Hexahydrocurcumin ameliorates hypertensive and vascular remodeling in L-NAME-induced rats.

Hexahydrocurcumin (HHC), a major metabolite of curcumin, possesses several biological activities such as antioxidant, anti-inflammation, and cardioprotective properties. This study aimed to investigate the effect of HHC on high blood pressure, vascular dysfunction, and remodeling induced by N-nitro L-arginine methyl ester (L-NAME) in rats. Male Wistar rats (200-250 g) received L-NAME (40 mg/kg) via drinking water for seven weeks. HHC at doses of 20, 40 or 80 mg/kg or enalapril 10 mg/kg was orally administered for the last three weeks. Blood pressure was measured weekly. Rats induced with L-NAME showed the development of hypertension, vascular dysfunction, and remodeling as demonstrated by an increase in wall thickness, cross-sectional area, and collagen deposition in the aorta. The overexpression of nuclear factor kappa B (NF-кB), vascular cell adhesion molecule 1 (VCAM1), intercellular adhesion molecule 1 (ICAM1), tumor necrosis factor-alpha (TNF-α), phosphorylated-extracellular-regulated kinase 1/2 (p-ERK1/2), phosphorylated-c-Jun N-terminal kinases (p-JNK), phosphorylated-mitogen activated protein kinase p38 (p-p38), transforming growth factor-beta 1 (TGF-ß1), matrix metalloproteinase-9 (MMP-9) and collagen type 1 was observed in L-NAME-induced hypertensive rats. Increased oxidative stress markers, decreased plasma nitric oxide (NO) levels and the down-regulation of endothelial nitric oxide synthase (eNOS) expression in aortic tissues were also found in L-NAME-induced rats. Moreover, L-NAME-induced rats showed enhanced synthetic protein expression in aortic tissues. These alterations were suppressed in hypertensive rats treated with HHC or enalapril. The present study shows that HHC exhibited antihypertensive effects by improving vascular function and ameliorated the development of vascular remodeling. The responsible mechanism may involve antioxidant and anti-inflammation potential.

L-NAME Administration Enhances Diabetic Kidney Disease Development in an STZ/NAD Rat Model.

One of the most important risk factors for developing chronic kidney disease (CKD) is diabetes. To assess the safety and efficacy of potential drug candidates, reliable animal models that mimic human diseases are crucial. However, a suitable model of diabetic kidney disease (DKD) is currently not available. The aim of this study is to develop a rat model of DKD by combining streptozotocin and nicotinamide (STZ/NAD) with oral N(ω)-Nitro-L-Arginine Methyl Ester (L-NAME) administration. Diabetes was induced in male Wistar rats by intravenous injection of 65 mg/kg STZ, 15 min after intraperitoneal injection of 230 mg/kg NAD. Rats were assigned to different groups receiving L-NAME (100 mg/kg/day) (STZ/NAD/L-NAME) or vehicle (STZ/NAD) for a period of 9 or 12 weeks by daily oral gavage. All rats developed hyperglycemia. Hyperfiltration was observed at the start of the study, whereas increased serum creatinine, albumin-to-creatinine ratio, and evolving hypofiltration were detected at the end of the study. Daily L-NAME administration caused a rapid rise in blood pressure. Histopathological evaluation revealed heterogeneous renal injury patterns, which were most severe in the STZ/NAD/L-NAME rats. L-NAME-induced NO-deficiency in STZ/NAD-induced diabetic rats leads to multiple characteristic features of human DKD and may represent a novel rat model of DKD.

Vasorelaxant-Mediated Antihypertensive Effect of the Leaf Aqueous Extract from Stephania abyssinica (Dillon & A. Rich) Walp (Menispermaceae) in Rat.

