Protective effect of adaptation to hypoxia and its prolongation by pharmacological agents in rats prone to audiogenic epilepsy

Cytophotometric determination of RNA in various brain structures of hypoxia-adapted and unadapted epilepsy-prone rats at different times after an epileptic seizure shows much smaller decreases in RNA levels and their much more rapid return to normal in the adapted than in the unadapted rats. The adaptation to hypoxia produces a marked anticonvulsive effect, and this effect is enhanced and prolonged considerably by pharmacotherapy. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 2, pp. 120–123, February, 1994     

Effect of cycloheximide on the initiation and maintenance of increased seizure readiness in the rat sensorimotor cortex

Cycloheximide does not affect the thresholds of elicitation of either direct or transcallosal responses of the sensorimotor cortex, the poststimulation elevation of brain excitability immediately after termination of the 20th series of rhythmic electrostimulations, or the diminishment of its excitability 24 h later. Cycloheximide administration does not change the latency or the duration of the first seizure discharge but does abolish the potentiation of the duration of the seizure discharges. When tested again a day later, control rats exhibit a marked decrease of the latency of the first seizure discharge and an increase of discharge amplitude as compared to the corresponding parameters in the first series of rhythmic electrostimulations. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 610–615, June, 1995     

Threshold of seizure activity of the brain and higher nervous activity in the postresuscitation period for intracerebral allotransplantation of fetal neocortex tissue

The threshold of seizure activity of the brain, long-term memory, and learning ability are studied in Wistar rats for bilateral transplantation of fetal nervous tissue in area CA1 of the hippocampus. The grafts are performed on the 2nd, 7th, 14th and 30th days after clinical death caused by asphyxia. A neurotransplantation performed on the 2nd day of the postresuscitation period is found to prevent seizure activity, whereas that performed on the 7th–14th days results in a sharp decline or cessation of spontaneous and induced epileptiform convulsive seizures, prolonged preservation of the long-term memory trace, an improvement of learning ability, and a lessening of defensive and phobic behavior in a large proportion of the animals. Translated fromByulleten's Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 234–237, February, 1996 Presented by V. A. Negovskii, Member of the Russian Academy of Medical Sciences     

Effect of the organophosphorus pesticide anthio on the blood supply to the brain

Experiments with cats using ultrasound shown that exposure to the organophosphorus compound Anthio leads to a reduction of vascular resistance of the carotid and internal maxillary arteries. The bloodflow in these arteries does not decrease for a long time. The share of bloodflow in the internal maxillary artery is increased vis-a-vis the total flow in the carotid artery. A reduction of the blood supply to the brain is observed only by the end of the experiment witb a blood pressure of 40 to 50 mm Hg. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 3, pp. 270–275, March, 1995 Presented by N. A. Agadzhanyan, Member of the Russian Academy of Medical Sciences     

Morphology of cortical structures in cerebral ischemia and its combination with audiogenic seizures

Studies of the sensorimotor and auditory areas of the brain in rats after ligation of the left common carotid artery reveal polymorphous alterations in cortical vessels, neurons, and glial cells. Compensatory reversible alterations constitute the largest group. In cerebral ischemia combined with audiogenic seizures dystrophic and destructive alterations in cortical elements become more significant. Alterations in cortical structures after bilateral ligation of the common carotid arteries are more pronounced than those occurring after unilateral occlusion. During the postseizure period after ligation of both arteries, dystrophic and destructive alterations become more severe, while reparative processes are inhibited. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 331–334, September, 1994 Presented by O. S. Adrianov, Member of the Russian Academy of Medical Sciences     

Reactivity of the conjunctival microcirculatory bed in students from various regions of the world as an indicator of adaptation of the organism

Microcirculatory vessels of the eyeball conjunctiva were examined during exercise in students from Asia, Africa, and Latin America. The reactivity of microvessels was found to be increased at the early stages of adaptation, which indicates a high-level compensatory potential of the organism. An appreciable reduction of microvessel reactivity after 1 to 2 years of university studies indicates a decrease of the compensatory potential in this period of adaptation. After 4–5 years of studies the reactivity of the microvessels is virtually the same in foreign and Russian students, this indicating the formation of a stable phase of adaptation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp. 423–426, April, 1995 Presented by N. A. Agadzhanyan, Member of the Russian Academy of Medical Sciences     

