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ABSTRACT: The expression of mitochondrial protein UCP2 and cytochrome C-oxidase subunit III genes in the hippocampus and prefrontal cortex was evaluated by real-time PCR 3 and 7 days after microinjection of kainic acid into the dorsal hippocampus. In contrast to cytochrome C-oxidase subunit III mRNA, the level of UCP2 mRNA in the hippocampus increased 1 week after microinjection of kainic acid. The expression of both genes in the prefrontal cortex did not differ from the control. Presumably, activation of UCP2 synthesis in hippocampal injury indicates the neuroprotective effects of this protein.
Bulletin of Experimental Biology and Medicine 12/2010; 150(2):185-7. · 0.27 Impact Factor
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ABSTRACT: The expression of synaptophysin (vesicular protein) and mGluR5 (metabotropic glutamate receptor) genes was studied 3, 7, and 20 days after cainic acid injury of the dorsal hippocampal area in Wistar rats. The expression of both genes was characteristically reduced in the hippocampus. Twenty days after the exposure the expression of mGluR5 in this brain area reached the control level, while synaptophysin expression remained low. An opposite trend was observed in the frontal cortex: synaptophysin expression 20 days after exposure did not differ from the control, while mGluR5 expression was reduced. The peculiar time course of both genes' expression in the hippocampus and frontal cortex indicates the involvement of the frontal cortex in mechanisms of functional recovery after hippocampal injuries.
Bulletin of Experimental Biology and Medicine 03/2009; 147(2):236-9. · 0.27 Impact Factor
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ABSTRACT: We studied behavioral reactions of rats after injection of subconvulsive dose of kainic acid into the frontal cortex and mitochondrial respiration in the hippocampus and frontal and temporal cortex 17-20 days after administration of kainic acid. Retention of acquired habit and the dynamics of its extinction in experimental rats were close to those in the control group. Changes in mitochondrial function were observed only in the region of kainic acid injection: activation of phosphorylating respiration during oxidation of succinate. Presumably, the detected activation of energy metabolism in the frontal cortex indicates functional restructuring in mitochondria, aimed at compensation of disorders caused by the neurotoxin.
Bulletin of Experimental Biology and Medicine 12/2007; 144(5):670-3. · 0.27 Impact Factor
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ABSTRACT: Single administration of kainic acid to Wistar rats impaired quenching of the conditioned response and increased the number of perseverative reactions 2 weeks postinjection. Indomethacin prevented behavioral disturbances induced by kainic acid.
Bulletin of Experimental Biology and Medicine 03/2006; 141(2):208-10. · 0.27 Impact Factor
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ABSTRACT: The effects of the neurotoxin kainic acid on a food-producing habit were studied in Wistar rats in an experimental chamber. Single doses of kainic acid at a subconvulsive dose (8 mg/kg, i.p.) were found to impair the habit, onset of impairment being delayed by several weeks rather than immediate. Conversely, administration of the neurotoxin at the convulsive dose (10 mg/kg) impaired reproduction of the habit with onset within several hours after treatment and persistence for periods of up to 10 days, though this dose did not prevent the acquisition of a new food-procuring habit. These defects in the reproduction of long-term memory traces were explained in terms of the characteristics of the effects of kainic acid on the hippocampal system, which is the most susceptible to systemic administration of the neurotoxin.
Neuroscience and Behavioral Physiology 11/2005; 35(8):829-34.
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ABSTRACT: Lipid composition of homogenate and neuronal and glial nuclei of the brain cortex of Wistar rats was studied under normal conditions and after seizures induced by injection of picrotoxin. Seizures increased contents of lysophosphatidylcholine, sphingomyelin, and total phospholipids in the homogenate. In neuronal nuclei contents of total phospholipids, sphingomyelin, phosphatidylcholine, and phosphatidylserine decreased, and contents of free fatty acids and lysophosphatidylcholine increased. In glial nuclei content of total phospholipids decreased and content of free fatty acids increased. The role of changes in the lipid composition of the neocortex cells during seizures and the involvement of lipid messengers in signal mechanisms are discussed.
Biochemistry (Moscow) 11/2004; 69(10):1143-7. · 1.06 Impact Factor
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ABSTRACT: Effect of the neurotoxin kainic acid to the food-procuring task were studied in Wistar rats. A single injection of the acid in subconvulsive dose (8 mg/kg) impaired the task performance within some weeks but not immediately after the treatment. Higher doses of kainic acid (10 mg/kg) impaired the task performance within a few hours after treatment for up to 10 days. The treatment did not prevent rat's learning of a new task in the same experimental chamber. The revealed deficit in the long-term memory retrieval might be explained by specific effects of kainic acid upon the hippocampal system.
