Rotenone, a mitochondrial electron transport inhibitor, ameliorates ischemia-reperfusion-induced intestinal mucosal damage in rats

Therapeutic Targets for Regulating Oxidative Damage Induced by Ischemia-Reperfusion Injury: A Study from a Pharmacological Perspective

Ischemia-reperfusion (I-R) injury is damage caused by restoring blood flow into ischemic tissues or organs. This complex and characteristic lesion accelerates cell death induced by signaling pathways such as apoptosis, necrosis, and even ferroptosis. In addition to the direct association between I-R and the release of reactive oxygen species and reactive nitrogen species, it is involved in developing mitochondrial oxidative damage. Thus, its mechanism plays a critical role via reactive species scavenging, calcium overload modulation, electron transport chain blocking, mitochondrial permeability transition pore activation, or noncoding RNA transcription. Other receptors and molecules reduce tissue and organ damage caused by this pathology and other related diseases. These molecular targets have been gradually discovered and have essential roles in I-R resolution. Therefore, the current study is aimed at highlighting the importance of these discoveries. In this review, we inquire about the oxidative damage receptors that are relevant to reducing the damage induced by oxidative stress associated with I-R. Several complications on surgical techniques and pathology interventions do not mitigate the damage caused by I-R. Nevertheless, these therapies developed using alternative targets could work as coadjuvants in tissue transplants or I-R-related pathologies

Metabolic shifts modulate lung injury caused by infection with H1N1 influenza A virus

Influenza A virus (IAV) infection alters lung epithelial cell metabolism in vitro by promoting a glycolytic shift. We hypothesized that this shift benefits the virus rather than the host and that inhibition of glycolysis would improve infection outcomes. A/WSN/33 IAV-inoculated C57BL/6 mice were treated daily from 1 day post-inoculation (d.p.i.) with 2-deoxy-d-glucose (2-DG) to inhibit glycolysis and with the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) to promote flux through the TCA cycle. To block OXPHOS, mice were treated every other day from 1 d.p.i. with the Complex I inhibitor rotenone (ROT). 2-DG significantly decreased nocturnal activity, reduced respiratory exchange ratios, worsened hypoxemia, exacerbated lung dysfunction, and increased humoral inflammation at 6 d.p.i. DCA and ROT treatment normalized oxygenation and airway resistance and attenuated IAV-induced pulmonary edema, histopathology, and nitrotyrosine formation. None of the treatments altered viral replication. These data suggest that a shift to glycolysis is host-protective in influenza.

Ischemia/Reperfusion Injury Revisited: An Overview of the Latest Pharmacological Strategies

Ischemia/reperfusion injury (IRI) permeates a variety of diseases and is a ubiquitous concern in every transplantation proceeding, from whole organs to modest grafts. Given its significance, efforts to evade the damaging effects of both ischemia and reperfusion are abundant in the literature and they consist of several strategies, such as applying pre-ischemic conditioning protocols, improving protection from preservation solutions, thus providing extended cold ischemia time and so on. In this review, we describe many of the latest pharmacological approaches that have been proven effective against IRI, while also revisiting well-established concepts and presenting recent pathophysiological findings in this ever-expanding field. A plethora of promising protocols has emerged in the last few years. They have been showing exciting results regarding protection against IRI by employing drugs that engage several strategies, such as modulating cell-surviving pathways, evading oxidative damage, physically protecting cell membrane integrity, and enhancing cell energetics.

Intervention of mitochondrial activity attenuates cisplatin-induced acute kidney injury

OBJECTIVES

The dysfunction of mitochondrial respiratory chain induced by cisplatin results in overproduction of reactive oxygen species (ROS) which contributes to kidney injury. The current study aimed to evaluate the effect of a mitochondrial electron transport inhibitors of rotenone (mitochondrial complex I inhibitor) and azoxystrobin (mitochondrial complex III inhibitor), in cisplatin-induced kidney injury.