Stephania abyssinica is a medicinal plant used in Cameroon alternative medicine to treat arterial hypertension (AHT). Previous in vitro studies demonstrated the endothelium nitric oxide-independent vasorelaxant property of the aqueous extract from Stephania abyssinica (AESA). But its effect on AHT is unknown. The present study was undertaken to explore other vasorelaxant mechanisms and to determine the antihypertensive effects of AESA in male Wistar rats. Phytochemical analysis of AESA was carried out using the liquid chromatography-mass spectrometry (LC-MS) method. The vasorelaxant effects of AESA (1-1000 µg/mL) were studied on rat isolated thoracic aorta rings, in the absence or presence of indomethacin (10 µM) or methylene blue (10 µM). The inhibitory effect of AESA on phenylephrine (PE, 10 µM) or KCl- (60 mM) induced contraction as well as the intracellular calcium release was also evaluated. The in vivo antihypertensive activity of AESA (43, 86, or 172 mg/kg/day) or captopril (20 mg/kg/day) administered orally was assessed in L-NAME- (40 mg/kg/day) treated rats. Blood pressure and heart rate (HR) were measured at the end of each week while serum or urinary nitric oxide (NO), creatinine, and glomerular filtration rate (GFR) were determined at the end of the 6 weeks of treatment, as well as histological analysis of the heart and the kidney. The LC-MS profiling of AESA identified 9 compounds including 7 alkaloids. AESA produced a concentration-dependent relaxation on contraction induced either by PE and KCl, which was significantly reduced in endothelium-denuded vessels, as well as in vessels pretreated with indomethacin and methylene blue. Moreover, AESA inhibited the intracellular Ca2+ release-induced contraction. In vivo, AESA reduced the AHT, heart rate (HR), and ventricular hypertrophy and increased serum NO, urine creatinine, and GFR. AESA also ameliorated heart and kidney lesions as compared to the L-NAME group. These findings supported the use of AESA as a potential antihypertensive drug.

Short-lived sensitization of cardiovascular outcomes of postpartum endotoxemia in preeclamptic rats: Role of medullary solitary tract neuroinflammation.

Preeclampsia (PE) is a pregnancy-related disorder with serious maternal complications. Considering the increased importance of postpartum infection in maternal morbidity and mortality, we investigated whether preeclamptic maternal programming alters cardiovascular consequences of endotoxemia in rats and the role of cardiac and brainstem neuroinflammation in this interaction. Preeclampsia was induced by oral administration of L-NAME (50 mg/kg/day) for 7 days starting from day 14 of conception. Changes in blood pressure, heart rate, and cardiac autonomic function caused by lipopolysaccharide (LPS, 5 mg/kg i.v.) were assessed in mothers at 3 weeks (weaning time) and 9 weeks postnatally. Compared with respective non-PE counterparts, LPS treatment of weaning PE mothers caused significantly greater (i) falls in blood pressure, (ii) rises in heart rate and left ventricular contractility (dP/dtmax), (iii) reductions in time and frequency domain indices of heart rate variability and shifts in cardiac sympathovagal balance (low-frequency/high-frequency ratio, LF/HF) towards parasympathetic dominance, and (iv) attenuation of reflex bradycardic responses measured by the vasoactive method. The intensified LPS effects in weaning PE rats subsided after 9 weeks of delivery. Immunohistochemical studies showed increased protein expression of nuclear factor kappa B (NF-κB) in brainstem neuronal pools of the nucleus of the solitary tract (NTS), but not rostral ventrolateral medulla (RVLM), in endotoxic PE weaning rats compared with non-PE rats. Cardiac NF-κB expression was increased by LPS but this was similarly noted in PE and non-PE rats. Together, preeclamptic maternal programming elicits short-term exacerbation of endotoxic cardiovascular and autonomic derangements due possibly to exaggerated NTS neuroinflammatory insult.

Protective role of the mitochondrial fusion protein OPA1 in hypertension.

Hypertension is associated with excessive reactive oxygen species (ROS) production in vascular cells. Mitochondria undergo fusion and fission, a process playing a role in mitochondrial function. OPA1 is essential for mitochondrial fusion. Loss of OPA1 is associated with ROS production and cell dysfunction. We hypothesized that mitochondria fusion could reduce oxidative stress that defect in fusion would exacerbate hypertension. Using (a) Opa1 haploinsufficiency in isolated resistance arteries from Opa1+/- mice, (b) primary vascular cells from Opa1+/- mice, and (c) RNA interference experiments with siRNA against Opa1 in vascular cells, we investigated the role of mitochondria fusion in hypertension. In hypertension, Opa1 haploinsufficiency induced altered mitochondrial cristae structure both in vascular smooth muscle and endothelial cells but did not modify protein level of long and short forms of OPA1. In addition, we demonstrated an increase of mitochondrial ROS production, associated with a decrease of superoxide dismutase 1 protein expression. We also observed an increase of apoptosis in vascular cells and a decreased VSMCs proliferation. Blood pressure, vascular contractility, as well as endothelium-dependent and -independent relaxation were similar in Opa1+/- , WT, L-NAME-treated Opa1+/- and WT mice. Nevertheless, chronic NO-synthase inhibition with L-NAME induced a greater hypertension in Opa1+/- than in WT mice without compensatory arterial wall hypertrophy. This was associated with a stronger reduction in endothelium-dependent relaxation due to excessive ROS production. Our results highlight the protective role of mitochondria fusion in the vasculature during hypertension by limiting mitochondria ROS production.