Rossiĭskii fiziologicheskiĭ zhurnal imeni I.M. Sechenova / Rossiĭskaia akademiia nauk 08/2004; 90(7):849-56.
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ABSTRACT: Wistar rats were trained food-procuring task for 5 days and then extinction of the operant behavior was studied for 6 days after injection of an epileptogen (kainic acid, 8 mg/kg, intraperitoneally). Kainic acid induced long-term impairment of inhibitory processes in the brain, which impeded extinction of a conditioned response. This effect was prevented by daily injections of anticonvulsant sodium valproate (300 mg/kg for 4 days).
Bulletin of Experimental Biology and Medicine 07/2002; 133(6):553-5. · 0.27 Impact Factor
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ABSTRACT: The content of lipids in rat cortical tissue homogenate and fraction of neuronal nuclei was determined under normal conditions and after picrotoxin-induced seizures. Changes in lipid composition of homogenate and nuclear fraction differed considerably. In homogenate, the content of sphingomyelin, lysophosphatidylcholine, and total phospholipids increased, while the content of free fatty acid remained unchanged; in the nuclear fraction the total phospholipid content decreased, while the concentration of free fatty acids increased.
Bulletin of Experimental Biology and Medicine 10/2000; 130(9):864-6. · 0.27 Impact Factor
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V I Arkhipov
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ABSTRACT: The stage of retrieving long-term memory traces is discussed; studies of this stage can be performed using the phenomenon of dissociated brain states. These states arise in response to various external influences and are accompanied by selective, reversible derangements of retrieval processes without alteration of the mechanisms involved in perceiving and fixing information. Analysis of the appearance of dissociated states induced by pharmacological treatments leads to several conclusion: a) reversible derangements affecting the retrieval function are typical of types of memory which depend on attention; b) the hippocampus plays a key role in selecting engrams for extraction from long-term memory; c) the brain's cholinergic and GABAergic mediator systems are involved in regulating the retrieval of long-term memory traces; d) stable derangements of the retrieval of long-term memory traces are accompanied by deep molecular-cellular changes in the hippocampus, including alterations in genetic elements and phosphorylation of synaptic proteins.
Neuroscience and Behavioral Physiology 10/1999; 29(6):703-9.
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ABSTRACT: The possibility of the use of saponin for permeabilization of synaptic vesicles from P2 fraction is explored. This fraction is isolated from rat brain cortex. Phosphorylation of membrane-bound proteins is performedin vitro. At the saponin:protein ratio 1:10 (w/w) phosphorylation of these proteins increases 2-fold due to increased membrane permeability
for ATP and cAMP. Treatment of synaptic vesicles with saponin at the same ratio leads to the loss of cytosolic but not membrane-bound
protein. This concentration of saponin can be used for permeabilization of other membranes, providing that the protein:cholesterol
ratio is taken into consideration.
Bulletin of Experimental Biology and Medicine 09/1996; 122(4):1044-1046. · 0.27 Impact Factor
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ABSTRACT: In vitro protein phosphorylation of synaptic membranes isolated from neocortex and hippocampus of ground squirrels was studied. Three functional states of animals were investigated: torpid, awakened and active normothermic. Phosphorylation of a protein with a mol. wt of 53 kDa was independent on the functional state of the animals. Incorporation of 32P into this protein was greater in membranes of torpid and awakened squirrels than in membranes of active animals. These results suggest that protein phosphorylation is involved in the maintenance of membrane functions during hibernation.
Neuroreport 01/1996; 7(1):278-80. · 1.66 Impact Factor
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ABSTRACT: In the present investigation the functional activity of transport systems mediating the GABA and L-glutamate uptake into nerve terminals of the rat brain cortex and hippocampus in response to a single carbacholine administration to hippocampus was studied. It has been established that synaptosomes isolated from the brain cortex and hippocampus of rats used in the experiments 24 h after a single carbacholine injection possess an increased capability of GABA and L-glutamate accumulation, and 48 h later the GABA and L-glutamate uptake begins to return to its control level and was equal to it on seventh day after injection.
Behavioral and Neural Biology 06/1994; 61(3):214-7.
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V I Arkhipov
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ABSTRACT: Dissociated learning of rats in the normal state and the state of amnesia produced by pentobarbital (15 mg/kg, ip) was carried out. Rats were trained to approach a shelf where they received food reinforcement. In Group 1 the rats were trained under the influence of pentobarbital to run to the same shelf as in the normal state. In Group 2 the rats were trained to approach different shelves in different drug states. It was shown that memory dissociation occurred in both groups. Differences in the parameters of training under the influence of pentobarbital between Groups 1 and 2 were revealed. These findings show that the brain-dissociated state induced by pentobarbital is formed with the participation of the mechanisms of information perception.
