[The time course of changes in the state of monoaminergic systems in the brain of mice under the acute hypoxia with hypercapnia]. / Dinamika izmenenii sostoianiia monoaminergicheskikh sistem golovnogo mozga myshei pod vliianiem ostroi gipoksii s giperkapniei.

In socially isolated male outbred albino mice, the changes of monoaminergic systems under acute hypoxia with hypercapnia were studied. In cerebral cortex, hippocampus and striatum of the right and left sides of the brain, the concentrations of norepinephrine, dopamine, serotonin and their metabolites - dihydroxyphenylacetic, homovanillic and 5-hydroxyindoleacetic acids were investigated using the HPLC method. In isolated mice, which were not subjected to hypoxia with hypercapnia, higher levels of dopamine and serotonin in the left cortex were found. There was no asymmetry in monoamines and their metabolites in other studied brain structures. 10 min after the onset of exposure, acute hypoxia with hypercapnia resulted in a right-sided increase in norepinephrine levels and a decrease in dopamine levels in the striatum and serotonin levels in the hippocampus. In the cerebral cortex, 10 min after of hypoxic exposure beginning, there was a left-sided decrease in the dopamine content, while the original asymmetry found in the cortex of intact animals disappeared. In isolated mice perished of hypoxia with hypercapnia, almost all parameters returned to the control level. The exception was the ratio of serotonin metabolite level to the neurotransmitter, which in the right cortex became lower than in control animals. In white outbred mice, the brain monoaminergic systems are suggested to be relatively resistant to the negative consequences of hypoxia and hypercapnia, and corresponding shifts resulting in the reflex brain response to changes in the gas composition of the respiratory air.

[The effect of acute hypoxia with hypercapnia on the content of monoamines in symmetrical areas of the brain in albino mice]. / Vliianie ostroi gipoksii s giperkapniei na soderzhanie monoaminov v simmetrichnykh strukturakh golovnogo mozga u belykh besporodnykh myshei.

Changes in the activity of monoaminergic systems of the left and right hemispheres of the brain after acute hypoxia with hypercapnia were investigated in male albino mice. The concentrations of dopamine (DA), serotonin (5-HT) and their metabolites dihydroxyphenylacetic (DOPAC), homovanilic (HVA) and 5-hydroxyindolacetic (5-HIAA) acids were measured by HPLC in the brain cortex, hippocampus and striatum of the right and the left hemispheres. In the control mice not exposed to hypoxia with hypercapnia, a higher concentration of DA in the left cortex was detected. No asymmetry in the content of other substances has been identified in the investigated structures. Acute hypoxia with hypercapnia led to the right-sided increase of DA and 5-HT levels and to the left-sided reduction DOPAC in the cerebral cortex. Under the condition of hypoxia with hypercapnia, in the hippocampus, the left-sided increase of the DA content was revealed. In the striatum the contents of monoamines and their metabolites were insignificantly changed. It has been concluded that acute hypoxia with hypercapnia causes asymmetric changes in monoaminergic systems of the archicortex and the neocortex.

[Central monoaminergic systems sensitivity to acute hypoxia with hypercapnia changes after the maintenance under the long-term social isolation]. / Izmenenie chuvstvitel'nosti tsentral'nykh monoaminergicheskikh sistem k ostroi gipoksii s giperkapniei pod vozdeistviem dlitel'noi sotsial'noi izoliatsii.

The experiments were performed in male albino outbred mice kept in a group and under the conditions of long-term social isolation. The changes in the monoaminergic systems of the left and right hemispheres of the brain after acute hypoxia with hypercapnia have been studied. The levels of dopamine (DA), serotonin (5-HT) and their metabolites - dioxyphenylacetic (DOPAC), homovanillic (HVA), and 5-hydroxyindoleacetic (5-HIAA) acids - were determined by HPLC in the cerebral cortex, hippocampus and striatum of the right and left sides of the brain. In the control mice kept both in the group and under the conditions of social isolation, a higher content of DA in the cortex of the left hemisphere has been found. In the other brain structures the monoamine content was symmetric. In the cerebral cortex of the mice in the group, acute hypoxia with hypercapnia led to a right-sided increase in the DA and 5HT levels. At the same time, the DOPAC content decreased in the left cortex. In mice in the group, under the hypoxia with hypercapnia conditions, the DA level in the left hippocampus increased. In the striatum, the content of monoamines and their metabolites did not change significantly. In animals kept for a long time under the conditions of social isolation, hypoxia with hypercapnia no statistically significant changes in the monoamines and their metabolites levels were found. It has been concluded that the preliminary maintenance under the conditions of prolonged social isolation changes the reaction of central monoaminergic systems to acute hypoxia with hypercapnia.

