Peculiarities of latent inhibition formation in SHR rats in conditioned task of different complexity.

Inhibition of attention to irrelevant stimuli was studied in SHR rats using latent inhibition test. Latent inhibition was formed in two types of conditioned tasks with different levels of complexity and stress. Passive and active avoidance conditioning was preceded by preexposure to conditioned stimulus consisting of 20 and 100 non-reinforced presentations, respectively.

[Disruption of latent inhibition in adult rats after prepubertal dopamine terminals lesions in the ventral hippocampus].

Wistar rats were submitted to bilateral ventral hippocampal injection of 6-hydroxydopamine on 32nd day after birth. Latent inhibition was measured in passive or active avoidance tasks when the rats received 20 and 100 pre-exposures of conditioned stimulus. Prepubertal and adult lesioned rats showed a deficit in the latent inhibition but not in the capacity to avoidance learning in presence of the conditioned stimulus novelty.

Involvement of different types of dopamine receptors in the formation of latent inhibition of a conditioned passive avoidance reaction in rats.

The effects of systemic injections of dopaminergic agents on normal and weak latent inhibition of a conditioned passive avoidance reaction were studied in rats. Formation of normal latent inhibition was induced using 20 pre-exposures to a contextual conditioned stimulus prior to training. Weak latent inhibition was modeled using 10 pre-exposures.

Effects of memantine on latent inhibition of active avoidance in wistar rats.

Latent inhibition of active avoidance reaction was acquired by mature Wistar rats. It manifested in marked delay of habit acquisition after preexposure to the conditional stimulus in the first experimental session. Single dose of NMDA-receptor antagonist memantine (10 and 14 mg/kg) was applied 60 min before training in the second session.

[Involvement of dopamine receptors of different types in formation of latent inhibition of passive avoidance reaction in Wistar rats].

The effect of the intraperitoneal injection of dopaminergic agents on normal and weak latent inhibition of step-through passive avoidance task was studied in rats. Normal latent inhibition was caused by 20-fold preexposure (four times daily) of environmental conditional stimulus before training. For modeling of the weak latent inhibition 10-fold preexposure was used.

Immune response in Wistar rats with high and low level of situational anxiety.

A large sample of Wistar rats was divided into 2 groups of high-anxiety and low-anxiety animals by the time spent in the open arms of the elevated plus-maze. This selection was based on the criterion of time (low-anxiety animals, not less than 10 sec; high-anxiety animals, not more than 2 sec). Immunization with T-dependent antigen was performed on the day of behavioral testing.

Comparative analysis of the persistence of a conditioned passive avoidance reflex in rats with different forms of inherited hypertension.

The characteristics of anxiety behavior and reproduction of a conditioned passive avoidance reflex acquired in response to a single combination with an unconditioned aversive stimulus were studied in NISAG rats with inherited stress-sensitive arterial hypertension and spontaneously hypertensive SHR rats. SHR rats were characterized by hyperactive behavior, very low levels of anxiety, and poor reproduction of the conditioned reflex as compared with NISAG and control Wistar and WAG rats. Intermediate-anxiety NISAG rats showed no difficulties in acquiring and subsequently retaining the conditioned reflex.

[GABA(B) receptors and amnesia in mice withalternative stereotypes of behavior].

The influence of agonists and antagonists of GABA(B) receptors on the development of amnesia has been studied using the passive avoidance test in C57Bl/6J mice with previously generated aggressive and submissive behavioral stereotypes. It is established that baclofen in a dose of 1 mg/kg produces amnesia in aggressive mice and imparts stability with respect to the amnestic influence in submissive mice. Phaclofen in a dose of 5 mg/kg prevents the development of amnesia that is most strongly pronounced in submissive mice.

Peculiarities of active avoidance conditioning in rats with various forms of inherited arterial hypertension.

Peculiarities of active avoidance conditioning were studied in NISAG rats (hereditary stress-induced arterial hypertension) and spontaneously hypertensive SHR rats. Conditioning was successful in 90% normotensive Wistar rats and in only 9.1% NISAG rats.

[Comparative analysis of conditioned passive avoidance retention in rats with different forms of inherited arterial hypertension].

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.

Long-term antioxidant supplementation attenuates oxidative stress markers and cognitive deficits in senescent-accelerated OXYS rats.

Oxidative damage of biomolecules increases with age and is postulated to be a major causal factor of various neurodegenerative disorders. Consequently, the concept of neuroprotection by antioxidants has been developed. Recently we have shown that the behaviour of young senescent-accelerated OXYS rats is similar to the behaviour of old Wistar animals.

[Effect of forced swimming on the memory track retention in mice with various behavioral stereotypes].

The effects of forced swimming on retrieval of the passive avoidance during its extinction were found to depend on aggressive and submissive behavior. In mice without generated behavioral stereotypes, swim stress applied before or after training stabilized retention of the memory trace retrieval. The similar improved influence of forced swimming on memory storage is revealed in submissive, but not aggressive mice.

The effects of the duration of adaptation to laboratory conditions on the formation of a passive avoidance reflex in rats.

The level of adaptation of rats to their new living conditions was studied during formation of a passive avoidance habit using a single combination. A short acclimation period (3 days) had positive influences on the ability of rats to retain a memory trace. There was a negative correlation between step-through latency and measures of anxiety behavior in the elevated cross maze.

[Typological features of behavior and memory in Norway rats selected for absence of aggression toward a man].