Effect of pulsed infrared laser radiation on DNA synthesis in tissues of intact rats and during strenuous physical exercise

The motor zone of the rat brain cortex is subjected to pulsed infrared (0.89 μ) laser radiation, which is found to stimulate DNA synthesis both in intact animals and after strenuous physical exercise (swimming). Preliminary laser irradiation exerts a stress-limiting effect on cells of the brain cortex and thymus but does not prevent swimminginduced reduction of³H-thymidine incorporation in nuclear DNA of muscles. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 625–627, June, 1995 Presented by V. M. Bogolyubov, Member of the Russian Academy of Medical Sciences     

Analysis of changes in the electroencephalogram power spectrum on a new model of brain ischemia in rats

The bioelectrical activity is studied in the left and right parietal cortex by recording the power spectrum of the electroencephalogram in brain ischemia caused by complete ligation of the left common carotid artery and 50% reduction of the blood flow in the right common carotid artery in experiments carried out on nonnarcotized Wistar rats. Ischemia results in marked and stable disorders in the bioelectrical activity manifested in a decrease of the total EEG power, depression of the dominating frequency in the Θ-range, increase of the δ-range power, and interhemispheric asymmetry of some spectrogram parameters. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny Vol. 118, N ^o 12, pp. 565–567, December, 1994 Presented by E. D. Gol'dberg, Member of the Russian Academy of Medical Sciences     

Antenatal effects of ethanol and limontar on lipid peroxidation and the antioxidant defense system in the brain and liver of rat progeny

In contrast to short-term exposure, prolonged exposure to ethanol in the anternatal period is found to inhibit lipid peroxidation in the brain and liver of rats. Activation of the system of antioxidant defense in the brain and liver is observed after both short-and long-term exposure to ethanol. After short-term ethanol exposure, limontar normalizes lipid peroxidation. Translated fromByulleten' Eksperimental'noii Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 41–44, January, 1994 Presented by M. Ya. Studenikin, Member of the Russian Academy of Medical Sciences     

The effect of morphine on RNA synthesis in some brain structures of rats with various narcological resistance

Different incorporation of³H-uridine in RNA and increased RNA synthesis after the addition of morphine are demonstrated in all brain structures of resistant rats, as well as in the cortex, nucleus accumbens, griseum centrale, and nucleus ventriculus hypothalami of prone rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 100–102, January, 1994     

The microcirculatory bed of hamster cheek pouches after occlusion of the common carotid arteries

The responses of hamster cheek pouch microvessels after occlusion of the common carotid artery on the ipsilateral side are compared. It is found that under conditions of limited inflow the microvessels preserve the inflow on the left side and the outflow on the right side, with venular constriction predominating in the left cheek and arteriolar in the right. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 144–147, February, 1996 Presented by V. V. Kupriyanov, Member of the Russian Academy of Medical Sciences)     

Rat brain gangliosides during hypoxia

The content and composition of rat brain gangliosides in various forms of hypoxia is studied. The content of lipid-bound sialic acid is found to be considerably elevated in the earliest stages of hypoxia combined with hypercapnia and cooling. The content of gangliosides remains elevated over the hypoxia period and returns to control values 48 hours after its discontinuation. Repeated hypoxia results in the same changes in rat brain gangliosides. Hemic sodium nitrite-induced hypoxia also leads to a reliable elevation of these lipids. Hypoxia also causes changes in the content of individual ganglioside fractions: a decreased content of mono- and an increased content of polysialogangliosides. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 7 pp. 19–21, July, 1994 Presented by A. N. Klimov, Member of the Russian Academy of Medical Sciences     

Effect of cytochromec on the necrosis zone in transitory myocardial ischemia

The cardioprotector effect of cytochromec during a 15-min complete blocking of the anterior descending branch of the left coronary artery was studied in rat experiments. Cytochromec in a dose of 20 mg/kg was found to noticeably reduce the necrosis zone 4 h after transitory ischemia. The protective effect of a single injection of cytochromec was virtually undetectable after 72, h, this pointing to the need for a course of treatment. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o , 4, pp. 439–440, April, 1994     

