[Moving activity and wakefulness-sleep cycle changes in a mouse MPTP model of Parkinson's disease].

A group of mice with preliminary implanted (under general anesthesia) electrodes for cortical EEG and nuchal EMG was subjected to continuous baseline 24-hr video and digital polysomnographic recording with the 12/12 light/dark schedule, and then injected subcutaneously with 24 or 48 mg/kg of MPTP toxin or (the control group) saline. The recordings were continued for 2 weeks more. A significant increase in activity and the waking percentage as well as decrease in REM sleep and NREM sleep (tendency) during the dark period as compared to the baseline and control recordings was found. The effect was seen just on the 7th day following MPTP administration and became significant by the 14th day. The effect was more pronounced after 48 mg/kg injection than after 24. There were no changes during the light period. Morphological control revealed a 70% and 35% decreases in the amount of tyrosine hydroxylase positive neurons in substancia nigra/pars compacta after 48 and 24 mg/kg of MPTP, respectively, as compared to the saline group.

[Brain and sleep: from neurons - to the molecules].

Disputable questions of modern somnology, the neuroscience branch involving wakefulness-sleep cycle regulation, circadian and diurnal rhythms and other related problems, are regarded. Among them are the questions of the extent of similarity of the alternation of active-rest periods in the nematode, fruit fly, zebrafish and other simple model organisms to the waking-sleeping rhythm in warm-blooded animals (birds and mammals); the relation between molecular-biological and electrophysiological events in sleep-wake cycle; the role of paradoxical (REM) sleep in early ontogenesis; biochemical features of slow wave and paradoxical sleep.

[The role of histaminergic system of the brain in the regulation of sleep-wakefulness cycle].

The structure, morphological and neurochemical bindings ofhistaminergic system of the brain as one of the most important mechanisms of waking maintenance, are regarded. The biochemistry of histamine turnover and histamine receptors are briefly described. The special role of the relation between histamine and orexin/hypocretin systems is stressed. Some examples of the responses on wakefulness-sleep cycle of the effects of experimental manipulations with the histaminergic system are given.

[Molecular changes in inbred mice with individual vulnerability vs resilience to stress-induced depressive-like state].

The C57BL/6 mice were subjected to a chronic combined stress which resulted in the induction of a depressive-like state. The occurrence of a depressive-like state was defined by a decrease in sensitivity to the reward determined by the diminished preference of sweetened solutions over regular drinking water. Such decrease is generally considered as a sign of an unhedonic-like state: one of the key features of clinical depression. Applied here, the paradigm in mice allows unhedonia induction in a subpopulation of stressed animals (54% in the current study); remaining mice are regarded as resilient to stress-induced hedonic deficit. The resilient subgroup is taken, therefore, as a "functional control" for those effects of stress that are not accompanied by development of the stress-induced depressive-like state in mice. The analysis of the mRNA extracted from the hippocampi of stress-subjected and home-cage control mice enabled the assessment of gene expression level of over 13 000 genes. This study showed that unhedonic mice are characterized by an up-regulation of 278 and down-regulation of 174 genes related mostly to the CNS development and functions, inter-cellular interactions and signalling, neurological disorders, apoptosis and behavioural regulation. Resilient animals demonstrated up-regulation of 924 and down-regulation of only 29 genes that control formation of cell assemblies, molecular transport, CNS functioning, neurological disorders and various biochemical reactions. Thus, gene expression profiles in the hippocampus of susceptible vs resilient to stress-induced unhedonia inbred subgroups of animals are strictly distinct in both quantity and quality.

[Central mechanisms of sleep-wakefulness cycle].

Brief anatomical, physiological and neurochemical basics of the regulation of wakefulness, slow wave (NREM) sleep and paradoxical (REM) sleep are regarded as representing by the end of the first decade of the second millennium.

[Sleep deprivation effect upon spatial memory consolidation in rats after one-day learning in a Morris water maze].

The effect of sleep deprivation by 'carousel' method on spatial memory consolidation in a Morris water maze was studied in Wistar male rats after one-day learning (in accordance to a protocol by Frick et al., 2000). It was found that after fast 3-hr learning the memory trace retains during 24-hr. Twenty four hour sleep deprivation followed learning impaired consolidation of spatial memory. So the rat model of a one-day learning is suitable for the studying of neurophysiological mechanisms of sleep deprivation effects on spatial memory consolidation.

