Abstract 170: Arginase Contributes to Delayed Constriction of Large Cerebral Arteries in a Model of Subarachnoid Hemorrhage

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Weiyun Sun ◽  
Kathleen K Kibler ◽  
Herman Kwansa ◽  
Ewa Kulikowicz ◽  
Weizhu Tang ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Ex Vivo ◽  
Cerebral Arteries ◽  
Arginase Activity ◽  
Male Rats ◽  
Control Value ◽  
Age Related ◽  
Arterial Constriction ◽  
Oxide Synthase ◽  
Nitric Oxide Synthase Activity

Introduction: Increased arginase activity can limit nitric oxide synthase activity and contribute to age-related increase in aortic stiffness. Hypothesis: Subarachnoid hemorrhage (SAH) produces a delayed increase in arginase activity that contributes to delayed decreases in diameter of major cerebral arteries. Methods: Male rats underwent injection of blood into the cisterna magna on day 0 and again on day 2. Shams had double injection of artificial CSF. Measurements of arginase activity on vessels in the Circle of Willis and pia matter were made with an assay based on the conversion of radiolabeled arginine to urea. Measurements of diameter of basilar, posterior (PCA), middle (MCA), and anterior (ACA) cerebral arteries were made ex vivo after perfusion with paraformaldehyde and black latex casting. Results: Arginase activity (nmol of urea/min/mg of protein) increased from the control value of 13±3 (±SE; n=17) to 24±6 (n=6) at 3 days, 36±14 (n=4) at 5 days, and 48±16 (n=9) at 7 days after SAH and then recovered at 10 days (14±5; n=4) and 14 days (18±6; n=5) after SAH. Infusion of the arginase inhibitor 2(S)-amino-6-boronohexanoic acid (ABH) for 7 days after SAH with an ip osmotic pump blocked the increase in arginase activity (10±2; n=4). Assessment of arterial diameter at 3, 5, 7, 10, and 14 days after SAH revealed the smallest diameters occurring at 7 days (except for MCA which occurred at 5 days). Continuous ip infusion of 10 mg/kg/day ABH significantly attenuated the decrease in diameter (μm) 7 days after SAH in PCA (sham = 249±9, n=8; SAH = 209±12, n=10; SAH+ABH = 255±9, n=6) and ACA (sham = 178±11; SAH = 141±11; SAH+ABH = 198±10). Effects on basilar artery were of marginal significance (P=0.065). Conclusion: SAH produces an increase in vascular arginase activity that is temporally related to delayed decreases in diameter of cerebral arteries. Inhibition of arginase activity prevents the decrease in diameter at 7 days after SAH, thereby indicating a contribution of arginase to delayed arterial constriction/remodeling in post-fixed arteries.

scholarly journals Depolarization of mitochondria in neurons promotes activation of nitric oxide synthase and generation of nitric oxide

2016 ◽  
Vol 310 (9) ◽  
pp. H1097-H1106 ◽  
Author(s):  
Prasad V. G. Katakam ◽  
Somhrita Dutta ◽  
Venkata N. Sure ◽  
Samuel M. Grovenburg ◽  
Angellica O. Gordon ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Cortical Neurons ◽  
Ex Vivo ◽  
Cerebral Arteries ◽  
Resonance Spectroscopy ◽  
No Production ◽  
Cultured Neurons ◽  
Mitochondrial Depolarization ◽  
Oxide Synthase

The diverse signaling events following mitochondrial depolarization in neurons are not clear. We examined for the first time the effects of mitochondrial depolarization on mitochondrial function, intracellular calcium, neuronal nitric oxide synthase (nNOS) activation, and nitric oxide (NO) production in cultured neurons and perivascular nerves. Cultured rat primary cortical neurons were studied on 7–10 days in vitro, and endothelium-denuded cerebral arteries of adult Sprague-Dawley rats were studied ex vivo. Diazoxide and BMS-191095 (BMS), activators of mitochondrial KATP channels, depolarized mitochondria in cultured neurons and increased cytosolic calcium levels. However, the mitochondrial oxygen consumption rate was unaffected by mitochondrial depolarization. In addition, diazoxide and BMS not only increased the nNOS phosphorylation at positive regulatory serine 1417 but also decreased nNOS phosphorylation at negative regulatory serine 847. Furthermore, diazoxide and BMS increased NO production in cultured neurons measured with both fluorescence microscopy and electron spin resonance spectroscopy, which was sensitive to inhibition by the selective nNOS inhibitor 7-nitroindazole (7-NI). Diazoxide also protected cultured neurons against oxygen-glucose deprivation, which was blocked by NOS inhibition and rescued by NO donors. Finally, BMS induced vasodilation of endothelium denuded, freshly isolated cerebral arteries that was diminished by 7-NI and tetrodotoxin. Thus pharmacological depolarization of mitochondria promotes activation of nNOS leading to generation of NO in cultured neurons and endothelium-denuded arteries. Mitochondrial-induced NO production leads to increased cellular resistance to lethal stress by cultured neurons and to vasodilation of denuded cerebral arteries.

