antimycin and Disease-Models--Animal

Paclitaxel is an effective first-line chemotherapeutic with the major dose-limiting side effect of painful neuropathy. Mitochondrial dysfunction and oxidative stress have been implicated in paclitaxel-induced painful neuropathy. Here we show the effects of pharmacological modulation of mitochondrial sites that produce reactive oxygen species using systemic rotenone (complex I inhibitor) or antimycin A (complex III inhibitor) on the maintenance and development of paclitaxel-induced mechanical hypersensitivity in adult male Sprague Dawley rats. The maximally tolerated dose (5 mg/kg) of rotenone inhibited established paclitaxel-induced mechanical hypersensitivity. However, some of these inhibitory effects coincided with decreased motor coordination; 3 mg/kg rotenone also significantly attenuated established paclitaxel-induced mechanical hypersensitivity without any motor impairment. The maximally tolerated dose (.6 mg/kg) of antimycin A reversed established paclitaxel-induced mechanical hypersensitivity without any motor impairment. Seven daily doses of systemic rotenone or antimycin A were given either after paclitaxel administration or before and during paclitaxel administration. Rotenone had no significant effect on the development of paclitaxel-induced mechanical hypersensitivity. However, antimycin A significantly inhibited the development of paclitaxel-induced mechanical hypersensitivity when given before and during paclitaxel administration but had no effect when given after paclitaxel administration. These studies provide further evidence of paclitaxel-evoked mitochondrial dysfunction in vivo, suggesting that complex III activity is instrumental in paclitaxel-induced pain.. This study provides further in vivo evidence that mitochondrial dysfunction is a key contributor to the development and maintenance of chemotherapy-induced painful neuropathy. This work also indicates that selective modulation of the electron transport chain can induce antinociceptive effects in a preclinical model of paclitaxel-induced pain.

Topics: Animals; Antimycin A; Antineoplastic Agents, Phytogenic; Disease Models, Animal; Electron Transport; Electron Transport Chain Complex Proteins; Enzyme Inhibitors; Hyperalgesia; Male; Motor Activity; Paclitaxel; Pain; Pain Measurement; Peripheral Nervous System Diseases; Psychomotor Disorders; Rats; Rats, Sprague-Dawley; Rotenone; Single-Blind Method; Time Factors

Defects in the mitochondrial respiratory chain (RC) underlie a spectrum of human conditions, ranging from devastating inborn errors of metabolism to aging. We performed a genome-wide Cas9-mediated screen to identify factors that are protective during RC inhibition. Our results highlight the hypoxia response, an endogenous program evolved to adapt to limited oxygen availability. Genetic or small-molecule activation of the hypoxia response is protective against mitochondrial toxicity in cultured cells and zebrafish models. Chronic hypoxia leads to a marked improvement in survival, body weight, body temperature, behavior, neuropathology, and disease biomarkers in a genetic mouse model of Leigh syndrome, the most common pediatric manifestation of mitochondrial disease. Further preclinical studies are required to assess whether hypoxic exposure can be developed into a safe and effective treatment for human diseases associated with mitochondrial dysfunction.

Topics: Anaerobiosis; Animals; Antimycin A; Bacterial Proteins; Biomarkers; Body Temperature; Body Weight; CRISPR-Associated Protein 9; Disease Models, Animal; Electron Transport; Electron Transport Complex I; Endonucleases; Energy Metabolism; Gene Knockout Techniques; Genome-Wide Association Study; Glycine; Humans; Hypoxia-Inducible Factor 1; Isoquinolines; K562 Cells; Leigh Disease; Mice; Mice, Knockout; Mitochondria; Oxygen; Respiration; Suppression, Genetic; Von Hippel-Lindau Tumor Suppressor Protein; Zebrafish

Mitochondrial dysfunction has been widely associated with the pathology of Alzheimer's disease, but there is no consensus on whether it is a cause or consequence of disease, nor on the precise mechanism(s). We addressed these issues by testing the effects of expressing the alternative oxidase AOX from Ciona intestinalis, in different models of AD pathology. AOX can restore respiratory electron flow when the cytochrome segment of the mitochondrial respiratory chain is inhibited, supporting ATP synthesis, maintaining cellular redox homeostasis and mitigating excess superoxide production at respiratory complexes I and III. In human HEK293-derived cells, AOX expression decreased the production of beta-amyloid peptide resulting from antimycin inhibition of respiratory complex III. Because hydrogen peroxide was neither a direct product nor substrate of AOX, the ability of AOX to mimic antioxidants in this assay must be indirect. In addition, AOX expression was able to partially alleviate the short lifespan of Drosophila models neuronally expressing human beta-amyloid peptides, whilst abrogating the induction of markers of oxidative stress. Our findings support the idea of respiratory chain dysfunction and excess ROS production as both an early step and as a pathologically meaningful target in Alzheimer's disease pathogenesis, supporting the concept of a mitochondrial vicious cycle underlying the disease.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antimycin A; Antioxidants; Ciona intestinalis; Disease Models, Animal; Electron Transport Complex I; Electron Transport Complex IV; Gene Expression Regulation; HEK293 Cells; Humans; Hydrogen Peroxide; Mitochondria; Mitochondrial Proteins; Oxidative Stress; Oxidoreductases; Plant Proteins; Reactive Oxygen Species; Superoxides

