RESUMEN
The effect of the modulators of the mitochondrial ATP-dependent potassium channel (mitoKATP) on the structural and biochemical alterations in the substantia nigra and brain tissues was studied in a rat model of Parkinson's disease induced by rotenone. It was found that, in experimental parkinsonism accompanied by characteristic motor deficits, both neurons and the myelin sheath of nerve fibers in the substantia nigra were affected. Changes in energy and ion exchange in brain mitochondria were also revealed. The nucleoside uridine, which is a source for the synthesis of the mitoKATP channel opener uridine diphosphate, was able to dose-dependently decrease behavioral disorders and prevent the death of animals, which occurred for about 50% of animals in the model. Uridine prevented disturbances in redox, energy, and ion exchanges in brain mitochondria, and eliminated alterations in their structure and the myelin sheath in the substantia nigra. Cytochemical examination showed that uridine restored the indicators of oxidative phosphorylation and glycolysis in peripheral blood lymphocytes. The specific blocker of the mitoKATP channel, 5-hydroxydecanoate, eliminated the positive effects of uridine, suggesting that this channel is involved in neuroprotection. Taken together, these findings indicate the promise of using the natural metabolite uridine as a new drug to prevent and, possibly, stop the progression of Parkinson's disease.
Asunto(s)
Mitocondrias , Canales de Potasio , Rotenona , Uridina , Animales , Uridina/farmacología , Uridina/metabolismo , Ratas , Canales de Potasio/metabolismo , Mitocondrias/metabolismo , Mitocondrias/efectos de los fármacos , Masculino , Modelos Animales de Enfermedad , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/etiología , Enfermedad de Parkinson/patología , Sustancia Negra/metabolismo , Sustancia Negra/efectos de los fármacos , Sustancia Negra/patología , Fármacos Neuroprotectores/farmacología , Fosforilación Oxidativa/efectos de los fármacos , Ratas Wistar , Ácidos Decanoicos/farmacología , Hidroxiácidos/farmacologíaRESUMEN
Using a model of Parkinson's disease (PD) induced by the bilateral injection of neurotoxin 6-hydroxydopamine (6-OHDA) into rat brain substantia nigra (SN), we showed uridine to exert a protective effect associated with activation of the mitochondrial ATP-dependent potassium (mitoK-ATP) channel. Injection of 4 µg neurotoxin evoked a 70% decrease in the time the experimental animal spent on the rod in the RotaRod test, an increase in the amount of lipid peroxides in blood serum and cerebral-cortex mitochondria and the rate of reactive oxygen species formation, and a decrease in Ca2+ retention in mitochondria. Herewith, lymphocytes featured an increase in the activity of lactate dehydrogenase, a cytosolic enzyme of glycolysis, without changes in succinate-dehydrogenase activity. Structural changes occurring in the SN and striatum manifested themselves in the destruction of mitochondria, degeneration of neurons and synapses, and stratification of myelin sheaths in them. Subcutaneous injections of 30 µg/kg uridine for 22 days restored the neurotoxin-induced changes in these parameters to levels close to the control. 5-Hydroxydecanoate (5 mg/kg), a specific mitoK-ATP channel inhibitor, eliminated the beneficial effect of uridine for almost all characteristics tested, indicating the involvement of the mitoK-ATP channel in the protective effect of uridine. The mechanism of the protective effect of uridine and its therapeutic applications for the prevention and treatment of PD are discussed.
Asunto(s)
Neurotoxinas , Enfermedad de Parkinson , Animales , Ratas , Oxidopamina , Uridina/farmacología , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/etiología , Encéfalo , Adenosina TrifosfatoRESUMEN
The cellular mechanisms of neuroplastic changes in the structure of motoneurons and neuropils of the oculomotor (III) nuclei in mice after a 30-day space flight and 7 days after landing were studied. The results showed that microgravity caused degenerative phenomena in neurons: a decrease in the number of terminal dendritic branches was found both after flight and after readaptation to Earth's gravity. In mice after the flight, the number of axodendritic synapses was less than in the control, and their number was not restored after the readaptation. The number of mitochondria in the motoneurons of animals after the flight also decreased and after the readaptation reached only the control value. In addition, a significant number of dark motorneurons were found in mice after readaptation, which indicates that degeneration was caused not only by microgravity, but also by a reaction to the landing of the biosatellite. On the contrary, in the trochlear nucleus, as we showed earlier (Mikheeva et al. in Brain Res 15(1795):148077. https://doi.org/10.1016/j.brainres.2022.148077 , 2022), after readaptation, the dendrites and synaptic contacts were restored, and mitogenesis is significantly enhanced. It has been suggested that morphological changes in the oculomotor nucleus may be the main cause of microgravity-induced nystagmus.
