Baicalein Ameliorates Pulmonary Arterial Hypertension Caused by Monocrotaline through Downregulation of ET-1 and ETAR in Pneumonectomized Rats.

Baicalein (BE) extracted from Scutellaria baicalensis Georgi is able to alleviate various cardiovascular and inflammatory diseases. However, the effects of BE on pulmonary arterial hypertension (PAH) remain unknown. Therefore, the present study aimed to examine whether BE ameliorates pneumonectomy and monocrotaline-induced PAH in rats and further investigate the underlying molecular mechanisms. Administration of BE greatly attenuated the development of PAH as evidenced by an improvement of its characteristic features, including elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary vascular remodeling. Moreover, the increased protein expression of endothelin-1 (ET-1) and ETA receptor (ETAR), superoxide overproduction, and activation of Akt/ERK1/2/GSK3[Formula: see text]/[Formula: see text]-catenin pathway that occurred in the lungs of PAH rats were markedly reversed by BE treatment. Compared with the untreated PAH rats, higher expression of endothelial nitric oxide synthase (eNOS), but lower levels of inducible nitric oxide synthase and vWF were observed in BE-treated PAH rats. Collectively, treatment with BE remarkably attenuates the pathogenesis of PAH, and the protection of BE may be associated with suppressing Akt/Erk1/2/GSK3[Formula: see text]/[Formula: see text]-catenin/ET-1/ETAR signaling and preventing endothelial dysfunction. These results suggest that BE is a potential agent for treatment of PAH.

Astragalus Polysaccharides Attenuate Monocrotaline-Induced Pulmonary Arterial Hypertension in Rats.

Astragalus polysaccharides (APS) have been shown to possess a variety of biological activities including anti-oxidant and anti-inflammation functions in a number of diseases. However, their function in pulmonary arterial hypertension (PAH) is still unknown. Rats received APS (200[Formula: see text]mg/kg once two days) for 2 weeks after being injected with monocrotaline (MCT; 60[Formula: see text]mg/kg). The pulmonary hemodynamic index, right ventricular hypertrophy, and lung morphological features of the rat models were examined, as well as the NO/eNOS ratio of wet lung and dry lung weight and MPO. A qRT-PCR and p-I[Formula: see text]B was used to assess IL-1[Formula: see text], IL-6 and TNF-[Formula: see text] and WB was used to detect the total I[Formula: see text]B. Based on these measurements, it was found that APS reversed the MCT-induced increase in mean pulmonary arterial pressure (mPAP) (from 32.731[Formula: see text]mmHg to 26.707[Formula: see text]mmHg), decreased pulmonary vascular resistance (PVR) (from 289.021[Formula: see text]mmHg[Formula: see text][Formula: see text] min/L to 246.351[Formula: see text]mmHg[Formula: see text][Formula: see text][Formula: see text]min/L), and reduced right ventricular hypertrophy (from 289.021[Formula: see text]mmHg[Formula: see text][Formula: see text][Formula: see text]min/L to 246.351 mmHg[Formula: see text][Formula: see text][Formula: see text]min/L) ([Formula: see text]0.05). In terms of pulmonary artery remodeling, the WT% and WA% decreased with the addition of APS. In addition, it was found that APS promoted the synthesis of eNOS and the secretion of NO, promoting vasodilation and APS decreased the MCT-induced elevation of MPO, IL-1[Formula: see text], IL-6 and TNF-[Formula: see text], reducing inflammation. Furthermore, APS was able to inhibit the activation of pho-I[Formula: see text]B[Formula: see text]. In couclusion, APS ameliorates MCT-induced pulmonary artery hypertension by inhibiting pulmonary arterial remodeling partially via eNOS/NO and NF-[Formula: see text]B signaling pathways.

[Effect of sesamin on pulmonary vascular remodeling in rats with monocrotaline-induced pulmonary hypertension].