Effect of paraoxon and sulfhydryl reagents on3H-quinuclidinol benzoate and3H-methylscopolamine with synaptic membranes of rat brain

Paraoxon is shown to reduce the density of M-choline receptors in the cortex of rat brain. Inhibition of³H-QNB is noncompetitive and reversible in nature. Sulfhydryl reagents do not affect this process. The mechanism of action of PO is thought to include direct effects on brain muscarine receptors. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 7, pp. 51–53, July, 1994     

Transplantation of fetal nerve cells from insects to the brain of amphibians and mammals

Cells of the neural primordia of the Notch mutant ofDrosophila melanogaster are transplanted to the neural tube of four amphibian species and two mammalian species. It is shown that cells of the neural primordia of drosophila survive and differentiate in the amphibian and mammalian brain. Differentiated cells of the transplant establish axon-dendrite junctions with cells of the recipient and penetrate into the structures of its brain. Tailed amphibians die several days after xenotransplantation. Transplantation of drosophila cells to the nervous system of tailless amphibians and mammals does not cause developmental abnormalities or death of the animals. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 4, pp. 364–368, April, 1994 Presented by N. K. Permyakov, Member of the Russian Academy of Medical Sciences     

Structural and functional changes in the brain of rats with different behavioral types at later stages of circulatory hypoxia

Structural changes in the brain were studied at later (one and three months) stages of cerebral hypoxia caused by occlusion of the common carotid arteries, which were indicative of the development of recovery and destructive processes. Brain ultrastructure was found to be better preserved in rats with an active type of behavior one month after the onset of ischemia than in rats of the other groups; motor activity was restored to the baseline level, thus demonstrating a higher rate of recovery processes. Significant ultrastructural damage to the brain at the same stage of ischemia was observed in rats with a passive type of behavior (especially in rats of the middle group), while motor activity was increased. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 11, pp. 529–534, November, 1994 Presented by P. V. Simonov, Member of the Russian Academy of Sciences     

Protective action of M- and N-cholinoceptor blockers in acute ammonium intoxication

Atropine and d-tubocurarine are shown to prevent convulsions in rats and mice poisoned by ammonium acetate and to protect these animals from its toxic effects. Ammonium and lactate levels in their brain were found to correlate directly with ammonium toxicity. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 11, pp. 489–492, November, 1995     

Mice selected for low brain weight show heightened sensitivity to the convulsive action of pentylenetetrazole

Convulsive activity of pentylenetetrazole (25–120 mg/kg) measured in mice selected for large or small brain weight was evaluated, and mice with a smaller brain weight proved to be more susceptible to the damaging action of this compound than those with a larger weight. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5, pp. 460–462, May, 1995 Presented by V. S. Rusinov, Member of the Russian Academy of Medical Sciences     

Effect of nimodipine on the circulation in the midbrain and carotid arteries of rats

It is found that nimodipine induces biphasic changes in the circulation in the midbrain artery: an initial slight and transient reduction gives way to a considerable and long-term increase of the circulation. Nimodipine also boosts the circulation in the common and internal carotid arteries, which coincides in time with, but is shorter than, the first phase of changes in the hemodynamics in the midbrain artery. The findings are not consistent with the common view on the selectivity of the cerebrovascular effect of nimodipine. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 410–413, October, 1994 Presented by M. D. Mashkovskii, Member of the Russian Academy of Medical Sciences     

Effects of adaptation to hypoxia on cytochrome levels in the brain and liver of rats

After a prolonged (for 30 days) adaptation of rats to intermittent hypoxia, their brains contained lowered levels of mitochondrial cytochromes, despite an increase in the number of mitochondria in the brain tissue mass, along with similar levels of high-energy compounds and more protein as compaired to the brains of unadapted controls. A mitochondrial population with novel properties presumably emerged in the brain. These effects were all more strongly marked in rats with an initially low resistance to hypoxia. In the liver of hypoxiaadapted animals, unlike in their brain, cytochrome levels in the mitochondrial and microsomal redox chains were lowered and the biogenesis of mitochondria was much less intensive. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 12, pp. 576–579, December, 1995