METHODS

In vivo, cisplatin was administered to male C57BL/6J mice by a single intraperitoneal (i.p.) injection (20 mg/kg). Then the mice were treated with or without 200 ppm rotenone in food. Mice were sacrificed after cisplatin administration for 72 h. The serum and the kidney tissues were collected for further analysis. In vitro, mouse proximal tubular cells (mPTCs) were treated with cisplatin (5 µg/mL) and rotenone/azoxystrobin for 24 h. Flow cytometry, Western blotting, and TUNEL staining were used to evaluate the cell injury.

RESULTS

In vivo, rotenone treatment obviously ameliorated cisplatin-induced renal tubular injury evidenced by the improved histology and blocked NGAL upregulation. Meanwhile, cisplatin-induced renal dysfunction shown by the increased levels of serum creatinine (Scr), blood urea nitrogen (BUN), and cystatin C were significantly reduced by rotenone treatment. Moreover, the increments of cleaved caspase-3 and transferase dUTP nick-end labeling (TUNEL)-positive cells were markedly decreased in line with the attenuated mitochondrial dysfunction and oxidative stress after rotenone administration. In vitro, rotenone and azoxystrobin protected against mitochondrial dysfunction, oxidative stress, and renal tubular cell apoptosis induced by cisplatin.

CONCLUSIONS

Our results demonstrated that inhibition of mitochondrial activity significantly attenuated cisplatin nephrotoxicity possibly by inhibiting mitochondrial oxidative stress.

Rotenone Attenuates Renal Injury in Aldosterone-Infused Rats by Inhibiting Oxidative Stress, Mitochondrial Dysfunction, and Inflammasome Activation

BACKGROUND

Reactive oxygen species (ROS) and inflammation both contribute to the progression of aldosterone-induced renal injury. To better understand the underlying mechanisms, we examined mitochondrial dysfunction and NLRP3 inflammasome activation in aldosterone-infused rats, and explored the role of rotenone in attenuating these injuries.

MATERIAL AND METHODS

Sprague-Dawley rats were divided into 3 groups: vehicle-treated, aldosterone-infused, and aldosterone plus rotenone. Renal damage was evaluated using PAS staining and electron microscopy. Levels of ROS were measured from renal tissue and serum; immunohistochemistry analysis examined the inflammation pathway; Western blot and real-time PCR assessed NLRP3 inflammasome activity.

RESULTS

Glomerular segmental sclerosis, foot process effacement, and proteinuria were demonstrated in the aldosterone-infused rats. Specifically, the thiobarbituric acid-reactive substances (TBARS) oxidative stress marker, MDA, was significantly increased; ATP content and mtDNA copy number were markedly decreased; inflammatory mediators NF-κB p65 and CTGF were upregulated; and NLRP3 inflammasome and its related target proteins, IL-1β and IL-18, were also increased. Treatment with rotenone, an inhibitor of mitochondrial complex I, significantly attenuated oxidative stress, mitochondrial dysfunction, and inflammasome response in aldosterone-infused rats.

CONCLUSIONS

Rotenone ameliorated aldosterone-infused renal injury, possibly by inhibiting oxidative stress, mitochondrial dysfunction, and NLRP3 inflammasome activity. These results provide novel evidence for the role of rotenone in aldosterone-induced renal injury or other chronic kidney disease.

Reperfusion injury and reactive oxygen species: The evolution of a concept

Reperfusion injury, the paradoxical tissue response that is manifested by blood flow-deprived and oxygen-starved organs following the restoration of blood flow and tissue oxygenation, has been a focus of basic and clinical research for over 4-decades. While a variety of molecular mechanisms have been proposed to explain this phenomenon, excess production of reactive oxygen species (ROS) continues to receive much attention as a critical factor in the genesis of reperfusion injury. As a consequence, considerable effort has been devoted to identifying the dominant cellular and enzymatic sources of excess ROS production following ischemia-reperfusion (I/R). Of the potential ROS sources described to date, xanthine oxidase, NADPH oxidase (Nox), mitochondria, and uncoupled nitric oxide synthase have gained a status as the most likely contributors to reperfusion-induced oxidative stress and represent priority targets for therapeutic intervention against reperfusion-induced organ dysfunction and tissue damage. Although all four enzymatic sources are present in most tissues and are likely to play some role in reperfusion injury, priority and emphasis has been given to specific ROS sources that are enriched in certain tissues, such as xanthine oxidase in the gastrointestinal tract and mitochondria in the metabolically active heart and brain. The possibility that multiple ROS sources contribute to reperfusion injury in most tissues is supported by evidence demonstrating that redox-signaling enables ROS produced by one enzymatic source (e.g., Nox) to activate and enhance ROS production by a second source (e.g., mitochondria). This review provides a synopsis of the evidence implicating ROS in reperfusion injury, the clinical implications of this phenomenon, and summarizes current understanding of the four most frequently invoked enzymatic sources of ROS production in post-ischemic tissue.

