Monocrotaline-induced Pulmonary Hypertension Research Articles

Dimethylarginine dimethylaminohydrolase 1 deficiency aggravates monocrotaline-induced pulmonary oxidative stress, pulmonary arterial hypertension and right heart failure in rats

Patients with pulmonary arterial hypertension (PAH) and right ventricular (RV) failure have a poor clinical outcome, but the mechanisms of PAH and RV failure development are not totally clear. PAH is associated with reduced NO bioavailability and increased endogenous NOS inhibitor asymmetric dimethylarginine (ADMA). Dimethylarginine dimethylaminohydrolase-1 (DDAH1) plays a critical role in ADMA degradation. Here we generated a novel DDAH1 deficiency rat strain using the CRISPR-Cas9 technique, and studied the effect of DDAH1 dysfunction on monocrotaline-induced PAH, lung vascular remodeling and RV hypertrophy. DDAH1 knockout resulted in abolished DDAH1 expression in various tissues, and significant increases of plasma and lung ADMA content. DDAH1 knockout has no detectable effect on cardiac and lung structure, and LV function under control conditions in rats. However, DDAH1 knockout significantly aggravated monocrotaline-induced lung and RV oxidative stress, lung vascular remodeling and fibrosis, pulmonary hypertension and RV hypertrophy in rats. DDAH1 KO resulted in significantly greater increases of plasma and lung ADMA content under control conditions. In the wild type rats monocrotaline resulted in significant increases of plasma and lung ADMA contents and reduction of lung eNOS protein content and these changes were more marked in DDAH1 KO rats. Together, our results demonstrated that DDAH1 plays an important role in attenuating monocrotaline-induced lung oxidative stress, pulmonary hypertension and RV hypertrophy in rats.

Suppressed baroreflex peripheral arc overwhelms augmented neural arc and incapacitates baroreflex function in rats with pulmonary arterial hypertension.

What is the central question of this study? The impact of pulmonary arterial hypertension on open-loop baroreflex function, which determines how powerfully and rapidly the baroreflex operates to regulate arterial pressure, remains poorly understood. What is the main finding and its importance? The gain of the baroreflex total arc, indicating the baroreflex pressure-stabilizing function, is markedly attenuated in rats with monocrotaline-induced pulmonary arterial hypertension. This is caused by a rightward shift of the baroreflex neural arc and a downward shift of the peripheral arc. These findings contribute greatly to our understanding of arterial pressure regulation by the sympathetic nervous system in pulmonary arterial hypertension. Sympathoexcitation has been documented in patients with established pulmonary arterial hypertension (PAH). Although the arterial baroreflex is the main negative feedback regulator of sympathetic nerve activity (SNA), the way in which PAH impacts baroreflex function remains poorly understood. In this study, we conducted baroreflex open-loop analysis in a rat model of PAH. Sprague-Dawley rats were injected with monocrotaline (MCT) s.c. to induce PAH (60mgkg-1 ; n=11) or saline as a control group (CTL; n=8). At 3.5weeks after MCT injection, bilateral carotid sinuses were isolated, and intrasinus pressure (CSP) was controlled while SNA at the coeliac ganglia and arterial pressure (AP) were recorded. To examine the static baroreflex function, CSP was increased stepwise while steady-state AP (total arc) and SNA (neural arc) responses to CSP and the AP response to SNA (peripheral arc) were measured. Monocrotaline significantly decreased the static gain of the baroreflex total arc at the operating AP compared with CTL (-0.80±0.31 versus -0.22±0.22, P<0.05). Given that MCT markedly increased plasma noradrenaline, an index of SNA, by approximately 3.6-fold compared with CTL, calibrating SNA by plasma noradrenaline revealed that MCT shifted the neural arc to a higher SNA level and shifted the peripheral arc downwards. Monocrotaline also decreased the dynamic gain of the baroreflex total arc (-0.79±0.16 versus -0.35±0.17, P<0.05), while the corner frequencies that reflect the speed of the baroreflex remained unchanged (0.06±0.02 versus 0.08±0.02Hz, n.s.). In rats with MCT-induced PAH, the suppressed baroreflex peripheral arc overwhelms the augmented neural arc and, in turn, attenuates the gain of the total arc, which determines the pressure-stabilizing capacity of the baroreflex.