NADPH oxidase-induced oxidative stress in the eyes of hypertensive rats.

Purpose: Increased reactive oxygen species (ROS) released by NADPH oxidase and inflammation are associated with arterial hypertension and eye diseases associated with high blood pressure, including glaucoma, retinopathies (e.g., age-related macular degeneration), and choroidopathies affecting ocular function; however, the mechanisms underlying these adverse outcomes remain undefined. The present study was designed to highlight the importance of oxidative stress in severe hypertension-related eye damage. Methods: Male Wistar rats (n = 7, unless otherwise specified for specific experiments) were administered an oral dose of 30 mg of Nω-nitro-L-arginine methyl ester (L-NAME) per kilogram of bodyweight and day for 3 weeks; chronic administration with L-NAME is a validated experimental approach resulting in severe hypertension secondary to nitric oxide (NO) depletion and subsequent vasoconstriction in the systemic circulation. Upon treatment completion, histomorphometric studies, NADPH oxidase activity, and ROS production were measured in eyecup homogenates and paraffin-embedded sections from control and L-NAME-treated animals. In addition, immunohistofluorescence, western blotting, and real-time PCR (RT-qPCR) analyses were performed in the eye and the retina to evaluate the expression of i) NADPH oxidase main isoforms (NOX1, NOX2, and NOX4) and subunits (p22phox and p47phox); ii) glial fibrillary acidic protein (GFAP), as a marker of microglial activation in the retina; iii) antioxidant enzymes; and iv) endothelial constitutive (eNOS) and inflammation inducible (iNOS) nitric oxide synthase isoforms, and nitrotyrosine as a versatile biomarker of oxidative stress. Results: Increased activity of NADPH oxidase and superoxide anion production, accompanied by transcriptional upregulation of this enzyme isoforms, was found in the retina and choroid of the hypertensive rats in comparison with the untreated controls. Histomorphometric analyses revealed a significant reduction in the thickness of the ganglion cell layer and the outer retinal layers in the hypertensive animals, which also showed a positive strong signal of GFAP in the retinal outer segment and plexiform layers. In addition, L-NAME-treated animals presented with upregulation of nitric oxide synthase (including inducible and endothelial isoforms) and abnormally elevated nitrotyrosine levels. Experiments on protein and mRNA expression of antioxidant enzymes revealed depletion of superoxide dismutase and glutathione peroxidase in the eyes of the hypertensive animals; however, glutathione reductase was significantly higher than in the normotensive controls. Conclusions: The present study demonstrated structural changes in the retinas of the L-NAME-treated hypertensive animals and strengthens the importance of NADPH oxidase as a major ROS-generating enzyme system in the oxidative and inflammatory processes surrounding hypertensive eye diseases. These observations might contribute to unveiling pathogenic mechanisms responsible for developing ocular disturbances in the context of severe hypertension.

Inhibition of L-NAME-induced hypertension by combined treatment with apocynin and catalase: the role of Nox 4 expression.

Reactive oxygen species (ROS) such as superoxide (O2-) generated by NAD(P)H oxidases have emerged as important molecules in blood pressure regulation. This study investigated the effect of apocynin and catalase on blood pressure and renal haemodynamic and excretory function in an L-NAME induced hypertension model. Forty Male Wistar-Kyoto (WKY) rats (n=8 per group) were treated with either: vehicle (WKY-C); L-NAME (WKY-L, 15 mg/kg/day in drinking fluid); WKY-L given apocynin to block NAD(P)H oxidase (WKY-LApo, 73 mg/kg/day in drinking water.); WKY-L given catalase to enhance ROS scavenging (WKY-LCat, 10000 U/kg/day i.p.); and WKY-L receiving apocynin plus catalase (WKY-LApoCat) daily for 14 days. L-NAME elevated systolic blood pressure (SBP), 116+/-1 to 181±4 mmHg, reduced creatinine clearance, 1.69+/-0.26 to 0.97+/-0.05 ml/min/kg and fractional sodium excretion, 0.84+/-0.09 to 0.55+/-0.09 % at day 14. Concomitantly, plasma malondialdehyde (MDA) increased six fold, while plasma total superoxide dismutase (T-SOD), plasma nitric oxide (NO) and plasma total antioxidant capacity (T-AOC) were decreased by 60-70 % and Nox 4 mRNA expression was increased 2-fold. Treatment with apocynin and catalase attenuated the increase in SBP and improved renal function, enhanced antioxidative stress capacity and reduced the magnitude of Nox4 mRNAs expression in the L-NAME treated rats. This study demonstrated that apocynin and catalase offset the development of L-NAME induced hypertension, renal dysfunction and reduced oxidative stress status, possibly contributed by a reduction in Nox4 expression during NOS inhibition. These findings would suggest that antioxidant compounds such as apocynin and catalase have potential in treating cardiovascular diseases.