Asunto(s)
Complejo Nuclear Oculomotor , Vuelo Espacial , Ingravidez , Ratones , Animales , Neuronas Motoras , NeurópiloRESUMEN
The effect of a single one-hour exposure to three modes of hypobaric hypoxia (HBH) differed in the content of O2 in inhaled air (FiO2-14%, 10%, 8%) in the development of mitochondrial-dependent adaptive processes in the myocardium was studied in vivo. The following parameters have been examined: (a) an urgent reaction of catalytic subunits of mitochondrial enzymes (NDUFV2, SDHA, Cyt b, COX2, ATP5A) in the myocardium as an indicator of the state of the respiratory chain electron transport function; (b) an urgent activation of signaling pathways dependent on GPR91, HIF-1α and VEGF, allowing us to assess their role in the formation of urgent mechanisms of adaptation to hypoxia in the myocardium; (c) changes in the ultrastructure of three subpopulations of myocardial mitochondria under these conditions. The studies were conducted on two rat phenotypes: rats with low resistance (LR) and high resistance (HR) to hypoxia. The adaptive and compensatory role of the mitochondrial complex II (MC II) in maintaining the electron transport and energy function of the myocardium in a wide range of reduced O2 concentrations in the initial period of hypoxic exposure has been established. The features of urgent reciprocal regulatory interaction of NAD- and FAD-dependent oxidation pathways in myocardial mitochondria under these conditions have been revealed. The data indicating the participation of GPR91, HIF-1a and VEGF in this process have been obtained. The ultrastructure of the mitochondrial subpopulations in the myocardium of LR and HR rats differed in normoxic conditions and reacted differently to hypoxia of varying severity. The parameters studied together are highly informative indicators of the quality of cardiac activity and metabolic biomarkers of urgent adaptation in various hypoxic conditions.
Asunto(s)
Ácido Succínico , Factor A de Crecimiento Endotelial Vascular , Ratas , Animales , Ácido Succínico/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo , Hipoxia/metabolismo , Miocardio/metabolismo , Transducción de Señal , Mitocondrias Cardíacas/metabolismoRESUMEN
The negative effect of hypogravity on the human organism is manifested to a greater extent after the astronauts return to the conditions of habitual gravity. In this work, to elucidate the causes underlying atypical nystagmus, arising after the flight, we studied structural changes in the motoneurons of the trochlear nerve after a 7-day readaptation of mice to the conditions of Earth's gravity. It is known, that motoneurons of the trochlear nerve innervate the muscle that controls the movement of the eyes in the vertical direction. We showed that the number of axodendritic synapses and some other morphological parameters of motoneurons changed by microgravity can return to their original state in 7 days. However, according to some parameters, motoneurons retain a "memory" of the action of microgravity and do not completely restore the structure. The volume of the soma, the shape of the nuclei, the number and orientation of dendrites do not return to pre-flight parameters. The number of dendrites after 7 days of adaptation remained increased, and the proportion of dendrites in the ventrolateral direction became 2.5 times greater than in motoneurons after space flight. The increased number of mitochondria after space flight became even more significant after readaptation. Microgravity-induced plastic changes retain to some extent "memory traces" after readaptation to Earth's gravity. It can be assumed that the restoration of the function of the trochlear nuclei (overcoming nystagmus) is carried out not only by reversible restoration of the structure of neurons, but partially using those mechanisms that are formed in weightlessness.