Improvement of pulmonary arterial hypertension, inflammatory response, and epithelium injury by dual activation of cAMP/cGMP pathway in a rat model of monocrotaline-induced pulmonary hypertension.

Pulmonary hypertension (PH) is a life-threatening lung disease. PH with concomitant lung diseases, e.g., idiopathic pulmonary fibrosis, is associated with poor prognosis. Development of novel therapeutic vasodilators for treatment of these patients is a key imperative. We evaluated the efficacy of dual activation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) using an active, small-molecule phosphodiesterase (PDE4)/PDE5 dual inhibitor (Compound A). Compound A increased both cAMP and cGMP levels in WI-38 lung fibroblasts and suppressed the expressions of type-1 collagen α1 chain and fibronectin. Additionally, compound A reduced right ventricular weight/left ventricular weight+septal weight ratio, brain natriuretic peptide expression levels in right ventricle, C─C motif chemokine ligand 2 expression levels in lung, and plasma surfactant protein D. Our data indicate that dual activation of cAMP/cGMP pathways may be a novel treatment strategy for PH.

Isoliquiritigenin Attenuates Monocrotaline-Induced Pulmonary Hypertension via Inhibition of the Inflammatory Response and PASMCs Proliferation.

Pulmonary hypertension (PH) is a progressive and serious disease, where exacerbated inflammatory response plays a critical role. Isoliquiritigenin (ISL), an important flavonoid isolated from Glycyrrhizae radix, exhibits a wide range of pharmacological actions including anti-inflammation. Previously we found ISL alleviated hypoxia-induced PH; in the present study, to extend this, we evaluated the effects of ISL on monocrotaline (MCT)-induced PH and the relevant mechanisms. Rats received a single intraperitoneal injection of MCT, followed by intragastric treatments with ISL (10 mg/kg/d or 30 mg/kg/d) once a day for 28 days. The MCT administration increased the right ventricular systolic pressure (RVSP) (p < 0.001), the median width of pulmonary arteries (p < 0.01), and the weight ratio of the right ventricular wall/left ventricular wall plus septum (Fulton index) (p < 0.01) in rats; however, these changes were inhibited by both doses of ISL (p < 0.05). In addition, treatment with ISL suppressed the upregulated production of serum interleukin-6 (p < 0.01) and tumor necrosis factor-α (p < 0.05) by MCT and reversed the increases in the numbers of proliferating cell nuclear antigen (PCNA)-positive cells (p < 0.01) in the medial wall of pulmonary arteries. In in vitro experiments, ISL (10 μM, 30 μM, and 100 μM) inhibited excessive proliferation of cultured primary pulmonary artery smooth muscle cells (PASMCs) (p < 0.05, p < 0.01, and p < 0.001) in a dose-dependent manner and prevented an increase in the expressions of PCNA (p < 0.01) and phospho-Akt (p < 0.05) in PASMCs induced by hypoxia. These results suggest that ISL can attenuate MCT-induced PH via its anti-inflammatory and antiproliferative actions.

Fasudil dichloroacetate (FDCA), an orally available agent with potent therapeutic efficiency on monocrotaline-induced pulmonary arterial hypertension rats.

Given the therapeutic efficacy of fasudil hydrochloride (F) and dichloroacetate (DCA) on pulmonary arterial hypertension (PAH), a new salt fasudil dichloroacetate (FDCA) was designed, synthesized and biologically evaluated. FDCA exhibited comparable ROCK II inhibitory activity relative to fasudil hydrochloride, and suppressed the expression of TNF-α and IL-6 in both PDGF-BB and hypoxia-treated pulmonary arterial smooth muscle cells (PASMCs) and endothelial cells (PAECs). Significantly, FDCA lowered mean pulmonary artery pressure (mPAP) and right ventricular systolic pressure (RVSP), and decreased right ventricular hypertrophy (RVH) in monocrotaline (MCT)-induced PAH rats. Meanwhile, FDCA remarkably decreased pulmonary artery medial thickness (PAMT) and hyperplasia, restoring the elasticity of elastic fiber, reduced cardiac hypertrophy, and attenuated fibrosis of heart and lung. Collectively, FDCA exhibited triple activities of pulmonary vasodilation, vascular remodeling inhibition and RVH inhibition, suggesting that it may be a promising agent for PAH intervention.

