Motor and Cognitive Functions in Aging C57BL/6 Mice: Association with Activity of the Monoaminergic Systems in the Cerebellum and Frontal Cortex.

The activity in the open field, short- and long-term memory in the novel object recognition test, and gait features were evaluated in 6- and 12-month-old male C57BL/6 mice. The levels of norepinephrine, dopamine, serotonin, and their metabolites were determined in the cerebellum and frontal cortex. In the observed age range, a decrease in locomotion speed, impairment of gait initiation and stability, and long-term memory deficit were revealed. In the cerebral cortex, reduced levels of dopamine and its metabolites and accelerated metabolism of all neurotransmitters under study were found. In the cerebellum, the content of all studied monoamines was elevated, while dopamine metabolism was decelerated. Analysis of correlations between the neurochemical and behavioral parameters showed that the mechanisms of compensation of brain functions during the early aging may be associated with an increase in activity of the monoaminergic systems in the cerebellum.

Analysis of NAPA Gene Expression in Brain Structures of Wistar Rats during the Formation of Long-Term Spatial Memory and Physical Activity under Stress Situation.

In the cerebellum, hippocampus, and prefrontal cortex of mature male Wistar rats with trained spatial navigational skill in the Morris water maze, the transcriptional activity the NAPA gene that regulates the transport and secretion of synaptic vesicles, release of neurotransmitters, and protein degradation was determined by real-time PCR. Animals subjected to forced swimming in a time-matched regime (active control) and naïve rats were used as the comparison groups. Suppression of NAPA gene activity was found in the hippocampus and cerebellum of the active control group, while navigation skill training led to a significant increase in gene expression in all brain structures under study. The findings suggest the existence of specific mechanisms regulating NAPA gene activity during the formation of spatial memory and adaptive behavior under stress conditions.

Epigenetic Processes of DNA Methylation Are Selectively Involved in the Mechanisms of Retrograde and Anteograde Amnesia.

The participation of DNA methylation processes in the mechanisms of anterograde and retrograde amnesia caused by impaired reconsolidation of conditioned food aversion memory by NMDA glutamate receptor antagonists or serotonin receptor antagonists, respectively, were studied on grape snails. Anterograde amnesia was characterized by impaired formation of long-term memory during repeated learning. Administration of a DNA methyltransferase (DNMT) inhibitor to amnestic animals resulted in accelerated formation of long-term memory during 1 day of repetitive training vs 3 days during initial training. In serotonin-dependent retrograde amnesia, repeated learning without DNMT inhibitor administration or after inhibitor injections led to the formation of long-term memory. The dynamics of memory formation was similar in both cases and did not differ from that during the initial training: the memory was formed within 3 days of training. Thus, epigenetic processes of DNA methylation are selectively involved in the mechanisms of anterograde amnesia, but do not participate in the mechanisms of retrograde amnesia.

[Neurophysiological differentiation of personality disorders]. / Neirofiziologicheskaya differentsiatsiya rasstroistv lichnosti.

OBJECTIVE: The neurophysiological objectification of intranosological differentiation of main clusters (schizoid/paranoid and hysterical/emotionally unstable) within the typology of personality disorders (PD), as well as the differentiation of schizoid/paranoid PD and schizophrenia. MATERIAL AND METHODS: Two groups of patients with PD participated in the study: PD1 - with schizoid/paranoid pattern (n=16), and PD2 - with hysterical/emotionally unstable pattern (n=18). The data were compared with the control group of healthy volunteers (n=86) and the group of schizophrenic patients (Sz, n=67). The analysis of four neurophysiological endophenotypes (measures of prepulse inhibition (PPI) of acoustic startle response and of P50 suppression, P300 amplitude, percentage of antisaccade errors) was carried out. RESULTS: The decrease of PPI and P50 suppression (measures of sensorimotor and sensory gating) relative to the control group was found both for Sz (p<0.01) and PD1 (p<0.05) groups. The highest P300 amplitude was observed in the control group, while the lowest values were observed in the Sz group (p<0.001); the values of PD1 and PD2 groups were intermediate. In all clinical groups percent of antisaccade errors was significantly higher compared to the control group (Sz - p<0.001; PD1 - p<0.05; PD2 - p<0.01). However, the level of the fronto-central cortical activation during antisaccade performance (estimated by contingent negative variation amplitude) was significantly reduced only in the Sz group (p<0.01), which is consistent with the concept of «hypofrontality¼ in schizophrenia. The changes associated with increased emotional reactivity were found in PD2 group only (P300 amplitude frontal maximum, asymmetry of error percent in antisaccade task). CONCLUSION: The study showed that two personality patterns in PD patients are related to the individual specificity of functional brain networks.