Effects of Oxytocin on the Levels and Metabolism of Monoamines in the Brain of White Outbred Mice during Long-Term Social Isolation.

The effects of intranasal administration of oxytocin on the levels and metabolism of monoamines in symmetrical structures of the brain of white outbred mice kept under conditions of long-term social isolation were studied by HPLC. Disappearance of initial right-sided asymmetry in the content of dopamine metabolites in the striatum, increased 5-hydroxyacetic acid content in the right striatum, and disappearance of the initial left-sided asymmetry in serotonin level in the cortex were noted; we also found a decrease in norepinephrine content in the left hippocampus with appearance of asymmetry and higher content in the right olfactory tubercle. It can be hypothesized that minor changes in the serotoninergic and dopaminergic systems against the background of high reactivity of noradrenergic system represent specific response of the brain to oxytocin in aggressive animals.

Oxytocin-Induced Changes in Monoamine Level in Symmetric Brain Structures of Isolated Aggressive C57Bl/6 Mice.

Changes in activity of monoaminergic systems of the left and right brain hemispheres after administration of saline and oxytocin were studied in male C57Bl/6 mice subjected to social isolation. The concentrations of dopamine, norepinephrine, serotonin, and their metabolites dihydroxyphenylacetic, homovanillic, and 5-hydroxyindoleacetic acids were measured in the cerebral cortex, hippocampus, olfactory tubercle, and striatum of the left and right brain hemispheres by HPLC. In isolated aggressive males treated intranasally with saline, the content of serotonin and 5-hydroxyindoleacetic acid was significantly higher in the right hippocampus. Oxytocin reduces aggression caused by long-term social isolation, but has no absolute ability to suppress this type of behavior. Oxytocin reduced dopamine content in the left cortex and serotonin content in the right hippocampus and left striatum. Furthermore, oxytocin evened the revealed asymmetry in serotonin and 5-hydroxyindoleacetic acid concentrations in the hippocampus. At the same time, asymmetry in dopamine concentration appeared in the cortex with predominance of this transmitter in the right hemisphere. The data are discussed in the context of lateralization of neurotransmitter systems responsible for intraspecific aggression caused by long-term social isolation.

[The time course of experimentally altered thyroid status manifestations in female C3H-A mice].

The female C3H-A mice with agouty fur color were used to model hyper- and hypothyroidism in the long lasting experiment. The study was carried out for 44 weeks. Hyperthyroidism was induced by the administration of the L-thyroxine injections on alternate days during the whole period of the investigation. Hypothyroidism was achieved by adding propylthiouracil to the drinking water. The change of thyroid state was characterized by biphasic change in body weight. At the beginning of the experiment the hypothyroid animals were retarding by their weight. Otherwise the hyperthyroid animals were advancing by their weight. But since the 18th-21st week the initial trends changed, i. e. the hypothyroid mice body weight started ahead the hyperthyroid one. In the open field test both hypo- and hyperthyroid animals demonstrated the higher level of the investigating activity in comparison with the euthyroid mice. In the hyperthyroid mice the frequency of side-activity acts (grooming) increased significantly. Thus, the hyperthyroid animals appeared to be more anxious. To the 18th week of the experiment the animals of study groups started to demonstrate the apparent visual difference in their fur color. The hyperthyroid mice fur color became darker than one of the hypothyroid and the euthyroid mice. It is worthy of note that the hyperthyroid mice fur color was getting lighter than one of the euthyroid animals. The results are discussed in the context of hypothalamic-pituitary-thyroid axis functioning. The possible mechanisms of hormonal regulation of the fur color in mice are considered to include the hypothalamic-pituitary-thyroid axis hormones activities.