Function of Adipose-Derived Mesenchymal Stem Cells in Monocrotaline-Induced Pulmonary Arterial Hypertension through miR-191 via Regulation of BMPR2.

Pulmonary arterial hypertension (PAH) is a serious condition. However, prevailing therapeutic strategies are not effective enough to treat PAH. Therefore, finding an effective therapy is clearly warranted. Adipose-derived mesenchymal stem cells (ASCs) and ASCs-derived exosomes (ASCs-Exos) exert protective effects in PAH, but the underlying mechanism remains unclear. Using a coculture of ASCs and monocrotaline pyrrole (MCTP)-treated human pulmonary artery endothelial cells (HPAECs), we demonstrated that ASCs increased cell proliferation in MCTP-treated HPAECs. Results showed that ASCs-Exos improved proliferation of both control HPAECs and MCTP-treated HPAECs. In addition, by transfecting ASCs with antagomir we observed that low exosomal miR-191 expression inhibited HPAECs proliferation whereas the agomir improved. Similar results were observed in vivo using a monocrotaline (MCT)-induced PAH rat model following ASCs transplantation. And ASCs transplantation attenuated MCT-induced PAH albeit less than the antagomir treated group. Finally, we found that miR-191 repressed the expression of bone morphogenetic protein receptor 2 (BMPR2) in HPAECs and PAH rats. Thus, we conjectured that miR-191, in ASCs and ASCs-Exos, plays an important role in PAH via regulation of BMPR2. These findings are expected to contribute to promising therapeutic strategies for treating PAH in the future.

Echocardiographic assessment of right ventricular function in experimental pulmonary hypertension.

Echocardiography, a non-invasive and cost-effective method for monitoring cardiac function, is commonly used for evaluation and pre-clinical diagnostics of pulmonary hypertension (PH). Previous echocardiographic studies in experimental models of PH are fragmentary in terms of the evaluation of right ventricle (RV) function. In this study, three rodent models of PH: a mouse model of hypoxia-induced PH, a rat model of hypoxia+Sugen induced PH and a rat model of monocrotaline-induced PH, were employed to measure RV fractional area change (RVFAC), RV free wall thickness (RVFWT), pulmonary acceleration time (PAT), pulmonary ejection time (PET), and tricuspid annular plane systolic excursion (TAPSE). We found that, in these models, RVFWT significantly increased, but RVFAC, PAT, or PAT/PET ratios and TAPSE values significantly decreased. Accurate and complete TAPSE patterns were demonstrated in the three rodent models of PH. The RV echocardiography data matched the corresponding invasive hemodynamic and heart histologic data in each model. This serves as a reference study for real-time and non-invasive evaluation of RV function in rodent models of PH using echocardiography.

STUDY OF THE PHARMACOLOGICAL ACTIVITY OF LOWMOLECULAR ARGINASE II SELECTIVE INHIBITOR USING A MODEL OF MONOCROTALINE-INDUCED PULMONARY HYPERTENSION