Knockout of γ-Adducin Promotes NG-Nitro-L-Arginine-Methyl-Ester-Induced Hypertensive Renal Injury.

Previous studies identified a region on chromosome 1 associated with NG-nitro-L-arginine methyl ester (L-NAME) hypertension-induced renal disease in fawn-hooded hypertensive (FHH) rats. This region contains a mutant γ-adducin (Add3) gene that impairs renal blood flow (RBF) autoregulation, but its contribution to renal injury is unknown. The present study evaluated the hypothesis that knockout (KO) of Add3 impairs the renal vasoconstrictor response to the blockade of nitric oxide synthase and enhances hypertension-induced renal injury after chronic administration of L-NAME plus a high-salt diet. The acute hemodynamic effect of L-NAME and its chronic effects on hypertension and renal injury were compared in FHH 1Brown Norway (FHH 1BN) congenic rats (WT) expressing wild-type Add3 gene versus FHH 1BN Add3 KO rats. RBF was well autoregulated in WT rats but impaired in Add3 KO rats. Acute administration of L-NAME (10 mg/kg) raised mean arterial pressure (MAP) similarly in both strains, but RBF and glomerular filtration rate (GFR) fell by 38% in WT versus 15% in Add3 KO rats. MAP increased similarly in both strains after chronic administration of L-NAME and a high-salt diet; however, proteinuria and renal injury were greater in Add3 KO rats than in WT rats. Surprisingly, RBF, GFR, and glomerular capillary pressure were 41%, 82%, and 13% higher in L-NAME-treated Add3 KO rats than in WT rats. Hypertensive Add3 KO rats exhibited greater loss of podocytes and glomerular nephrin expression and increased interstitial fibrosis than in WT rats. These findings indicate that loss of ADD3 promotes L-NAME-induced renal injury by altering renal hemodynamics and enhancing the transmission of pressure to glomeruli. SIGNIFICANCE STATEMENT: A mutation in the γ-adducin (Add3) gene in fawn-hooded hypertensive rats that impairs autoregulation of renal blood flow is in a region of rat chromosome 1 homologous to a locus on human chromosome 10 associated with diabetic nephropathy. The present results indicate that loss of ADD3 enhanced NG-nitro-L-arginine methyl ester-induced hypertensive renal injury by altering the transmission of pressure to the glomerulus.

Ruta Montana Evokes Antihypertensive Activity Through an Increase of Prostaglandins Release in L-NAME-Induced Hypertensive Rats.

AIMS: The aim of the study was to experimentally investigate the antihypertensive effect of Ruta Montana. BACKGROUND: Ruta montana L. is traditionally used in Moroccan herbal medicine to treat hypertension. This study aimed to experimentally evaluate the hypotensive and vasoactive properties of this plant. OBJECTIVE: The objective of the study was to evaluate the effect of the aqueous extract of Ruta Montana on blood pressure parameters in LNAME-induced hypertensive rats and to determine the vasorelaxant activity of this aqueous extract. METHODS: The antihypertensive effect of the aqueous extract obtained from Ruta montana aerial parts (RMAPAE) (200 mg/kg) was evaluated in normal and anesthetized hypertensive rats. Blood pressure parameters (systolic blood pressure (SBP), mean blood pressure (MBP) and diastolic blood pressure (DBP)) and heart rate were measured using a tail-cuff and a computer-assisted monitoring device. The acute and chronic effect of RMAPAE was recorded for 6 hours for the acute experiment and for 7 days for the sub-chronic test. In the other set, the vasorelaxant effect of RMAPAE on the contractile response was observed in the isolated thoracic aorta. RESULTS: The results indicated that the RMAPAE extract significantly decreased SBP, MBP, DBP and heart rate in L-NAME-induced hypertensive rats. Furthermore, RMAPAE was demonstrated to induce a dose-dependent relaxation in the aorta precontracted with Epinephrine or KCl. More interestingly, this vasorelaxant activity of RMAPAE seems to be probably mediated through the prostaglandins pathway. CONCLUSION: The present study illustrates the beneficial action of Ruta montana on hypertension and supports its use as an antihypertensive agent.

