Photobiomodulation therapy reverses spermatogenesis arrest in hyperthermia-induced azoospermia mouse model.

Testicular heat stress leads to impairment of spermatogenesis in mammals. Involved mechanism in this vulnerability to heat-induced injury remains unclear, and research is being conducted to find an approach to reverse spermatogenesis arrest caused by hyperthermia. Recently, different studies have utilized photobiomodulation therapy (PBMT) therapy for the improvement of sperm criteria and fertility. This study aimed at evaluating the effect of PBMT on the improvement of spermatogenesis in mouse models of hyperthermia-induced azoospermia. A total of 32 male NMRI mice were equally divided into four groups consisting of control, hyperthermia, hyperthermia + Laser 0.03 J/cm2, and hyperthermia + Laser 0.2 J/cm2. To induce scrotal hyperthermia, mice were anesthetized and placed in a hot water bath at 43 °C for 20 min for 5 weeks. Then, PBMT was operated for 21 days using 0.03 J/cm2 and 0.2 J/cm2 laser energy densities in the Laser 0.03 and Laser 0.2 groups, respectively. Results revealed that PBMT with lower intensity (0.03 J/cm2) increased succinate dehydrogenase (SDH) activity and glutathione (GSH)/oxidized glutathione (GSSG) ratio in hyperthermia-induced azoospermia mice. At the same time, low-level PBMT reduced reactive oxygen species (ROS), mitochondrial membrane potential, and lipid peroxidation levels in the azoospermia model. These alterations accompanied the restoration of spermatogenesis manifested by the elevated number of testicular cells, increased volume and length of seminiferous tubules, and production of mature spermatozoa. After conducting experiments and analyzing the results, it has been revealed that the use of PBMT at a dosage of 0.03 J/cm2 has shown remarkable healing effects in the heat-induced azoospermia mouse model.

Effects of Sertoli Cell Transplantation on Spermatogenesis in Azoospermic Mice.

BACKGROUND/AIMS: The aim of this study was to evaluate the potential and significant applications of Sertoli cells (SCs) transplantation, and to explore the effect of transplantation on spermatogenesis process, in azospermic mice. METHODS: In this study, we utilized 18 adult mice (28‒30 g), divided into four experimental groups: (1) control, (2) vehicle (DMSO 2%) (10 µl) (3) busulfan and (4) busulfan+ SCs (1×104 cells/µL). SCs were isolated from the testis of 4-week-old mouse and after using anesthetics, 10 µl of SCs suspension (1×104 cells/µL) was injected over 3-5 min, into each testis and subsequently, sperm samples were collected from the tail of the epididymis. Afterward, the animals were euthanized and testis samples were taken for histopathology experiments, and RNA extraction, in order to examine the expression of c-kit, STRA8 and PCNA genes. RESULTS: Our data showed that SCs transplantation could notably increase the total sperm count and the number of testicular cells, such as spermatogonia, primary spermatocyte, round spermatid, SCs and Leydig cells, compared to the control, DMSO and busulfan groups. Furthermore, the result showed that the expression of c-kit and STRA8 were significantly decreased in busulfan and busulfan/SCs groups, at 8 weeks after the last injection (p<0.001), but no significant decrease was found for PCNA, compared to the control and DMSO groups (P<0.05). CONCLUSION: These findings suggest that SCs transplantation may be beneficial as a practical approach for therapeutic strategies in reproductive and regenerative medicine. We further highlighted the essential applications that might provide a mechanism for correcting fertility in males, suffering from cell deformity.

High doses of sodium tungstate can promote mitochondrial dysfunction and oxidative stress in isolated mitochondria.