The aimof the present work was to study the pharmacological activity of a low-molecular arginase II selective inhibitor (low-molecular compound with laboratory code ZB49) with the chemical formula 2-{1-[3-(3-[chloroisoxazole-5-yl) propyl] piperidin-4-yl}-6-(digibroxyboryl) norleucine dihydrochloride) using a model of monocrotaline-induced pulmonary hypertensionMaterials and methods.The work was performed on 40 adult male Wistar rats weighing 180– 220 g. The simulation of monocrotaline pulmonary hypertension was performed on 20 animals using a subcutaneous injection of an alcohol-aqueous solution of monocrotaline (MCT) at a dose of 60 mg/kg in a volume of 0.5 ml per animal. 7 days after the MCT injection, the administration of the studied pharmaceutical substance (PS) (laboratory code ZB49) was started at a dose of 5 mg/kg. ZB49 was administered intragastrically, once a day with the administration duration of 21 days.Results.Under the intragastric FS ZB49 administration at a dose of 5 mg/kg, a statistically significant decrease in the coefficient of endothelial dysfunction, systolic right ventricle pressure (SRVP), average the right ventricle pressure (ARVP), diastolic right ventricle pressure (DRVP), maximum contraction rate (dP/dt max) and minimum contraction rate (dP/dt min) was established at the background of the simulation of monocrotaline-induced pulmonary hypertension. At the same time, a statistically significant positive effect of ZB49 on the blood gas composition was established.Conclusion.The study has confirmed the possibility of using arginase inhibitors to prevent the development of endothelial dysfunction and the disorders of nitric oxide metabolism in pulmonary arterial hypertension. Among the substances of this group, arginase II selective inhibitors should be considered as the most promising.Conflict of interest: the authors declare no conflict of interest.

Exploration of the Notch3-HES5 signal pathway in monocrotaline-induced pulmonary hypertension using rat model.

This study explores the role of the Notch3-HES5 signal pathway in monocrotaline-induced pulmonary hypertension (PH) using rat models. Sprague Dawley rats (n=45) were randomly grouped into normal group, control group, and model group. Rats in the model group were used to establish the PH rat model. Four weeks after model establishment, right catheterization was used to measure the mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP) to analyze hemodynamic changes. The severity of PH was assessed by the right ventricular hypertrophy index (RVHI) and percentage of media thickness (MT%). The expressions of Notch3 and HES5 were determined by ELISA and reverse transcription-polymerase chain reaction. The correlation of mRNA expressions of Notch3 and HES5 with mPAP was analyzed. Rats in the model group had higher mPAP, RVSP, RVHI, and MT% as well as thicker pulmonary arterioles wall than those in the normal group. Immunohistochemistry showed Notch3 and HES5 were mainly expressed in the smooth muscle cell in pulmonary arterioles. In comparison with the normal group, rats in the model group had elevated expressions of Notch3 and HES5. The mean pulmonary arterial pressure was positively related with mRNA expressions of Notch3 and HES5. Taken together, our study demonstrates that monocrotaline-induced PH rats had high expressions of the Notch3-HES5 signal pathway in the pulmonary arterioles. The signal of the Notch3-HES5 signal pathway was positively related to the hemodynamics of the lung vasculature.

Activation of Nicotinic Acetylcholine α7 Receptor Attenuates Progression of Monocrotaline-Induced Pulmonary Hypertension in Rats by Downregulating the NLRP3 Inflammasome.

Background: Inflammation and altered immunity contribute to the development of pulmonary arterial hypertension (PH). The alpha 7 nicotinic acetylcholine receptor (α7nAChR) possesses anti-inflammatory activities. The current study was performed to investigate the effects of a selective α7nAChR agonist, PNU-282987, on controlling a monocrotaline (MCT)-induced rat model of PH and explored the underlying mechanisms.Methods: Sprague-Dawley rats were injected with MCT and treated with PNU-282987 at the prevention (starting 1 week before MCT) and treatment (starting 2 weeks after MCT) settings. Four weeks after MCT injection, hemodynamic changes, right ventricular structure, and lung morphological features were assessed. Enzyme-linked immunosorbent assay, Western blot and qRT-PCR were performed to assess levels of inflammatory cytokines and NLRP3 (Nod-like receptor family pyrin domain-containing 3) inflammasome pathway in the rat lung tissues. In addition, the lung macrophage line NR8383 was used to confirm the in vivo data.Results: Monocrotaline injection produced PH in rats and downregulated α7nAChR mRNA and protein expression in rat lung tissues compared to sham controls. Pharmacological activation of α7nAChR by PNU-282987 therapy improved the rat survival rate, attenuated the development of PH as assessed by remodeling of pulmonary arterioles, reduced the right ventricular (RV) systolic pressure, and ameliorated the hypertrophy and fibrosis of the RV in rats with MCT-induced PH. The expression of TNF-α, IL-6, IL-1β, and IL-18 were downregulated in rat lung tissues, which implied that PNU-282987 therapy may help regulate inflammation. These protective effects involved the inhibition of the NLRP3 inflammasome. In vitro assays of cultured rat lung macrophages confirmed that the anti-inflammation effect of PNU-282987 therapy may contribute to the disturbance of NLRP3 inflammasome activation.Conclusion: Targeting α7nAChR with PNU-282987 could effectively prevent and treat PH with benefits for preventing ongoing inflammation in the lungs of rats with MCT-induced PH by inhibiting NLRP3 inflammasome activation.