To evaluate if coenzyme Q10 (CoQ10) can protect retinal ganglion cells (RGCs) from apoptosis and, when instilled as eye drops on the cornea, if it can reach the retina and exert its antiapoptotic activity in this area in a mouse model of kainate (KA)-induced retinal damage.. Rat primary or cultured RGCs were subjected to glutamate (50 μM) or chemical hypoxia (Antimycin A, 200 μM) or serum withdrawal (FBS, 0.5%) in the presence or absence of CoQ10 (10 μM). Cell viability was evaluated by light microscopy and fluorescence-activated cell sorting analyses. Apoptosis was evaluated by caspase 3/7 activity and mitochondrion depolarization tetramethylrhodamine ethyl ester analysis. CoQ10 transfer to the retina following its instillation as eye drops on the cornea was quantified by HPLC. Retinal protection by CoQ10 (10 μM) eye drops instilled on the cornea was then evaluated in a mouse model of KA-induced excitotoxic retinal cell apoptosis by cleaved caspase 3 immunohistofluorescence, caspase 3/7 activity assays, and quantification of inhibition of RGC loss.. CoQ10 significantly increased viable cells by preventing RGC apoptosis. Furthermore, when topically applied as eye drops to the cornea, it reached the retina, thus substantially increasing local CoQ10 concentration and protecting retinal layers from apoptosis.. The ability of CoQ10 eye drops to protect retinal cells from apoptosis in the mouse model of KA-induced retinal damage suggests that topical CoQ10 may be evaluated in designing therapies for treating apoptosis-driven retinopathies.

Topics: Administration, Topical; Animals; Antimycin A; Apoptosis; Caspase 3; Caspase 7; Cell Count; Cell Survival; Cells, Cultured; Chromatography, High Pressure Liquid; Cornea; Disease Models, Animal; Dose-Response Relationship, Drug; Fluorescent Antibody Technique, Indirect; Glutamic Acid; Kainic Acid; Male; Mice; Mice, Inbred C57BL; Mitochondria; Ophthalmic Solutions; Rabbits; Rats; Rats, Wistar; Retina; Retinal Diseases; Retinal Ganglion Cells; Time Factors; Ubiquinone; Vitamins

Although peripheral nerve function is strongly dependent on energy stores, the role of the mitochondrial electron transport chain, which drives ATP synthesis, in peripheral pain mechanisms, has not been examined. In models of HIV/AIDS therapy (dideoxycytidine), cancer chemotherapy (vincristine), and diabetes (streptozotocin)-induced neuropathy, inhibitors of mitochondrial electron transport chain complexes I, II, III, IV, and V significantly attenuated neuropathic pain-related behavior in rats. While inhibitors of all five complexes also attenuated tumor necrosis factor alpha-induced hyperalgesia, they had no effect on hyperalgesia induced by prostaglandin E2 and epinephrine. Two competitive inhibitors of ATP-dependent mechanisms, adenosine 5'-(beta,gamma-imido) triphosphate and P1,P4-di(adenosine-5') tetraphosphate, attenuated dideoxycytidine, vincristine, and streptozotocin-induced hyperalgesia. Neither of these inhibitors, however, affected tumor necrosis factor alpha, prostaglandin E2 or epinephrine hyperalgesia. These experiments demonstrate a role of the mitochondrial electron transport chain in neuropathic and some forms of inflammatory pain. The contribution of the mitochondrial electron transport chain in neuropathic pain is ATP dependent.

Topics: Adenosine Triphosphate; Analysis of Variance; Animals; Antimycin A; Disease Models, Animal; Drug Interactions; Electron Transport; Enzyme Inhibitors; Hyperalgesia; Male; Mitochondria; Multienzyme Complexes; Neuralgia; Neurogenic Inflammation; Pain Measurement; Pain Threshold; Peripheral Nerves; Rats; Rats, Sprague-Dawley; Rotenone; Streptozocin; Time Factors; Uncoupling Agents; Vincristine; Zalcitabine

Glutamate-induced excitotoxicity is implicated as playing a key role in the pathogenesis of amyotrophic lateral sclerosis (ALS), and mitochondrial dysfunction is also found in ALS patients. We investigated the relationship between glutamate excitotoxicity and mitochondrial dysfunction elicited by rotenone (a complex I inhibitor), malonate (a complex II inhibitor), or antimycin (a complex III inhibitor), in primary cultures of the embryonic rat spinal cord. Rotenone and malonate induced relatively selective toxicity against motor neurons as compared to non-motor neurons, whereas antimycin caused non-selective toxicity. The toxicity of rotenone was prevented by a non-N-methyl-D-aspartate (NMDA) receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) but not by an NMDA receptor antagonist, 5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate (MK-801). The toxicity of malonate was blocked by both CNQX and MK-801. The toxicity of antimycin was affected by neither CNQX nor MK-801. When mitochondrial complex I was mildly inhibited by a sub-lethal concentration of rotenone, AMPA-induced motor neuron death was significantly exacerbated. A sub-lethal concentration of malonate exacerbated both NMDA- and AMPA-induced motor neuron death. These data suggest that mitochondrial dysfunction predisposes motor neurons to ionotropic glutamate receptor-mediated excitotoxicity.

Topics: Animals; Antimycin A; Calcium Channel Blockers; Calcium Channels; Cell Death; Disease Models, Animal; Drug Synergism; Electron Transport Chain Complex Proteins; Enzyme Inhibitors; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Glutamic Acid; Malonates; Mitochondria; Motor Neurons; Neurotoxins; Rats; Rats, Wistar; Receptors, Glutamate; Rotenone; Spinal Cord