Aqueous extract of oakmoss produces antihypertensive activity in L-NAME-induced hypertensive rats through sGC-cGMP pathway.

BACKGROUND: Lichens are a symbiotic association of a fungus with a green alga or cyanobacterium. They are widely used in traditional medicine as a treatment against skin disorders, diabetes and hypertension. THE AIM OF THE STUDY: The goal of this paper was to assess the possible antihypertensive and vasorelaxant capacity of the aqueous extract of a lichen species called Oakmoss or Evernia prunastri (L.). MATERIAL AND METHODS: In the present study, the aqueous extract of Oakmoss was prepared, its antihypertensive activity was examined in N(ω)-nitro-L-arginine methyl ester (L-NAME)-induced hypertensive rats, and its vasorelaxant ability was performed in rat isolated thoracic aorta. RESULTS: The results proved that Oakmoss reduced the systolic, diastolic, mean arterial blood pressure, and heart rate in hypertensive rats but not in normotensive rats. Besides, the data showed that Oakmoss exerts its antihypertensive effect through vasorelaxant ability. CONCLUSION: The present study presents the favorable action of Oakmoss as an antihypertensive agent.

Anti-lipidemic Effect of Fractions of Peristrophe bivalvis Leaf in NG-nitro-L-arginine Methyl Ester (L-NAME) Treated Rats.

PURPOSE: The reduction in nitric oxide (NO) bioavailability accelerates atherosclerosis development, augments lipolysis, elevates blood pressure and upregulate leukocyte level. This study was designed to examine the biochemical constituents of fractions of Peristrophe bivalvis (PB) leaf, their effect on blood pressure, serum lipid contents and complete blood count in NG-nitro-L-arginine methyl ester (L-NAME) hypertensive rats. METHOD: Male Wistar rats were grouped into control and hypertensive groups. The hypertensive group was pretreated with 60 mg/kg b.w of L-NAME (L-NAME60) daily for two weeks. They were then randomly sub-grouped into: Hypertensive (H), Hypertensive+n-hexane fraction (HHF), Hypertensive+dichloromethane fraction (HDF), Hypertensive+ethyl acetate fraction (HEF) and Hypertensive+aqueous fraction (HAF) groups. These were orally gavaged with L-NAME60 and L-NAME60+200 mg/kg b.w of fractions of PB respectively, daily for two weeks. RESULT: The biochemical components analysis of the fractions of PB identified numerous polar and non polar compounds like alkaloids, organic acids and esters. The results showed a significant increase in NO level in HHF and HEF groups compared to H. Total cholesterol, triglyceride, low density lipoprotein cholesterol (LDL-C) and very LDL-C were significantly decreased in HAF group compared to H. High density lipoprotein cholesterol (HDL-C) increased significantly and atherogenic indices decreased significantly in HHF, HDF and HAF groups compared to H, while reduced glutathione level increased significantly in HHF group compared to H. White blood cells count effectively decreased in HEF group compared to H. CONCLUSION: In brief, the fractions of PB leaf increased HDL-C and NO, and decrease atherogenic indices in L-NAME treated rats.

Cardiovascular Effects of Micromeria graeca (L.) Benth. ex Rchb in Normotensive and Hypertensive Rats.

AIMS: The present study was performed in order to analyze the antihypertensive activity of Micromeria graeca (L.) Benth. ex Rchb. BACKGROUND: Micromeria graeca (L.) Benth. ex Rchb is an aromatic and medicinal plant belonging to the Lamiaceae family. This herb is used to treat various pathologies such as cardiovascular disorders. Meanwhile, its pharmacological effects on the cardiovascular system have not been studied. OBJECTIVE: The present study aimed to evaluate the effect of aqueous extract of aerial parts of Micromeria graeca (AEMG) on the cardiovascular system in normotensive and hypertensive rats. METHODS: In this study, the cardiovascular effect of AEMG was evaluated using in vivo and in vitro investigations. In order to assess the acute effect of AEMG on the cardiovascular system, anesthetized L-NAME-hypertensive and normotensive rats received AEMG (100 mg/kg) orally and arterial blood pressure parameters were monitored during six hours. In the sub-chronic study, rats were orally treated for one week, followed by blood pressure assessment during one week of treatment. Blood pressure was measured using a tail-cuff and a computer-assisted monitoring device. In the second experiment, isolated rat aortic ring pre-contracted with Epinephrine (EP) or KCl was used to assess the vasorelaxant effect of AEMG. RESULTS: Oral administration of AEMG (100 mg/kg) provoked a decrease of arterial blood pressure parameters in hypertensive rats. In addition, AEMG induced a vasorelaxant effect in thoracic aortic rings pre-contracted with EP (10 µM) or KCl (80 mM). This effect was attenuated in the presence of propranolol and methylene blue. While in the presence of glibenclamide, L-NAME, nifedipine or Indomethacin, the vasorelaxant effect was not affected. CONCLUSION: This study showed that Micromeria graeca possesses a potent antihypertensive effect and relaxes the vascular smooth muscle through ß-adrenergic and cGMP pathways.