NLRC3 inhibits MCT-induced pulmonary hypertension in rats via attenuating PI3K activation.

Phosphoinositide 3-kinase (PI3K) activation plays a critical role in the pulmonary vascular remodeling of pulmonary hypertension (PH). The nucleotide-oligomerization domain (NOD)-like receptor subfamily C3 (NLRC3) inhibits proliferation and inflammation via PI3K signaling in cancer. We previously showed NLRC3 was significantly reduced in PH patients, but the mechanism of function remains unclear. This study aimed to determine the potential role of NLRC3 in PH. We found that NLRC3 was downregulated in the pulmonary arteries of PH animal models and platelet-derived growth factor-BB (PDGF-BB) stimulated pulmonary arterial smooth muscle cells (PASMCs). NLRC3 pretreatment reduced right ventricular systolic pressure, attenuated pulmonary vascular remodeling and RVHI, and ameliorated proliferation, migration, and inflammation. Monocrotaline (MCT)- and PDGF-BB-mediated PI3K activation were suppressed by NLRC3 pretreatment. 740Y-P decreased the effect of NLRC3. Collectively, NLRC3 protected against MCT-induced rat PH and PDGF-BB-induced PASMC proliferation, migration, and inflammation through a mechanism involving PI3K inhibition. NLRC3 may have a therapeutic effect on PH and provide a promising therapeutic strategy for PH.

Grape seed proanthocyanidin inhibits monocrotaline-induced pulmonary arterial hypertension via attenuating inflammation: in vivo and in vitro studies

Inflammation in pulmonary arterioles initiates and maintains pathological processes in pulmonary arterial hypertension (PAH), and inhibition of it attenuates PAH development. Grape seed proanthocyanidin (GSP) is believed to be effective in protecting vascular system via inhibiting inflammation, while its effect on pulmonary circulation remains inconclusive. In this study, we made observations in monocrotaline (MCT)-induced PAH rats and found decreases in mean pulmonary arterial pressure, pulmonary vessel resistance, right ventricular hypertrophy index, percentage of medial wall thickness, percentage of medial wall area, and lung weight of wet and dry tissue ratio after GSP administration in vivo. At the cellular and molecular levels, we also found several effects of GSP on MCT-induced PAH: (a) endothelial nitric oxide synthase expression in lung tissue and plasma NO level were increased; (b) Ca2+ level in pulmonary arterial smooth muscle cell (PASMC) was decreased; (c) transcription of inflammatory factors such as myeloperoxidase, interleukin (IL)-1β, IL-6 and tumor necrosis factor alpha (TNF-α) was down-regulated in lung tissue; (d) nuclear factor-κB pathway was inhibited as IκBα was less phosphorylated; (e) TNFα-induced PASMC overproliferation could be inhibited. These results indicated a possible mechanism of GSP reversing pulmonary vascular remodeling and vascular contraction by inhibiting inflammation, and it may be useful for preventing PAH development.

Effect of estrogen on right ventricular remodeling of monocrotaline-induced pulmonary arterial hypertension in rats and its mechanism.

