Influence of selenium therapy on liver microcirculation after warm ischemia/reperfusion: an intravital microscopy study

Assessing the Efficacy of Dietary Selenomethionine Supplementation in the Setting of Cardiac Ischemia/Reperfusion Injury

Oxidative stress is a major hallmark of cardiac ischemia/reperfusion (I/R) injury. This partly arises from the presence of activated phagocytes releasing myeloperoxidase (MPO) and its production of hypochlorous acid (HOCl). The dietary supplement selenomethionine (SeMet) has been shown to bolster endogenous antioxidant processes as well as readily react with MPO-derived oxidants. The aim of this study was to assess whether supplementation with SeMet could modulate the extent of cellular damage observed in an in vitro cardiac myocyte model exposed to (patho)-physiological levels of HOCl and an in vivo rat model of cardiac I/R injury. Exposure of the H9c2 cardiac myoblast cell line to HOCl resulted in a dose-dependent increase in necrotic cell death, which could be prevented by SeMet supplementation and was attributed to SeMet preventing the HOCl-induced loss of mitochondrial inner trans-membrane potential, and the associated cytosolic calcium accumulation. This protection was credited primarily to the direct oxidant scavenging ability of SeMet, with a minor contribution arising from the ability of SeMet to bolster cardiac myoblast glutathione peroxidase (GPx) activity. In vivo, a significant increase in selenium levels in the plasma and heart tissue were seen in male Wistar rats fed a diet supplemented with 2 mg kg⁻¹ SeMet compared to controls. However, SeMet-supplementation demonstrated only limited improvement in heart function and did not result in better heart remodelling following I/R injury. These data indicate that SeMet supplementation is of potential benefit within pathological settings where excessive HOCl is known to be generated but has limited efficacy as a therapeutic agent for the treatment of heart attack.

Comparison of pre-treatment and post-treatment use of selenium in retinal ischemia reperfusion injury

AIM

To investigate the effects of selenium in rat retinal ischemia reperfusion (IR) model and compare pre-treatment and post-treatment use.

METHODS

Selenium pre-treatment group (n=8) was treated with intraperitoneal (i.p.) selenium 0.5 mg/kg for 7d and terminated 24h after the IR injury. Selenium post-treatment group (n=8) was treated with i.p. selenium 0.5 mg/kg for 7d after the IR injury with termination at the end of the 7d period. Sham group (n=8) received i.p. saline injections identical to the selenium volume for 7d with termination 24h after the IR injury. Control group (n=8) received no intervention. Main outcome measures were retina superoxide dismutase (SOD), glutathione (GSH), total antioxidant status (TAS), malondialdehyde (MDA), DNA fragmentation levels, and immunohistological apoptosis evaluation.

RESULTS

Compared to the Sham group, selenium pre-treatment had a statistical difference in all parameters except SOD. Post-treatment selenium also resulted in statistical differences in all parameters except the MDA levels. When comparing selenium groups, the pre-treatment selenium group had a statistically higher success in reduction of markers of cell damage such as MDA and DNA fragmentation. In contrast, the post-selenium treatment group had resulted in statistically higher levels of GSH. Histologically both selenium groups succeeded to limit retinal thickening and apoptosis. Pre-treatment use was statistically more successful in decreasing apoptosis in ganglion cell layer compared to post-treatment use.

CONCLUSION

Selenium was successful in retinal protection in IR injuries. Pre-treatment efficacy was superior in terms of prevention of tissue damage and apoptosis.

Selenium has a protective effect on ischemia/reperfusion injury in a rat ovary model: biochemical and histopathologic evaluation

BACKGROUND/PURPOSE

The aim of the study was to evaluate the effects of selenium (Se) on ischemia/reperfusion (I/R) injury in rat ovaries.

METHODS

Thirty-five female Sprague-Dawley rats were randomly divided into 5 groups (n = 7): sham (S), I/R1, I/R2, Se1, and Se2. In the I/R1 and Se1 groups, 4 hours of ischemia was followed by 6 hours of reperfusion, and in the I/R2 and Se2 groups, 4 hours of ischemia was followed by 12 hours of reperfusion. In the Se groups, 30 minutes before reperfusion, a single dose of 0.2 mg/kg Se was administered intraperitoneally. The ovarian tissue levels of malondialdehyde (MDA) and nitric oxide (NO), and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured biochemically. Tissue damage to ovarian tissue was scored by histopathologic examination.

RESULTS

The I/R groups had significantly higher MDA levels and lower CAT, SOD, and GPx activities than the sham group (P < .05). Although NO levels were significantly higher in the I/R1 group than in the sham group (P < .05), the NO levels in the I/R2 and sham groups were similar. Selenium pretreatment significantly lowered tissue MDA and NO levels and increased tissue SOD and GPx activities in the Se groups, compared with those in the I/R groups (P < .05). Catalase activities were significantly higher in the Se2 group than in the I/R2 group (P < .05). Catalase activities were higher in the Se1 group than in the I/R1 group, but the difference was not statistically significant. Treatment with Se significantly decreased the ovarian tissue damage scores in the Se2 group compared with those in the I/R2 group (P < .05).

CONCLUSION

Selenium is effective in preventing tissue damage induced by I/R in rat ovaries.

Serum selenium and prognosis in cardiovascular disease: results from the AtheroGene study

OBJECTIVE

Experimental data suggest a protective role of the essential trace element selenium against cardiovascular disease (CVD), whereas epidemiological data remains controversial. We aimed to investigate the impact of serum selenium concentration in patients presenting with stable angina pectoris (SAP) or acute coronary syndrome (ACS) on long term prognosis.

METHODS

Baseline selenium concentration was measured in 1731 individuals (852 with SAP, and 879 with ACS). During a median follow-up of 6.1 years, 190 individuals died from cardiovascular causes.