Asteriscus graveolens exhibits Antihypertensive Activity through Activation of Vascular KATP Channels Activation in Rats.

OBJECTIVE: The objective of the study was to evaluate the antihypertensive activity of Asteriscus graveolens. METHODS: L-NAME hypertensive and normotensive rats have received orally the aqueous extract of Asteriscus graveolens aerial parts (AGAPE) (100 mg/kg) during six hours for the acute experiment and during seven days for the sub-chronic treatment. Thereafter, blood pressure parameters were evaluated. Concerning the in vitro investigation, the vasorelaxant effect of AGAPE was tested in isolated thoracic aortic rings. RESULTS: AGAPE extract significantly decreased the blood pressure parameters in hypertensive rats. Moreover, the results revealed that AGAPE exhibited antihypertensive effect through its vasorelaxant properties. More interestingly, this vasorelaxant activity seems to be probably mediated through activation of K+ ATP-sensitive (KATP) channels. CONCLUSION: The study demonstrates the antihypertensive activity of aqueous Asteriscus graveolens extract in hypertensive rats through activation of vascular KATP channels. This finding supports the use of this plant for the management of hypertension in Morocco.

Pattern of sympathetic vasomotor activity in a model of hypertension induced by nitric oxide synthase blockade.

We aimed to investigate the effects of nitric oxide (NO) synthesis inhibition by NO synthase inhibitor N-nitro-L-arginine-methyl ester (L-NAME) treatment on the sympathetic vasomotor nerve activity (SNA) on two sympathetic vasomotor nerves, the renal and splanchnic. NO plasma level and systemic oxidative stress were assessed. Hypertension was induced by L-NAME (20 mg/kg per day, by gavage, for seven consecutive days) in male Wistar rats. At the end of the treatment, blood pressure, heart rate, arterial baroreflex sensitivity, renal SNA (rSNA), and splanchnic SNA (sSNA) were assessed in urethane anesthetized rats. L-NAME-treated rats presented increased blood pressure (152 ± 2 mmHg, n = 17) compared to the control group (101 ± 2 mmHg, n = 15). Both rSNA (147 ± 10, n = 15 vs. 114 ± 5 Spikes/s, n = 9) and sSNA (137 ± 13, n = 14 vs. 74 ± 13 spikes/s, n = 9) were significantly increased in the L-NAME-treated compared to the control group. A differential response on baroreflex sensitivity was found, with a significant reduction for rSNA but not for sSNA arterial baroreceptor sensitivity in L-NAME-treated rats. The adjusted regression model revealed that the reduction of systemic NO levels partially explains the variation in sSNA and blood pressure, but not rSNA. Taken together, our data show that hypertension induced by NO synthase blockade is characterized by increased SNA to the rSNA and sSNA. In addition, we found that the rats that had the greatest reduction in NO levels in plasma by L-NAME were those that developed higher blood pressure levels. The reduction in the NO level partially explains the variations in sSNA but not in rSNA.

Nꭃ-nitro-l-arginine methyl model of pre-eclampsia elicits differential IBA1 and EAAT1 expressions in brain.

