Naringenin adds to the protective effect of L-arginine in monocrotaline-induced pulmonary hypertension in rats: favorable modulation of oxidative stress, inflammation and nitric oxide

Blueberry Extract and Resistance Training Prevent Left Ventricular Redox Dysregulation and Pathological Remodeling in Experimental Severe Pulmonary Arterial Hypertension

OBJECTIVE

To investigate whether the regular administration of blueberry extract and low-intensity resistance exercise training (RT), either alone or in combination, during the development of monocrotaline (MCT)-induced severe pulmonary arterial hypertension (PAH) in rats protect the left ventricle (LV) from redox dysregulation and pathological remodeling.

METHODS

Groups of seven male Wistar rats were formed for the experiment: sedentary control; sedentary hypertensive; sedentary hypertensive blueberry; exercise hypertensive; and exercise hypertensive blueberry. PAH was experimentally induced through a single intraperitoneal administration of MCT at a dose of 60 mg/kg. One day after injection, the blueberry groups started receiving a daily dose of blueberry extract (100 mg/kg) by gavage, while the exercise groups initiated a three-week program of RT (ladder climbing; 15 climbs carrying 60% of maximum load; one session/day; 5 times/week). Echocardiographic evaluations were conducted 23 days after injection, and the rats were euthanized the next day to harvest LV tissue.

RESULTS

Separately, blueberry extract and RT mitigated augments in pulmonary artery resistance, LV tissue redox dysregulation (i.e., increased PC levels) and detrimental remodeling (i.e., reduced inflammation), and reductions in ejection fraction (EF) and fractional shortening (FS) caused by PAH. The combination of treatments prevented reductions in EF and FS, along with the development of a D-shaped LV.

CONCLUSIONS

blueberry extract and moderate-intensity resistance training administered during the development of MCT-induced severe PAH in rats prevented LV redox dysregulation and pathological remodeling, thereby preserving its function.

Therapeutic potential of natural flavonoids in pulmonary arterial hypertension: A review

BACKGROUND

Pulmonary arterial hypertension (PAH) is a fatal disease caused by pulmonary vascular remodeling, with a high incidence and mortality. At present, many clinical drugs for treating PAH mainly exert effects by relaxing the pulmonary artery, with limited therapeutic effects, so the search for viable therapeutic agents continues uninterrupted. In recent years, natural flavonoids have shown promising potential in the treatment of cardiovascular diseases. It is necessary to comprehensively elucidate the potential of natural flavonoids to combat PAH.

PURPOSE

To evaluate the potential of natural flavonoids to hinder or slow down the occurrence and development of PAH, and to identify promising drug discovery candidates.

METHODS

Literature was collected from PubMed, Science Direct, Web of science, CNKI databases and Google scholar. The search terms used included "pulmonary arterial hypertension", "pulmonary hypertension", "natural products", "natural flavonoids", "traditional chinese medicine", etc., and several combinations of these keywords.

RESULTS

The resources, structural characteristics, mechanisms, potential and prospect strategies of natural flavonoids for treating PAH were summarized. Natural flavonoids offer different solutions as possible treatments for PAH. These mechanisms may involve various pathways and molecular targets related to the pathogenesis of PAH, such as inflammation, oxidative stress, vascular remodeling, genetic, ion channels, cell proliferation and autophagy. In addition, prospect strategies of natural flavonoids for anti-PAH including structural modification and nanomaterial delivery systems have been explored. This review suggests that the potential of natural flavonoids as alternative therapeutic agents in the prevention and treatment of PAH holds promise for future research and clinical applications.

CONCLUSION

Despite displaying the enormous potential of flavonoids in PAH, some limitations need to be further explored. Firstly, using advanced drug discovery tools, including computer-aided design and high-throughput screening, to further investigate the safety, biological activity, and precise mechanism of action of flavonoids. Secondly, exploring the structural modifications of these compounds is expected to optimize their efficacy. Lastly, it is necessary to conduct well controlled clinical trials and a comprehensive evaluation of potential side effects to determine their effectiveness and safety.