•

Reperfusion injury is implicated in a variety of human diseases and disorders.

•

Evidence implicating ROS in reperfusion injury continues to grow.

•

Several enzymes are candidate sources of ROS in post-ischemic tissue.

•

Inter-enzymatic ROS-dependent signaling enhances the oxidative stress caused by I/R.

.

Effects of Low Concentrations of Rotenone upon Mitohormesis in SH-SY5Y Cells

The mitochondrial toxin rotenone exerts cytotoxicity via overproduction of reactive oxygen species (ROS) and depolarization of the mitochondrial membrane. We investigated the effects of rotenone (12.5, 25, 50, 100 nmol/L) on mitochondrial biogenesis and the potential roles of ROS production in SH-SY5Y cells. Mitochondrial biogenesis was assessed by counting the number of mitochondria, determining protein expression of peroxisome proliferator-activated receptor γ coactivator α (PGC1-α) and its regulator, SIRT1, and oxygen consumption. ROS production and levels of reduced glutathione (GSH) and oxidized glutathione (GSSG) were also determined. Compared with controls, rotenone (12.5 nmol/L) significantly increased the quantity of mitochondria and amount of oxygen consumption, whereas rotenone at >12.5 nmol/L decreased the quantity of mitochondria and amount of oxygen consumption. GSH contents and GSH/GSSG were also significantly enhanced by rotenone at 12.5 nmol/L and decreased by rotenone at >12.5 nmol/L. Except for ROS production and SIRT1 protein expression, all concentration-response relationships showed a typical inverted-U shape. ROS production was continually increased in cells treated with rotenone. These data indicate that low concentrations of rotenone can induce mitohormesis, which may be attributed to ROS production.

Effects of rotenone on inducible nitric oxide synthase and cyclooxygenase-2 mRNA levels detected by real-time PCR in a rat bladder ischemia/reperfusion model

We aimed to determine whether rotenone treatment prevents induced ischemia/reperfusion (I/R) damage in rat bladders by detecting inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) levels by real-time PCR (RT-PCR). A total of 18 Sprague-Dawley albino rats were used in this experiment. The experimental groups each consisted of 6 rats and were treated as follows: group I, control; group II, I/R; group III, rotenone + I/R. In the control group, the rat bladders were removed by lower abdominal incision without any procedure. In the I/R group, 1 h prior to the ischemia 1 cc physiological serum was administered and the abdominal aortas were clamped for 1 h to achieve bladder ischemia. Following the ischemia, reperfusion was induced for 1 h and the bladders were removed. In the rotenone + I/R group, the rats were treated with 25 mg/kg rotenone intraperitoneally. The iNOS and COX-2 mRNA levels in each group were detected using RT-PCR. In the I/R group, the COX-2 levels in the bladder tissue were higher compared with the control group (P<0.05). The COX-2 levels in the rotenone-treated group were statistically lower compared with the I/R group (P<0.01). Vascularization and edema were markedly increased in the I/R group. Following rotenone treatment these were abrogated inversely to inflammation. Although iNOS levels were slightly higher in the I/R group compared with the control group, iNOS levels did not decrease and no significant difference was observed between the groups with regard to rotenone treatment (P>0.05). We suggest that rotenone may be used clinically to treat I/R damage due to its diminishing effect on COX-2 levels.