Tungstate (W) is recognized as an agent of environmental pollution and a substitute to depleted uranium. According to some preliminary studies, tungstate toxicity is related to the formation of reactive oxygen species (ROS) under abnormal pathological conditions. The kidneys and liver are the main tungstate accumulation sites and important targets of tungstate toxicity. Since the mitochondrion is the main ROS production site, we evaluated the mechanistic toxicity of tungstate in isolated mitochondria for the first time, following a two-step ultracentrifugation method. Our findings demonstrated that tungstate-induced mitochondrial dysfunction is related to the increased formation of ROS, lipid peroxidation, and potential membrane collapse, correlated with the amelioration of adenosine triphosphate and glutathione contents. The present study indicated that mitochondrial dysfunction was associated with disruptive effects on the mitochondrial respiratory chain and opening of mitochondrial permeability transition (MPT) pores, which is correlated with cytochrome c release. Our findings suggest that high concentrations of tungstate (2 mM)-favored MPT pore opening in the inner membranes of liver and kidney mitochondria of rats. Besides, the results indicated higher tungstate susceptibility in the kidneys, compared with the liver.

Nickel oxide nanoparticles exert selective toxicity on skin mitochondria and lysosomes isolated from the mouse model of melanoma.

Nickel oxide nanoparticles (NiO-NPs) are progressively used for an immense number of new applications in modern industries sectors. Nevertheless, the toxic impact of NiO-NPs has not been clearly elucidated on human melanoma cell lines at the cellular and molecular level. Hence, this study was designed to examine the in vitro cytotoxicity potentials of NiO-NPs on malignant cutaneous melanoma (MCM) mitochondria. Results revealed that NiO-NPs significantly increased reactive oxygen species level, lipid peroxidation, and mitochondrial membrane potential and decreased succinate dehydrogenase activity, glutathione level, and ATP content on skin mitochondria isolated from the mouse model of melanoma compared with the non-cancerous mouse skin mitochondria. Our results revealed that NiO-NPs induced lysosomal membrane labialization on mentioned mitochondria. The current study showed that NiO-NPs could significantly induce selective cytotoxicity on MCM mitochondria. Therefore, this compound may be considered as a promising candidate for further in vivo and clinical studies to reach a new anti-MCM drug.

The effects of para-phenylenediamine (PPD) on the skin fibroblast cells.

1. Para-phenylenediamine (PPD) is the commonest and most well-known component of hair dyes. PPD is found in more than 1000 hair dye formulations and is the most frequently used permanent hair dye component in Europe, North America and East Asia. PPD containing hair dyes have been associated with cancer and mutagenicity. Apart from that, PPD has potential toxicity which includes acute toxicity such as allergic contact dermatitis and subacute toxicity. 2. In this study, we examined the effects of the PPD composition on the skin-isolated fibroblast cells. Fibroblast cells were isolated from the skin and cell viability, reactive oxygen species (ROS) production, the collapse of mitochondrial membrane potential (MMP), lipid peroxidation (LPO), damage to the lysosome release of lactate dehydrogenase (LDH) and finally release of cytochrome c were examined following the exposure to various concentrations of PPD. 3. Our results showed that exposure to PPD increased ROS generation, LPO, the collapse of MMP, LDH release and cytochrome c release. Our results suggest that PPD can induce damage to the lysosomal membrane. 4. These results showed that PPD composition has a selective toxicity on skin fibroblasts cell and mitochondria are considered one of the goals of its toxicity.

An improvement in acute wound healing in mice by the combined application of photobiomodulation and curcumin-loaded iron particles.