[Effect of acute hypoxia with hypercapnia on the content of monoamines in symmetrical brain structures of the BALB/c male mice].

The changes in activity of monoaminergic systems of both the right and the left brain hemispheres of the BALB/c male mice after an acute hypoxia with hypercapnia were studied. The concentrations of dopamine, serotonin and their metabolites dihydroxyphenylacetic, homovanilic and 5-hydroxyindolacetic acids were measured by HPLC in the brain cortex, hippocampus and striatum of the right and the left hemispheres. The more high concentration of serotonin was revealed only in the cortex of the left hemisphere in control mice without hypoxia with hypercapnia. The asymmetry in dopamine level was not registered in all structures studied. Acute hypoxia with hypercapnia decreased the dopamine level in the striatum and the serotonin level both in the hippocampus and the brain cortex. The dopamine metabolites level was reduced in the striatum and in the brain cortex of hypoxed mice: both metabolites in the right brain cortex and only dihydroxyphenylacetic acid in the left br ain cortex. Serotonin metabolism was decreased in all brain structures studied after hypoxia with hypercapnia in mice. Therefore, serotoninergic system of the brain is more sensitive to acute hypoxia with hypercapnia than dopaminergic system.

Effect of amtizol on resistance of SHR mice to acute hypoxia with hypercapnia under conditions of isolated functioning of one cerebral hemisphere.

Antihypoxant amtizol (25 mg/kg) prolonged the lifespan of intact SHR mice by 46.2% under conditions of isolated functioning of one cerebral hemisphere. The effect of amtizol on sham-operated animals was less pronounced: the lifespan of mice was prolonged by just 28.1%. Injection of amtizol to mice with active right hemisphere significantly prolonged the lifespan of experimental animals (by 64.8%). The drug was ineffective under conditions of active left hemisphere: the result coincided with the lifespan of similar mice without the drug injection. Hence, antihypoxic effect of amtizol was largely determined by its effect on the right, but not the left cerebral hemisphere.

Effect of unilateral inactivation of brain hemispheres on hypoxic resistance in mice.

The effects of unilateral cortical spreading depression on the resistance to acute hypoxia with hypercapnia were studied in male SHR mice. The life-span of mice with active right hemisphere was significantly longer than that of intact, but not of sham-operated (active control) animals. Mice with active left hemisphere differed significantly from intact and active control animals. It seems that the right hemisphere supports the optimal level of resistance to hypoxia with hypercapnia, while the left hemisphere performs the "antihypoxic" function. Additional analysis found no differences between the hemispheres in mice with low hypoxic resistance. The differences between the hemispheres increased with increasing the resistance to hypoxia.

[Effect of morphine and naloxone on the biorhythm of pain sensitivity of mice after unilateral inactivation of cerebral hemispheres]. / Vliianie morfina i naloksona na bioritmy bolevoi chuvstvitel'nosti myshei posle unilateral'noi inaktivatsii bol'shikh polusharii golovnogo mozga.

The effects of morphine (5 mg/kg, i.p.) and naloxone (1 mg/kg, i.p.) on the formation of pain sensitivity biorhythms was studied in the tail-flick test on adult male SHR mice upon unilateral inactivation of cerebral hemispheres by Leao's method of spreading potassium depression. It was established that morphine changed the rhythmogenic properties of both left and right hemispheres, inverted the phase of circadian rhythm, and produced the most pronounced analgesic action in the stage of maximum pain sensitivity (minimum pain threshold). Naloxone affected the pain rhythm predominantly in the operated and right-hemisphere-active animals, which confirmed the increased role of opioids in the process of rhythm regulation in mice.

[Effect of the unilateral activation of brain hemispheres on visceral pain sensitivity in BALB/c mice]. / Vliianie unilateral'noi inaktivatsii bol'shikh polusharii golovnogo mozga na uroven' vistseral'noi bolevoi chuvstvitel'nosti myshei linii BALB/c.