[The comparative study of the early stages of sensory and sensory-motor information processing in aggressive and non-aggressive schizophrenic patients]. / Sravnitel'naia otsenka pokazatelei rannikh étapov obrabotki sensornoi i sensomotornoi informatsii u agressivnykh i neagressivnykh bol'nykh shizofreniei.

AIM: To study the early stages of sensory (P50 suppression) and sensorimotor (prepulse modification of acoustic startle reaction - ASR) information processing in aggressive and non-aggressive patients with schizophrenia. MATERIAL AND METHODS: Two groups (aggressive group A, 44 s. and non-aggressive group NA, 27 s.) and 48 healthy people were studied using oculography and encephalography. Symptoms of schizophrenia were assessed by PANSS. RESULTS AND CONCLUSION: The analysis of ASR and P50 revealed the increased ASR latency, deficit of prepulse inhibition (PPI) with 60 ms leading interval, and P50 suppression in patients compared to controls. Aggressive behavior impacted on lateral features of ASR changes in the group A. The increase of ASR amplitude and the decline of prepulse facilitation were found in the group NA. The P50 analysis revealed the increased P50 amplitude and the shortened latency in response to 2nd stimulus in the pair. The increase in scores on item G14 of the PANSS (Poor impulse control) in the group A and its correlations with ASR and P50 parameters in this group suggested the important role of impulsivity in aggressive behavior in the studied sample of aggressive patients. ASR and P50 characteristics in the group NA are associated with increased sensitivity to incoming stimuli and such personality traits as increased alertness and fear, which might inhibit aggression. Thus, indicators of the early stages of information processing can be considered as potential predictors of aggressive behavior.

Studying the Specific Activity of the Amide Form of HLDF-6 Peptide using the Transgenic Model of Alzheimer's Disease.

The neuroprotective and nootropic activities of the amide form (AF) of the HLDF-6 peptide (TGENHR-NH2) were studied in transgenic mice of the B6C3-Tg(APPswe,PSEN1de9)85Dbo (Tg+) line (the animal model of familial Alzheimer's disease (AD)). The study was performed in 4 mouse groups: group 1 (study group): Tg+ mice intranasally injected with the peptide at a dose of 250 µg/kg; group 2 (active control): Tg+ mice intranasally injected with normal saline; group 3 (control 1): Tg- mice; and group 4 (control 2): C57Bl/6 mice. The cognitive functions were evaluated using three tests: the novel object recognition test, the conditioned passive avoidance task, and the Morris water maze. The results testify to the fact that the pharmaceutical substance (PhS) based on the AF of HLDF-6 peptide at a dose of 250 µg/kg administered intranasally efficiently restores the disturbed cognitive functions in transgenic mice. These results are fully consistent with the data obtained in animal models of Alzheimer's disease induced by the injection of the beta-amyloid (ßA) fragment 25-35 into the giant-cell nucleus basalis of Meynert or by co-injection of the ßA fragment 25-35 and ibotenic acid into the hippocampus, and the model of ischemia stroke (chronic bilateral occlusion of carotids, 2VO). According to the overall results, PhS based on AF HLDF-6 was chosen as an object for further investigation; the dose of 250 µg/kg was used as an effective therapeutic dose. Intranasal administration was the route for delivery.

Pattern of Notch2, Numb, and Cas8 Gene Expression in Relevant Structures of the Rat Brain during Formation of Spatial Memory.

The expression of Notch2, Numb, and Cas8 genes, whose protein products are involved in regulation of neurogenesis/neuroapoptosis processes, was studied in the relevant cerebral structures of male Wistar rats trained in a spatial habit. The formation of long-term spatial memory was found to be associated with the formation of a specific pattern of transcription activity of the studied genes in different brain structures. The maximum expression of Notch2 gene was found in the hippocampus and cerebellum, the maximum expression of Numb was detected in the prefrontal cortex and cerebellum, and the maximum expression of Cas8 was revealed in the prefrontal cortex of trained animals.

A Hardware-and-Software System for Experimental Studies of the Acoustic Startle Response in Laboratory Rodents.

We developed and tested a novel hardware-and-software system for recording the amplitude of the acoustic startle response in rodents. In our experiments, the baseline indexes of acoustic startle response in laboratory rats and pre-stimulation inhibition under the standard delivery of acoustic stimulation were similar to those evaluated by other investigators on foreign devices. The proposed system is relatively cheap and provides the possibility of performing experiments on freely moving specimens. It should be emphasized that the results of studies can be processed with free-access software.

