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Background: Alzheimer is a Progressive dementia disease along with destruction of brain neurons and severe deficiency of memory. The present work was designed to assess the effect of the maze training in improvement of learning behavior of the Alzheimeric rats. Materials and Methods: This experimental study was carried out on 20 Wistar male rats randomly divided in 2 groups. One group that receiving a dose of beta-amyloid intraventriculrly characterized as alzheimeric rats (ALZ). In the control group (CO) the animals were injected saline at the same volume. To assess spatial learning of the animals in the first phase of the experiment they were introduced to the Morris water maze to locate on fixed hidden platform during 4 trials/day for 5 days. Probe test was applied to evaluate the memory retrieval. In the second phase the same procedure was repeated after 20 days. The measured parameters were the time elapsed and distance passed in during the maze searching. Results: Our findings indicated that in the first phase of experiment, the time elapsed and distance passed for the CO group were decreased compared to the ALZ group. In the second phase, however, significant variation was observable between the two tested groups. There was no significant difference between the performance of the CO and ALZ groups in probe trial testing. Conclusion: It seems that the behavioral training positively influenced the maze learning in the ALZ subjects so that however both groups behaved similarly in the second phase of the experiment. [ABSTRACT FROM AUTHOR]

Numerous experimental and clinical studies have shown high efficiency of plant polyphenolic compounds in restoring age-related memory and learning disorders. In the present study a functional food ingredient (FFI) was obtained by sorption of an aqueous solution of bilberry leaves extract on buckwheat flour, which allowed to concentrate polyphenols and increase their storage stability. The aim of this study was to evaluate the impact of a developed FFI, enriched with bilberry leaves` polyphenols, on the anxiety level, locomotor activity, memory and spatial learning of db/db mice with genetical type 2 diabetes. Material and methods . The experiment was conducted using 10 heterozygote male db/db mice and 10 homozygote male db/+ mice as the comparison control group (7 weeks of age). According to body weight, blood glucose level, the results of insulin resistance test and elevated plus-maze (EPM) test, animals were randomized into three groups: control group C1 - db/+ animals, control group C2 and experimental group G3 - obese db/db mice. Buckwheat flour was included into the diet of C2 group in a dose 22.5 g/100 g; FFI was included into the diet of G3 group in a dose 2.5 g/100 g (that was equal to 59.2± 1.4 mg-eq gallic acid per 100 g of the diet). The anxiety level and general locomotor activity were evaluated in the EPM test. The evaluation of behavior, memory and spatial learning was performed using passive avoidance test (PAT). Glycated hemoglobin level was determined in blood, insulin and leptin levels were determined in blood plasma, general antioxidant activity was determined in liver cytosolic fraction. Results and discussion . The obtained data on biochemical parameters and insulin resistance tests showed the absence of normalizing effects of developed FFI. However, the inclusion of polyphenol-containing FFI into the diet led to beneficial changes in physiological parameters. Animals of G3 group, provided with FFI, were significantly less anxious compared to both control groups. During PAT testing of short-term memory, no animals in G3 group entered to the dark compartment (0%), what demonstrated increased learning ability and well-established memory of these animals in comparison with C1 (50%) and C2 groups (80%). Conclusion . The results prove the effectiveness of bilberry leaves` polyphenols, sorbed on the brown buckwheat flour, in the correction of central nervous system disorders in db/ db mice with genetically altered type 2 diabetes, what points at possible prospect of FFI inclusion in therapeutic products for patients with type 2 diabetes mellitus., Competing Interests: The authors declare no overt and potential conflict of interest related to the publication of this article., (Copyright© GEOTAR-Media Publishing Group.)

It was established that chronic unpredictable stress, which was reproduced by repeated exposure of adverse factors on the pregnant rats (food deprivations during one day, immobilization in the water of room temperature and contact with Felis excrements) results in the stable and sex-specific offspring's behavioural changes in the «open field» test, disorders of motor and coordinator functions and the increased sensitivity to pain at the age of both 1 and 3 months. Male and female rats, which were exposed to the prenatal stress, demonstrate elevated blood pressure. Enhanced lipoperoxidation in the blood serum of male rats after prenatal stress was indicated. Thus, prenatal stress leads to the stable alteration of the reactivity, which may favour persistent social maladjustment and the development of different pathologies.