Exploring the Mechanism of Zhishi-Xiebai-Guizhi Decoction for the Treatment of Hypoxic Pulmonary Hypertension based on Network Pharmacology and Experimental Analyses

BACKGROUND

Hypoxic Pulmonary Hypertension (HPH), a prevalent disease in highland areas, is a crucial factor in various complex highland diseases with high mortality rates. Zhishi-Xiebai-Guizhi decoction (ZXGD), traditional Chinese medicine with a long history of use in treating heart and lung diseases, lacks a clear understanding of its pharmacological mechanism.

OBJECTIVE

This study aimed to investigate the pharmacological effects and mechanisms of ZXGD on HPH.

METHODS

We conducted a network pharmacological prediction analysis and molecular docking to predict the effects, which were verified through in vivo experiments.

RESULTS

Network pharmacological analysis revealed 51 active compounds of ZXGD and 701 corresponding target genes. Additionally, there are 2,116 targets for HPH, 311 drug-disease co-targets, and 17 core-targets. GO functional annotation analysis revealed that the core targets primarily participate in biological processes such as apoptosis and cellular response to hypoxia. Furthermore, KEGG pathway enrichment analysis demonstrated that the core targets are involved in several pathways, including the phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt) signaling pathway and Hypoxia Inducible Factor 1 (HIF1) signaling pathway. In vivo experiments, the continuous administration of ZXGD demonstrated a significant improvement in pulmonary artery pressure, right heart function, pulmonary vascular remodeling, and pulmonary vascular fibrosis in HPH rats. Furthermore, ZXGD was found to inhibit the expression of PI3K, Akt, and HIF1α proteins in rat lung tissue.

CONCLUSION

In summary, this study confirmed the beneficial effects and mechanism of ZXGD on HPH through a combination of network pharmacology and in vivo experiments. These findings provided a new insight for further research on HPH in the field of traditional Chinese medicine.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Impact of l-citrulline on nitric oxide signaling and arginase activity in hypoxic human pulmonary artery endothelial cells

Impaired nitric oxide (NO) signaling contributes to the development of pulmonary hypertension (PH). The l-arginine precursor, l-citrulline, improves NO signaling and has therapeutic potential in PH. However, there is evidence that l-citrulline might increase arginase activity, which in turn, has been shown to contribute to PH. Our major purpose was to determine if l-citrulline increases arginase activity in hypoxic human pulmonary artery endothelial cells (PAECs). In addition, to avoid potential adverse effects from high dose l-citrulline monotherapy, we evaluated whether the effect on NO signaling is greater using co-treatment with l-citrulline and another agent that improves NO signaling, folic acid, than either alone. Arginase activity was measured in human PAECs cultured under hypoxic conditions in the presence of l-citrulline (0-1 mM). NO production and endothelial nitric oxide synthase (eNOS) coupling, as assessed by eNOS dimer-to-monomer ratios, were measured in PAECs treated with l-citrulline and/or folic acid (0.2 μM). Arginase activity increased in hypoxic PAECs treated with 1 mM but not with either 0.05 or 0.1 mM l-citrulline. Co-treatment with folic acid and 0.1 mM l-citrulline increased NO production and eNOS dimer-to-monomer ratios more than treatment with either alone. The potential to increase arginase activity suggests that there might be plasma l-citrulline concentrations that should not be exceeded when using l-citrulline to treat PH. Rather than progressively increasing the dose of l-citrulline as a monotherapy, co-therapy with l-citrulline and folic acid merits consideration, due to the possibility of achieving efficacy at lower doses and minimizing side effects.