RESULTS

In those ACS patients who subsequently died of cardiac causes, selenium levels were lower compared to survivors (61.0microg/L versus 71.5microg/L; P<0.0001). In a fully adjusted model, patients in the highest tertile of selenium concentration had a hazard ratio of 0.38 (95% CI: 0.16-0.91; P=0.03) as compared with those in the lowest. No association between selenium levels and cardiovascular outcome was observed in SAP.

CONCLUSIONS

Low selenium concentration was associated with future cardiovascular death in patients with ACS.

Acute high-dose sodium selenite administration improves intestinal microcirculation without affecting cytokine release in experimental endotoxemia

We evaluated the effects of acute high-dose sodium selenite (SEL) administration on the intestinal microcirculation and the release of the cytokines TNF-alpha, IL-1beta, IL-6 and IL-10 in experimental endotoxemia (induced by lipopolysaccharide-LPS). Three groups of animals (n=30) were studied: control group, endotoxemic group (15 mg kg(-1) i.v. LPS from E. coli) and SEL-treated LPS group (100 microg kg(-1) SEL i.v.). SEL treatment resulted in a significant reduced number of firmly adhering leukocytes in intestinal submucosal venules and reduced significantly the impairment of the intestinal functional capillary density. Despite of the improvement of microcirculatory parameters, we did not detect any changes in the pattern of cytokine release. In conclusion, administration of high-dose sodium SEL attenuates leukocyte adhesion and improves capillary perfusion within the intestinal microcirculation without affecting release of the cytokines TNF-alpha, IL-1beta, IL-6 and IL-10 in experimental endotoxemia.

Effects of carvacrol on defects of ischemia-reperfusion in the rat liver

Many plants found in nature have been used to treat various illnesses. One such plant is oregano (Kekik in Turkish). Health beneficial effects of carvacrol obtained from oregano oil have been shown scientifically. We have investigated the comparative effects of carvacrol in the liver of rats subjected to ischemia-reperfusion defect, with silymarin. To test the effects we formed four groups using male Wistar albino rats. Group I was control. The other three groups of animals were administered 60min prior to surgical operation single doses of physiological serum, carvacrol and silymarin, respectively. Group II, III and IV animal were subjected to 45min long liver ischemia and 60min reperfusion. Blood and tissue samples were collected for biochemical and histological analysis following the test. AST and ALT values obtained after biochemical analysis of the serums showed statistically significant difference in group II than the other three groups. A statistical evaluation of the serum AST levels among the groups II, III and IV showed that both groups III and IV which had no difference in between were significantly different in a positive way from group II (p<0.001). As to the serum ALT levels, difference between group II and group III (p<0.001) and group II and group IV (p<0.01) was found significant. No statistical difference was observed in groups I, III and IV for GSH, MDA and CAT levels of the liver. A statistical evaluation of the GSH level in group III and group IV was found to be significantly different from group II (p<0.001) without any difference between them. A similar evaluation for MDA and CAT levels among the revealed no difference between group III and group IV, however, group II showed difference with group II and group IV (p<0.05). Histological findings were in harmony with the biochemical results. We conclude that carvacrol protects the liver against defects caused by ischemia and reperfusion, and carvacrol is not hepatotoxic at the applied dosage.

Selenium improves cardiac function by attenuating the activation of NF-kappaB due to ischemia-reperfusion injury

Although selenium, an essential trace element and a component of glutathione peroxidase, is known to protect the heart from ischemia-reperfusion (I/R)-induced injury, the mechanisms of this protection are not fully understood. For this purpose, isolated rat hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion; sodium selenite (25-1,000 nM) was added in the perfusion medium 10 min prior to ischemia, as well as during reperfusion. Selenium caused a dose-dependent improvement in cardiac performance and attenuated the decrease in the ratio of reduced glutathione to oxidized glutathione, as well as the increased level of malondialdehyde in I/R heart. Elevated ratios of nuclear factor-kappaB (NF-kappaB) in particulate and cytosolic fraction and of phosphorylated NF-kappaB and total NF-kappaB in I/R hearts were reduced by selenium. Cardiac dysfunction in hearts perfused with xanthine plus xanthine oxidase mixture, as well as hydrogen peroxide, or subjected to Ca2+ paradox was also attenuated by selenium. These data suggest that selenium protects the heart against I/R injury due to its action on the redox state and deactivation of NF-kappaB in I/R hearts.

The protective effect of selenium on ipsilateral and contralateral testes in testicular reperfusion injury

This study was designed to investigate the effect of selenium on ipsilateral and contralateral testicular damage after unilateral testicular torsion/detorsion (T/D). Thirty-two male rats were divided into four groups, each containing eight rats. Torsion was created by rotating the right testis 720 degrees in a clockwise direction. Group 1 underwent sham operation to determine basal values for biochemical and histopathological evaluation. Sham operation was performed in group 2, and sodium selenate (0.2 mg/kg) was given intraperitoneally. Group 3 served as a T/D group, receiving 4-h torsion and 4-h detorsion. Similarly, in group 4 sodium selenate (0.2 mg/kg) was injected intraperitoneally 20 min before detorsion. Bilateral orchiectomies were performed for measurement of tissue malondialdehyde (MDA) levels and superoxide dismutase (SOD) activities and histopathologic examination. The results were compared statistically. The highest MDA and the lowest SOD values were determined in both testes in group 3. There were statistically significant differences in MDA levels and SOD activities in group 3 compared with group 4. Specimens from group 3 had a significantly greater histologic injury than other groups. These results suggest that ischemia-reperfusion injury occurred in both testes after unilateral testicular T/D and that selenium administration before detorsion prevents reperfusion injury in testicular torsion.