Oxidative stress and ischemia-reperfusion injury in gastrointestinal tract and antioxidant, protective agents

Exacerbation of hypoxic injury after reoxygenation is a crucial mechanism mediating organ injury in transplantation, and in myocardial, hepatic, gastrointestinal, cerebral, renal, and other ischemic syndromes. The occlusion and reperfusion of the splanchnic artery is a useful animal model to elucidate the mechanism of gastrointestinal injury induced by ischemia-reperfusion (I/R). Although xanthine oxidase is a major source of reactive oxygen species (ROS), which plays an important role in the I/R-induced intestinal injury, there are many other sources of intracellular ROS. Various treatment modalities have been successfully applied to attenuate the I/R injury in animal models. This review focuses on the role of oxidant stress in the mechanism of I/R injury and the use of antioxidant agents for its treatment.

Dexamethasone and the inflammatory response in explants of human omental adipose tissue

Dexamethasone is a synthetic glucocorticoid that is a potent anti-inflammatory agent. The present studies examined the changes in gene expression of 64 proteins in human omental adipose tissue explants incubated for 48h both in the absence and presence of dexamethasone as well as the release of 8 of these proteins that are putative adipokines. The proteins were chosen because they are inflammatory response proteins in other cells, are key regulatory proteins or are proteins with known functions. About 50% were significantly up-regulated while about 10% were unchanged and the remaining 40% were down-regulated. Dexamethasone significantly up-regulated the expression of about 33% of the proteins but down-regulated the expression of about 12% of the proteins. We conclude that dexamethasone is a selective anti-inflammatory agent since it inhibits only about one-fourth of the proteins up-regulated during in vitro incubation of human omental adipose tissue.

Atrophic gastritis: deficient complex I of the respiratory chain in the mitochondria of corpus mucosal cells

BACKGROUND

Mitochondrial dysfunction is one of the most characteristic properties of the cancer cell. However, it is not known whether oxidative energy metabolism has already become altered in conditions of atrophic gastritis, a precancerous state of gastric disease. The purpose of our study was to comparatively characterize oxidative phosphorylation (OXPHOS) in the atrophic and nonatrophic gastric corpus mucosa.

METHODS

Mucosal biopsies were taken from 12 patients with corpus dominant atrophic gastritis and from 12 patients with nonatrophic mucosa (controls). One part of the tissue samples was permeabilized with saponin for analysis of the function of the respiratory chain using high-resolution respirometry, and another part was used for histopathological examination. The serum level of pepsinogen I (S-PGI) was determined with a specific enzyme immunoassay (EIA).

RESULTS

Compared to the control group, the maximal capacity of OXPHOS in the atrophy group was almost twofold lower, the respiratory chain complex I-dependent respiration, normalized to complex II-dependent respiration, was reduced, and respiratory control by ADP in the presence of succinate was increased in the atrophic corpus mucosa. In the whole cohort of the patients studied, serum S-PGI level correlated positively with complex I-dependent respiration or complex I-dependent to complex II-dependent respiration ratio.

CONCLUSIONS

Corpus dominant atrophic gastritis is characterized by decreased respiratory capacity and relative deficiency of the respiratory complex I of mitochondria in the mucosa, the latter defect probably limiting mitochondrial ATP production and energetic support of the secretory function of the zymogenic mucosal cells.

High rates of superoxide production in skeletal-muscle mitochondria respiring on both complex I- and complex II-linked substrates