OBJECTIVE: To observe the effect of sesamin (Ses) on pulmonary vascular remodeling in rats with monocrotaline ( MCT)-induced pulmonary hypertension (PH). METHOD: Totally 48 male Sprague-Dawley (SD) rats were fed adaptively for one week and then divided into the normal control group, the MCT group, the MCT +Ses (50 mg x kg(-1)) group and the MCT + Ses (100 mg x kg(-1)) group, with 12 rats in each group. The PH rat model was induced through the subcutaneous injection with MCT(60 mg x kg(-1)). After the administration for four weeks, efforts were made to measure the right ventricular systolic pressure( RVSP) and mean pulmonary artery pressure (mPAP) through right jugular vein catheterization, and isolate right ventricle( RV) and left ventricle( LV) +septum (S) and measure their length to calculate RV/ ( LV + S) and ratio of RV to tibial length. Pathologic changes in arterioles were observed by HE staining. Masson's trichrome stain was used to demonstrate changes in collagen deposition of arterioles. The alpha-smooth muscle actin (alpha-SMA) expression in pulmonary arteries was measured by immunohistochemisty. The total antioxidative capacity (T-AOC) and malondialdehyde (MDA) content in pulmonary arteries were determined by the colorimetric method. The protein expressions of collagen I, NOX2 and NOX4 were analyzed by Real-time PCR and Western blot. RESULT: After the administration for 4 weeks, Ses could attenuate RVSP and mPAP induced by MCT, RV/ (LV + S) and ratio of RV to Tibial length, alpha-SMA and collagen I expressions and remodeling of pulmonary vessels and right ventricle. Meanwhile, Ses could obviously inhibit the expressions of NOX2, NOX4 and MDA content and increase T-AOC. CONCLUSION: Sesamin could ameliorate pulmonary vascular remodeling induced by monocrotaline in PH rats. Its mechanism may be related to expressions of NOX2 and NOX4 expression and reduction in oxidative stress injury.

Sorafenib attenuates monocrotaline-induced sinusoidal obstruction syndrome in rats through suppression of JNK and MMP-9.

BACKGROUND & AIMS: Sinusoidal obstruction syndrome (SOS) is a drug-induced liver injury that occurs with oxaliplatin treatment and is associated with postoperative morbidity after hepatectomy. The aim of this study was to investigate the effects of sorafenib in a monocrotaline (MCT)-induced model of SOS in rats. METHODS: Rats were divided into groups treated with sorafenib (2mg/kg) or vehicle, 36 h and 12h before MCT (90 mg/kg) administration by gavage. Liver tissues and blood were sampled 48 h after MCT administration to evaluate SOS. Survival after hepatectomy was examined and immunohistochemistry and electron microscopy were performed to assess sinusoidal injury. RESULTS: In the vehicle group, liver histology showed sinusoidal dilatation, coagulative necrosis of hepatocytes, endothelial damage of the central vein, and sinusoidal hemorrhage. In the sorafenib group, these changes were significantly suppressed, total SOS scores were significantly decreased, and the elevation of serum transaminase levels observed in the vehicle group was significantly reduced. Survival after hepatectomy was significantly higher in the sorafenib group compared to the vehicle group (45% vs. 20%, p=0.0137). Immunohistochemistry and electron microscopy revealed a protective effect of sorafenib on sinusoidal endothelial cells at 6h after MCT treatment. Sorafenib also attenuated the activity of metallopeptidase-9 (MMP-9) and phosphorylation of c-Jun N-terminal kinase (JNK). CONCLUSIONS: Sorafenib reduced the severity of MCT-induced SOS in rats through suppression of MMP-9 and JNK activity, resulting in improvement of survival after hepatectomy.

Influence of estrogen on pulmonary arterial hypertension: role of oxidative stress.

Pulmonary arterial hypertension (PAH) is a disease that increases the pulmonary vascular resistance, causing hypertrophy and subsequent right heart failure. Oxidative stress is involved in the pathogenesis of PAH, and estrogen is considered an antioxidant. Thus, the aim of this study was to test the hypothesis that estrogen could attenuate PAH by modulating oxidative stress. Female Wistar rats were ovariectomized or suffered the surgery simulation (sham). After 7 days, subcutaneous pellets with 17ß-estradiol or sunflower oil were implanted. At this time, PAH was induced by means of a single dose of monocrotaline (MCT) (60 mg·kg(-1) i.p.). The experimental groups were as follows: (1) sham, (2) sham + MCT, (3) ovariectomy (O), (4) ovariectomy + MCT (OM), (5) ovariectomy + estrogen replacement + MCT (ORM). Hemodynamic measurements were performed 21 days after MCT or saline. Nonovariectomized animals were assessed in the stage of diestrus. Afterwards, the rats were killed to collect the heart, the lung and the liver to evaluate morphometry. Samples of the right ventricle were used to analyse the reduced glutathione : oxidized glutathione ratio. Lung congestion in the OM group, which was decreased in the ORM group, was observed. Right ventricle end-diastolic pressure was increased in the OM and the ORM groups. The glutathione ratio decreased in the groups O, OM and ORM. The data suggest that estrogen can exert great influence on the cellular redox balance. The maintenance of physiological estrogen levels may help to avoid the appearance of pulmonary oedema, characteristic of this model of PAH, and right ventricular failure.

[Effects of rosuvastatin on monocrotaline-induced pulmonary artery hypertension in rats].