Asunto(s)
Vuelo Espacial , Ingravidez , Animales , Astronautas , Humanos , Ratones , Plásticos , Nervio Troclear , Ingravidez/efectos adversosRESUMEN
Mitochondria are capable of synchronized oscillations in many variables, but the underlying mechanisms are still unclear. In this study, we demonstrated that rat liver mitochondria, when exposed to a pulse of Sr2+ ions in the presence of valinomycin (a potassium ionophore) and cyclosporin A (a specific inhibitor of the permeability transition pore complex) under hypotonia, showed prolonged oscillations in K+ and Sr2+ fluxes, membrane potential, pH, matrix volume, rates of oxygen consumption and H2O2 formation. The dynamic changes in the rate of H2O2 production were in a reciprocal relationship with the respiration rate and in a direct relationship with the mitochondrial membrane potential and other indicators studied. The pre-incubation of mitochondria with Ca2+(Sr2+)-dependent phospholipase A2 inhibitors considerably suppressed the accumulation of free fatty acids, including palmitic and stearic acids, and all spontaneous Sr2+-induced cyclic changes. These data suggest that the mechanism of ion efflux from mitochondria is related to the opening of short-living pores, which can be caused by the formation of complexes between Sr2+(Ca2+) and endogenous long-chain saturated fatty acids (mainly, palmitic acid) that accumulate due to the activation of phospholipase A2 by the ions. A possible role for transient palmitate/Ca2+(Sr2+)-induced pores in the maintenance of ion homeostasis and the prevention of calcium overload in mitochondria under pathophysiological conditions is discussed.
RESUMEN
During spaceflight and immediately after it, adaptive neuroplastic changes occur in the sensorimotor structures of the central nervous system, which are associated with changes of mainly vestibular and visual signals. It is known that the movement of the eyeball in the vertical direction is carried out by muscles that are innervated by the trochlear nerve (CN IV) and the oculomotor nerve (CN III). To elucidate the cellular processes underlying the atypical vertical nystagmus that occurs under microgravity conditions, it seems necessary to study the state of these nuclei in animals in more detail after prolonged space flights. We carried out a qualitative and quantitative light-optical and ultrastructural analysis of the nuclei of the trochlear nerve in mice after a 30-day flight on the Bion-M1 biosatellite. As a result, it was shown that the dendrites of motoneurons in the nucleus of the trochlear nerve significantly reorganized their geometry and orientation under microgravity conditions. The number of dendritic branches was increased, possibly in order to amplify the reduced signal flow. To ensure such plastic changes, the number and size of mitochondria in the soma of motoneurons and in axons coming from the vestibular structures increased. Thus, the main role in the adaptation of the trochlear nucleus to microgravity conditions, apparently, belongs to the dendrites of motoneurons, which rearrange their structure and function to enhance the flow of sensory information. These results complement our knowledge of the causes of atypical nystagmus in microgravity.
Asunto(s)
Adaptación Fisiológica/fisiología , Neuronas Motoras/ultraestructura , Vuelo Espacial , Nervio Troclear/ultraestructura , Ingravidez/efectos adversos , Animales , Masculino , Ratones , Ratones Endogámicos C57BLRESUMEN
S-15176, a potent derivative of the anti-ischemic agent trimetazidine, was reported to have multiple effects on the metabolism of mitochondria. In the present work, the effect of S-15176 (1.5 mg/kg/day i.p.) on the ultrastructure and functions of liver mitochondria of C57BL/6 mice with type 2 diabetes mellitus (T2DM) induced by a high-fat diet combined with a low-dose streptozotocin injection was examined. An electron microscopy study showed that T2DM induced mitochondrial swelling and a reduction in the number of liver mitochondria. The number of mtDNA copies in the liver in T2DM decreased. The expression of Drp1 slightly increased, and that of Mfn2 and Opa1 somewhat decreased. The treatment of diabetic animals with S-15176 prevented the mitochondrial swelling, normalized the average mitochondrial size, and significantly decreased the content of the key marker of lipid peroxidation malondialdehyde in liver mitochondria. In S-15176-treated T2DM mice, a two-fold increase in the expression of the PGC-1α and a slight decrease in Drp 1 expression in the liver were observed. The respiratory control ratio, the level of mtDNA, and the number of liver mitochondria of S-15176-treated diabetic mice tended to restore. S-15176 did not affect the decrease in expression of Parkin and Opa1 in the liver of diabetic animals, but slightly suppressed the expression of these proteins in the control. The modulatory effect of S-15176 on dysfunction of liver mitochondria in T2DM can be related to the stimulation of mitochondrial biogenesis and the inhibition of lipid peroxidation in the organelles.
