Effects of hypoxia versus ischaemia on vascular functions of isolated rat thoracic aorta: revisiting the in vitro vascular ischaemia/reperfusion model.

Introduction: The in vitro rat vascular ischaemia and reperfusion model is used to evaluate the molecular and functional effects of potential agents against ischaemia and reperfusion injury of autologous graft veins. However, there is no consensus on whether hypoxia, rather than ischaemia, is sufficient to induce vascular dysfunction. Aim: To compare the effects of hypoxia and ischaemia, with or without reperfusion, on the vascular functions of isolated thoracic aortic rings of rats. Material and methods: Thoracic aortas of 12 male Sprague-Dawley rats (350-500 g, 18-24 months old) were isolated and divided into rings that were randomly allocated to control, ischaemia, hypoxia, ischaemia-reperfusion, and hypoxia-reperfusion groups. Aortic rings other than those of the control group were stored at 4°C for 24 h in saline. For ischaemia, saline was gassed with nitrogen. After 24 h, aortic rings in the ischaemia-reperfusion and hypoxia-reperfusion groups were incubated with 200 µM sodium hypochlorite for 30 min. Vascular and endothelial functions were tested in an organ bath set-up. Results: Vascular response to potassium chloride (80 mM) decreased in all experimental groups compared to the control group (p = 0.007), but phenylephrine-induced contraction (10-5 M) increased only in the ischaemia-reperfusion group (p < 0.0001). Acetylcholine (10-11-10-5 M)-induced endothelium-dependent vasorelaxations were impaired in all groups - particularly in the ischaemia-reperfusion group (p = 0.0011). Sodium nitroprusside (10-12-10-7 M)-induced endothelium-independent vasorelaxations were similar across all groups (p = 0.1258). Conclusions: Ischaemia followed by reperfusion should be implanted to achieve maximum endothelial and contractile dysfunction in vitro, and to replicate ischaemia and reperfusion injury of autologous graft veins.

Effect of hydrogen sulfide on ischemia-reperfusion injury of kidney: A systematic review and meta-analysis of in vivo animal studies.

Hydrogen sulfide (H2S) has been shown to be effective against kidney ischemia-reperfusion injury (IRI) in animal studies. We aimed to evaluate the current evidence from in vivo animal studies for the protective effects of H2S against kidney IRI by systematically reviewing the literature and performing a meta-analysis. Based on the preregistered protocol (PROSPERO: CRD42021295469); PubMed, Medline, Embase, Web of Science, and Scopus were searched to identify in vivo animal studies evaluating the effect of H2S against kidney IRI. Standardized mean difference (SMD) with 95% confidence interval (CI) was calculated and pooled using random-effects meta-analysis. Twenty-two articles complied with eligibility criteria, from which the creatinine levels of 152 control animals and 182 animals treated with H2S from 27 individual experiments were pooled. H2S treatment significantly decreased serum creatinine (SMD = -1.82 [95% CI -1.12, -2.51], p < 0.0001), blood urea nitrogen (-2.50 [-1.46, -3.54], p < 0.0001), tissue malondialdehyde (-2.59 [-3.30, -1.88], p < 0.0001), tunel positive cells (-3.16 [-4.38, -1.94], p < 0.0001), and tubular damage score (-2.01 [-3.03, -0.99], p < 0.0001). There was a high heterogeneity across studies (I2 = 83.5% for serum creatinine level). In meta-regression analysis, the type of H2S donor and its application time accounted for 11.3% (p = 0.025) and 16.6% (p = 0.039) of heterogeneity, respectively. Accordingly, H2S protects the kidney against IRI only if it is given as GYY4137 before or during ischemia. Although H2S is a potential candidate against kidney IRI, further well-designed preclinical studies focusing on GYY4137 are warranted before clinical implication.

Effect of rosuvastatin on spatial learning, memory, and anxiety-like behaviour in ovariectomized rats.