Pre-eclampsia (PE) is a pregnancy syndrome associated with an increased risk of both the mother and the baby developing cardiovascular disorders later in life. It is widely accepted that women with severe PE develop a neurological impairment however studies have revealed that the mother and baby are at jeopardy for a neurological deficit later in life. The present study examined expression of Ionized calcium binding adaptor molecule 1 (IBA1) and Excitatory amino acid transporter 1 (EAAT1) as neuroinflammatory markers in an Nꭃ-nitro-l-arginine methyl (L-NAME) model of early- and late-onset (EOPE/ LOPE) PE-like syndrome in rat models. Forty-five adult nulliparous pregnant Sprague-Dawley rats were used for this experiment. They were divided into Control, EOPE and LOPE groups. Administration of L-Name was done between gestational days 8-17 for the treated groups. Animals were sacrificed at gestational day (GD) 19, post-natal day (PND) 1 and 60 and the brain excised for further analysis. Our study confirmed L-NAME induced PE-like symptoms in rat models as evidenced by significant increase in systolic blood pressure and urine protein compared with Control. There was upregulation of IBA1 expression and increased microglial activation in the brain of PE rat models assessed at gestational day 19, post-natal day 1 and 60. Also, IBA1 expression is up regulated in the pups at post-natal day 1 and 60. Contrastingly, EAAT1 expression is down-regulated in the brain of PE rat models assessed at gestational day 19, post-natal day 1 and 60, as well as offspring at post-natal day 1 and 60. These results demonstrate likely neuro-inflammation within the brain of PE mothers during pregnancy, that persist into later life, as well as possible neuro-inflammation in brains of offspring of PE mothers.

5-Lipoxagenase deficiency attenuates L-NAME-induced hypertension and vascular remodeling.

BACKGROUND: Abnormalities of the L-arginine-nitric oxide pathway induce hypertension. 5-Lipoxygenase (5-LO) is the key enzyme involved in synthesis of leukotrienes (LTs). However, whether nitricoxide synthase dysfunction induces hypertensive vascular remodeling by regulating 5-LO activity and its downstream inflammatory metabolites remains unknown. METHODS AND RESULTS: Six-week L-NAME treatment significantly induced hypertension and vascular remodeling in both wild-type (WT) and 5-LO-knockout (5-LO-KO) mice, and blood pressure in caudal and carotid arteries was lower in 5-LO-KO than WT mice with L-NAME exposure. On histology, L-NAME induced less media thickness, media-to-lumen ratio, and collagen deposition and fewer Ki-67-positive vascular smooth muscle cells (VSMCs) but more elastin expression in thoracic and mesenteric aortas of 5-LO-KO than L-NAME-treated WT mice. L-NAME significantly increased LT content, including LTB4 and cysteinyl LT (CysLTs), in plasma and neutrophil culture supernatants from WT mice. On immunohistochemistry, L-NAME promoted the colocalization of 5-LO and 5-LO-activating protein on the nuclear envelope of cultured neutrophils, which was accompanied by elevated LT content in culture supernatants. In addition, LTs significantly promoted BrdU incorporation, migration and phenotypic modulation in VSMCs. CONCLUSION: L-NAME may activate the 5-LO/LT pathway in immune cells, such as neutrophils, and promote the products of 5-LO metabolites, including LTB4 and CysLTs, which aggravate vascular remodeling in hypertension. 5-LO deficiency may protect against hypertension and vascular remodeling by reducing levels of 5-LO downstream inflammatory metabolites.

Effects of hydrogen sulphide donor, sodium hydrosulphide treatment on the erectile dysfunction in L-NAME-induced hypertensive rats.

Men with hypertension often develop erectile dysfunction (ED). The present study aimed to examine the effects of sodium hydrosulphide (NaHS), a hydrogen (H2 S) donor, treatment on ED in nitric oxide synthase (NOS) inhibitor (L-NAME)-induced hypertensive rats. Forty adult Sprague-Dawley rats were divided into four groups: control, NaHS (0.037 mg kg day-1 )-treated control, L-NAME-induced hypertension (40 mg kg day-1 ) and NaHS-treated L-NAME-induced hypertension. The ratio of intracavernosal pressure to mean arterial pressure and isometric tension of corpus cavernosum (CC) were measured. The penile expression of endothelial and neuronal NOS (eNOS and nNOS), inflammation markers [nuclear factor kappa B (NF-κB) and inhibitor kappa B alpha (IκBα)], H2 S-producing enzymes[cystathionine ß-synthase (CBS) and cystathionine γ-lyase (CSE)], the smooth muscle/collagen ratio and H2 S concentrations were determined. The blood pressure was significantly increased in the hypertensive group, but not reversed by NaHS. The erectile response in hypertensive rats was partially prevented by NaHS. The relaxation response to electrical field stimulation was increased in CC from NaHS-treated hypertensive rats. NaHS treatment restored decreased protein expression of eNOS, nNOS and CSE as well as smooth muscle/collagen ratio and H2 S levels and increased NF-κB and IκBα protein expression in the penile tissue of hypertensive rats. NaHS promoted the recovery of erectile responses in hypertensive rats by improvement of neuronal function and downregulation of fibrosis and NF-κB signalling.