Traditional Herbal Medicine Discovery for the Treatment and Prevention of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterized by pulmonary artery remodeling that may subsequently culminate in right heart failure and premature death. Although there are currently both non-pharmacological (lung transplantation, etc.) and pharmacological (Sildenafil, Bosentan, and new oral drugs on trial) therapies available, PAH remains a serious and fatal pulmonary disease. As a unique medical treatment, traditional herbal medicine (THM) treatment has gradually exerted its advantages in treating PAH worldwide through a multi-level and multi-target approach. Additionally, the potential mechanisms of THM were deciphered, including suppression of proliferation and apoptosis of pulmonary artery smooth muscle cells, controlling the processes of inflammation and oxidative stress, and regulating vasoconstriction and ion channels. In this review, the effects and mechanisms of the frequently studied compound THM, single herbal preparations, and multiple active components from THM are comprehensively summarized, as well as their related mechanisms on several classical preclinical PAH models. It is worth mentioning that sodium tanshinone IIA sulfonate sodium and tetramethylpyrazine are under clinical trials and are considered the most promoting medicines for PAH treatment. Last, reverse pharmacology, a strategy to discover THM or THM-derived components, has also been proposed here for PAH. This review discusses the current state of THM, their working mechanisms against PAH, and prospects of reverse pharmacology, which are expected to facilitate the natural anti-PAH medicine discovery and development and its bench-to-bedside transformation.

Neuroprotective properties of ethanolic extract of Citrus unshiu Markovich peel through NADPH oxidase 2 inhibition in chemotherapy-induced neuropathic pain animal model

The present study aimed to determine the antioxidant effect of Citrus unshiu Markovich (CUM) extract in neuronal cell lines under oxidative stress and to investigate the effect of chemotherapy-induced peripheral neuropathy (CIPN) on the nociceptive response in a preclinical mice model. We tested the inhibition of H₂ O₂ in Neuro2A cells treated with CUM. Experimental animals were treated with oxaliplatin to induce CINP, and then administered oral CUM for 4 weeks in order to observe the effect of CUM. Animals were evaluated weekly for thermal hyperalgesia and digital motor nerve conduction velocity (NCV). Lumbar dorsal root ganglia (DRG) isolated from each animal were evaluated through immunochemical and western blot analysis for nerve damage, inflammatory response, and expression of redox signaling factors. The main mechanisms were determined to be decreased inducible nitric oxide synthase (iNOS) production due to the inhibition of NADPH oxidase 2 (NOX2). To determine the functional role of NOX2 in CINP, we administrated CUM into NOX2-deficient mice with neuropathic pain. Therefore, we suggest that CUM controls the expression levels of inflammatory factors in CINP via NOX2 inactivation. This study demonstrated that a complementary medicine such as CUM might be a potential novel therapeutic agent for the treatment of CINP.

Folic acid, either solely or combined with L-citrulline, improves NO signaling and ameliorates chronic hypoxia-induced pulmonary hypertension in newborn pigs

Concomitant with developing pulmonary hypertension (PH), newborn piglets exposed to chronic hypoxia develop pulmonary vascular NO signaling impairments. PH is reduced and NO signaling is improved in chronically hypoxic piglets treated with the NO-arginine precursor, L-citrulline. Folic acid positively impacts NO signaling. We evaluated whether the effect on NO signaling and PH is greater using co-treatment with folic acid and L-citrulline than either alone. From day 3 to day 10 of hypoxia, piglets were treated solely with folic acid, solely with L-citrulline, or co-treated with both. Catheters were placed to measure in vivo hemodynamics. NO production was measured in vitro in dissected pulmonary arteries. Compared to normoxic piglets, pulmonary vascular resistance (PVR) was elevated and NO production was reduced in untreated hypoxic piglets. Regardless of treatment strategy, PVR was less in all three treated groups of hypoxic piglets when compared to the untreated hypoxic group. In addition, for all three groups of treated hypoxic piglets, NO production was higher than the untreated group. Improvements in PVR and NO production did not differ between piglets co-treated with folic acid and L-citrulline and those treated solely with either. Thus, the impact on NO production and PVR was not augmented by combining folic acid and L-citrulline treatments. Nonetheless, treatment with folic acid, either singly or when combined with L-citrulline, increases NO production and inhibits PH in chronically hypoxic newborn piglets. Folic acid merits consideration as a therapy for PH in human infants with chronic heart and lung conditions that are associated with chronic hypoxia.

