early-Onset Preeclampsia Promotes Exosomal Release of SMPD1 Causing Endothelial Dysfunction

2021 ◽  
Vol 9 ◽  
Author(s):  
Leonardo Ermini ◽  
Abby Farrell ◽  
Sruthi Alahari ◽  
Jonathan Ausman ◽  
Chanho Park ◽  
...  
Keyword(s):  
Endothelial Dysfunction ◽  
Early Onset ◽  
Nuclear Translocation ◽  
Endothelial Activation ◽  
Maternal Circulation ◽  
Tubule Formation ◽  
Early Onset Preeclampsia ◽  
Ceramide Accumulation

Aberrant ceramide build-up in preeclampsia, a serious disorder of pregnancy, causes exuberant autophagy-mediated trophoblast cell death. The significance of ceramide accumulation for lysosomal biogenesis in preeclampsia is unknown. Here we report that lysosome formation is markedly increased in trophoblast cells of early-onset preeclamptic placentae, in particular in syncytiotrophoblasts. This is accompanied by augmented levels of transcription factor EB (TFEB). In vitro and in vivo experiments demonstrate that ceramide increases TFEB expression and nuclear translocation and induces lysosomal formation and exocytosis. Further, we show that TFEB directly regulates the expression of lysosomal sphingomyelin phosphodiesterase (L-SMPD1) that degrades sphingomyelin to ceramide. In early-onset preeclampsia, ceramide-induced lysosomal exocytosis carries L-SMPD1 to the apical membrane of the syncytial epithelium, resulting in ceramide accumulation in lipid rafts and release of active L-SMPD1 via ceramide-enriched exosomes into the maternal circulation. The SMPD1-containing exosomes promote endothelial activation and impair endothelial tubule formation in vitro. Both exosome-induced processes are attenuated by SMPD1 inhibitors. These findings suggest that ceramide-induced lysosomal biogenesis and exocytosis in preeclamptic placentae contributes to maternal endothelial dysfunction, characteristic of this pathology.

Abstract P639: Sildenafil Treatment Improves Placental Levels of Placental Growth Factor in the Dahl Salt-Sensitive Pregnant Rat Model of Superimposed Preeclampsia

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Ana C Palei ◽  
Jennifer M Sasser ◽  
Joey P Granger
Keyword(s):  
Growth Factor ◽  
Umbilical Vein ◽  
Resistance Index ◽  
Placental Growth Factor ◽  
Trophoblast Invasion ◽  
Maternal Circulation ◽  
Pregnant Rats ◽  
Pregnant Rat

Although the etiology of preeclampsia (PE) remains unclear, evidence indicates that impaired trophoblast invasion followed by placental ischemia promotes the release of placental anti-angiogenic factors into the maternal circulation. These factors then elicit maternal endothelial dysfunction and hypertension by blocking the action of molecules such as the placental growth factor (PlGF). Inhibition of phosphodiesterase (PDE)-5 with sildenafil or other has been proposed as a potential therapy for PE; however, the mechanisms whereby PDE-5 inhibitors reduce blood pressure (BP) and improve uteroplacental perfusion during pregnancy are not clear. While previous studies have shown that PDE-5 inhibition induces PlGF production from human umbilical vein endothelial cells; it is unknown whether PDE-5 inhibitors also increase PlGF from placenta. Thus, the aim of this study was to evaluate whether sildenafil enhance placental secretion/production of PlGF in vitro and in vivo. In our in vitro protocol, we incubated placental villous explants from Sprague Dawley (SD) pregnant rats (n=4, 2-3 placentas per rat) at gestational day (GD)19 with different doses of sildenafil for 48h at 37°C under normoxia (8% O 2 ). PlGF-2 was measured in media of cultured explants by ELISA. We observed that sildenafil had no effect on PlGF-2 secretion from rat placental villi (vehicle: 562.7±46.6, 10nM: 559.3±39.5, 100nM: 556.4±35.9, 10uM: 546.2±37.5, and 100uM: 558.7±48.2pg/mg; P>0.05). In our in vivo protocol, we treated Dahl Salt-Sensitive (DS) pregnant rats (n=6-8 per group), which we had previously characterized as a model of superimposed PE, with sildenafil (50mg/kg per day, via food) from GD10 to 20. PlGF-2 was measured in placental homogenates by ELISA. While untreated DS dams exhibited an increase in BP and uterine artery resistance index (UARI) from baseline to late pregnancy, sildenafil-treated DS dams exhibited a significant decrease in BP and UARI. In addition, we found that placental levels of PlGF-2 were elevated in sildenafil-treated DS dams compared with untreated counterparts (1019±107.3 and 646.8±125.1pg/mg; P=0.0407). In conclusion, our findings suggest that the BP and UARI reduction in response to sildenafil may involve the indirect production of PlGF.