To elucidate the effect of estrogen on right ventricular remodeling of pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT) in rats and its underlying mechanism. Male Sprague- Dawley (SD) rats were adaptively fed for one week, and then, randomly divided into control group, MCT group, MCT+17-β estradiol (50 mg·kg-1·d-1) group, and MCT+17-β estradiol (100 mg·kg-1·d-1) group, with 8 rats in each group. PAH rat model was constructed by subcutaneous injection of 60 mg·kg-1 MCT for consecutive 4 weeks. The right external jugular vein was intubated to monitor rat RVSP (right ventricular systolic pressure) and mPAP (mean pulmonary arterial pressure). After animal procedures, RV (right ventricle) and LV+S (left ventricle+ventricular septum) of rat were harvested and weighed. Rat tibia was collected and recorded for its length, followed by calculation of RV/(LV+S) and RV/length of the tibia. HE staining and Masson staining were conducted to observe the pathological change and collagen deposition in RV, respectively. RV was prepared for homogenate, followed by detection of total antioxidant capacity (T-AOC) and malondialdehyde (MDA) activities. Expression levels of collagen I, collagen III, NOX4, and NF-κB in RV of PAH rats were detected by qRT-PCR and Western blot. Lower RVSP, mPAP, RV/(LV+S) and RV/length of the tibia were observed in rats of MCT+17-β estradiol (50 mg·kg-1·d-1) group and MCT+17-β estradiol (100 mg·kg-1·d-1) group compared with those of MCT group. Injection of 17-β estradiol (50 mg·kg-1·d-1 and 100 mg·kg-1·d-1) in PAH rats remarkably alleviated pathological changes and collagen deposition in RV. T-AOC activity increased, whereas MDA activity decreased in PAH rats injected with 17-β estradiol. Expression levels of collagen I, collagen III, NOX4, and NF-κB in RV of PAH rats were all downregulated by 17-β estradiol treatment. 17-β estradiol could remarkably alleviate MCT-induced right ventricular remodeling of PAH rats. It is suggested that 17-β estradiol exerts its protective role in PAH by inhibiting NOX4-mediated oxidative stress and NF-κB-mediated collagen deposition.

Therapeutic effects of the selective farnesoid X receptor agonist obeticholic acid in a monocrotaline-induced pulmonary hypertension rat model

Activation of the farnesoid X receptor (FXR), a member of the nuclear receptor steroid superfamily, leads to anti-inflammatory and anti-fibrotic effects in several tissues, including the lung. We have recently demonstrated a protective effect of the farnesoid X receptor (FXR) agonist obeticholic acid (OCA) in rat models of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and bleomycin-induced pulmonary fibrosis. The aim of the present study was to investigate whether the positive effects of OCA treatment could be exerted also in established MCT-induced PAH, i.e., starting treatment 2weeks after MCT administration. Rats with MCT-induced PAH were treated, 2weeks after MCT administration, with OCA or tadalafil for two additional weeks. Pulmonary functional tests were performed at week 2 (before treatment) and four (end of treatment). At the same time points, lung morphological features and expression profile of genes related to smooth muscle relaxation/contraction and tissue remodeling were also assessed. 2weeks after MCT-induced injury, the treadmill resistance (a functional parameter related to pulmonary hypertension) was significantly decreased. At the same time point, we observed right ventricular hypertrophy and vascular remodeling, with upregulation of genes related to inflammation. At week 4, we observed a further worsening of the functional and morphological parameters, accompanied by dysregulation of inflammatory and extracellular matrix markers mRNA expression. Administration of OCA (3 or 10mg/kg/day), starting 2weeks after MCT-induced injury, significantly improved pulmonary function, effectively normalizing the exercise capacity. OCA also reverted most of the lung alterations, with a significant reduction of lung vascular wall thickness, right ventricular hypertrophy, and restoration of the local balance between relaxant and contractile pathways. Markers of remodeling pathways were also normalized by OCA treatment. Notably, results with OCA treatment were similar, or even superior, to those obtained with tadalafil, a recently approved treatment for pulmonary hypertension. The results of this study demonstrate a significant therapeutic effect of OCA in established MCT-induced PAH, improving exercise capacity associated with reduction of right ventricular hypertrophy and lung vascular remodeling. Thus, OCA dosing in a therapeutic protocol restores the balance between relaxant and contractile pathways in the lung, promoting cardiopulmonary protective actions in MCT-induced PAH.