Long-term effects of peripheral pain, brief stress of maternal isolation and their combination in one-day- and repeatedly two-day-old rat pups or seven-day- and repeatedly eight-day-old pups were investigated on indices of basal pain (in the absence of inflammation), a prolonged response to again evoked inflammation in the formalin test, the level of anxiety and depression and of spatial learning ability in the animals as adults (90-day-olds). Changes in the indices under investigation were revealed in adult rats depending on the type of early life impact and age during which it occurred: inflammatory pain induced hypoalgesia in the test of hot plate and deterioration in spatial learning ability in the Morris test; the stress of maternal isolation on the first and second days, but not seventh and eighth days of life caused a strengthening of formalin-induced pain response. Regardless of the age when rat pups were exposed to impact, again induced inflammation evoked strengthening of pain response when the animals reached adulthood. In the forced swim test the time of immobility was increased in rats exposed early to any from impacts investigated. The effect of combination pain with stress did not exceed the effect of each impact separately. The new data contribute to the urgent problem of the long-term effects of the damaging impacts of pain and stress during the neonatal period on the functional activity of the tonic nociceptive system and behavior.

Elaboration of conditioned place preference (CPP) associated with own and foster pups, and maternal behavior were compared in females of WAG/Rij and Wistar rats. In addition, behavior of females in the open field, elevated plus-maze and forced swimming tests were investigated before pregnancy and after pup delivery. In has been found that females of WAG/Rij rats elaborate worse CPP task associated with both their own (WAG/Rij) and foster (Wistar) pups. Thus, the number of females that increase time spent in initially non-preferred compartment after its association with pups and the number of females that reach criterion of CPP elaboration in WAG/Rij rats were less than in Wistar controls. WAG/Rij females exhibited less maternal care in the place preference test both to their own and foster pups: less number of approaches to pups, pups carrying and the time spent in contact with pups non-associated with feeding. In WAG/Rij females compared with Wistar controls immobility time in the forced swimming test was higher both before pregnancy and after pup delivery indicating a stable depression-like state. Before pregnancy, statistically significant inter-strain differences in the anxiety level have not been revealed. After pup delivery, in WAG/Rij females anxiety level decreased but in Wistar females didn't substantially change. Results suggest that worse elaboration of CPP task and reduced maternal care in depressive WAG/Rij females are not associated with specific features of their own pups but are due to their depression-like state. Put into other words, pups for depressive mothers are less potent reinforcer than for "normal" (non-depressive) mothers.

An article describes the original method allowing to study a mechanism of food preference related to the sensory properties of foods in animals. The method gives a good possibility to select the role of visual and orosensory signaling in food preference as well as to model the processes of physiological and pathological food and drug dependence in animal experiments. The role of discrete food presentation in the formation of the current motivations and food preferences was discussed.

The study is devoted to the investigation of the effects of the repeated inflammatory pain syndrome of newborn male rat pups at the age of one and two days of life on characteristics of adaptive behaviors in the formalin test, the elevated-plus maze, the forced swim test and also in the swimming pool spatial test in these animals at the age of 25 days. The new data are enhancement of functional activity of the tonic nociceptive system, an increase in depression like behavior, impairment of spatial learning. A priority fact has been obtained that indicates that a short (60 min) repeated maternal deprivation of newborn rat pups (a stressful impact) without inflammatory noxious impact results in changes of the adaptive behaviors in 25-day-old animals. The evaluation of pain patterns organized at different levels of the central nervous system in the formalin test let us to find differences between effects of early painful and stressful impacts on the behavioral indices under study.

It is established, that chronic alcoholic defeat of hepatobiliarity sistems leads to infringement of cognitive functions at posterity. At the given group of animals revealed distress of memory and ability to orientation in space in the conditions of Morris water maze is, the research behavior is oppressed. Besides, the animals, born from mothers with chronic alcoholic defeat of hepatobiliarity systems have raised free-radical activity, which plays an important role in maintenance of adaptive possibilities of a brain.

Effect of chronic mild uncontrollable stress on behaviour was studied on rats with opposite behavioural coping styles--active and passive. In a population of outbred animals, specimens with opposite coping style of behaviour were selected based on their reactions in the active avoidance (AA) test. Both groups were subjected to chronic mild stress during 30 days and tested for depressive behaviour (forced swim test, 32% glucose solution consumption test), anxiety (elevated plus maze) and learning (AA test). The behavioural test showed that depressive behaviour after chronic mild stress is more common in animals with active behaviour strategy.