Here, we examined the combined effect of pulse wave photobiomodulation (PBM) with curcumin-loaded superparamagnetic iron oxide (Fe3O4) nanoparticles (curcumin), in an experimental mouse model of acute skin wound. Thirty male adult mice were randomly allocated into 5 groups. Group 1 was served as the control group. Group 2 was a placebo and received distilled water, as a carrier of curcumin. Group 3 received laser (890 nm, 80 Hz, 0.2 J/cm2). Group 4 received curcumin by taking four injections around the wound. Group 5 received laser + curcumin. One full-thickness excisional round wound was made on the back of all the mice. On days 0, 4, 7, and 14, bacterial flora, wound surface area, and tensile strength were examined and microbiological examinations were performed. In case of wound closure, the two-way ANOVA shows that wound surface area of entire groups decreased progressively. However, the decrease in laser + curcumin and laser groups, and especially data from laser + curcumin group were statistically more significant, in comparison with the other groups (F statistics = 2.28, sig = 0.019). In terms of microbiology, the two-way ANOVA showed that laser, and laser + curcumin groups have statistically a lower bacterial count than the curcumin, control, and carrier groups (F statistics = 35, sig = 0 = 000). Finally, the one-way ANOVA showed that laser + curcumin, curcumin, and curcumin significantly increased wound strength, compared to the control and carrier groups. Furthermore, laser + curcumin significantly increased wound strength, compared to the control, laser, and curcumin groups (LSD test, p = 0.003, p = 0.002, and p = 0.005, respectively). In conclusion, curcumin nanoparticles, pulse wave laser, and pulse wave laser + curcumin nanoparticles accelerate wound healing, through a significant increase in wound closure rate, as well as wound strength, and a significant decrease in Staphylococcus aureus counts. Furthermore, the statistical analysis of our data suggests that the combined treatment of pulse wave laser + curcumin nanoparticles enhances the wound closure rate, and wound strength, compared to the laser and curcumin nanoparticles alone.

Investigation of the effect of magnetite iron oxide particles size on cytotoxicity in A549 cell line.

INTRODUCTION: Magnetite as iron oxide is widely used in various industries, in the pharmaceutical industry in particular where it is used for its magnetic properties. The environmental and occupational exposure to airborne nanoparticles and microparticles of iron oxide compounds have been reported. Since authors have reported contradictory results, the objective of this study was to investigate the effect of particles' size in their toxicities. METHODS: The human cell line A549 was exposed with magnetite iron oxide in two size categories of micro (≥5 µm) and nano (<100 nm), with four concentrations of 10, 50, 100, and 250 µg/ml at two time periods of 24 and 72 h. The cell viability, reactive oxygen species (ROS), changes in mitochondrial membrane potential, and incidence of apoptosis were studied. RESULTS: Nano and micro magnetite particles demonstrated diverse toxicity effects on the A549 cell line at the 24- and 72-h exposure periods; however, the effects produced were time- and concentration-dependent. Nano magnetite particles produced greater cellular toxicities in forms of decreased viabilities at concentration exposures greater than 50 µg/ml (p < 0.05), along with increased ROS (p < 0.05), decreased cellular membrane potential (p < 0.05), and reduced rate of apoptosis (p < 0.05). DISCUSSION: The results of this study demonstrated that magnetite iron in nano-range sizes had a greater absorbability for the A549 cell line compared to micro sizes, and at the same time, nanoparticles were more toxic than microparticles, demonstrating higher production of ROS and decreased viabilities. Considering the greater toxicity of nanoparticles of magnetite iron in this study, thorough precautionary control measures must be taken before they can be used in various industries.

Comparison of the effects of MnO2-NPs and MnO2-MPs on mitochondrial complexes in different organs.

Today, nanoparticles (NPs) have been widely used in various fields. Manganese oxide nanoparticles have attracted a lot of attention due to many applications. One of the major concerns regarding the widespread use of various NPs is the exposure and accumulation in human organs and finally toxicity. The generation of reactive oxygen species (ROS) by mitochondria is one of the most important mechanisms of toxicity suggested by published studies induced by other NPs. However, limited studies have been conducted on the mechanism of toxicity of MnO2-NPs and MnO2-microparticles (MnO2-MPs). In this study, we compared the accumulation of MnO2-NPs and MnO2-MPs in different tissues and evaluated their effects on mitochondrial complexes in isolated mitochondria. Our results showed that intravascular (iv) administration of the MnO2-NPs in the same dose compared to the MnO2-MPs resulted in more accumulation in the C57 mouse female tissues. The effect of MnO2-NPs and MnO2-MPs in mitochondria showed that complexes I and III play an important role in increasing ROS generation and this effect is related to type of tissue. Also, our results showed that exposure to MnO2-NPs and MnO2-MPs reduced the activity of mitochondrial complexes II and IV. Our results suggest that the toxicity of the MnO2-NPs is higher than that of the MnO2-MPs and can lead to the depletion of antioxidant status, likely induction of apoptosis, cancer, and neurodegenerative disease. Abbreviations: NPs: nanoparticles; ROS: reactive oxygen species; SDH: succinate dehydrogenase; DCFH-DA: dichloro-dihydro-fluorescein diacetate; ELISA: enzyme-linked immunosorbent assay; MnO2-NPs: manganese oxide nanoparticles.