Glucagon-like peptide-1 (GLP-1) mediates the protective effects of dipeptidyl peptidase IV inhibition on pulmonary hypertension

BackgroundPulmonary hypertension (PH) is a progressive disease leading to death ultimately. Our recently published data demonstrated that inhibiting dipeptidyl peptidase IV (DPP-4) alleviated pulmonary vascular remodeling in experimental PH. However, whether glucagon-like peptide-1 (GLP-1) mediated the protective effect of DPP-4 inhibition (DPP-4i) on PH is unclear.ResultsIn the present study, GLP-1 receptor antagonist (exendin-3) abolished the protective effects of DPP-4 inhibitor (sitagliptin) on right ventricular systolic pressure (RVSP) and pulmonary vascular remodeling (PVR) in monocrotaline (MCT, 60 mg/kg)-induced PH in rat. Notably, activation of GLP-1 receptor by GLP-1 analogue liraglutide directly attenuated RVSP and PVR in MCT-induced PH, as well as bleomycin- and chronic hypoxia-induced PH. Moreover, liraglutide potently inhibited MCT-induced inflammation and suppressed MCT-induced down-regulation of vascular endothelial marker (VE-cadherin and vWF) in lung. In vitro studies showed liraglutide reversed TGF-β1 (5 ng/ml) combining IL-1β (5 ng/ml) induced endothelial-mesenchymal transition (EndMT) in human umbilical vein endothelial cells (HUVECs), which could be abolished by GLP-1 receptor antagonist (exendin-3). Furtermore, liraglutide suppressed TGF-β1-IL-1β-induced phosphorylation of both Smad3 and ERK1/2.ConclusionsOur data suggest that GLP-1 mediated the protective effects of DPP-4i on pulmonary vascular and RV remodeling in experimental PH, which may be attributed to the inhibitory effect on EndMT.

Параметры биоэлектрического импеданса легких у самок крыс линии Вистар при экспериментальной легочной гипертензии

The aim of the study was to reveal changes in bioelectrical impedance of the lung and body in female Wistar rats with monocrotaline-induced pulmonary hypertension. Multifrequency bioimpedance measurements were taken in rats a month before and after of administration of monocrotaline (100 mg/kg). Histological lung tissue sections of 5 μm thickness were stained with hematoxylin and eosin. Monocrotaline-induced pulmonary vascular remodeling that confirmed the development of pulmonary hypertension, emphysematous changes, and the inflammatory process in the lung were histologically shown in rats. At low frequencies, a significant increase of active resistance, amplitude of bioelectrical impedance of the lung revealed in monocrotaline-treated rats in comparison to the rats in the control group may testify to emphysematous changes, and at higher frequencies, that may be connected with the inflammatory process and narrowing of the lumen of blood vessels in the lung. In monocrotaline-treated rats, a significant decrease of the phase angle of pulmonary electrical bioimpedance and reactive resistance of bioelectrical impedance of the body at low frequency may indicate cell membrane injury.

Preventive effect of olmesartan on right ventricular fibrosis in rats with monocrotaline-induced pulmonary hypertension.

Preventive effect of olmesartan on right ventricular fibrosis in rats with monocrotaline-induced pulmonary hypertension.

Effect of Ambrisentan Therapy on the Expression of Endothelin Receptor, Endothelial Nitric Oxide Synthase and NADPH Oxidase 4 in Monocrotaline-induced Pulmonary Arterial Hypertension Rat Model.