RESUMEN
The paper considers the effects of bedaquiline (BDQ), an antituberculous preparation of the new generation, on rat liver mitochondria. It was shown that 50⯵M BDQ inhibited mitochondrial respiration measured with substrates of complexes I and II (glutamate/malate and succinate/rotenone systems respectively) in the states V3 and VDNP. At the same time, at concentrations below 50⯵M, BDQ slightly stimulated respiration with substrates of complex I in the state V2. BDQ was also found to suppress, in a dose-dependent manner, the activity of complex II and the total activity of complexes IIâ¯+â¯III of the mitochondrial transport chain. It was discovered that at concentrations up to 10⯵M, BDQ inhibited H2O2 production in mitochondria. BDQ (10-50⯵M) suppressed the opening of Ca2+-dependent CsA-sensitive mitochondrial permeability transition pore. The latter was revealed experimentally as the inhibition of Ca2+/Pi-dependent swelling of mitochondria, suppression of cytochrome c release, and an increase in the Ca2+ capacity of the organelles. BDQ also decreased the rate of mitochondrial energy-dependent K+ transport, which was evaluated by the energy-dependent swelling of mitochondria in a K+ buffer and DNP-induced K+ efflux from the organelles. The possible mechanisms of BDQ effect of rat liver mitochondria are discussed.
Asunto(s)
Diarilquinolinas/farmacología , Mitocondrias Hepáticas/efectos de los fármacos , Animales , Antituberculosos/farmacología , Ciclosporina/metabolismo , Citocromos c/metabolismo , Transporte de Electrón , Ácido Glutámico/metabolismo , Peróxido de Hidrógeno/química , Malatos/metabolismo , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , Mitocondrias Hepáticas/metabolismo , Proteínas de Transporte de Membrana Mitocondrial , Membranas Mitocondriales/metabolismo , Poro de Transición de la Permeabilidad Mitocondrial , Dilatación Mitocondrial/efectos de los fármacos , Consumo de Oxígeno/efectos de los fármacos , Permeabilidad , Potasio/metabolismo , Ratas , Ratas Wistar , Rotenona/metabolismo , Ácido Succínico/metabolismoRESUMEN
The purpose of this study is to demonstrate the presence of three more receptors in mitochondria. Two N-methyl-d-aspartate receptor (NMDAR) subunits (NR1 and NR2B) are found by protein immunoblot and immunogold labeling in mitochondria fraction isolated from rat heart. These data allow supposing NMDAR presence and functioning in the inner mitochondrial membrane. There are no signs of receptor presence obtained in heart tissue lysate, that indicates the receptor localization exactly in mitochondria. The possible receptor functions discussed are its participation in calcium transport and in excitation-metabolism coupling. Besides, preliminary evidence is obtained of GABAA and GABAB receptors presence in heart mitochondria. One can surmise their role in metabolism regulation and their possible co-operation with NMDAR just as in the nervous system.
Asunto(s)
Mitocondrias Cardíacas/metabolismo , Receptores de GABA/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Animales , Western Blotting , Mitocondrias Cardíacas/ultraestructura , Membranas Mitocondriales/metabolismo , Subunidades de Proteína/metabolismo , Ratas WistarRESUMEN
The effect of the antimicrobial compound triclosan (5-chloro-2'-(2,4-dichlorophenoxy)phenol) on the permeability of lecithin liposomes and rat liver mitochondria was studied. It was found that triclosan was able to increase nonspecific permeability of liposomes in a dose-dependent manner, which was detected by the release of the fluorescent probe sulforhodamine B (SRB) from vesicles. A partial release of SRB occurs instantly at the moment of triclosan addition, which is followed by a slow leakage of the dye. The triclosan-induced release of SRB from liposomes grew as pH of the medium was decreased from 9.5 to 7.5. As revealed by the laurdan generalized polarization (GP) technique, triclosan increased laurdan GP in lecithin liposomes, indicating a decrease in membrane fluidity. Measurements of GP as a function of fluorescence excitation wavelength gave an ascending line for triclosan-containing liposomes, which can be interpreted as phase heterogeneity of the lipid/triclosan system. Dynamic light scattering experiments also showed that at a high triclosan-to-lipid molar ratio (~0.5), a population of smaller light-scattering particles (~0.4 of the size of liposomes) appear in the system. Experiments with rat liver mitochondria demonstrated that triclosan (10-70µM) induced a high-amplitude cyclosporin Ð-insensitive swelling of the organelles accompanied the release of cytochrome c. On the basis of the results obtained, possible mechanisms of the toxic effect of triclosan in eukaryotic cells are discussed.