Evaluation of the toxicity effects of silk fibroin on human lymphocytes and monocytes.

Silk fibroin nanoparticles (SFNPs) as a natural polymer have been utilized in biomedical applications such as suture, tissue engineering-based scaffolds, and drug delivery carriers. Since there is little data regarding the toxicity effects on different cells and tissues, we aimed to determine the toxicity mechanisms of SFNPs on human lymphocytes and monocytes based on reliable methods. Our results showed that SFNPs (0.5, 1, and 2 mg/mL) induced oxidative stress via increasing reactive oxygen species production, mitochondrial membrane potential (∆Ψ) collapse, which was correlated to cytochrome c release and Adenosine diphosphate (ADP)/Adenosine tri phosphate (ATP) ratio increase as well as lysosomal as another toxicity mechanism, which led to cytosolic release of lysosomal digestive proteases, phosphor lipases, and apoptosis signaling. Taken together, these data suggested that SFNPs toxicity was associated with mutual mitochondrial/lysosomal cross-talk and oxidative stress on human lymphocytes and monocytes with activated apoptosis signaling.

Inhalation exposure of nano diamond induced oxidative stress in lung, heart and brain.

1. Today, diamond nanoparticles have several industrial applications. Nano diamond (ND) as a carbon allotrope diffuses in the air easily during producing and processing procedures. 2. In this study, we investigated sub-acute exposed to ND at the exposure chamber in mice. The animals were divided into two groups (control and exposed group to ND at the concentration of 3 µg/m3 for 3 h/day, 5 days/week for 30 days) in a whole-body inhalation chamber. 3. Our results showed that exposure to ND induced the hematological and biochemical changes. The target organs for ND were the lungs, brain and heart in the mice, respectively. Also, ND increased reactive oxygen species (ROS) generation, lipid peroxidation (LPO), the collapse of mitochondrial membrane potential (MMP), decreased a level of reduced glutathione (GSH) and finally increased a level of glutathione disulfide (GSSG) in lung, brain and heart tissues. Our results suggest that exposure to ND can induce oxidative stress in the tissue mentioned. 4. These results suggest that exposure of researchers and workers with diamond nanoparticles probably increase a risk of respiratory, cardiovascular and cerebral disorders through oxidative stress. However, good ventilation, appropriate personal protective equipment and using of anti-oxidant compounds in daily diet of worker are suggested.

Toxicity of new synthetic amphetamine drug mephedrone On Rat Heart mitochondria: a warning for its abuse.

1. Mephedrone, a new and popular amphetamine drug, is widely abused and is still legal in some parts around the world. Little data on mechanisms involved in mephedrone induced cardiotoxicity are available. 2. Therefore, we decided to explain the mechanisms of mephedrone cardiotoxicity by using mitochondria isolated from rat heart. The isolated heart mitochondria were incubated with different concentrations of mephedrone (5, 10 and 20 µM). 3. Results showed that mephedrone induced mitochondrial dysfunction via an increase in mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) collapse, mitochondrial swelling and damage in the mitochondrial outer membrane (MOM) which is associated with the cytochrome c release. Our results showed that decrease of ATP levels is an indicator of disturbance in oxidative phosphorylation. Also, mephedrone increased the caspase-3 activity. 4. According to the results, we suggest that mephedrone induced cardiotoxicity is the result of a disruptive effect on the mitochondrial respiratory chain and induction of ROS-mediated apoptosis signaling in heart cardiomyocytes.

Protection of manganese oxide nanoparticles-induced liver and kidney damage by vitamin D.