scholarly journals Cruzipain, a major Trypanosoma cruzi antigen, promotes arginase-2 expression and survival of neonatal mouse cardiomyocytes

2004 ◽  
Vol 286 (2) ◽  
pp. C206-C212 ◽  
Author(s):  
Maria P. Aoki ◽  
Natalia L. Guiñazú ◽  
Andrea V. Pellegrini ◽  
Tomomi Gotoh ◽  
Diana T. Masih ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Cell Types ◽  
Arginase Activity ◽  
Cardiac Damage ◽  
Host Cell Apoptosis ◽  
Growth Factor Deprivation ◽  
Oxide Synthase ◽  
Nitric Oxide Synthase Activity ◽  
Prime Target ◽  
Cruzi Infection

An intense myocarditis is frequently found in the acute phase of Trypanosoma cruzi infection. Despite the cardiac damage, infected individuals may remain asymptomatic for decades. Thus T. cruzi may directly prevent cardiomyocyte death to keep heart destruction in check. Recently, it has been shown that Schwann cell invasion by T. cruzi, their prime target in the peripheral nervous system, suppressed host cell apoptosis caused by growth factor deprivation. Likewise, the trans-sialidase of T. cruzi reproduced this antiapoptotic activity of the parasite. In this study, we have investigated the effect of cruzipain, another important T. cruzi antigen, on survival and cell death of neonatal BALB/c mouse cardiomyocyte cultures. We have found that cruzipain, as well as T. cruzi infection, promoted survival of cardiomyocytes cultured under serum deprivation. The antiapoptotic effect was mediated by Bcl-2 expression but not by Bcl-xL expression. Because arginase activity is involved in cell differentiation and wound healing in most cell types and it favors parasite growth within the cell, we have further investigated the effect of cruzipain on the regulation of l-arginine metabolic pathways. Our results have revealed that cruzipain enhanced arginase activity and the expression of arginase-2 isoform but failed to induce nitric oxide synthase activity. In addition, the inhibition of arginase activity by NG-hydroxy-l-arginine, abrogated the antiapoptotic action of cruzipain. The results demonstrate that cruzipain may act as a survival factor for cardiomyocytes because it rescued them from apoptosis and stimulated arginase-2.

Dihydrotestosterone attenuates hypoxia inducible factor-1α and cyclooxygenase-2 in cerebral arteries during hypoxia or hypoxia with glucose deprivation

2011 ◽  
Vol 301 (5) ◽  
pp. H1882-H1890 ◽  
Author(s):  
Kristen L. Zuloaga ◽  
Rayna J. Gonzales
Keyword(s):  
Smooth Muscle ◽  
Androgen Receptor ◽  
Vascular Smooth Muscle ◽  
Ex Vivo ◽  
Cerebral Arteries ◽  
Hypoxia Inducible Factor ◽  
Glucose Deprivation ◽  
Male Rats ◽  
Cox 2

Dihydrotestosterone (DHT) attenuates cytokine-induced cyclooxygenase-2 (COX-2) in coronary vascular smooth muscle. Since hypoxia inducible factor-1α (HIF-1α) activation can lead to COX-2 production, this study determined the influence of DHT on HIF-1α and COX-2 following hypoxia or hypoxia with glucose deprivation (HGD) in the cerebral vasculature. COX-2 and HIF-1α levels were assessed via Western blot, and HIF-1α activation was indirectly measured via a DNA binding assay. Experiments were performed using cerebral arteries isolated from castrated male rats treated in vivo with placebo or DHT (18 days) followed by hypoxic exposure ex vivo (1% O2), cerebral arteries isolated from castrated male rats treated ex vivo with vehicle or DHT (10 or 100 nM; 18 h) and then exposed to hypoxia ex vivo (1% O2), or primary human brain vascular smooth muscle cells treated with DHT (10 nM; 6 h) or vehicle then exposed to hypoxia or HGD. Under normoxic conditions, DHT increased COX-2 (cells 51%; arteries ex vivo 31%; arteries in vivo 161%) but had no effect on HIF-1α. Following hypoxia or HGD, HIF-1α and COX-2 levels were increased; this response was blunted by DHT (cells HGD: −47% COX-2, −34% HIF-1α; cells hypoxia: −29% COX-2, −54% HIF-1α; arteries ex vivo: −37% COX-2; arteries in vivo: −35% COX-2) and not reversed by androgen receptor blockade. Hypoxia-induced HIF-1α DNA-binding was also attenuated by DHT (arteries ex vivo and in vivo: −55%). These results demonstrate that upregulation of COX-2 and HIF-1α in response to hypoxia is suppressed by DHT via an androgen receptor-independent mechanism.