Previous studies have reported that repeated experience of aggression is attended with the development of increased anxiety in male mice. The paper aimed to investigate effect of anxiolytic, diazepam, on the level of anxiety and aggression in these animals. The drug was chronically administrated for two weeks at the process of aggression experience acquisition. It was shown that diazepam decreased anxiety but didn't influence aggression level assessed by total time of attacks. However, diazepam decreased demonstration of aggressive grooming in part of aggressive males. Group of diazepam-treated aggressive males which displayed aggressive grooming didn't differ in level of anxiety and aggression in saline-treated male mice. Diazepam had anxiolytic and pro-aggressive effects in male mice without demonstrating aggressive grooming. Thus, we can conclude that anxiolytic effect of diazepam is accompanied with increased aggression as side effect in some male mice which have repeated experience of aggression.

Changes in the behavior of DBA/2J mice after gaining repeated experience of aggression have been investigated. It was shown that the long-term experience of aggression led to development of hyperactivity estimated as increased motor activity in different tests: open field, elevated plus maze and during testing of reaction to a novelty. Symptoms of attention deficit estimated in the "partition" test as a reduction of the communicativeness and the lack of reaction to unfamiliar partner were noticed. Appearance of a large number of hyperkinesis manifested most often in the form of sudden involuntary head movements (jerks) was observed in the behavior of aggressive males during agonistic interactions. Most of the changes in the behavior of DBA/2J mice differed significantly from previously detected in the behavior of aggressive mice of C57BL/6J and CBA/Lac strains, suggesting a significant contribution of heredity that determines the features of behavioral disorders that occur under the influence of long-term experience of aggression. Similarity of symptomatics of movement disturbances in mice and in humans with some neurological diseases is discussed.

Behavioral indicators of anxiety and body weight dynamics were compared in rats kept under standard conditions (4-5 animals per cage) and in overpopulated cages (17 rats per cage). The behavior of rats exposed to overcrowding for a short and long period was evaluated in the open field, light-darkness, and elevated plus-maze tests. The anxiety parameters of animals increased only in the light-darkness test during the acute period of overcrowding and in all tests during chronic overcrowding. Behavioral tests had a negative impact on body weight gain in controls and rats living in overpopulated cages. If the behavioral tests were carried out at the beginning of the experiment, body weight ceased to increase in animals exposed to overcrowding and continued to increase in the controls. Overcrowding without behavioral tests had no effects on the body weight dynamics. The model of chronic (but not acute) overcrowding may be used for evaluation of anxiolytic effects of drugs.

Learning and reverse learning in a complex maze, behavior in the open field test, novelty-suppressed feeding test, and forced swimming test were studies in WAG/Rij and Wistar rats. As compared with Wistar rats, WAG/Rij rats more slowly learned the spatial task, more slowly performed in the learning and reverse learning tasks, and made more errors in the complex maze (18% of WAG/Rij rats didn't reach learning criterion). Moreover, WAG/Rij rats exhibited reduced grooming reactions in the open field test, longer latency of approaching to food in the novel open field, reduced amount of food consumed in the home cage in the novelty-suppressed feeding test, and increased immobility time in the forced swimming test. The results suggest cognitive impaiment in WAG/Rij rats with depression-like behavior.

We studied the influence of late prenatal stress on free radical oxidation processes in Sprague-Dawley rats cortex, striatum, hippocampus, hypothalamus proteins. It was shown that after prenatal stress most changes were observed in hypothalamus and hippocampus. It was shown that in hypothalamus spontaneous oxidation level increased, but level of induced oxidation decreased, the opposite changes were found in hippocampus. Simultaneously minor changes of protein modification were observed in cortex and striatum. It was shown that prenatal stress changed both correlation of proteins free radical oxidation in studied structures and values of these data regarding to control. In test of "open field" motor activity in rats after prenatal stress decreased and time of freezing and grooming increased; opposite, in T-labyrinth motor activity and time of grooming in rats after prenatal stress increased, but time of freezing decreased.