Despite the considerable interest in superoxide as a potential cause of pathology, the mechanisms of its deleterious production by mitochondria remain poorly understood. Previous studies in purified mitochondria have found that the highest rates of superoxide production are observed with succinate-driven reverse-electron transfer through complex I, although the physiological importance of this pathway is disputed because it necessitates high concentrations of succinate and is thought not to occur when NAD is in the reduced state. However, very few studies have examined the rates of superoxide production with mitochondria respiring on both NADH-linked (e.g. glutamate) and complex II-linked substrates. In the present study, we find that the rates of superoxide production (measured indirectly as H2O2) with glutamate+succinate (approximately 1100 pmol of H2O2 x min(-1) x mg(-1)) were unexpectedly much higher than with succinate (approximately 400 pmol of H2O2 x min(-1) x mg(-1)) or glutamate (approximately 80 pmol of H2O2 x min(-1) x mg(-1)) alone. Superoxide production with glutamate+succinate remained high even at low substrate concentrations (<1 mM), was decreased by rotenone and was completely eliminated by FCCP (carbonyl cyanide p-trifluoromethoxyphenylhydrazone), indicating that it must in large part originate from reverse-electron transfer through complex I. Similar results were obtained when glutamate was replaced with pyruvate, alpha-ketoglutarate or palmitoyl carnitine. In contrast, superoxide production was consistently lowered by the addition of malate (malate+succinate approximately 30 pmol of H2O2 x min(-1) x mg(-1)). We propose that the inhibitory action of malate on superoxide production can be explained by oxaloacetate inhibition of complex II. In summary, the present results indicate that reverse-electron transfer-mediated superoxide production can occur under physiologically realistic substrate conditions and suggest that oxaloacetate inhibition of complex II may be an adaptive mechanism to minimize this.

Dehydroepiandrosterone inhibits complex I of the mitochondrial respiratory chain and is neurotoxic in vitro and in vivo at high concentrations

Dehydroepiandrosterone (DHEA) is widely used as a food supplement and considered to be relatively safe. In animal studies, however, additions of high concentrations of DHEA to the diet have led to hepatotoxicity as well as liver mitochondrial dysfunction. This study was therefore designed to find out whether DHEA is able to inhibit the respiratory activity also in neuronal mitochondria and to reveal whether this leads to functional disturbance in the brain. Using different mitochondrial substrates, we show here that DHEA suppresses the mitochondrial respiration in permeabilized neurons (half maximal inhibitory concentration 13 microM) by inhibiting complex I of the mitochondrial electron transport chain. Treatment with DHEA was associated with increased glucose expenditure in intact cultures and led to neuronal death. The latter was most prominent in hypoglycemic conditions. Mice fed with pellet containing 0.6% DHEA for 3 months showed a significant neuronal loss in the cerebral cortex and hippocampus, a slightly decreased dopamine/dihydroxyphenylacetic acid ratio, as well as motor impairment. The main conclusion of the present study is that high concentrations of DHEA inhibit complex I of the mitochondrial respiratory chain and are neurotoxic in vitro and in vivo.

Estrogen prevents cardiomyocyte apoptosis through inhibition of reactive oxygen species and differential regulation of p38 kinase isoforms

From human and animal studies, estrogen is known to protect the myocardium from an ischemic insult. However, there is limited knowledge regarding mechanisms by which estrogen directly protects cardiomyocytes. In this report, we employed an in vitro model, in which cultured rat cardiomyocytes underwent prolonged hypoxia followed by reoxygenation (H/R), to study the cardioprotective mechanism of estrogen. 17-beta-estradiol (E2) acting via estrogen receptors inhibited H/R-induced apoptosis of cardiomyocytes. Mitochondrial reactive oxygen species (ROS) generated from H/R activated p38alpha MAPK, and inhibition of p38alpha with SB203580 significantly prevented H/R-induced cell death. E2 suppressed ROS formation and p38alpha activation by H/R and concomitantly augmented the activity of p38beta. Unlike p38alpha, p38beta was little affected by H/R. Dominant negative p38beta protein expression decreased E2-mediated cardiomyocyte survival and ROS suppression during H/R stress. The prosurvival signaling molecule, phosphoinositol-3 kinase (PI3K), has previously been linked to cell survival following ischemia-reperfusion injury. Here, E2-activated PI3K was found to inhibit ROS generated from H/R injury, leading to inhibition of downstream p38alpha. We further linked these signaling pathways in that p38beta was activated by E2 stimulation of PI3K. Thus, E2 differentially modulated two major isoforms of p38, leading to cardiomyocyte survival. This was achieved by signaling through PI3K, integrating cell survival mediators.