Upregulation of estrogen receptor α and mediation of 17β-estradiol vasoprotective effects via estrogen receptor α in basilar arteries in rats after experimental subarachnoid hemorrhage

2008 ◽  
Vol 109 (1) ◽  
pp. 92-99 ◽  
Author(s):  
Huei-Chuan Shih ◽  
Chih-Lung Lin ◽  
Shu-Chuan Wu ◽  
Aij-Lie Kwan ◽  
Yi-Ren Hong ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Estrogen Receptor ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Vasospasm ◽  
Estrogen Receptor Α ◽  
Male Rats ◽  
Enos Expression ◽  
Basilar Arteries ◽  
17Β Estradiol ◽  
Oxide Synthase

Object The authors previously demonstrated that 17β-estradiol benzoate (E2) treatment prevents subarachnoid hemorrhage (SAH)–induced cerebral vasospasm and preserves endothelial nitric oxide synthase (eNOS) in male rats. Changes in the expression of estrogen receptor (ER) subtypes ERα and -β and their roles in the E2-mediated preservation of eNOS in SAH remain unknown. In the present study the effects of SAH on the expression of ERα and -β in the cerebral arteries were clarified, and the receptor roles in the E2-mediated preservation of eNOS expression in SAH were differentiated. Methods A 2-hemorrhage SAH model was induced by 2 autologous blood injections into the cisterna magna of adult male rats. The effect of SAH on ERα and -β expression was evaluated. Other rats subcutaneously received implanted Silastic tubes containing corn oil with E2 and daily injections of various doses of an ERα- (methyl-piperidinopyrazole [MPP]) or ERβ-selective antagonist (R,R-tetrahydrochrysene) after the first hemorrhage. The protein levels of ERα, ERβ, eNOS, and inducible nitric oxide synthase (iNOS) from basilar arteries were examined using Western blot analysis, and their mRNAs were evaluated by reverse transcription–polymerase chain reaction. Results The ERα but not the ERβ was upregulated in the basilar artery after SAH. Treatment with MPP eliminated E2-mediated effects in SAH, relieved cerebral vasospasm, preserved eNOS expression, and suppressed iNOS expression. Conclusions Estrogen receptor α is upregulated in the basilar artery after SAH. Note that E2 exerts its protective effects through ERα-dependent pathways to relieve cerebral vasospasm and preserve eNOS expression. A selective ERα agonist may be the drug of choice for the treatment of patients with SAH.

scholarly journals Uncoupling of Endothelial Nitric Oxide Synthase after Experimental Subarachnoid Hemorrhage

2010 ◽  
Vol 31 (1) ◽  
pp. 190-199 ◽  
Author(s):  
Mohammed Sabri ◽  
Jinglu Ai ◽  
Britta Knight ◽  
Asma Tariq ◽  
Hyojin Jeon ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Subarachnoid Hemorrhage ◽  
Nitric Oxide Synthase ◽  
Endothelial Nitric Oxide Synthase ◽  
Cerebral Arteries ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Anterior Circulation ◽  
Experimental Subarachnoid Hemorrhage ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

We studied whether endothelial nitric oxide synthase (eNOS) is upregulated and uncoupled in large cerebral arteries after subarachnoid hemorrhage (SAH) and also whether this causes cerebral vasospasm in a mouse model of anterior circulation SAH. Control animals underwent injection of saline instead of blood ( n=16 SAH and n=16 controls). There was significant vasospasm of the middle cerebral artery 2 days after SAH (lumen radius/wall thickness ratio 4.3±1.3 for SAH, 23.2±2.1 for saline, P<0.001). Subarachnoid hemorrhage was associated with terminal deoxynucleotidyl transferase dUTP nick-end labeling, cleaved caspase-3, and Fluoro-Jade-positive neurons in the cortex and with CA1 and dentate regions in the hippocampus. There were multiple fibrinogen-positive microthromboemboli in the cortex and hippocampus after SAH. Transgenic mice expressing lacZ under control of the eNOS promoter had increased X-gal staining in large arteries after SAH, and this was confirmed by the increased eNOS protein on western blotting. Evidence that eNOS was uncoupled was found in that nitric oxide availability was decreased, and superoxide and peroxynitrite concentrations were increased in the brains of mice with SAH. This study suggests that artery constriction by SAH upregulates eNOS but that it is uncoupled and produces peroxynitrite that may generate microemboli that travel distally and contribute to brain injury.

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