We studied the effect of preliminary three-fold administration of dehydroepiandrosterone-sulphate (DHEA-S) on behavioral disturbance, induced by water-immobilization stress in high- and low-anxiety active rats. Active rats were selected from Wistar rats on the basis of T-maze testing. Active rats were then divided into the groups with high and low anxiety level after testing in elevated plus maze. We found that DHEA-S injections (3 mg/100 g, i.p.) had an anti-stress-like effect, as shown by a decrease stress corticosterone level in both groups of rats. DHEA-S also demonstrated an anxiolytic-like effects in high anxiety rats and anxiogenic-like effects in low anxiety rats. These results suggest that DHEA-S anxiolytic and anti-stress effects depend on the individual psycho-emotional status and baseline anxiety level.

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.

The study was aimed at evaluating the behavioral correlations of the forced administration of psychoactive drugs. Wistar rats received the following drugs in elevated doses (over 4 days, i. p.): (i) physiological saline (control; 0.1-0.2-0.4-0.8 ml/rat), (ii) psychostimulant amphetamine (0.5-1.0--2.0-4.0 mg/kg); (iii) opioid analgetic fentanyl (0.00625-0.0125--0.025-0.05 mg/kg), (iv) ethanol 40% solution (0.5-1.0--2.0-4.0 g/kg), (v) barbiturate sodium ethaminal (2.5-5--10-20 mg/kg); and(vi) synthetic glucocorticoid dexamethasone (0.5-1.0--2.0-4.0 mg/kg). The forced regime of drug administration led to gradual load of the organism and prevented drug tolerance. The dynamics of self-stimulation reaction of the lateral hypothalamus was registered every day over drug administration period and revealed the following regularities: (I) dose-dependent effect of psychostimulant amphetamine and opioid analgetic fentanyl; (II) dexamethasone modulated self-stimulation, increasing (2 day, 1 mg/kg) or decreasing it (3 day, 2 mg/kg); (III) ethanol (1-2 g/kg) activated self-stimulation slightly; (IV) sodium ethaminal slightly inhibited self-stimulation and increased the thresholds of self-stimulation. In 24 h and 72 h after the last administration of drugs, the rat behavior was assessed in open field, elevated plus maze, resident-intruder paradigm, and Porsolt's test. In the open field, significant signs of post-intoxication exposure of psychoactive drugs were revealed, which were registered for 24-72 h after drug withdrawal. The withdrawal of drugs was accompanied with reduction (in 24 h) and subsequent recovery (in 72 h) of the vertical motor activity, exploration behavior, and emotionality. The anxiety indexes were increased up to the 3rd day after withdrawal. The antidepressant effect was also increased. The system of aggression-defense was restored only in rats treated with ethanol. The indexes of individual behavior and communicability in the post-intoxication period were decreased as well. It is suggested that the forced regime of drug administration in increasing doses with subsequent withdrawal of drug injections is a suitable method to evaluate the behavioral elements of drug dependence.

The aim of the present work was to assess long-lasting effects of acute prenatal stress in white rats. Forced swimming in cold water on the 7th or the 14th gestational day was used as a prenatal stressor. The prenatal stress led to low birthweight of offspring and their delayed growth rate during the second month of life. Prenatally stressed animals showed abnormalities in exploratory behavior and anxiety, increased emotionality and impaired learning capabilities at the age of 1-2 month. Consequently, acute stress on the 7th and at the 14th day of pregnancy induced long-lasting negative behavioral changes in offspring of stressed white rats.

Behavioral effects of neurotensin administration into the nucleus accumbens were studied in rats with neurotoxic lesions of serotoninergic structures of the dorsal raphe nucleus or periaqueductal grey matter. Changes in recall of passive avoidance conditioned reactions and aftereffects of painful stimulation in the locomotor activity were studied in the "open field" and elevated plus-maze and T-maze tests. The toxin administration into the dorsal raphe nucleus did not impair the recall of the passive avoidance reactions, but enhanced the oppressive aftereffects of painful stimulation, which can specify the development of anxiety in rats. The toxin administration into the periaqueductal grey matter had an opposite effect, which can be considered as a manifestation of the panic state. Neurotensin weakened the above mentioned effects of the toxin and, depending on the evoked emotional disorders, produced the anxiolytic or antipanic effects.

A new conditioned reflexes approach for assessment of attention deficit hyperactivity disorder (ADHD) symptoms in children has been used. Successful solving of behavioral task was related with the ability of children to shift their attention on spatially located sensory signals in radial labyrinth with asymmetric schedule of rewards. The innovative method developed gives a good possibility to increase the accuracy of ADHD evaluation in children of different age as well as to reduce the time for their behavioral testing.

