Low molecular weight heparin improves proteinuria in rats with L-NAME induced preeclampsia by decreasing the expression of nephrin, but not podocin

The antithrombin binding regions of heparin mediate fetal growth and reduced placental damage in the RUPP model of preeclampsia†

Preeclampsia is a serious hypertensive disorder of pregnancy, which is only cured with delivery of the placenta, thereby commonly necessitating preterm birth of the fetus. Low-molecular-weight heparin (LMWH) has demonstrated potential to reduce the incidence of preeclampsia in high-risk pregnant women, although the underlying mechanism by which LMWH protects against preeclampsia is unknown. Given the complex structure and biologic actions of heparin, we tested the hypothesis that heparin can mediate preeclampsia prevention via nonanticoagulant pathways. We compared the effects of a nonanticoagulant, glycol-split LMWH (gsHep)—rendered nonanticoagulant through disruption of the antithrombin binding regions—with the LMWH dalteparin in the rat reduced uterine perfusion pressure (RUPP) surgical model of preeclampsia. Although RUPP animals exhibit significantly elevated blood pressure and reduced plasma levels of placental growth factor (PGF) compared to sham, neither dalteparin nor gsHep treatment significantly impacted these parameters. However, the observed positive correlation between PGF levels and number of viable fetuses in RUPP-induced animals suggests that reduced PGF levels were predominately due to placental loss. Daily subcutaneous injections of low-dose dalteparin but not gsHep significantly restored fetal growth that was impaired by RUPP surgery. Placentas from RUPP animals exhibited an abnormal labyrinth structure, characterized by expanded sinusoidal blood spaces, relative to sham-operated animals. Morphometric analysis demonstrated that dalteparin but not gsHep treatment normalized development of the labyrinth in RUPP-exposed conceptuses. These data suggest that the antithrombin-binding regions of LMWH are required to confer its protective effects on fetal growth and placental development.

Prophylactic low-molecular-weight heparin administration protected against severe acute pancreatitis partially by VEGF/Flt-1 signaling in a rat model

BACKGROUND

The present study was aimed to explore the effects and the underlying mechanism of prophylactic low-molecular-weight heparin (LMWH) treatment on taurocholate-induced severe acute pancreatitis (SAP) in a rat model.

METHODS

Rat SAP model was induced by injection of 4% sodium taurocholate into the pancreatic duct. LMWH was applied half an hour before the induction of pancreatitis at the dose of 200 IU/kg subcutaneous injection. The rats were euthanized at 1 h, 6 h, and 12 h after taurocholate-induced SAP. The inflammatory and oxidative response markers were assessed. And the vascular endothelial growth factor (VEGF) and Fms-related tyrosine kinase 1 (Flt-1) expression were evaluated by immunohistochemistry (IHC) and western blot methods.

RESULTS

The expression of inflammatory and oxidative response markers increased after induction of SAP. IHC and western blot results showed the VEGF and Flt-1 expression were increased in SAP group. Prophylactic LMWH administration reduced the inflammatory and oxidative response markers expression and decreased the expression of VEGF and Flt-1.

CONCLUSIONS

This study suggested that prophylactic LMWH treatment mitigated the severity of pancreatitis in rat SAP model by anti-inflammation and oxidative response. The underlying mechanism may result from downregulating VEGF/Flt-1 signaling of LMWH in SAP rat model.

Animal Models of Preeclampsia: Causes, Consequences, and Interventions

Preeclampsia is a common pregnancy complication, affecting 2% to 8% of pregnancies worldwide, and is an important cause of both maternal and fetal morbidity and mortality. Importantly, although aspirin and calcium are able to prevent preeclampsia in some women, there is no cure apart from delivery of the placenta and fetus, often necessitating iatrogenic preterm birth. Preclinical models of preeclampsia are widely used to investigate the causes and consequences of preeclampsia and to evaluate safety and efficacy of potential preventative and therapeutic interventions. In this review, we provide a summary of the published preclinical models of preeclampsia that meet human diagnostic criteria, including the development of maternal hypertension, together with new-onset proteinuria, maternal organ dysfunction, and uteroplacental dysfunction. We then discuss evidence from preclinical models for multiple causal factors of preeclampsia, including those implicated in early-onset and late-onset preeclampsia. Next, we discuss the impact of exposure to a preeclampsia-like environment for later maternal and progeny health. The presence of long-term impairment, particularly cardiovascular outcomes, in mothers and progeny after an experimentally induced preeclampsia-like pregnancy, implies that later onset or reduced severity of preeclampsia will improve later maternal and progeny health. Finally, we summarize published intervention studies in preclinical models and identify gaps in knowledge that we consider should be targets for future research.