Behavioral and Neural Biology 06/1992; 57(3):244-7.
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Neuroscience and Behavioral Physiology 22(1):51-6.
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ABSTRACT: 1. Uptake of [3H]uridine into the nucleotide precursor pool after intraventricular injection occurs with the same intensity in the brain of torpid and normothermic awakened ground squirrels. This indicates that the membrane uridine transporters and uridine kinases operate in the hibernator's brain in a hypothermia-tolerant way. 2. Utilization of the [3H]uridine pool for synthesis of the rapidly labelled RNA in the brain of torpid ground squirrels falls more than eight times against RNA labelling in the brain of the active animals between bouts of hibernation. 3. Two hours from the beginning of the artificially provoked awakening, RNA uridine incorporation in the brain of ground squirrels has risen 6.5 times. 4. Drastic changes in [3H]uridine RNA labelling under the stable uridine uptake exclude the precursors and energy supply as the main factors determining changes in intensity of the brain RNA synthesis in the different stages of hibernation.
Comparative biochemistry and physiology. B, Comparative biochemistry 101(1-2):189-92.
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ABSTRACT: Cognitive processes and functional state of mitochondria in brain structures of Wistar rats were studied after intrahippocampal injection of kainic acid, an agonist of glutamate receptors. A single administration of 0.25 microg kainic acid into the dorsal part of the left and right hippocampi affected task retrieval and decreased inhibition of unrewarded responses. The injection of 0.75 microg kainic acid induced recurrent seizures and completely disorganized animal behavior. The functional state of mitochondria, as an important marker of excitotoxicity, was studied after intrahippocampal injections of kainic acid in the same doses. Kainic acid at 0.25 microg proved to activate the oxidative phosphorylation in hippocampal mitochondria. A higher (epileptogenic) dose of kainic acid inhibited mitochondrial respiration in the frontal cortex, but had an insignificant effect on mitochondrial respiration in the hippocampus. The disturbed interaction between the hippocampal system and frontal cortex after kainic acid administration can be the main factor of the revealed cognitive dysfunctions.
Izvestiia Akademii nauk. Seriia biologicheskaia / Rossiiskaia akademiia nauk
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V I Arkhipov
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ABSTRACT: A minireview of some questions raised in experimental studies of memory. The problems of the functional significance of long-term potentiation, the hippocampus as a cognitive map, selective attention and the neuronal theta rhythm in the hippocampus and others are discussed on the basis of O.S. Vinogradova's works.
Zhurnal vysshei nervnoi deiatelnosti imeni I P Pavlova 54(1):5-10. · 0.33 Impact Factor
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V I Arkhipov
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ABSTRACT: Phenomenon of memory dissociation is proposed as a paradigm for studying the retrieval processes of the long-term memory. The memory-dissociated states of brain are produced by external influence and result in selective reversible disturbances of the retrieval processes without substantial changes in perception and storage of new information. Analysis of dissociated states induced by pharmacological influences has led us to the following conclusions: 1) the reversible failures of the retrieval processes are usual for the attention-dependent form of long-term memory, 2) hippocampus is the key structure in brain mechanisms that realize the engram selection during memory retrieval, 3) the central cholinergic and GABAergic systems regulate the retrieval of information, 4) steady disturbances of retrieval of the long-term attention-dependent memory are accompanied by strongly pronounced changes in hippocampal cells including those at the membrane and genomic levels.
Zhurnal vysshei nervnoi deiatelnosti imeni I P Pavlova 48(5):836-45. · 0.33 Impact Factor
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ABSTRACT: Learning and memory disorders accompanying epileptogenesis were studied in rats with the use of two experimental models of epilepsy, picrotoxin kindling and kainic treatment. Rise of exploratory activity and decrease in animal's capability for experimental extinction of a response were characteristic of the initial stage of epileptogenesis. It was suggested that a dysfunction of brain hippocampal system can be responsible for cognitive disorders. To reveal their mechanisms, lipid contents were determined in the neocortex and hippocampus in appropriate periods after exposure to epileptogenic factors. Long-term changes in hippocampal lipid spectrum were found five days after the exposure to kainic acid. In particular, after sodium valproate treatment (the compensation of kainic effects), the total content of phospholipids in hippocampus was decreased. The hippocampal sphingomyelin level dropped as a result of picrotoxin kindling. The sphingomyelin changes suggest some recovery processes in hippocampal cells and point to an adaptive role of membrane lipids in the mechanisms of the damaging epiptogenous effects.
Zhurnal vysshei nervnoi deiatelnosti imeni I P Pavlova 54(2):202-9. · 0.33 Impact Factor