Taurine Ameliorates Thyroid Hypofunction and Renal Injury in L-NAME-Induced Hypertensive Rats.

There is a growing global interest in hypertension due to its associated complications including renal dysfunction in patients. The thyroid system reportedly regulates renal function in both animal and human. The present study investigated the therapeutic efficacy of taurine on renal and thyroid dysfunctions in hypertensive rats. Hypertension was induced by oral administration of nitric oxide synthase inhibitor, N-nitro L-arginine-methyl-ester (L-NAME), at 40 mg/kg body weight to the male Wistar rats for 14 consecutive days. The hypertensive rats were subsequently treated with either taurine (100 and 200 mg/kg) or reference drug atenolol (10 mg/kg) for another 14 consecutive days. Hypertensive rats showed renal damage evidenced by elevated plasma creatinine and urea levels when compared with normotensive control rats. Furthermore, L-NAME-induced hypertensive rats showed decreased circulatory concentrations of thyroid stimulating hormone, thyroxine, triiodothyronine and the ratio of triiodothyronine to thyroxine. The marked decrease in the renal antioxidant enzyme activities and nitric oxide level was accompanied by significant increase in myeloperoxidase activity and biomarkers of oxidative stress in hypertensive rats. Histological examination of kidneys from hypertensive rats revealed congestion of blood vessels, hemorrhagic lesion and disorganized glomerular structure. However, treatment with taurine or atenolol significantly reversed the suppression of thyroid function, ameliorated renal oxidative stress and histopathological lesions in L-NAME-induced hypertensive rats. Taurine may be a useful chemotherapeutic supplement in enhancing renal and thyroid functions in hypertensive patients.

Effect of co-administration of two different phosphodiesterase inhibitors and a ß3-adrenoceptor agonist in an experimental model of detrusor overactivity.

The purpose of this study was to evaluate in vitro the effect of the combination of BRL 37344 (ß3-adrenoceptor agonist) with tadalafil (phosphodiesterase type 5 inhibitor) or rolipram (phosphodiesterase type 4 inhibitor) in an experimental model of detrusor overactivity. The experiments were carried out in two phases using bladder strips of mice. In the first phase, on the top of 40 mM potassium-induced contraction, strips isolated from control mice were exposed to increasing concentrations of each study drug. In another series of experiments, prior to contraction, strips were incubated with either tadalafil or rolipram, followed by the addition of increasing concentrations of BRL 37344. In the second phase, the same protocols were performed with animals previously treated with L-NAME for 30 days. Chronic L-NAME administration leads to detrusor overactivity due to nitric oxide synthase inhibition. In phase one, preincubation with tadalafil enhanced relaxation response to BRL 37344 at two concentrations. Pretreatment with rolipram had no effect on BRL 37344-induced relaxation. In L-NAME-treated mice, rolipram induced more relaxation than the other drugs, enhancing relaxation response to BRL 37344 at almost all concentrations, but no synergistic effect with tadalafil was observed. The relaxant effect of BRL 37344 was enhanced by rolipram but not by tadalafil, suggesting that PDE4 inhibition, especially when associated with ß3-adrenoceptor stimulation, could represent a potential treatment for overactive bladder.

Beneficial Effects of Different Flavonoids on Vascular and Renal Function in L-NAME Hypertensive Rats.

BACKGROUND: we have evaluated the antihypertensive effect of several flavonoid extracts in a rat model of arterial hypertension caused by chronic administration (6 weeks) of the nitric oxide synthesis inhibitor, L-NAME. METHODS: Sprague Dawley rats received L-NAME alone or L-NAME plus flavonoid-rich vegetal extracts (Lemon, Grapefruit + Bitter Orange, and Cocoa) or purified flavonoids (Apigenin and Diosmin) for 6 weeks. RESULTS: L-NAME treatment resulted in a marked elevation of blood pressure, and treatment with Apigenin, Lemon Extract, and Grapefruit + Bitter Orange extracts significantly reduced the elevated blood pressure of these animals. Apigenin and some of these flavonoids also ameliorated nitric oxide-dependent and -independent aortic vasodilation and elevated nitrite urinary excretion. End-organ abnormalities such as cardiac infarcts, hyaline arteriopathy and fibrinoid necrosis in coronary arteries and aorta were improved by these treatments, reducing the end-organ vascular damage. CONCLUSIONS: the flavonoids included in this study, specially apigenin, may be used as functional food ingredients with potential therapeutic benefit in arterial hypertension.