Background and ObjectivesElevated endothelin (ET)-1 level is strongly correlated with the pathogenesis of pulmonary arterial hypertension (PAH). Expression level of nicotinamide adenine dinucleotide phosphate oxidase (NOX) 4 is increased in the PAH patients. Ambrisentan, a selective endothelin receptor A (ERA) antagonist, is widely used in PAH therapy. The current study was undertaken to evaluate the effects of ambrisentan treatment in the monocrotaline (MCT)-induced PAH rat model.MethodsRats were categorized into control group (C), monocrotaline group (M) and ambrisentan group (Am). The M and Am were subcutaneously injected 60 mg/kg MCT at day 0, and in Am, ambrisentan was orally administered the day after MCT injection for 4 weeks. The right ventricle (RV) pressure was measured and pathological changes of the lung tissues were observed by Victoria blue staining. Protein expressions of ET-1, ERA, endothelial nitric oxide synthase (eNOS) and NOX4 were confirmed by western blot analysis.ResultsAmbrisentan treatment resulted in a recovery of the body weight and RV/left ventricle+septum at week 4. The RV pressure was lowered at weeks 2 and 4 after ambrisentan administration. Medial wall thickening of pulmonary arterioles and the number of intra-acinar arteries were also attenuated by ambrisentan at week 4. Protein expression levels of ET-1 and eNOS were recovered at weeks 2 and 4, and ERA levels recovered at week 4.ConclusionsAmbrisentan administration resulted in the recovery of ET-1, ERA and eNOS protein expression levels in the PAH model. However, the expression level of NOX4 remained unaffected after ambrisentan treatment.

Arctigenin prevents monocrotaline-induced pulmonary arterial hypertension in rats.

The hallmark features of the development of pulmonary arterial hypertension (PAH) include the proliferation of pulmonary vascular smooth muscle cells, oxidative stress, inflammation, and pulmonary artery remodeling. Arctigenin is a bioactive component of Arctium lappa that exerts anti-inflammatory and antiproliferative effects in several diseases; however, its effects on pulmonary arteries are still unclear. This study aimed to investigate the efficacy of arctigenin to prevent PAH. Rats injected with monocrotaline (MCT) progressively developed PAH. Arctigenin treatment (50 mg per kg per day, intra-peritoneally) ameliorated right ventricular systolic pressure and pulmonary arterial remodeling, decreased the expression of inflammatory cytokines, and limited the proliferation of pulmonary vascular smooth muscle cells in lungs. Mechanistically, arctigenin effectively inhibited the MCT-induced elevation of NLRP3, caspase-1, and interleukin 1-beta expression in the lungs. These results indicate that arctigenin ameliorates MCT-induced PAH, at least in part, through exerting its anti-inflammatory, antioxidant, and antiproliferative effects, which inhibit the NLRP3 inflammasome signal pathway in rats.

Preventive Effect and Mechanism of Ethyl Acetate Extract of Sceptridium ternatum in Monocrotaline-Induced Pulmonary Arterial Hypertension

To observe the effect and molecular mechanism of ethyl acetate extract of Sceptridium ternatum (STE) on the monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). The main chemical components of Sceptridium ternatum were determined, and the effects in PAH rats were observed. A total of 140 Sprague Dawley rats were randomly and equally divided into the normal group, the model group, the Bosentan group, and the STE groups (2.5, 5, 10 g/kg) by the random number table method. The characteristic indicators of PAH were measured, and immunohistochemistry was used to observe the lung tissue of rats. Morphological changes of the lung tissue were observed under the light microscope. Compared with the normal group, rats in the model group showed a significant increase in right ventricular free wall thickness (RVFWT), mean pulmonary arterial pressure (mPAP), mean right ventricular pressure (mRVP), max right ventricular pressure (max RVP), weight of right ventricle (RV), and lung index (LI), while a significant decrease in pulmonary artery acceleration time (PAAT, P<0.01). Compared with the model group, rats treated with STE had a significant decrease of RVFWT, mPAP, mRVP, max RVP, and RV, while a significant increase of PAAT (P<0.01). After injection of MCT, nuclear factor- κB (NF- κB) p65 and α -smooth muscle actin (α -SMA) expression levels were up-regulated, and on the contrary, the treatment groups showed a significant down-regulation without dose-dependent trend. STE can relieve the PAH in rats. STE may relieve pulmonary vascular disease and pulmonary injury by down-regulating the expression of NF- κB p65 and α -SMA.