A hemispheric asymmetry of the visceral pain sensitivity control was revealed in the BALB/c mice: animals with the left hemisphere inactivation did not differ from sham-operated control mice in respect to the pain response parameters. A right hemisphere inactivation reduced or suppressed the pain response. This suggests that the right hemisphere domineers in the visceral pain control.

[Left and right brain hemispheres in the regulation of pain sensitivity biorhythms in mice during stress]. / Analiz roli levogo i pravogo polusharii golovnogo mozga v reguliatsii bioritmov bolevoi chuvstvitel'nosti myshei pri stresse.

The foot-shock effects on ultradian and circadian rhythms of pain sensitivity in the SHR mice were studied after unilateral brain cortex hemisphere inactivation by means of the Leao spreading depression. Under acute painful stress, the left hemisphere partially loses its synchronizing effect on circadian rhythm and supports the 12-hour and particularly 6-hour periodicities. The left hemisphere effect dominates in intact animals under stress. The right hemisphere under the same conditions mainly loses its activating effect on circadian rhythm and supports the 8- and 16-hour periodicities. The right hemisphere effect dominates in animals under stress operated 2-3 days prior to the experiment.

[Hemispheric participation in the shaping of spatial-motor asymmetry in visual recognition in rats]. / Ob uchastii polusharii v formirovanii prostranstvenno-motornoi asimmetrii pri zritel'nom raspoznavanii u krys.

Asymmetry of movement direction was found in Wistar rats at establishing of motor alimentary conditioned reflex to simultaneously presented visual stimuli. In the course of learning the asymmetry weakened on the whole, but some individuals retained right- or left side preference. The analysis of asymmetry change before and after unilateral cortical inactivation revealed a special role of right hemisphere influences for the formation of right-side preference and of the left hemisphere--for the choice of the left direction. The lack of asymmetry was observed at the presence of the influences from the left hemisphere cortex depressing ipsilateral nigro-striate system and activating the contralateral one. Influences of the cortex of both hemispheres reduce the absolute value of the asymmetry coefficient; the left hemisphere has a special significance for manifestation of temporal asymmetry parameters. Photic interference is a factor modulating the asymmetry. It reduces the right hemisphere activity more than that of the left one; it intensifies right hemisphere influences, contributes to the involvement of the transcallosal conduction channel in the formation of spatial-motor asymmetry.

[Effect of unilateral spreading cortical depression on intraspecies aggression and sociability of isolated mice]. / Vliianie odnostoronnei korkovoi rasprostraniaiushcheisia depressii na vnutrividovuiu agressiiu i obshchitel'nost' izolirovannykh myshei.

It has been shown that aggressive forms of behaviour are controlled preferentially by the left hemisphere and sociability by the right one. Consequently, the opposite poles of the continuum "aggression-sociability" have different lateralization. Interconnection between functional interhemispheric asymmetry and aggression degree has been revealed: in high-aggressive mice the differences in the effect of left and right hemispheres inactivation are expressed stronger as compared to low-aggressive and nonaggressive animals.

[Resistance of visual recognition to interference in the intact and callosotomized rat]. / Pomekhoustoichivost' zritel'nogo raspoznavaniia u intaktnykh i kallozotomirovannykh krys.

Recognition of structured visual stimuli under the action of light interference was studied by means of conditioning in rats with intact and dissected callosal body. Addition of noise to conditioned signals was achieved by insertion of additional element into their image. It was found that as more noise was added the number of correct responses decreased and latencies of conditioned food-procuring reactions became longer. The number of individuals in the sample, which possessed a differentiation level higher than the random one decreased. Noise immunity of males in the range of weak and average noises proved to be higher than in females, and, as a rule, equal at high noises. Section of the callosal body produced changes in noise immunity of visual recognition; the nature and degree of the changes depended on the intensity of noise and on the animal's sex. The existence of modulating callosal influences on noise immunity of visual recognition is suggested.