Asunto(s)
Lecitinas/metabolismo , Mitocondrias Hepáticas/efectos de los fármacos , Triclosán/farmacología , Liposomas Unilamelares/metabolismo , Animales , Antiinfecciosos Locales/farmacología , Citocromos c/metabolismo , Concentración de Iones de Hidrógeno , Lecitinas/química , Microscopía Confocal , Microscopía Electrónica de Transmisión , Mitocondrias Hepáticas/metabolismo , Mitocondrias Hepáticas/ultraestructura , Dilatación Mitocondrial/efectos de los fármacos , Permeabilidad/efectos de los fármacos , Ratas Wistar , Rodaminas/metabolismo , Espectrometría de Fluorescencia , Liposomas Unilamelares/químicaRESUMEN
The purpose of this work was to study the regulative role of the glutamate receptor found earlier in the brain mitochondria. In the present work a glutamate-dependent signaling system with similar features was detected in mitochondria of the heart. The glutamate-dependent signaling system in the heart mitochondria was shown to be suppressed by γ-aminobutyric acid (GABA). The GABA receptor presence in the heart mitochondria was shown by golding with the use of antibodies to α- and ß-subunits of the receptor. The activity of glutamate receptor was assessed according to the rate of synthesis of hydrogen peroxide. The glutamate receptor in mitochondria could be activated only under conditions of hypoxic stress, which in model experiments was imitated by blocking Complex I by rotenone or fatty acids. The glutamate signal in mitochondria was shown to be calcium- and potential-dependent and the activation of the glutamate cascade was shown to be accompanied by production of hydrogen peroxide. It was discovered that H2O2 synthesis involves two complexes of the mitochondrial electron transfer system - succinate dehydrogenase (SDH) and fatty acid dehydrogenase (ETF:QO). Thus, functions of the glutamate signaling system are associated with the system of respiration-glycolysis switching (the Pasteur-Crabtree) under conditions of hypoxia.
Asunto(s)
Mitocondrias Cardíacas/metabolismo , Receptores de Glutamato/metabolismo , Animales , Hipoxia de la Célula , Respiración de la Célula , Complejo I de Transporte de Electrón/antagonistas & inhibidores , Complejo I de Transporte de Electrón/metabolismo , Flavoproteínas Transportadoras de Electrones/metabolismo , Ácido Glutámico/metabolismo , Glucólisis , Peróxido de Hidrógeno/metabolismo , Proteínas Hierro-Azufre/metabolismo , Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH/metabolismo , Ratas Wistar , Receptores de GABA-A/metabolismo , Receptores de GABA-B/metabolismo , Transducción de Señal , Succinato Deshidrogenasa/metabolismoRESUMEN
Goldfish are known to exhibit motor asymmetry due to functional asymmetry of their Mauthner neurons that induce the turns to the right or left during free swimming. It has been previously found that if the less active neuron is subjected to prolonged aimed visual stimulation via its ventral dendrite, the motor asymmetry of goldfish is inverted, testifying that this neuron becomes functionally dominant, while the size of the ventral dendrite under these conditions is reduced 2-3 times compared to its counterpart in mirror neuron. Earlier it has been also revealed that training optokinetic stimulation induces adaptation, a substantial resistance of both fish motor asymmetry and morphofunctional state of Mauthner neurons against prolonged optokinetic stimulation. The aim of this work was to study the cellular mechanisms of the effect of an unusual visual afferent input on goldfish motor asymmetry and Mauthner neuron function in norm and under adaptation. It was shown that serotonin applied onto Mauthner neurons greatly reduces their activity whereas its antagonist ondansetron increases it. Against the background of visual stimulation, serotonin strengthens functional asymmetry between neurons whereas ondansetron smoothes it. Taken together these data suggest the involvement of serotonergic excitatory synaptic transmission in the regulation of Mauthner neurons by vision. Ultrastructural study of the ventral dendrites after prolonged optokinetic stimulation has revealed depletions of numeral axo-axonal synapses with specific morphology, identified by means of immunogold label as serotonergic ones. These latter in turn are situated mainly on shaft boutons, which according to specific ultrastructural features are assigned to axo-dendritic inhibitory synapses. Thus, the excitatory serotonergic synapses seem to affect Mauthner neuron indirectly through inhibitory synapses. Further, it was morphometrically established that adaptation is accompanied by the significant decrease of active zones dimensions in both serotonergic and inhibitory synapses. Finally, it was determined in model experiments that the interaction of globular actin with glycine, a main inhibitory neurotransmitter supposedly directly and chronically affecting the ventral dendrite, results in actin filaments formation. It is assumed that glycine-induced cytosolic actin polymerization is a cause of reduction in the ventral dendrite size under stimulation. Thus, it was established that a rather small group of synapses situated on an individual dendrite of the neuron determines the execution of the important form of animal behavior.