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Rat Brain Mitochondria (rat + brain_mitochondria)
Selected AbstractsPRECLINICAL STUDY: Ecstasy-induced oxidative stress to adolescent rat brain mitochondria in vivo: influence of monoamine oxidase type AADDICTION BIOLOGY, Issue 2 2009Ema Alves ABSTRACT The administration of a neurotoxic dose of 3,4-methylenedioxymethamphetamine (MDMA; ,ecstasy') to the rat results in mitochondrial oxidative damage in the central nervous system, namely lipid and protein oxidation and mitochondrial DNA deletions with subsequent impairment of the correspondent protein expression. Although these toxic effects were shown to be prevented by monoamine oxidase B inhibition, the role of monoamine oxidase A (MAO-A) in MDMA-mediated mitochondrial damage remains to be evaluated. Thus, the aim of the present study was to clarify the potential interference of a specific inhibition of MAO-A by clorgyline, on the deleterious effects produced by a binge administration of a neurotoxic dose of MDMA (10 mg MDMA/kg of body weight, intraperitoneally, every 2 hours in a total of four administrations) to an adolescent rat model. The parameters evaluated were mitochondrial lipid peroxidation, protein carbonylation and expression of the respiratory chain protein subunits II of reduced nicotinamide adenine dinucleotide dehydrogenase (NDII) and I of cytochrome oxidase (COXI). Considering that hyperthermia has been shown to contribute to the neurotoxic effects of MDMA, another objective of the present study was to evaluate the body temperature changes mediated by MDMA with a MAO-A selective inhibition by clorgyline. The obtained results demonstrated that the administration of a neurotoxic binge dose of MDMA to an adolescent rat model previously treated with the specific MAO-A inhibitor, clorgyline, resulted in synergistic effects on serotonin- (5-HT) mediated behaviour and body temperature, provoking high mortality. Inhibition of MAO-A by clorgyline administration had no protective effect on MDMA-induced alterations on brain mitochondria (increased lipid peroxidation, protein carbonylation and decrease in the expression of the respiratory chain subunits NDII and COXI), although it aggravated MDMA-induced decrease in the expression of COXI. These results reinforce the notion that the concomitant use of MAO-A inhibitors and MDMA is counter indicated because of the resulting severe synergic toxicity. [source] Ca2+ -induced permeabilization promotes free radical release from rat brain mitochondria with partially inhibited complex IJOURNAL OF NEUROCHEMISTRY, Issue 3 2005Tatyana V. Votyakova Abstract Mitochondrial complex I dysfunction has been implicated in a number of brain pathologies, putatively owing to an increased rate of reactive oxygen species (ROS) release. However, the mechanisms regulating the ROS burden are poorly understood. In this study we investigated the effect of Ca2+ loads on ROS release from rat brain mitochondria with complex I partially inhibited by rotenone. The addition of 20 nm rotenone to brain mitochondria increased ROS release. Ca2+ (100 µm) alone had no effect on ROS release, but greatly potentiated the effects of rotenone. The effect of Ca2+ was decreased by ruthenium red. Ca2+ -challenged mitochondria lose about 88% of their glutathione and 46% of their cytochrome c under these conditions, although this depends only on Ca2+ loading and not complex I inhibition. ADP in combination with oligomycin decreased the loss of glutathione and cytochrome c and free radical generation. Cyclosporin A alone was ineffective in preventing these effects, but augmented the protection provided by ADP and oligomycin. Non-specific permeabilization of mitochondria with alamethicin also increased the ROS signal, but only when combined with partial inhibition of complex I. These results demonstrate that Ca2+ can greatly increase ROS release by brain mitochondria when complex I is impaired. [source] Calcium-induced Cytochrome c release from CNS mitochondria is associated with the permeability transition and rupture of the outer membraneJOURNAL OF NEUROCHEMISTRY, Issue 2 2002Nickolay Brustovetsky Abstract The mechanisms of Ca2+ -induced release of Cytochrome c (Cyt c) from rat brain mitochondria were examined quantitatively using a capture ELISA. In 75 or 125 mm KCl-based media 1.4 µmol Ca2+/mg protein caused depolarization and