scholarly journals Melanocortin-4 Receptor Deficiency Attenuates Placental Ischemia-Induced Hypertension in Pregnant Rats

Hypertension ◽  
2019 ◽  
Vol 73 (1) ◽  
pp. 162-170 ◽  
Author(s):  
Frank T. Spradley ◽  
Ana C. Palei ◽  
Christopher D. Anderson ◽  
Joey P. Granger
Keyword(s):  
Blood Pressure ◽  
Nervous System ◽  
Perfusion Pressure ◽  
Wild Type ◽  
Pregnant Rats ◽  
Melanocortin 4 Receptor ◽  
Induced Hypertension ◽  
Sympathetic Nervous ◽  
Uterine Perfusion ◽  
Placental Ischemia

Preeclampsia is a pregnancy-specific disorder of new-onset hypertension linked to placental ischemia. While obesity is a major risk factor for preeclampsia, not all obese pregnant women develop pregnancy-induced hypertension or preeclampsia. Previously, we reported that placental ischemia-induced hypertension is dependent upon intact signaling of the sympathetic nervous system. Moreover, in various models of obesity, blockade of MC4R (melanocortin-4 receptor) signaling protects against the development of hypertension via suppression of the sympathetic nervous system. Less is known about this pathway during obese pregnancy. Although blockade of MC4R may lead to increased body weight during pregnancy, we tested the hypothesis that placental ischemia-induced hypertension is attenuated in obese MC4R-deficient pregnant rats. On gestational day 14, MC4R wild-type or heterozygous-deficient (MC4R-def) rats were subjected to chronic placental ischemia via the reduced uterine perfusion pressure procedure or Sham surgery then examined on gestational day 19. In Sham MC4R-def versus Sham wild-type pregnant rats, there was increased body weight, fat mass, and circulating leptin levels but they had similar fetus weights. Reduced uterine perfusion pressure reduced fetus weights in both strains. Reduced uterine perfusion pressure increased blood pressure in wild-type rats but this response was significantly attenuated in MC4R-def rats, although blood pressure was elevated in Sham MC4R-def over Sham wild-type. These data indicate that while obese MC4R-def pregnant rats have higher blood pressure during pregnancy, placental ischemia-induced hypertension is attenuated in obese MC4R-def pregnant rats. Thus, obese women with abnormal MC4R signaling may be less susceptible to the development of placental ischemia-induced hypertension.

scholarly journals Induction of heme oxygenase-1 attenuates sFlt-1-induced hypertension in pregnant rats

2011 ◽  
Vol 301 (5) ◽  
pp. R1495-R1500 ◽  
Author(s):  
Eric M. George ◽  
Marietta Arany ◽  
Kathy Cockrell ◽  
Megan V. Storm ◽  
David E. Stec ◽  
...  
Keyword(s):  
Heme Oxygenase ◽  
Therapeutic Approach ◽  
Heme Oxygenase 1 ◽  
Pregnant Rats ◽  
Beneficial Effects ◽  
Promising Therapeutic Approach ◽  
Induced Hypertension ◽  
Exact Etiology ◽  
Placental Ischemia

Preeclampsia (PE) is one of the leading causes of fetal and maternal morbidity, affecting 5–10% of all pregnancies, and lacks an effective treatment. The exact etiology of the disorder is unclear, but placental ischemia has been shown to be a central causative agent. In response to placental ischemia, the antiangiogenic protein fms-like tyrosine kinase-1 (sFlt-1), a VEGF antagonist, and reactive oxygen species are secreted, leading to the maternal syndrome. One promising therapeutic approach to treat PE is through manipulation of the heme oxygenase-1 (HO-1) protein. It has been previously reported that HO-1 and carbon monoxide downregulate sFlt-1 production in vitro, and we have recently shown that HO-1 induction significantly attenuates placental ischemia-induced hypertension, partially through normalization of the sFlt-1-to-VEGF ratio in the placenta. The purpose of this study was to determine whether HO-1 induction would have beneficial effects independently of sFlt-1 suppression. To that end, pregnant rats were continuously infused with recombinant sFlt-1 from gestational days 14–19, and circulating sFlt-1 increased approximately twofold, similar to rats with experimentally induced placental ischemia. In response, mean arterial pressure increased 17 mmHg, which was completely normalized by HO-1 induction. Unbound circulating VEGF was decreased ∼17% in response to sFlt-1 infusion but was increased ∼50% in response to HO-1 induction. Finally, endothelial function was improved as measured by reductions in vascular expression of preproendothelin mRNA. In conclusion, manipulation of HO-1 presents an intriguing therapeutic approach to the treatment of PE.

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