[Genetics of sleep].

Main achievements in general and molecular genetics of sleep, especially NREM sleep, are regarded. Among them, discovery of such heredity disorders, as FFI, FASPS and DSPS, the finding of genetic hallmarks of sleep EEG, etc.

Convulsive activity in the electroencephalogram in rats sensitive and tolerant to pentylenetetrazol kindling.

Studies on rats divided into two groups with different sensitivities on the basis of manifest convulsive activity in response to pentylenetetrazol kindling showed that both "tolerant" and "sensitive" rats showed convulsive discharges on EEG traces. However, as compared with values in "tolerant" rats, the number of convulsive discharges in "sensitive" rats was 60% greater, convulsive discharges occurred 45 sec later, and had a duration in the first 45 post-injection minutes which was 70% longer. There was no difference between the mean durations of convulsive discharges in the two groups. The EEG frequency power peak in "tolerant" rats was more marked than that in "sensitive" animals, and was located at 7.2 Hz. These data led to the conclusion that pentylenetetrazol kindling induces epileptic activity on the EEG in rats independently of whether or not the animals showed behavioral seizures, though there were significant differences in measures of this activity in "sensitive" and "tolerant" rats.

[Effect of the exposure to factors inducing diffuse damage of cerebral tissue on sleep structure in laboratory rats].

Effects of strong stress inducing diffuse damage of the brain tissue on subsequent sleep were studied in rats preliminary implanted with chronic electrodes for the neocortical and hippocampal EEG as well as EMG of the neck muscles. An acute and three chronic experimental models were used: general cerebral ischemia induced by a permanent unilateral occlusion of the common carotid artery, hypoxic hypoxia, hypoglycemia, and "penicillinium" epilepsy. Polysomnographic recording was performed either continuously within 24 hrs (in case of the chronic stress model) or 3 hrs daily: from 09 to 12 a.m. (for three acute stress models). In all the models, a significant increase in the paradoxical sleep (PS) percentage was found which reached its maximum within 1-3 days since stress exposure. The following changes were found to be dependent upon the character of the stress factor. In acute stress models, the PS percentage returned to the baseline level within 5-6 days. In the chronic model, the PS percentage returned to baseline level on the 40-45th day after the day of occlusion. The sharp increase in the PS percentage following the exposure to stress factors inducing cerebral tissue damage corroborate the hypothesis of an increase in neural tissue restitution processes during PS periods.

[Seizure activity in the EEG of rats sensitive and resistant to pentylenetetrazol kindling].

Rats were subjected to pentylenetetrazol kindling and divided into 2 groups according to their ability to demonstrate convulsions: the "sensitive" and "tresistant" rats groups. Both groups demonstrated EEG afterdischarges; however, the number of the EEG seizures in "sensitive" rats was 60% higher, the latency by 45 sec longer, and the total duration during the first 45 min after injection 70% longer as compared to the "resistant" rats. The average duration of a single EEG seizure did not differ in these groups. The average EEG frequency power peak at 7.2 Hz was more pronounced in the "resistant" group. Thus, pentylenetetrazol kindling induces epileptiform activity in the rat EEG irrespective of the appearance of behavioral seizures; however, characteristics of this activity differ significantly between the "sensitive" and "resistant" rats.

[Depressive-like state and sleep in laboratory mice].

In order to induce the state of anhedonia, a key symptom of depression, mice were subjected to a one-month stress procedure comprised of various stressors. Anhedonic state was defined by a reduction of preference for sucrose solution over tap water. Conventional cortical and neck-muscle electrodes were implanted to control and stressed animals under chloral-hydrate anesthesia. After a two-week recovery and habituation period, mice from chronically stressed group were re-subjected to five-day stress, and the anhedonic state was verified. As not all the stressed mice displayed a decrease in sucrose preference, animals were divided in two groups: stressed-non-anhedonic and stressed-anhedonic animals. Seven-day continuous polygraphic recording was carried out in animals from both stressed groups and the control group in recording chambers under conditions of 12/12-hour light/dark schedule. The anhedonic mice demonstrated a significant advanced shift in circadian distribution of paradoxical sleep and increased amount of paradoxical sleep during the light period. In the course of the dark period, the anhedonic group showed a slight but significant decrease in total amount of slow-wave sleep as compared to the non-anhedonic and control groups. The results suggest that the changes in sleep structure documented in the model of anhedonia are similar to those described for human depression.