Evaluation of blood vessel injury, oxidative stress and circulating inflammatory factors in an L-NAME-induced preeclampsia-like rat model

Preeclampsia is a pregnancy-specific disease characterized by hypertension as well as proteinuria after the 20th week of pregnancy. Animal models are effective tools for studying the pathogenesis, diagnostic criteria and treatment methods of preeclampsia. The present study sought to establish and evaluate a preeclampsia-like Sprague Dawley (SD) rat model using N-nitro-L-arginine methyl ester (L-NAME). Rats were randomly assigned to 7 groups (n=10 in each): Control rats and rats treated with low-dose L-NAME (40 mg/kg body weight/day) starting from gestational day (GD) 9, medium-L-NAME (75 mg/kg body weight/day) starting from GD 9 (9D ML group), high-dose L-NAME (125 mg/kg body weight/day) starting from GD 9, low-dose L-NAME starting from GD 10, medium-dose L-NAME starting from GD 10 and high-dose L-NAME starting from GD 10. Blood pressure (BP), 24-h proteinuria, fetal intrauterine growth, histopathological changes, the plasma soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PLGF) ratio and cytokine levels were evaluated. Elevated BP, increased urinary albumin excretion, severe endotheliosis, mesangial expansion and increased sFlt-1/PLGF ratios were observed in the experimental groups compared with the control group (P<0.05), particularly in the 9D ML group. The results of the present study may optimize the conditions of the previously established L-NAME-induced preeclampsia SD rat model and aid further study into the pathogenesis of preeclampsia.

Low Molecular Weight Heparin Improves Endothelial Function in Pregnant Women at High Risk of Preeclampsia

Low molecular weight heparin (LMWH) has been investigated for the prevention of severe preeclampsia, although the mechanisms of action are unknown. The objective of this study was to investigate the cardiovascular effects of LMWH in pregnant women at high risk of preeclampsia. Pregnant women at high risk of preeclampsia (n=25) and low-risk pregnant controls (n=20) at 22 to 26 weeks' gestation underwent baseline cardiovascular assessments. High-risk women were then randomized to LMWH or saline placebo (30 mg IV bolus and 1 mg/kg subcutaneous dose). Cardiovascular function was assessed 1 and 3 hours post randomization. The in vitro endothelial effects of patient serum and exogenous LMWH on human umbilical venous endothelial cells were determined. High-risk women demonstrated a reduced cardiac output, high resistance hemodynamic profile with impaired radial artery flow-mediated dilation compared with controls. LMWH increased flow-mediated dilation in high-risk women 3 hours after randomization compared with baseline and increased plasma levels of placental growth factor, soluble fms-like tyrosine kinase-1, and myeloperoxidase. Serum from high-risk women impaired endothelial cell angiogenesis and increased PlGF-1 and PlGF-2 transcription compared with serum from low-risk controls. Coexposure of high-risk serum with LMWH improved the in vitro angiogenic response such that it was equivalent to that of low-risk serum and promoted placental growth factor secretion. LMWH improves maternal endothelial function in pregnant women at high risk of developing preeclampsia, possibly mediated through increased placental growth factor bioavailability.

Decitabine Improves the Clinical Manifestations of Rats With l-NAME-Induced Pre-eclampsia: A Potential Approach to Studying Pre-eclampsia

OBJECTIVE

Pre-eclampsia is a major cause of maternal mortality and morbidity. Conditions with low oxygen tension are regarded as a key factor. Decitabine can partly attenuate the effects of hypoxia. This research was designed to investigate the effects of decitabine in rats with NG-Nitro-L-arginine Methyl Eater (L-NAME) induced pre-eclampsia and to explore the molecular mechanisms.

METHODS

A Wistar rat model of pre-eclampsia was established by intraperitoneal injection of L-NAME, and the intervention reagent was decitabine. Blood pressure (BP) and 24-h urinary protein were monitored. The expression of Mammary Serine Protease Inhibitor (SERPINB5, maspin) in the placenta was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

Systolic BP in the tail artery of pregnant rats was increased by more than 30 mm Hg, and 24-h urinary protein was significantly increased after L-NAME was added. After decitabine treatment, blood pressure and 24-h urinary protein were significantly decreased. The expression of SERPINB5 in the placenta significantly increased after L-NAME was added. Decitabine significantly elevated the expression of SERPINB5 in the placenta of rats with L-NAME-induced preeclampsia.

CONCLUSION

Decitabine reduced 24-h urinary protein and partly decreased blood pressure of pre-eclampsia in late pregnancy in rats with L-NAME-induced pre-eclampsia and increased the expression of SERPINB5, but the molecular mechanism of decitabine's effect remains unknown. This research provided a potential approach to studying the pathogenesis, treatment and prevention of pre-eclampsia.

Resveratrol inhibits trophoblast apoptosis through oxidative stress in preeclampsia-model rats

Resveratrol has been shown to be a therapeutic agent for cardiovascular disorders by maintaining a lower redox level in vivo through its anti-oxidant properties. Resveratrol can prevent cells from p53- and reactive oxygen species-dependent apoptosis induced by interleukin-1b. We identified an inhibitory effect of resveratrol against oxidative stress and apoptosis using the TUNEL assay in NG-Nitro-l-arginine methyl ester-induced preeclampsia in rats. To investigate a possible association between resveratrol and the apoptosis caused by oxidative stress in vitro, assays for superoxide dismutase and malondialdehyde as well as flow cytometric analyses were conducted in HTR-8/SVneo cells after hypoxic treatment with or without resveratrol for 24 h. These data suggest that resveratrol significantly opposes the effects of oxidative stress in vivo and in vitro.