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.

[Extinction and amnesia in aggressive and submissive mice with various terms of agonistic interaction].

Dependence of the passive avoidance retrieval on the duration of agonistic interactions was analyzed in C57BL/6J mice in procedures of extinction and amnesia during formation of aggressive and submissive behavioral stereotypes. The resistance to amnestic stimulation was lower in aggressive mice with 10-day experience of victories than in aggressive animals after 20 daily confrontations. Prolongation of extinction in aggressive mice and fast extinction in submissive animals did not depend on the number of agonistic interactions.

The effects of novelty and behavioral stereotype on the development of amnesia in mice.

The aim of the present study was to analyze the significance of the interaction between the basic behavioral strategy, the extinction of the novelty of information, and the efficacy of amnesia-inducing influences. Using a combination of training to passive avoidance with holding the animal in the unsafe sector of the apparatus, comparative analysis was performed of the reproduction of a memory trace in aggressive and submissive mice of line C57BL/6J with and without six sessions of familiarization with the apparatus. These experiments showed that preliminary habituation prevented the development of amnesia in submissive but not aggressive individuals.

Efficiency of ultralow doses of antibodies to S100 protein and delta sleep-inducing peptide in rats with anxious depression.

We studied the effects of single peroral treatment with antibodies against S100 protein and delta sleep-inducing peptide in ultralow doses on behavioral characteristics of rats with anxious depression produced by acute stress (unavoidable electrical shock). Stress-produced behavioral changes and anxiolytic activity of antibodies were determined using the elevated plus-maze, open field, and tail suspension tests. High efficiency of the mixture of antibodies against S100 protein and delta sleep-inducing peptide was observed in all tests.

Comparative analysis of LPO products in brain structures of Wistar and OXYS rats of different age.

We analyzed the content of LPO products in various brain areas of Wistar and OXYS rats characterized by early appearance of changes in the emotional and cognitive spheres typical of aging. Marked differences between brain regions were found in both strains, but were more pronounced in Wistar rats. The content of LPO products in OXYS rats was higher in the midbrain, hippocampus, nuclei accumbens and striatum at the age of 2 months and in the midbrain, hippocampus, and nuclei accumbens at the age of 18 months.

[Comparative analysis of haloperidol effects on passive avoidance retention in aggressive and submissive mice].

The effects of haloperidol on retention of avoidance during its extinction in C57BL/6J mice were shown to depend on a behavioral stereotype (aggressive or submissive). In submissive mice, haloperidol (0.5 mg/kg) injected an hour before training stabilized retrieval of the conditioned reflex in repeated testings (up to 17 days) as compared to its fast extinction in control animals.

[Effect of haloperidol on development of amnesia in aggressive and submissive mice].

The effect of haloperidol on the passive avoidance habit retrieval upon amnesia was studied in C57BL/6J mice with aggressive and submissive behavioral stereotypes formed under agonist confrontation conditions. In the control (untreated) group, the efficacy of the amnesic action of detention in the dangerous compartment on the learning day was reduced for the aggressive stereotype as compared to the submissive one. In the aggressive mice, the administration of haloperidol (0.

[The effect of the duration of adaptation to laboratory conditions on the passive avoidance reflex in rats].

Influence of adaptation degree in new conditions on the passive avoidance was studied. The short period of habituation (3 days) positively influenced the rats' ability for memory trace retrieval. A negative correlation between the step through latency and anxiety in the elevated plus-maze, was shown.

[Effect of novelty and behavioral stereotype on development of amnesia in mice].

The research was aimed at analysis of interaction of basic behavioural strategy, extinction of information novelty and efficiency of amnesic influence. It is shown that preliminary habituation to the task apparatus prevented development of amnesia, induced detention of the animal in a dangerous compartment in submissive rather than aggressive mice C57BL/6J. The findings suggest that revealed distinctions in effects of pre-exposure on development of amnesia are essentially predetermined by selectivity of extinction of the information novelty specific to a stereotype of behaviour.

[Impairment of latent inhibition in OXYS rats with hereditary syndrome of premature aging].

The effect of latent inhibition has been tested in OXYS (strain selected for accelerated aging) and Wistar (control) rats at the age of 4 months using a conditioned passive avoidance reaction. The OXYS rats displayed a higher level of anxiety in the elevated plus-maze as compared to Wistar strain. The experimental procedure consisted of preexposure stage (presentation of non-reinforced environmental stimulus), conditioning (presentation of a preexposed stimulus paired with shock), and testing the effect of latent inhibition.

[Retention of a memory trace of learning induced by a new and extinctive stimulus in C57BL/6J and BALB/c mice].

Influence of preliminary habituation to the experimental box on passive avoidance learning was studied in mice of C57BL/6J and BALB/c strains. The 20-fold preexposure of mice to the environmental stimulus inhibited the acquisition and consequent retention of a memory trace in BALB/c mice and did not affect the acquisition in C57BL/6J mice. Subsequent retention in this strain was facilitated.

The effects of a serotoninergic substrate of the nucleus accumbens on latent inhibition.

Latent inhibition is an effect consisting of a delay in the acquisition of a stimulus in response to quenching of its significance by repeated presentation (pre-exposure) before combination with the reinforcement. This phenomenon is used for studies of the mechanisms of attention. Experiments were performed on rats to determine whether latent inhibition could be formed in a passive avoidance response in conditions of blockade of serotoninergic terminals in the nucleus accumbens.