Expression of genes encoding serotonin receptors and SERT in various brain structures of stressed rats after chronic exposure to ultrasound.

The expression of genes encoding serotonin receptors and serotonin transporter in emotiogenic structures of rat brain was shown to change after chronic stress with ultrasonic waves of varying frequencies. A QPCR-RT study revealed the increased expression of genes for SERT and 5-HT1B receptor and decreased expression of the 5-HT2A receptor in the prefrontal cortex of rats after chronic exposure to ultrasonic waves of varying frequencies. Gene expression was increased for SERT, but decreased for 5-HT1B, 5-HT2A, and 5-HT2B receptors in the midbrain of animals. The hippocampus was characterized by an increased expression of genes encoding SERT and 5-HT1A, 5-HT2A, and 5-HT2B receptors. Our results indicate that the exposure to this type of stress is followed by dysregulation in the serotoninergic system of the brain.

Effects of prenatal exposure to antibodies against brain-specific anion transporter on cognitive functions in rats.

We studied the effects of single intravenous injection of antibodies to brain-specific transmembrane anion transporter (BSAT1; 5 mg/kg) to pregnant rats (gestation day 10) on cognitive functions and behavior of their progeny. One of major functions of BSAT1 (or Oatp1c1) is specific transport of thyroxin across the blood-brain barrier. Female rats of two control groups were injected with non-specific Ig and 0.9% NaCl. The progeny of rats receiving monoclonal antibodies to BSAT1 demonstrated memory impairment in the Y-maze, novel object recognition test, passive avoidance test, and Morris water maze test in comparison with the control group. Our findings suggest that single injection of monoclonal antibodies to BSAT1 during the prenatal period was followed by cognitive impairments, which were probably related to thyroxin deficiency in the nervous tissue.

[Spontaneous enhancement of long-term memory retrieval during a few days after training].

The dynamics of long-term memory retrieval on the 1st and 5th days after rat training in spatial Morris water maze and snail conditioned taste aversion models was studied. It was found that animals trained for several days displayed stable and high level of memory retrieval both on 1st and on 5th days after training. Under conditions of single-session training the rate of memory retrieval in snails and rats on the 5th day was higher than on the 1st day after training. It has been proposed that spontaneous enhancement of habit retrieval during 5-days time interval after training is a result of "lingering" memory consolidation processes, which includes trace reorganization in particular molecular and morphological changes in animal brain neurons.

Effect of ultrasonic irradiation on the development of symptoms of depression and anxiety in rats.

Behavioral reactions of rats were studied under conditions of constant exposure to ultrasonic irradiation at a frequency of 20-45 kHz for 21 days. In rats subjected to ultrasound, impaired behavior in the social interest test and Porsolt forced swimming test was observed; the development of anhedonia in the sucrose preference test was revealed (manifested in the symptoms of depression). The effects of ultrasonic irradiation were abolished by an antidepressant fluoxetine, a selective serotonin reuptake inhibitor. Our results indicate that chronic exposure to ultrasonic radiation produces a modulatory effect on depressive symptoms in rats. These changes satisfy the requirements for experimental animals, which are used as a model of psychopathological processes.

[The endophenotype concept in the neurophysiological studies of schizophrenia].

The endophenotype concept is considered as theoretical basis for the study of pathobiological mechanisms of schizophrenia and for the development of the complex of instrumental diagnostic methods. The contemporary state of the problem and the most significant results of the study of three neurophysiological schizophrenia endophenotypes are presented in the review: P50 auditory evoked potential suppression, prepulse inhibition of the startle reflex and antisaccade task. The current understanding of the underlying neurophysiological and neurochemical mechanisms is described for each measure. The results of the association studies of neurophysiological endophenotypes with the relevant to schizophrenia genes' polymorphisms are laid down. High degree of independence of the considered endophenotypes is demonstrated. Taking into account the data on relatively low specificity of each endophenotype to schizophrenia compared to other mental disturbances the authors pay special attention to the model of multivariate endophenotype as a scientific and diagnostic tool.

Delayed effects of NMDA receptor antagonist MK-801 on storage and reconsolidation of spatial memory in rats.

We studied the effects of NMDA receptor antagonist MK-801 on the storage and reconsolidation of spatial memory in Morris water maze in adult rats. MK-801 (50 µg/kg) administered 24 h after the completion of training was shown to improve the resistance of spatial memory to spontaneous extinction, while reminder against the background of MK-801 suppresses its ameliorating effect on memory storage. The detected behavioral effects of MK-801 persisted over 60 days after administration and can be associated with its influence on coupled neurogenesis/apoptosis processes induced during memory trace formation in adult animals.