mitochondrial swelling. However, this resulted in partial Cyt c release only in 75 mm KCl. The release was inhibited by Ru360, an inhibitor of the Ca2+ uniporter, and by cyclosporin A plus ADP, a combination of mitochondrial permeability transition inhibitors. Transmission electron microscopy (TEM) revealed that Ca2+ -induced swelling caused rupture of the outer membrane only in 75 mm KCl. Koenig's polyanion, an inhibitor of mitochondrial porin (VDAC), enhanced swelling and amplified Cyt c release. Dextran T70 that is known to enhance mitochondrial contact site formation did not prevent Cyt c release. Exposure of cultured cortical neurons to 500 µm glutamate for 5 min caused Cyt c release into the cytosol 30 min after glutamate removal. MK-801 or CsA inhibited this release. Thus, the release of Cyt c from CNS mitochondria induced by Ca2+in vitro as well as in situ involved the mPT and appeared to require the rupture of the outer membrane. [source] ,-Amyloid inhibits integrated mitochondrial respiration and key enzyme activitiesJOURNAL OF NEUROCHEMISTRY, Issue 1 2002C. S. Casley Abstract Disrupted energy metabolism, in particular reduced activity of cytochrome oxidase (EC 1.9.3.1), ,-ketoglutarate dehydrogenase (EC 1.2.4.2) and pyruvate dehydrogenase (EC 1.2.4.1) have been reported in post-mortem Alzheimer's disease brain. ,-Amyloid is strongly implicated in Alzheimer's pathology and can be formed intracellularly in neurones. We have investigated the possibility that ,-amyloid itself disrupts mitochondrial function. Isolated rat brain mitochondria have been incubated with the ,-amyloid alone or together with nitric oxide, which is known to be elevated in Alzheimer's brain. Mitochondrial respiration, electron transport chain complex activities, ,-ketoglutarate dehydrogenase activity and pyruvate dehydrogenase activity have been measured. ,-Amyloid caused a significant reduction in state 3 and state 4 mitochondrial respiration that was further diminished by the addition of nitric oxide. Cytochrome oxidase, ,-ketoglutarate dehydrogenase and pyruvate dehydrogenase activities were inhibited by ,-amyloid. The Km of cytochrome oxidase for reduced cytochrome c was raised by ,-amyloid. We conclude that ,-amyloid can directly disrupt mitochondrial function, inhibits key enzymes and may contribute to the deficiency of energy metabolism seen in Alzheimer's disease. [source] Melatonin protects fetal rat brain against oxidative mitochondrial damageJOURNAL OF PINEAL RESEARCH, Issue 1 2001Akihiko Wakatsuki Our objective was to investigate the effects of melatonin on the free radical-induced oxidative damage to mitochondria in fetal rat brain. Female Wistar rats on day 19 of pregnancy were used. Melatonin (10 mg/kg) or vehicle (control) was injected intraperitoneally 60 min prior to laparotomy for removal of the fetuses. The mitochondrial fraction was isolated from the fetal rat brain of each group. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured. As indicators of mitochondrial respiratory activity, we determined the respiratory control index (RCI) and the adenosine 5-diphosphate/oxygen (ADP/O) ratio in the presence and absence of 2.5 ,M hypoxanthine and 0.02 units/mL xanthine oxidase. Mitochondrial lipid peroxidation was determined by measuring the concentration of thiobarbituric acid reactive substances in fetal brain mitochondria in the presence or absence of 2.5 ,M hypoxanthine, 0.02 units/mL xanthine oxidase, and 50 ,M FeSO4. The free radical-induced rates of inhibition of mitochondrial RCI and the ADP/O ratio were both significantly lower in the fetal rat brains treated with melatonin compared with those of the controls (RCI, 44.25±15.02% vs. 25.18±5.86%, P<0.01; ADP/O ratio, 50.74±23.05% vs. 13.90±7.80%, P<0.001). The mitochondrial lipid peroxidation induced by free radicals was significantly reduced in the melatonin-treated group compared with the controls (484.2±147.2% vs. 337.6±61.0%, P<0.01). Pretreatment with melatonin significantly increased the activity of GSH-Px (20.35±5.27 to 28.93±11.01 mU/min mg,1 protein, P<0.05) in fetal rat brain mitochondria, but the activity of SOD did not change significantly. Results indicate that the administration of melatonin to the pregnant rat may prevent the free radical-induced oxidative mitochondrial damage to fetal rat brain by a direct antioxidant effect and the activation of GSH-Px. [source] | ||||||||||