Nanonaringenin and Vitamin E Ameliorate Some Behavioral, Biochemical, and Brain Tissue Alterations Induced by Nicotine in Rats

Nicotine is the major alkaloid present in cigarettes that induces various biochemical and behavioral changes. Nanonaringenin (NNG) and vitamin E are antioxidants that are reported to mitigate serious impairments caused by some toxins and oxidants. Thus, we aimed to investigate the efficacy of NNG, vitamin E, and their combinations to ameliorate behavioral, biochemical, and histological alterations induced by nicotine in rats. Adult male albino rats were randomly grouped into six equal groups (10 rats/group): control, N (nicotine 1 mg/kg b.w./day S/C from 15^th to 45^th day, 5 days a week), NNG (25 mg/kg b.w./day orally for 45 days), N + NNG, N + E (nicotine + vitamin E 200 mg/kg b.w./day orally), and N + NNG + E (nicotine + NNG + vitamin E at the aforementioned doses). Behavioral tests were conducted on day 15 and 30 postnicotine injection, while memory tests, brain neurotransmitters, antioxidants, and histopathological examination were examined at day 30 only. As a result, nicotine impaired rats' activity (hypoactivity and hyperactivity) and memory, induced anxiolytic and anxiogenic effects on rats, and altered neurotransmitters (acetylcholinesterase, serotonin, and dopamine), and redox markers (MDA, H₂O₂, GSH, and catalase) levels in brain homogenates. Thickening and congestion of the meninges and degeneration of the cerebral neurons and glia cells were observed. Cosupplementation with NNG, vitamin E, and their combination with nicotine was beneficial in the alleviation of activity impairments and improved short memory and cognition defects and exploratory behaviors. Our results indicate the antioxidant potential of NNG and vitamin E by modulating redox markers and neurotransmitters in the brain. Thus, data suggest that the prophylactic use of NNG, vitamin E, and/or their combination for (45 days) may have a successful amelioration of the disrupted behavior and cognition and biochemical and histopathological alterations induced by nicotine.

Naringin Ameliorates Monocrotaline-Induced Pulmonary Arterial Hypertension Through Endothelial-To-Mesenchymal Transition Inhibition

Pulmonary arterial hypertension (PAH) caused by enhanced arterial pressure increases vessel resistance in the lung. Endothelial-to-mesenchymal transition (EndMT) plays key roles in the vascular remodeling in PAH. Naringin, a protective gaseous mediator is commonly extracted from tomatoes and citrus fruits (such as grapefruits), and demonstrates anti-inflammation, anti-oxidant, anti-proliferation, and anti-tumor effects. Meanwhile, the association of Naringin and the process of EndMT is still unclear. In this study, monocrotaline (MCT) administration (60 mg/kg) was delivered for the induction of PAH in rats. Following this, Naringin (concentrations: 25, 50, and 100 mg/kg/day) was used for treatments. Human Umbilical Vein Endothelial Cells (HUVECs) were stimulated with Naringin and transforming growth factor β1 (TGFβ1, 10 ng/ml). As the result, Naringin was demonstrated to inhibit EndMT and alleviate PAH progression. In particular, in HUVECs, Naringin significantly suppressed the mesenchymal marker expression induced by TGFβ1 treatment, enhanced the endothelial marker expression, and inhibited the activation of ERK and NF-κB signaling pathways. To conclude, this study provided novel evidence suggesting the beneficial effects of Naringin in PAH through the inhibition of the ERK and NF-κB signaling pathways and the EndMT progression in pulmonary arteries.

Pulmonary arterial hypertension and flavonoids: A role in treatment

Pulmonary arterial hypertension (PAH) is a high mortality progressive pulmonary vascular disease that can lead to right heart failure. The use of clinical drugs for the treatment of PAH is limited to a great extent because of its single target and high price. Flavonoids are widely distributed in nature, and have been found in fruits, vegetables, and traditional Chinese medicine. They have diverse biological activities and various pharmacological effects such as antitumor, antioxidation, and anti-inflammatory. This review summarizes the progress in pharmacodynamics and mechanism of flavonoids in the treatment of PAH in recent years, in order to provide some theoretical references for relevant researchers.