Long-term spatial memory retrieval at different times following formation in single session training in rats.

The dynamics of retrieval of spatial memory formed in single-day training in rats was studied at different terms after training. Good learners, i.e. rats successfully learned to find the hidden platform in the Morris water maze after single-day training session, demonstrated spontaneous improvement of maze performance on day 5 after training in comparison with that in 24 h after training. Poor learners (maze performance during learning session did not differ from random level) demonstrated spontaneous improvement of maze performance by day 20 after training. These findings attest to the existence of multiple mechanisms of memory trace transformation at delayed terms after training.

Regional features of the expression of genes involved in neurogenesis and apoptosis in the brain of adult rats.

The expression of mRNA of genes involved in neurogenesis and apoptosis (Apaf1, Ascl1, Bax, Bcl2, Casp3, Casp8, Casp9, Dffb, Myh10, Naip2, Napa, Notch2, Numb, Pura, S100a6, Tnf) in the prefrontal cortex, hippocampus, and cerebellum was studied in adult rats. The content of mRNA of these genes (except Apaf1) was several-fold higher in the cerebellum than in the hippocampus and brain cortex. In the hippocampus, the expression of Apaf1 was significantly lower than in the prefrontal cortex, while the expression of Ascl1, Pura, S100b, and Tnf was higher. Regional differences in the direction, strength, and numbers of significant correlations between the expression of the studied genes were detected. Documented differences in gene expression were regarded as validation of the structural and functional cooperation of neurogenesis and apoptosis at the molecular genetic level.

Neurogenesis enhancer RO 25-6981 facilitates repeated spatial learning in adult rats.

The effects of Ro 25-6981 (selective NMDA receptor blocker) in a dose stimulating neurogenesis on repeated learning, reversal learning, and memory reconsolidation were studied in adult rats in Morris water maze. Ro 25-6981 facilitated repeated learning 13 days after injection, but did not influence reversal learning. The blocker injected directly before reminder did not disturb repeated learning and reversal learning in Morris water maze. These effects of Ro 25-6981 on the dynamics of repeated learning seemed to be due to its effects on neurogenesis processes in adult brain.

[Effects of the neurogenesis stimulator Ro 25-6981 upon formation of spatial skill in adult rats depend on the term of its administration and the animals' ability to learn].

Effect of administration of selective N-methyl-D-aspartate (NMDA) receptor antagonist Ro 25-6981 on learning and memory in a dose which is known to stimulate neoneurogenesis was assessed in adult rats with different abilities to formation of spatial skills in different time periods after the antagonist injection. Wistar male rats were trained to find hidden platform in the Morris water maze for 5 consecutive days. Rats' learning ability for spatial skill formation was evaluated depending on platform speed achievements. In re-training sessions (cues and platform location changed), it was found that all rats received Ro 25-6981 13 days before the re-training demonstrated impaired spatial memory. At the same time the inhibitor injected 29 days before re-training selectively facilitated the formation of spatial skill in animals with initially low learning abilities.

[Prepulse modification of acoustic startle reaction in patients with schizophrenia and healthy controls].

Prepulse modification of acoustic startle reaction (ASR) was studied in patients with schizophrenia and healthy controls according to the protocol recommended by the Consortium on the genetics of schizophrenia. Patients displayed the reduced ASR magnitude of prepulse inhibition (PPI) and increased startle latency prepulse facilitation (PPF) at 60 ms lead interval. The ASR amplitude PPF at 2500 ms lead interval was also impaired in patients. Effects of the recent head trauma and psychoactive drug experience on the ASR prepulse modification were different in patients and controls. The high baseline amplitude and short ASR latency in patients were correlated with the excitation level measured with the PANSS (item P4) whereas the PPF reduction was correlated with the high total score on the PANSS positive subscale. These results suggest the possibility of using ASR prepulse modification in clinical neurophysiology.

Irreversible amnesia in rats and edible snails under conditions of associative memory reconsolidation disturbance caused by NMDA-glutamate receptor antagonist.

The effect of MK-801, an antagonist to NMDA-glutamate receptors, on reconsolidation of olfactory discrimination task in rats and taste discrimination in edible snails was examined. Twenty-four hours after conditioning, the animals received a single systemic injection of MK-801 followed by a reminding conditional stimulus. Disturbances in retrieval of the acquired task were observed 10 days after injection followed by a reminding procedure. Repeated conditioning of these animals did not restore the task. Injection of MK-801 without reminding stimulation had no effect on task retention. Thus, disturbances of NMDA-dependent reconsolidation of the associative memory in animals of different taxonomic groups irreversibly eliminated long-term memory.