Actions of pulsed ultra-broadband electromagnetic irradiation on the EEG and sleep in laboratory animals.

Irradiation of animals with ultrashort impulses of ultra-broadband magnetic irradiation with an impulse repetition frequency of 6 Hz for 1 h induced changes in the spectral composition of cerebral cortex electrical activity in rats, measured over the 5 min immediately after irradiation, as compared with controls. In particular, there was suppression of frequencies close to the impulse sequence frequency, along with a decrease in interhemisphere coherence. Continuous recording of polygrams for 22 h from rabbits after irradiation revealed a "delayed" effect--a significant increase in paradoxical sleep, starting 16 h after the end of irradiation and persisting to the end of the recording period. It is suggested that irradiation has a direct action both on the mechanisms of generation of the theta rhythm (septohippocampal) and on the system controlling circadian rhythms (the suprachiasmatic nucleus-epiphysis system).

[Effect of impulse extrabroad-band electromagnetic radiation on electroencephalogram and sleep in laboratory animals]. / Deistvie impul'snogo sverkhshirokopolosnogo izlucheniia na élektroéntsefalogrammu i son laboratornykh zhivotnykh.

1-hour exposure to ultra-short impulse low-frequency (6 Hz) superbroad band electromagnetic radiation altered cortical EEG in rats just after the exposure and increased the paradoxical sleep in rabbits within 16-22 hours following the radiation.

[Hypnogenic properties of DSIP peptide analogs: structural-functional relationship]. / Gipnogennye svoistva analogov peptida DSIP: strukturno-funktsional'nye vzaimootnosheniia.

The sleep-inducing activity of Delta Sleep-Inducing Peptide (DSIP) and its 13 synthetic analogs has been studied on rabbits with preliminary implanted electrodes. The peptides were injected into the lateral ventricle of cerebrum. Polygraphic computer monitoring of sleep-wake states was carried out at daytime for 7-12 h. DSIP and most analogs had no statistically significant effect on sleep compared to the control administration of saline to the same animals. [NMeAla2]DSIP and [Pro2]DSIP had a pronounced sleep-inducing effect and reliably increased the proportion of slow-wave sleep by 10-15% on average compared to the control. Several other analogs had a week sleep-inducing effect, increasing the proportion of slow-wave sleep during specific recording time only. [beta-Ala2]DSIP significantly suppressed sleep. In addition, this analog, as well as parent DSIP and four proline-containing nonapeptides, slightly increased the body temperature. The revealed differences may be due to both conformation properties and proteolytic resistance of the studied molecules, and it may reflect their indirect involvement in the control sleep-wake hormonal processes.

[Emotional stress and sleep: a study of adrenalectomized rats]. / Emotsional'noe napriazhenie i son: izuchenie u adrenaléktomirovannykh krys.

Polygraphic recordings were performed during 12-h dark period in 18 adrenalectomized rats with implanted electrodes for ECoG and EMG under normal conditions and following 1-h immobilization period. The exposure of rats to emotional immobilization stress evoked a highly significant increase in sleep which was especially pronounced for the slow wave sleep (about 40% above the control value). The immobilization effect was completely abolished by preliminary treatment with dexametazone (1 mg/kg subcutaneously). Thus, adrenal steroids are involved into the interrelation between the emotional stress and sleep as a link in a negative feedback loop.

[Muramyl peptides and sleep]. / Muramil-peptidy i son.

Effects of muramyl peptides from bacterial cell walls (MDP and GMDP), their fragments, steric isomers and structural analogues were studied on sleep in rabbits. An increase in the SWS, decrease in PS, rise in body temperature were found following minimal doses, whereas pathological responses in the EEG and sleep as well as pyrogenic effects occurred after higher doses. The GMDP analogues affected sleep weakly, and isomers and fragments were inactive. Possible role of muramyl peptides in normal and pathological regulation of sleep is discussed.