Evaluation of Naringenin as a Promising Treatment Option for COPD Based on Literature Review and Network Pharmacology

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease characterized by incompletely reversible airflow limitation and seriously threatens the health of humans due to its high morbidity and mortality. Naringenin, as a natural flavanone, has shown various potential pharmacological activities against multiple pathological stages of COPD, but available studies are scattered and unsystematic. Thus, we combined literature review with network pharmacology analysis to evaluate the potential therapeutic effects of naringenin on COPD and predict its underlying mechanisms, expecting to provide a promising tactic for clinical treatment of COPD.

Nutraceuticals in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterized by the loss and obstructive remodeling of the pulmonary arterial wall, causing a rise in pulmonary arterial pressure and pulmonary vascular resistance, which is responsible for right heart failure, functional decline, and death. Although many drugs are available for the treatment of this condition, it continues to be life-threatening, and its long-term treatment is expensive. On the other hand, many natural compounds present in food have beneficial effects on several cardiovascular conditions. Several studies have explored many of the potential beneficial effects of natural plant products on PAH. However, the mechanisms by which natural products, such as nutraceuticals, exert protective and therapeutic effects on PAH are not fully understood. In this review, we analyze the current knowledge on nutraceuticals and their potential use in the protection and treatment of PAH, as well as whether nutraceuticals could enhance the effects of drugs used in PAH through similar mechanisms.

Antihypertensive power of Naringenin is mediated via attenuation of mineralocorticoid receptor (MCR)/ angiotensin converting enzyme (ACE)/ kidney injury molecule (Kim-1) signaling pathway

Hypertension is a condition with chronic elevation of blood pressure and a common preventable risk factor for cardiovascular disease with attendant global morbidity and mortality. The present study investigated the novel antihypertensive and neuroprotective effect of Naringenin on L-N^G-Nitro arginine methyl ester (L-NAME) induced hypertension together with possible molecular mechanism of action. Rats were divided into four groups. Rats in Group A were normotensive. The hypertensive group (Group B) received 40 mg/kg) of L-NAME alone while Groups C and D were concurrently administered Naringenin (50 mg/kg) or Lisinopril (10 mg/Kg) together with L-NAME orally for 3 weeks. Blood pressure parameters, markers of oxidative stress and renal damage were measured. The immunohistochemistry of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme were also determined. Results indicated significant increases in malondialdehyde, advanced oxidation protein products, protein carbonyl contents and decrease in serum nitric oxide bioavailability in hypertensive rats. Furthermore, there were significant increases in serum myeloperoxidase, urinary creatinine, albumin and blood urea nitrogen in hypertensive rats in comparison to hypertensive rats treated with either Naringenin or Lisinopril. Immunohistochemistry reveal significant expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme in hypertensive rats. However, co-treatment with either Naringenin or Lisinopril mitigated both renal and neuronal oxidative stress, normalized blood pressure and lowered the expressions of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme. Collectively, Naringenin offered a novel antihypertensive and neuroprotective effect through down regulation of kidney injury molecule 1, mineralocorticoid receptor and angiotensin converting enzyme.

Naringenin ameliorates diabetic neuropathic pain by modulation of oxidative-nitrosative stress, cytokines and MMP-9 levels

Diabetes mellitus is a serious debilitating epidemic affecting all social strata, imposing huge health, social and economic burdens.

p-Coumaric acid as a prophylactic measure against normobaric hypoxia induced pulmonary edema in mice

AIMS

Previous studies indicate that the anti-hypoxia effects of Tibetan Turnip (Brassica rapa ssp. rapa) were closely related to its characteristic components being p-coumaric acid (CA) and p-coumaric acid‑β‑d‑glucopyranoside (CAG). Since CAG would be converted to CA in vivo, this study aims to further examine the efficacy and mechanism of CA against pulmonary edema induced by normobaric hypoxia.

MAIN METHODS

Male ICR mice were assigned to the normoxia group and several hypoxia groups, given sterile water, CA or dexamethasone orally, once daily for four consecutive days. One hour after the final gavage, mice in the above hypoxia groups were put into the normobaric hypoxia chamber (9.5% O₂) for 24 h while mice in normoxia group remained outside the chamber. After hypoxia exposure, lung water content (LWC), pulmonary vascular permeability, the protein content of bronchoalveolar lavage fluid (BALF), plasma total nitrate/nitrite (NO_x) and endothelin-1 (ET-1) content, histological and ultra-microstructure analyses were performed. Expression of occludin was assayed by immunohistochemistry.