In outbred population of white rats (Rattus norvegicus), we picked out two groups of male animals with high (HA) and low levels of anxiety (LA). Social preference for a familiar or unfamiliar conspecific were studied. The rats (n = 85) were housed five per cage for two months before the experiment. Thus, the social structures in every cage were stable. The anxiety was tested in an elevated plus-maze. For social interaction test we used the box, in which two opposite corners were separated with perforated transparent Plexiglas walls. A mate of a tested subject was placed into one corner the cage, an unfamiliar animal was put into another corner. During five minutes we measured the time spent near each of the conspecifics and in neutral area. For both high- and low-anxiety groups, the time spent in the neutral area was less than 60 sec. i.e. rats in a novel environment spent much more time in social contacts than in environmental exploration. Rats with high anxiety spent 88 +/- 32 s and 155 +/- 35 s close to an unfamiliar subject and a cage mate, respectively. On the contrary, the measurements for rats with low anxiety were 200 +/- 40 s for an unfamiliar subject, and 65 +/- 32 s for a cage mate. Consequently, high-anxiety rats preferred contacts with a familiar conspecific, whereas low-anxiety rats preferred to contact with an unfamiliar conspecific.

Photothrombosis of the vessels in the prefrontal areas of the rat cortex 20 days before learning leads to development of ischemic infarction in the exposed area with profound deficits in acquisition of the Morris water maze task: length of path and time of search of hidden-platform in water maze increased vs false-operated rats. It suggests prefrontal cortex involvement in spatial navigation.

Learning and retention of the spatial memory were studied in mice with alternative under conditions of various experimental protocols. Visible and hidden platform acquisition in a simple model of the water maze was similarly fast both in aggressive and submissive mice, but extinction differed. Retention of the platform location preference persisted in aggressive mice in four testing trials. In submissive mice, extiction of the spatial memory was accompanied with a prolongation of search with parallel production of episodes of "passive drift". Differences in spatial learning between aggressive and submissive mice were revealed in a water maze complicated with partitions. In this case, aggressors were able to learn the position of a hidden platform (in contrast to submissive mice with the dominant response of "passive drift"). During testing the response, aggressive mice longer retained the spatial preference without extinction.

The effect of intravenous transplantation of mesenchymal stem cells on the recovery of cognitive functions was studied in Wistar-Kyoto rats after brain stroke induced by occlusion of the middle cerebral artery in the left hemisphere. Analysis 2 and 5 weeks after stroke showed that transplantation of mesenchymal stem cells 3 days after middle cerebral artery occlusion reduced the area of cerebral injury, preserved cognitive functions, and decreased mortality in experimental animals.

Maternal choline diet influences the spatial learning processes. In this work, the learning ability of adult progeny of mothers who had received methyl diet enriched with choline and betain during pregnancy and lactation was studied in Morris test. The introduction of the diet to pregnant rats resulted in an increase in the time of search for invisible platform and time of swimming near the pool walls in offsprings, which meant a worsening of their learning ability. It was also found that change in platform searching strategy was not associated with an increase in anxiety of male rats. Possible involvement of maternal methyl diet in the change of expression of genes which control development of the nervous system is discussed.

Comparing behavioral traits of anxiety in elevated plus-maze and retention of passive avoidance response in two rat strains with hereditary arterial hypertension ISIAH (inherited stress induced arterial hypertension) and SHR (spontaneously hypertensive rats) has shown the following. The SHR rats demonstrate impairment in retrieval of passive avoidance, hyperactivity and low anxiety. ISIAH rats showned better avoidance performance, average level of anxiety and activity. The interdependence of two pathologies: hypertension and memory impairment is discussed.

In Wistar's rats, the postnatal influence of maternal behaviour on the motor and emotional state and the anxiety level of the posterity born from the intact rat-mothers-ambidexter but reared by the intact mothers-ambidexter with the motor deficit, were investigated. From the first day of life, the rat-mothers with the removed part of the sense-motor cortex (right or left) nursed and reared the litter. It was discovered that the reduction of motor activity and increase of negative emotional responses occurred in experimental litter at the age of 1 month as compared with the control group (intact litter reared by the ersatz healthy rat-mothers). In the test of elevated cruciform maze, a high level of anxiety was discovered. The experimental posterity showed an emotional tension as the dominant state. Left-side lesion of the sense-motor cortex of the ersatz mother resulted in a rougher disorder in the emotional state and movement than after right-side lesion.