The effect of rosuvastatin (Ros) on cognitive function and anxiety-like behaviour in ovariectomized rats were evaluated. Eighteen female Wistar rats (218-310 g, 6-8 months old) were allocated into sham (n = 6), ovariectomy (Ovx, n = 6) or Ovx + Ros (up to eighth week n = 6, then n = 4) groups. Ros was administered at 20 mg/kg/day by oral gavage for 12 weeks. Behavioural tests were performed at 4, 8 and 12 weeks following Ovx. At 12 weeks, Ovx group had significantly longer escape latency than the sham group at the first day of the four-day training period of the Morris Water Maze test (p < .01). In the Elevated Plus Maze test, Ovx group spent significantly more time in the closed arms than the sham group (p < .01), and this anxiety-like behavioural effect of Ovx was prevented by 12-weeks Ros treatment (p < .05). In conclusion, Ros prevents memory deficit and anxiety-like behaviour in the ovariectomized rats, a model for human surgical menopause. Impact StatementWhat is already known on this subject? Reduced levels of oestrogen in surgical postmenopausal period has been linked to an increased risk of cognitive dysfunction. Although statins have been shown to improve cognitive function in experimental and clinical studies, there are limited studies evaluating the effect of statins on the cognitive decline and anxiety-like behaviour associated with surgical menopause.What do the results of this study add? Rosuvastatin, a long-acting statin, prevents learning and memory deficit and anxiety-like behaviour in the ovariectomized rat model.What are the implications of these findings for future clinical practice and/or future clinical research? These findings will form the basis for further experimental and clinical research on the effects of statins on cognitive functions and anxiety-like behaviour in the surgical menopause.

Mechanism of acitretin-induced relaxations in isolated rat thoracic aorta preparations.

Acitretin is a member of vitamin A-derived retinoids, and its effect on vascular smooth muscle had not yet been studied. The aim of this study is to investigate the effect of acitretin, a retinoid, on vascular smooth muscle contractility. Thoracic aorta preparations obtained from 34 male Sprague-Dawley rats (355 ± 15 g) were studied in isolated organ baths containing Krebs-Henseleit solution. The relaxation responses were obtained with acitretin (10-12-10-4 M) in endothelium-preserved and endothelium-denuded aorta preparations precontracted with submaximal concentration of phenylephrine (10-6 M). The role of retinoic acid receptors (RARs), nitric oxide, adenylyl, and guanylyl cyclase enzymes, and potassium channels in these relaxation responses were investigated. Acitretin produced concentration-dependent relaxations, which were independent of its solvent dimethylsulfoxide (DMSO), in endothelium-denuded phenylephrine-precontracted thoracic aorta preparations. While incubation with the RAR antagonist (AGN193109, 10-5 M) had no effect on these relaxations; nitric oxide synthase inhibitor (L-NG-Nitro arginine methyl ester (L-NAME), 10-4 M), adenylyl cyclase inhibitor (SQ2253, 10-5 M), guanylyl cyclase inhibitor (oxadiazolo [4,3-a] quinoxalin-1-one (ODQ), 10-6 M), and potassium channel blocker (tetraethylammonium (TEA), 10-2 M) significantly eliminated the relaxation responses induced by acitretin. Acitretin induces relaxation in rat isolated thoracic aorta preparations without endothelium, which may be mediated by nitric oxide, cyclic adenosine monophosphate, and cyclic guanosine monophosphate-dependent kinases and potassium channels.

Effects of ozone therapy and taurine on ischemia/reperfusion-induced testicular injury in a rat testicular torsion model.

BACKGROUND/AIM: To investigate the effect of ozone and/or taurine treatment comparatively on testicular damage due to ischemia/ reperfusion (I/R) injury in an experimental torsion model in rats. MATERIALS AND METHODS: Adult Wistar rats with and without torsion/detorsion were used. In order to monitor the effect of ozone and/or taurine treatment on testicular damage due to I/R injury, following histopathological investigation apoptotic indexes were scored by TUNEL method. Moreover, tumor necrosis factor receptor 1 (TNFR1), caspase 3, caspase 8, endothelial nitric oxide synthase (eNOS), tumor necrosis factor alpha (TNFα), and cytochrome C immunostainings were performed and the levels of malondialdehyde, glutathione peroxidase, superoxide dismutase, catalase, total sulfhydryl, and nitric oxide were determined in the testicular tissue. RESULTS: Intraperitoneal ozone and/or taurine treatment prevented both histopathological damage and increase in the apoptotic index. Torsion did not exert an effect on the levels of TNFα and cytochrome C. Ozone and/or taurine treatment prevented increases in TNFR1, caspase 3, and caspase 8. The level of oxidative stress markers was unchanged. The increases in NO level and eNOS expression were prevented by ozone and/or taurine treatment in I/R groups. CONCLUSION: Using ozone therapy and/or taurine before reperfusion may be a solution for germ cell degeneration resulting from testicular torsion and related infertility.