KEY FINDINGS

In a hypoxic environment of 9.5% O₂, mice treated with 100 mg/kg body wt CA had significantly lower LWC and BALF protein content than mice in the hypoxia vehicle group. Meanwhile, mice in CA group showed intact lung blood-gas-barrier, increased levels of plasma total NO, decreased levels of plasma ET-1 and upregulation of occludin expression.

SIGNIFICANCE

CA exerts preventive effects against normobaric hypoxic pulmonary edema in mice, its mechanisms involved improving the integrity of the lung barrier, inhibiting oxidative stress and inflammation.

Naringenin induces mitochondria-mediated apoptosis and endoplasmic reticulum stress by regulating MAPK and AKT signal transduction pathways in endometriosis cells

STUDY QUESTION

Does the flavonoid naringenin inhibit proliferation of human endometriosis cells?

SUMMARY ANSWER

Naringenin suppresses proliferation and increases apoptosis via depolarization of mitochondrial membrane potential and generation of reactive oxygen species (ROS) in human endometriosis cells.

WHAT IS KNOWN ALREADY

For management of endometriosis, hormonal therapy is commonly used to decrease production of estrogens by the ovaries, but that has limitations including undesirable side effects with long-term therapies. To overcome these limitations, it is important to discover novel compounds which have no adverse effects, but inhibit expression of target molecules involved in the pathogenesis of endometriosis.

STUDY DESIGN SIZE, DURATION

Well-established endometriosis cell lines (VK2/E6E7 and End1/E6E7) were purchased from the American Type Culture Collection. Effects of naringenin on VK2/E6E7 and End1/E6E7 cells were assessed in diverse assays in a dose- and time-dependent manner.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Effects of naringenin on viability, apoptosis (Annexin V expression, propidium iodide staining, TUNEL and invasion assays), mitochondria-mediated apoptosis, production of ROS and endoplasmic reticulum (ER) stress proteins of VK2/E6E7 and End1/E6E7 cells were determined. Signal transduction pathways in VK2/E6E7 and End1/E6E7 cells in response to naringenin were determined by western blot analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

In the present study, we demonstrated that naringenin suppressed proliferation and increased apoptosis through depolarization of mitochondrial membrane potential and inducing pro-apoptotic proteins, Bax and Bak, in both endometriosis cell lines. In addition, naringenin increased ROS, ER stress, through activation of eIF2α and IRE1α, GADD153 and GRP78 proteins in a dose-dependent manner. Furthermore, the induction of apoptosis by naringenin involved activation of MAPK and inactivation of PI3K pathways in VK2/E6E7 and End1/E6E7 cells.

LIMITATIONS REASONS FOR CAUTION

Lack of in vivo animal studies is a major limitation of this research. Effectiveness of naringenin to induce apoptosis of human endometriosis cells requires further investigation.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that naringenin is a promising therapeutic compound for treatment of endometriosis in women.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (No. HI15C0810 awarded to G.S. and HI17C0929 awarded to W.L.). The authors declare that there are no conflicts of interest.

Combined oral administration of L-arginine and tetrahydrobiopterin in a rat model of pulmonary arterial hypertension

Alterations in the nitric oxide (NO) pathway play a major role in pulmonary arterial hypertension (PAH). L-arginine (LA) and tetrahydrobiopterin (BH₄) are main substrates in the production of NO, which mediates pulmonary vasodilation. Administration of either LA or BH₄ decrease pulmonary artery pressure (PAP). A combined administration of both may have synergistic effects in the therapy of PAH. In a telemetrically monitored model of unilateral pneumonectomy and monocrotaline-induced PAH, male Sprague-Dawley rats received either LA (300 mg/kg; n = 15), BH₄ (20 mg/kg; n = 15), the combination of LA and BH₄ (300 mg/kg, 20 mg/kg; n = 15), or vehicle (control group; n = 10) from day 28 after monocrotaline induction. Therapy was orally administered once daily over consecutive 14 days. LA, BH₄, or both equally lowered PAP, increased pulmonary vascular elasticity, restored spontaneous locomotoric activity, prevented body weight loss and palliated small vessel disease of severely pulmonary hypertensive rats. BH₄ substitution lowered asymmetric dimethylarginine levels sustainably at 60 min after administration and downregulated endothelial NO synthase mRNA expression. No significant survival, macro- and histomorphologic or hemodynamic differences were found between therapy groups at the end of the study period. Administration of LA and BH₄ both mediated a decrease of mean PAP, attenuated right ventricular hypertrophy and small vessel disease in monocrotaline-induced pulmonary hypertensive rats, though a combined administration of both substances did not reveal any synergistic therapy effects in our animal model.