Male white rats divided in three groups on the basis of their behavior in the elevated plus-maze were subjected to 10-min cardiac arrest. Analysis of the results of their subsequent food and active avoidance conditioning revealed the effects of the following factors: (1) a factor of initial typological features of the higher nervous activity, (2) a factor of general brain mechanisms of postresuscitation, and (3) a factor of postresuscitation features in rats with different behaviors, which represented changes in different mechanisms of conditioned reflex performance in these animals.

Long-lasting psychoemotional influence consisting of permanent stay of females with aggressive males separated with a perforated transparent partition in the same cage, and daily presence of females during intermale confrontations, is negative toward the females' behavior estimated in the some ethological tests. Elevated plus-maze and open field tests reveal an increased anxiety and inhibited exploratory behavior and motor activity. Within a month, the decreased females' reactions near the partition to both familiar and unfamiliar males testify to decreased communicativeness. In two months from the beginning, intermale confrontations become uninteresting for females too, as it was shown in the partition test. Abnormalities in the pain sensitivity estimated in the hot-plate test are found in females after the psychoemotional influence. More than half of all females have a prolonged diestrous stage of the estrous cycle. Moreover, after the psychoemotional influence females lose the capability to recognize intact female and male littermates as well as aggressive and submissive males. Taken together the results suggest that long-lasting psychoemotional influence can cause the anxiety-depression states in females.

The elevated cross-shaped labyrinth test carried out on highly, moderately, and low active experimental animals revealed significant differences in the baseline density and composition of neuroglial populations of numerous formations of the brain, as well as in the early structural and functional sequels of experienced clinical death. The most pronounced postresuscitation abnormal changes were observed in highly active animals and the least marked ones were seen in moderately active animals.

In chronic experiments in Wistar rats, the behavioral and hematological effects of the following stress factors were investigated: learning in complex maze and five multiple injections of the physiological saline (0.85%). Increasing of the erythrocyte volume and the contents of hemoglobin per erythrocyte in saline-induced groups and naive rats were observed after the learning. Moreover, the level of corticosterone in plasma of these rats was high. While in heparin-pretreated animals (unfractioned heparin, 64 and 640 IU/kg once per day, i.m., 5 days) these markers of stress are not revealed. The speed and efficiency of learning, behavior organization were significantly better in heparin pretreated rats than in naive and saline-induced groups. In heparin treated rats, a few types of unconditioned responses may be observed suggesting an anxiety or fear. We suppose that, after injections of heparin, complicated biochemical modifications of the rat organism that cause harmonization of inhibiting and excitatory processes of central nervous system, take place.

Behavioral reactions (open-field test, elevated plus-maze, pain stress, and feeding behavior) were studied in various periods after clinical death caused by circulatory arrest for 10 or 15 min. We revealed two different phases of behavioral changes: active behavior directed at attaining a specific goal and passive behavior directed towards isolation of the organism from external signals and functional minimization. Active behavior determined by pathological excitation in the central nervous system increased the severity of structural damage to hippocampal CA1 neurons during the postresuscitation period. By contrast, passive behavior and minimization of functions preserved structural integrity in these neurons.

The goal of this work was to find out to which degree the black coat color mutation nonagouti that appears in wild Norway rat in the course of breeding for the maintenance and enhancement of aggressiveness towards a human affects selected and other behavioral traits as well as stress reactivity and brain neurochemistry. Nonagouti rats displayed increased emotionality in the open-field and forced-swimming tests as compared to agouti animals, whereas there were no differences in anxiety estimated in the elevated plus-maze. Neither were there any differences in glucocorticoid reactions to a combined stressful procedure such as forced swimming. The dopamine content in the frontal cortex and striatum and noradrenaline content in the frontal cortex were increased in black rats as compared to gray rats. The result suggest that the nonagouti mutation in gray aggressive rats enhances the effects of selection for aggressiveness on some behavioral traits and brain catecholamine level.