Metal nanoparticles (NPs) have been extensively used in industry as well as in biomedical application. Manganese oxide-nanoparticles (MnO2-NPs) one of these materials, have many applications. This study was designed to evaluate the protective role of vitamin D against MnO2-NPs -induced toxicity in the BALB c mice. These mice were randomly assigned to 4 (n = 10). In this study, MnO2-NPs (10 mg/kg), vitamin D (10 mg/kg) and MnO2-NPs plus vitamin D were administered interperitoneally once daily for 50 consecutive days. The liver and kidney functions, the levels of serum glucose, albumin (ALB), bilirubin (BIL) and total protein were studied. The results indicated that MnO2-NPs administration significantly decreased liver and kidney functions, and increased glucose and bilirubin serum levels compared to control group (P < 0.05). However, vitamin D administration significantly boosted liver and kidney functions, decreased glucose and bilirubin serum level compared to the group received MnO2-NPs (P < 0.05). It seems that vitamin D administration could protect the liver and kidney damage induced by MnO2-NPs. Probably, given the use of these nanoparticles as a contest agent in humans, having normal levels of vitamin D or receiving it at the time of the test can inhibit liver and kidney toxicity induced by MnO2-NPs.

Methotrexate induced mitochondrial injury and cytochrome c release in rat liver hepatocytes.

Methotrexate (MTX) is a folic acid antagonist that is widely used to treat a variety of diseases. One of the most serious side effects of MTX therapy is hepatotoxicity. The potential molecular cytotoxic mechanisms of MTX toward isolated rat hepatocytes were investigated using Accelerated Cytotoxicity Mechanism Screening (ACMS) techniques. A concentration and time dependent increase in cytotoxicity and reactive oxygen species (ROS) formation and a decrease in mitochondrial membrane potential (MMP) were observed with MTX. Furthermore, a significant increase in MTX (300 µM)-induced cytotoxicity and ROS formation were observed when glutathione (GSH)-depleted hepatocytes were used whereas addition of N-acetylcysteine (a GSH precursor) decreased cytotoxicity. Catalase inactivation also increased MTX-induced cytotoxicity, while the direct addition of catalase to the hepatocytes decreased cytotoxicity. MTX treatment in isolated rat mitochondria caused swelling and significantly decreased adenosine triphosphate (ATP) and GSH content, and cytochrome c release. Potent antioxidants such as mesna, resveratrol and Trolox decreased MTX-induced cytotoxicity and ROS formation and increased MMP. This study suggests that MTX-induced cytotoxicity caused by ROS formation and GSH oxidation leads to oxidative stress and mitochondrial injury in rat hepatocytes.

Single-walled carbon nanotube, multi-walled carbon nanotube and Fe2O3 nanoparticles induced mitochondria mediated apoptosis in melanoma cells.

PURPOSE: Nanomaterials (NM) exhibit novel anticancer properties. MATERIALS AND METHODS: The toxicity of three nanoparticles that are currently being produced in high tonnage including single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT) and Fe2O3 nanoparticles, were compared with normal and melanoma cells. RESULTS: All tested nanoparticles induced selective toxicity and caspase 3 activation through mitochondria pathway in melanoma cells and mitochondria cause the generating of reactive oxygen species (ROS), mitochondrial membrane potential decline (MMP collapse), mitochondria swelling, and cytochrome c release. The pretreatment of butylated hydroxytoluene (BHT), a cell-permeable antioxidant and cyclosporine A (Cs. A), a mitochondrial permeability transition (MPT), pore sealing agent decreased cytotoxicity, caspase 3 activation, ROS generation, and mitochondrial damages induced by SWCNT, MWCNT, and IONPs. CONCLUSIONS: Our promising results provide a potential approach for the future therapeutic use of SWCNT, MWCNT, and IONPs in melanoma through mitochondrial targeting.

Toxicity of lithium on isolated heart mitochondria and cardiomyocyte: A justification for its cardiotoxic adverse effect.