Necroptosis inhibitors as therapeutic targets in inflammation mediated disorders - a review of the current literature and patents

INTRODUCTION

Recent studies have shown substantial interplay between the apoptosis and necroptosis pathways. Necroptosis, a form of programmed cell death, has been found to stimulate the immune system contributing to the pathophysiology of several inflammation-mediated disorders. Determining the contribution of necroptotic signaling pathways to inflammation may lead to the development of selective and specific molecular target implicated necroptosis inhibitors. Areas covered: This review summarizes the recently published and patented necroptosis inhibitors as therapeutic targets in inflammation-mediated disorders. The role of several necroptosis inhibitors, focusing on specific signaling molecules, was discussed with particular attention to inflammation-mediated disorders. Data was obtained from Espacenet®, WIPO®, USPTO® patent websites, and other relevant sources (2006-2016). Expert opinion: Necroptosis inhibitors hold promise for treatment of inflammation-mediated clinical conditions in which necroptotic cell death plays a major role. Although necroptosis inhibitors reviewed in this survey showed inhibitory effects against several inflammation-mediated disorders, only a few have passed to the stage of clinical testing and need extensive research for therapeutic practice. Revisiting the existing drugs and developing novel necroptosis inhibiting agents as well as understanding their mechanism are essential. A detailed study of necroptosis function in animal models of inflammation may provide us an alternative strategy for the development of drug-like necroptosis inhibitors.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model

AIM

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms.

METHODS

PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting.

RESULTS

Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs.

CONCLUSION

SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

Hydroxysafflor yellow A improves established monocrotaline-induced pulmonary arterial hypertension in rats

Objective

To evaluate the beneficial effects of hydroxysafflor yellow A (HSYA) on monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) in rats, and to investigate the main pathophysiological mechanism of HSYA in preventing development of MCT-induced PAH.

Methods

Four groups (control, control with HSYA treatment, MCT-exposed, and MCT-exposed with HSYA treatment) were evaluated at day 28 following MCT exposure. Haemodynamic measurements, right ventricular hypertrophy, morphometry, inflammatory cytokines and oxidant expression were assessed.

Results

HSYA significantly reduced haemodynamic changes, right ventricular hypertrophy and morphometric changes induced by exposure to MCT. HYSA also suppressed MCT-induced inflammation and oxidative stress in rat pulmonary tissue.

Conclusions

Experimental MCT-induced PAH may be reduced by HSYA treatment, and the mechanism may involve suppression of inflammation and oxidative stress.

Naringenin protects cardiac hypercholesterolemia-induced oxidative stress and subsequent necroptosis in rats

BACKGROUND

In earlier studies, the supplementation of the natural compound Naringenin (NGEN), improved the liver oxidative and inflammatory status, which indicates its direct effect via inhibition of the nuclear factor κB pathway on high cholesterol-induced hepatic damages. In this regard, the present study highlights the mechanisms associated with the protective efficacy of NGEN in the heart tissue of hypercholesterolemic diet rats.

RESULTS

The animals exposed to a high cholesterol diet (HCD) for 90 days exhibited a significant increase in the levels of serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities, nitric oxide (NO) levels, protein and lipid oxidative markers and cardiac lipids profile. Moreover, hypercholesterolemia decreased the levels of enzymatic and non enzymatic antioxidants associated with mitochondrial dysfunctions as proved by the decrease in the mitochondrial complexes in comparison to controls. Importantly, cholesterol-feeding significantly increased myocardial reactive oxygen species (ROS) and nuclear DNA damage and led to the activation of gene expression of the tumor necrosis factor-α (TNF-α) and receptor-interacting protein kinase 3 (RIP3) mRNA that contributed to the elucidation of cholesterol-induced necroptosis, a recently described type of programmed necrosis, in the cardiac tissue.