Features of behavior and retrieval of passive conditioned avoidance on a new and forgotten stimuli were compared in Wistar rats and Norway rats bred for the absence of aggression toward a man. As distinct from white rats, grey rats were characterized by low anxiety and high locomotor exploratory activity in the elevated plus maze and dark-light chamber. Norway rats demonstrated better avoidance performance with active defensive behavioral strategy than Wistar rats. Latent inhibition during conditioning with a previously forgotten situational stimulus was the same in both rat strains. The results are discussed in terms of the use of grey rats as a model for an in-depth analysis of the mechanisms of memory optimization.

Twelve adult hooded crows (Corvus cornix) were trained to perform a standard radial-maze task in a giant eight-arm outdoor radial maze constructed at the "Chistyi les" Biological Station (Tver oblast) for comparative investigations of spatial memory in birds and mammals. The maze consists of a central part of 250 cm diameter, and has arms of 650 cm length, 170 cm height and 80 cm width. The examined hooded crows showed good task performance. Errors (repeated visits to empty arms) were few in number and were predominantly connected with the tendency to avoid arms close to an observer.

The sensory contact technique allows an aggressive type of behavior to be formed as a result of repeated experience of social victories in daily agonistic confrontations. In mice of the low-aggressive and high-emotional CBA/Lac strain repeated positive fighting experience increases plus-maze anxiety. Behavioral reactivity of males to other conspecifics in the partition test (which measures aggressive motivation) significantly rises. It is concluded that repeated experience of aggression provokes the development of anxiety in male mice. The results suggest that level of anxiety and its behavioral realization depend on duration of aggressive experience and genetic strain.

Male Wistar rats (n = 18) were studied at the age of 120 days after social deprivation in the period from the 22nd to 70th days of postnatal development. They displayed significant lower activity in the open field, elevated plus-maze, and Porsolt test than control animals (n = 19). Decreased exploratory activity was found to be related with higher level of anxiety. This was confirmed by their avoidance of open arms of the elevated plusmaze and reactions to approaching hand. These animals had problems in the maze arm choice. They showed low time variability of choice-related actions (waiting in the center of the open field or elevated plus-maze and change in the movement direction along an open-field wall, including the movement per se, and arm choice and changing, i.e., alternative choice). Shorter time of choice-related actions was observed in situations of unequal alternatives.

The role of medial shell of the nucleus accumbens in acquisition of spatial behavior was studied in rats performing choice task in radial maze with asymmetrical water reinforcement. It has been found that the nucleus accumbens lesioned rats failed in finding larger rewards but preserve their reward-seeking behavior guided by visual discriminative stimuli. The results obtained are in good agreement with suggestion that the nucleus accumbens is a site of convergence of spatial information (from hippocampus) with reward information (from amygdala and VTA), providing bridge for effective limbic-motor interface underlying motivated goal-directed behavior in animals.

In view of the hypothesis that glutamatergic dysfunction of brain can underlie the negative symptoms of schizophrenia (including cognitive deficit), the aim of this study was to develop a model of cognitive impairment in Wistar male rats after administration of a noncompetitive NMDA-receptor antagonist in early postnatal period. Rat pups were daily subcutaneously injected with 0.05 mg/kg MK-801 on postnatal days 7-49. On the 27th and 28th days 24 h after the last previous injection, the MK-801-treated rats demonstrated lower spontaneous locomotor and exploratory activity in comparison with saline control, however, they retained the reaction of hyperlocomotion which developed immediately after the MK-801 administration. In these rats, the anxiety level in the elevated plus-maze (on the 40th postnatal day) was found to be decreased, and the spatial learning in food rewarded task was negatively affected (on the 50th-54th days). It is suggested that impairment of the input of sensory information and its correct assessment by the animals can be associated with the early neonatal blockade of NMDA glutamate receptors.

Administration of Interleukin-1 beta (IL-1 beta) in pyrogenic and subpyrogenic doses induced a depression of social and exploratory behaviour in rats. A reduction in locomotor activity only occurred with pyrogenic doses of the IL-1 beta. The low dose induced the reduction whereas the high dose the increase of anxiety in elevated plus maze. The opposite effects of two doses of IL-1 beta were observed also in a test with saccharine.

Prenatal stress was found not to affect learning capability in Morris Water Maze in rats, although some difference was revealed in the rats behaviour. 2-month old rats who had been subjected to a prenatal stress, revealed an obvious trend towards less flexible strategy of behaviour and perseveration. At the age of 4 months, the difference between the control and experimental groups becomes negligible.