Mitochondria play an important role in myocardial tissue homeostasis; therefore, deterioration in mitochondrial function will eventually lead to cardiomyocyte and endothelial cell death and consequently cardiovascular dysfunction. Lithium (Li+ ) is an effective drug for bipolar disorder with known cardiotoxic side effects. This study was designed to investigate the effects of Li+ on mitochondria and cardiomyocytes isolated from the heart of Wistar rat. Results revealed that Li+ induced a concentration- and time-dependent rise in mitochondrial ROS formation, inhibition of respiratory complexes (II), mitochondrial membrane potential (MMP) collapse, mitochondrial swelling, and cytochrome c release in rat heart mitochondria and also induced Caspase 3 activation through mitochondrial pathway, decline of ATP and lipid peroxidation in rat cardiomyocytes. These results indicate that the cardiotoxic effects of Li+ were initiated from mitochondrial dysfunction and oxidative stress, which finally ends in cytochrome c release and cell death signaling heart cardiomyocytes.

Protective effects of Ziziphora tenuior extract against chlorpyrifos induced liver and lung toxicity in rat: Mechanistic approaches in subchronic study.

Chlorpyrifos (CPF) is one of the most widely used organophosphorus, which has spurred renewed interest. This study was conducted to investigate the protective effect of ziziphora tenuior extract against CPF-induced liver and lung toxicity. This study conducted 8-week rat sub-chronic toxicity study and then the effect of ziziphora tenuior extract in 3 different doses (40, 80, 160 mg/kg) was determined. We administrated maximum tolerated dose of CPF (6.75 mg/kg) by gavage for 8 weeks (5 times in week) to male rats. Rats were sacrificed 24 h after last dose and the biochemical analysis, which confirms involvement of oxidative stress in the pathogenesis of CPF toxicity in liver including increased in lipid peroxidation, protein carbonyl content, and ROS formation, glutathione depletion, decreased of antioxidant effect via frap oxidation and cytochrome c expulsion. In addition, pathological lesions confirm the dysfunction of the organs (liver and lung). In addition, using of ziziphora extract as an antioxidant is resulted in amelioration of oxidative stress marker in liver and lung damage. In conclusion, the current study revealed that CPF toxicity is related to oxidative stress and induction of cell death signaling and cotreatment with ziziphora extract is recommended in the routine therapy for the protection against CPF induced liver and lung tissue damage.

Protective Effect of Ozone against Hemiscorpius lepturus Envenomation in Mice.

OBJECTIVE: Scorpion (Hemiscorpius lepturus) stings are a public health concern in Iran, particularly in south and southwestern regions of Iran. The gold standard for the treatment of a scorpion sting is anti-venom therapy. However, immunotherapy can have serious side effects, such as anaphylactic shock (which can sometimes even lead to death). The aim of the current study was to demonstrate the protective effect of ozone against toxicity induced by Hemiscorpius lepturus (H. lepturus) venom in mice. METHODS: Eight hours after the injection of ozone to the experimental design groups, the male mice were decapitated and mitochondria were isolated from five different tissues (liver, kidney, heart, brain, and spinal cord) using differential ultracentrifugation. Then, assessment of mitochondrial parameters including mitochondrial reactive oxidative species (ROS) production, mitochondrial membrane potential (MMP), ATP level, and the release of cytochrome c from the mitochondria was performed. RESULTS: Our results showed that H. lepturus venom-induced oxidative stress is related to ROS production and MMP collapse, which is correlated with cytochrome c release and ATP depletion, indicating the predisposition to the cell death signaling. CONCLUSION: In general, ozone therapy in moderate dose can be considered as clinically effective for the treatment of H. lepturus sting as a protective and antioxidant agent.

Tropisetron attenuated the anxiogenic effects of social isolation by modulating nitrergic system and mitochondrial function.