CONCLUSIONS

Our results show that the co-administration of NGEN (50 mg/kg/bw) in HCD rats improved all the altered parameters and provided insight into a possible molecular mechanism underlying NGEN suppression of necroptosis pathway in the heart.

Role of the KATP channel in the protective effect of nicorandil on cyclophosphamide-induced lung and testicular toxicity in rats

This study is the first to investigate the role of the KATP channel in the possible protection mediated by nicorandil against cyclophosphamide-induced lung and testicular toxicity in rats. Animals received cyclophosphamide (150 mg/kg/day, i.p.) for 2 consecutive days and then were untreated for the following 5 days. Nicorandil (3 mg/kg/day, p.o.) was administered starting from the day of cyclophosphamide injection with or without glibenclamide (5 mg/kg/day, p.o.). Nicorandil administration significantly reduced the cyclophosphamide-induced deterioration of testicular function, as demonstrated by increases in the level of serum testosterone and the activities of the testicular 3β- hydroxysteroid, 17β-hydroxysteroid and sorbitol dehydrogenases. Furthermore, nicorandil significantly alleviated oxidative stress (as determined by lipid peroxides and reduced glutathione levels and total antioxidant capacity), as well as inflammatory markers (tumour necrosis factor-α and interleukin-1β), in bronchoalveolar lavage fluid and testicular tissue. Finally, the therapy decreased the levels of fibrogenic markers (transforming growth factor-β and hydroxyproline) and ameliorated the histological alterations (as assessed by lung fibrosis grading and testicular Johnsen scores). The co-administration of glibenclamide (a KATP channel blocker) blocked the protective effects of nicorandil. In conclusion, KATP channel activation plays an important role in the protective effect of nicorandil against cyclophosphamide-induced lung and testicular toxicity.

Naringin ameliorates cognitive deficits via oxidative stress, proinflammatory factors and the PPARγ signaling pathway in a type 2 diabetic rat model

Naringenin is a flavonoid polyphenolic compound, which facilitates the removal of free radicals, oxidative stress and inflammation. The present study aimed to obtain a better understanding of the effects of curcumin on the regulation of diabetes‑associated cognitive decline, and its underlying mechanisms. An experimental diabetes mellitus (DM) rat model was induced by streptozoticin (50 mg/kg). Following treatment with naringin (100 and 200 mg/kg) for 16 weeks, the body weight and blood glucose levels of the DM rats were measured. A morris water maze test was used to analyze the effects of naringin on the cognitive deficit of the DM rats. The levels of oxidative stress, proinflammatory factors, caspase‑3 and caspase‑9, and the protein expression of peroxisome proliferator‑activated receptor γ (PPARγ) were quantified in the DM rats using a commercially‑available kit and western blot assay, respectively. In addition, a GW9662 PPARγ inhibitor (0.3 mg/kg) was administered to the DM rats to determine whether PPARγ affected the effects of naringin on the cognitive deficit of the DM rats. The results demonstrated that naringin increased the body weight, blood glucose levels, and cognitive deficits of the DM rats. The levels of oxidative stress and proinflammatory factors in the naringin‑treated rats were significantly lower, compared with those of the DM rats. In addition, naringin activated the protein expression of PPARγ, and administration of the PPARγ inhibitor decreased the protein expression of PPARγ, and attenuated the effects of naringin on cognitive deficit. The results also demonstrated that naringin decreased the expression levels of caspase‑3 and caspase‑9 in the DM rats. These results suggested that naringin ameliorated cognitive deficits via oxidative stress, proinflammatory factors and the PPARγ signaling pathway in the type 2 diabetic rat model. Furthermore, oxidative stress, proinflammatory factors and PPARγ signaling may be involved in mediating these effects.