OBJECTIVE: To investigate the effects of rosuvastatin on monocrotaline (MCT)-induced pulmonary artery hypertension in rats. METHODS: Pulmonary arterial hypertension was induced by a single subcutaneous injection of monocrotaline (50 mg/kg) in rats. In the prevention protocol, 32 male Sprague-Dawley rats were randomly divided into four groups (n = 8 each): low-dose rosuvastatin prevention group (2 mg×kg(-1)×d(-1)), high-dose rosuvastatin prevention group (10 mg×kg(-1)×d(-1)), pulmonary arterial hypertension group, normal control group. Beginning on the MCT injection day, rats were treated with rosuvastatin by daily gavage for 4 weeks. Normal control group and pulmonary arterial hypertension group received vehicle by gavage. In the treatment protocol, 52 male Sprague-Dawley rats were randomly divided into four groups (n = 13 each): low-dose rosuvastatin treatment group (2 mg×kg(-1)×d(-1)), high-dose rosuvastatin treatment group (10 mg×kg(-1)×d(-1)), pulmonary arterial hypertension group, normal control group. Four weeks after MCT injection, rats were treated with rosuvastatin by daily gavage for 4 weeks. Normal control group and pulmonary arterial hypertension group received vehicle by gavage. At the end of study, survival rates, mean pulmonary arterial pressure (mPAP), wall thickness of small pulmonary artery and right ventricular hypertrophy among groups were compared. The expression levels of proliferating cell nuclear antigen (PCNA) and endothelial nitricoxide synthase (eNOS) protein in small pulmonary artery, the expression levels of Rho kinase 1(ROCK-1) and eNOS mRNA in lung tissue were also detected. RESULTS: All rats in the prevention protocol survived. Rosuvastatin treatment improved survival in the treatment protocol (58%, 75% vs.30%, P < 0.05). Rosuvastatin therapy in both preventive or treatment protocols significantly lowered mPAP [prevention protocol: (27.53 ± 3.43), (25.72 ± 1.76) vs. (36.05 ± 2.45) mm Hg (1 mm Hg = 0.133 kPa), P < 0.01; treatment protocol: (30.39 ± 3.17), (27.59 ± 1.99) vs. (40.68 ± 1.39) mm Hg, P < 0.01], reduced thickening of small pulmonary artery wall (P < 0.01) and right ventricular hypertrophy (P < 0.01). Rosuvastatin also inhibited PCNA expression of SMC (P < 0.01), restored eNOS expression of EC (P < 0.05) and inhibited ROCK-1 mRNA expressions in lung tissue (P < 0.05). CONCLUSIONS: Rosuvastatin therapy reduced mPAP in monocrotaline-induced pulmonary arterial hypertension rat model and this effect is linked with inhibition of ROCK-1 expression, inhibition of smooth muscle cell proliferation and restoration of endothelial cell functions.

[The effect of compound macrostem onion capsule on metabolism of arachidonic acid in a rat model of monocrotaline-induced pulmonary artery hypertension].

OBJECTIVE: To study the effect of compound macrostem onion capsule (CMOC) on products of arachidonic acid metabolism in monocrotaline (MCT)-induced pulmonary artery hypertension rats. METHODS: Sixty SD rats were divided into a control group, a model group, and three experimental groups in which the rats were fed with captopril, small dose single dosage, and large dose (double dosage) of CMOC, respectively. The rat model was made by MCT peritoneal injection. The mean pulmonary arterial pressure (mPAP) and the mean right ventricular pressure (mRVP) were measured. Thromboxane B(2) (TXB(2)) and 6-keto-prostaglandin Fia (6-K-PGFia) were determined by RIA method. RESULTS: The mPAP in rats of the model group [(36.9 +/- 4.8) mm Hg, 1 mm Hg = 0.133 kPa] was significantly higher than that of the control group [(16.4 +/- 2.1) mm Hg, all P < 0.01]. The mPAP in rats of the double dosage and single dosage of CMOC groups were (26.2 +/- 2.8) mm Hg and (27.9 +/- 2.8) mm Hg, respectively; both were significantly lower than those of the model group (all P < 0.01). TXB(2) in rats of the model group was significantly higher than that of the control group (P < 0.05), while 6-K-PGFia in the model group was significantly lower than that of the control group (P < 0.01). TXB(2) in rats of the double dosage CMOC group was significantly lower than that of the model group, but 6-K-PGFia in rats of the CMOC groups was significantly higher than that of the model group (P < 0.05, < 0.01). CONCLUSION: CMOC is effective in reducing pulmonary artery hypertension. Inhibition of TXB(2) and augmentation of 6-K-PGFia might be the underlying mechanisms.

Effect of nolomirole on monocrotaline-induced heart failure.