BACKGROUND: Early social isolation stress (SIS) is associated with the occurrence of anxiety behaviors. It seems interaction between the nitrergic system and mitochondrial function plays a role in mediating the anxiety-like behaviors. In this study, we aimed to investigate the anxiolytic effects of tropisetron in animal model of SIS and we try to illustrate the possible role of nitrergic system and mitochondrial function. METHODS: We applied early social isolation paradigm to male NMRI mice. Animals treated with various doses of tropisetron, nitric oxide agents or their combination and anxiety-like behaviors of animals were assessed using valid behavioral tests including elevated plus maze (EPM), open-field test (OFT) and hole-board test (HBT) in their adulthood. Effects of housing conditions and drug treatments on the mitochondrial function were investigated in the hippocampus by assessing the ATP, GSH, ROS and nitrite levels. RESULTS: Anxiogenic effects of early SIS were assessed in the EPM, OFT, and HBT. Also, SIS disrupted mitochondrial function and caused oxidative stress in the hippocampus of stressed animals. Tropisetron showed an anxiolytic effect in the stressed mice. Also, these effects were mediated by nitrergic system by affecting mitochondrial function and modulating the oxidative stress. L-arginine, a nitric oxide precursor, abolished the anxiolytic effects of tropisetron in the behavioral tasks and blocked the protective effects of it against mitochondrial and oxidative challenge. CONCLUSIONS AND GENERAL SIGNIFICANCE: Our results demonstrated tropisetron attenuated the anxiogenic effects of SIS by mitigation of the negative effects of nitric oxide on mitochondrial function.

Toxicity of macrolide antibiotics on isolated heart mitochondria: a justification for their cardiotoxic adverse effect.

1. Macrolides belong to the polyketide class of natural products. These products are a group of drugs (typically antibiotics) which their activity stems from the presence of a macrolide ring. Antibiotic macrolides are used to treat infections caused by Gram-positive bacteria and Haemophilus influenzae infections such as respiratory tract and soft-tissue infections. Macrolides, mainly erythromycin and clarithromycin, rarely show QT prolongation, as their infamous adverse reaction which can lead to torsades de pointes. Electrophysiological studies showed that macrolides prolonging the QT interval inhibit the rapid component of the delayed rectifier K(+) current (IKr) through the block of potassium channels encoded by the human ether-a-go-go-related gene (HERG). Other studies suggest that increased ROS generation alters the kinetics of hERG K(+) conductance. 2. In our study, rat cardiomyocytes were isolated with collagen perfusion technique. Finally, mitochondria isolated from cardiomyocytes were exposed to erythromycin, azithromycin and clarithromycin for their probable toxicity effects. 3. Our results demonstrated that macrolides induced reactive oxygen species formation, mitochondrial membrane permeabilization and mitochondrial swelling and finally cytochrome c release in cardiomyocyte mitochondria. 4. These findings suggested that the toxicity of heart mitochondria is a starting point for cardiotoxic effects of macrolides including QT prolongation, torsades de pointes and arrhythmia.

Mitochondrial oxidative stress and dysfunction induced by isoniazid: study on isolated rat liver and brain mitochondria.

Isoniazid (INH or isonicotinic hydrazide) is used for the treatment and prophylaxis of tuberculosis. Liver and brain are two important target organs in INH toxicity. However, the exact mechanisms behind the INH hepatotoxicity or neurotoxicity have not yet been completely understood. Considering the mitochondria as one of the possible molecular targets for INH toxicity, the aim of this study was to evaluate the mechanisms of INH mitochondrial toxicity on isolated mitochondria. Mitochondria were isolated by differential ultracentrifugation from male Sprague-Dawley rats and incubated with different concentrations of INH (25-2000 µM) for the investigation of mitochondrial parameters. The results indicated that INH could interact with mitochondrial respiratory chain and inhibit its activity. Our results showed an elevation in mitochondrial reactive oxygen species (ROS) formation, lipid peroxidation and mitochondrial membrane potential collapse after exposure of isolated liver mitochondria in INH. However, different results were obtained in brain mitochondria. Noteworthy, significant glutathione oxidation, adenosine triphosphate (ATP) depletion and lipid peroxidation were observed in higher concentration of INH, as compared to liver mitochondria. In conclusion, our results suggest that INH may initiate its toxicity in liver mitochondria through interaction with electron transfer chain, lipid peroxidation, mitochondrial membrane potential decline and cytochrome c expulsion which ultimately lead to cell death signaling.