Neurohormonal activation has been shown to be a major factor in congestive heart failure progression and mortality. The beneficial effects obtained in clinical trials with angiotensin converting enzyme (ACE) inhibitors, beta-blockers and aldosterone antagonists have confirmed this hypothesis. 5,6-Diisobutirroyloxy-2-methyl-aminotetraline hydrochloride (nolomirole) is a selective agonist of prejunctional D(2)-dopaminergic and alpha(2)-adrenergic receptors. The stimulation of these receptors inhibits catecholamine release from sympathetic nerve endings. To confirm that this mechanism can be useful in congestive heart failure, we studied the effects of nolomirole on monocrotaline-induced congestive heart failure. The ACE inhibitor trandolapril was used as reference compound. Rats were given single intraperitoneal injection of either saline (control group; n=20) or monocrotaline (50 mg kg(-1)). Three days later, the monocrotaline-treated animals were randomly allocated (n=50 per group) to oral treatment with distilled water (vehicle group), nolomirole (0.25 mg kg(-1)) twice a day, or trandolapril (0.3 mg kg(-1)) once a day up to sacrifice. On the fourth week after monocrotaline injection, animals with signs of congestive heart failure were sacrificed for evaluation of heart hypertrophy and neuroendocrine alterations. Atrial natriuretic peptide (ANP) and alderosterone were determined by radioimmunoassay in plasma. Tissue norepinephrine concentration was quantified by high-pressure liquid chromatography. Nolomirole and trandolapril significantly reduced (a) hypertrophy of right atria and ventricles, (b) plasma levels of ANP and presence of pleural/peritoneal effusions and (c) norepinephrine depletion of right ventricle. These findings confirmed that nolomirole, like trandolapril, is able to attenuate the heart failure signs in the monocrotaline-induced congestive heart failure model.

Inhaled nitric oxide and nifedipine have similar effects on lung cGMP levels in rats.

UNLABELLED: Inhaled nitric oxide (NO) may downregulate the endogenous NO/cyclic guanosine monophosphate (cGMP) pathway, potentially explaining clinical rebound pulmonary hypertension. We determined if inhaled NO decreases pulmonary cGMP levels, if the possible down-regulation is the same as with nifedipine, and if regulation also occurs with the cyclic adenosine monophosphate (cAMP) pathway. Rats were exposed to 3 wk of normoxia, hypoxia (10% O2), or monocrotaline (MCT; single dose = 60 mg/kg) and treated with either nothing (control), inhaled NO (20 ppm), or nifedipine (10 mg x kg(-1) x day(-1). The lungs were then isolated and perfused with physiologic saline. Perfusate cGMP, prostacyclin, and cAMP levels were measured. Perfusate cGMP was not altered by inhaled NO or nifedipine in normoxic or MCT rats. Although hypoxia significantly increased cGMP by 128%, both inhaled NO and nifedipine equally prevented the hypoxic increase. Inhibition of the NO/cGMP pathway with N(G)-nitro-L-arginine methyl ester (L-NAME) decreased cGMP by 72% and 88% in normoxic and hypoxic lungs. Prostacyclin and cAMP levels were not altered by inhaled NO or nifedipine. L-NAME significantly decreased cGMP levels, whereas inhaled NO had no effect on cGMP in normoxic or MCT lungs, suggesting that inhaled NO does not inhibit the NO/cGMP pathway. Inhaled NO decreased cGMP in hypoxic lungs, however, nifedipine had the same effect, which indicates the decrease is not specific to inhaled NO. IMPLICATIONS: High pulmonary pressure after discontinuation of inhaled nitric oxide (NO) may be secondary to a decrease in the natural endogenous NO vasodilator. This rat study suggests that inhaled NO either does not alter endogenous NO or that it has similar effects as nifedipine.

Chronic pulmonary hypertension--the monocrotaline model and involvement of the hemostatic system.

Monocrotaline (MCT) is a toxic pyrrolizidine alkaloid of plant origin. Administration of small doses of MCT or its active metabolite, monocrotaline pyrrole (MCTP), to rats causes delayed and progressive lung injury characterized by pulmonary vascular remodeling, pulmonary hypertension, and compensatory right heart hypertrophy. The lesions induced by MCT(P) administration in rats are similar to those observed in certain chronic pulmonary vascular diseases of people. This review begins with a synopsis of the hemostatic system, emphasizing the role of endothelium since endothelial cell dysfunction likely underlies the pathogenesis of MCT(P)-induced pneumotoxicity. MCT toxicology is discussed, focusing on morphologic, pulmonary mechanical, hemodynamic, and biochemical and molecular alterations that occur after toxicant exposure. Fibrin and platelet thrombosis of the pulmonary microvasculature occurs after administration of MCT(P) to rats, and several investigators have hypothesized that thrombi contribute to the lung injury and pulmonary hypertension. The evidence for involvement of the various components of the hemostatic system in MCT(P)-induced vascular injury and remodeling is reviewed. Current evidence is consistent with involvement of platelets and an altered fibrinolytic system, yet much remains to be learned about specific events and signals in the vascular pathogenesis.