[Intranasal application of a thyrotropin-releasing hormone attenuates state-anxiety of the rats].

During the experiments we investigated the influence of thyrotropin-releasing hormone (TRH) on the changes in the behaviour of white rat (Rattus norvegicus) males (n = 90), induced by light uncontrolled impact. After two-week procedure of handling male rats were tested using elevated plus-maze to determine the basal level of anxiety, locomotor and investigative activity and emotionality. A month later we investigated the influence of intranasal administration of TRH-solution (10(-10) M) in a volume of 20 mkl on the anxiety-level increase, induced by stress: short electric foot-shocks. Four hours later animals were tested in the elevated plus-maze. In vehicle-treated animals we detected the increase of anxiety and emotionality level and the decrease of locomotor and investigative activity. In contrast there was no increase of anxiety and emotionality in TRH-treated rats. As to the locomotor and investigative activity, it decreased in TRH-treated animals as well as inthe vehicle-treated. It shows the specific influence on the level of anxiety, which doesn't affect other components of stress-induced behavioral changes Present results suggest TRH as a potential anxiolitic.

[Active coping style as a risk factor of depressive-like disorders after cronic mild stress].

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.

[Efficacy of vision correcting system "focus" for prevention and treatment of dry form of age macular degeneration].

The results of comparative study of efficacy and safety of vision correcting system "Focus" and Picamilon in patients with dry form of age macular degeneration are presented. 60 patients were enrolled into the study, follow-up was 3 months. Routine examination revealed positive impact of "Focus" on dynamics of main visual functions (visual acuity and field). In terms of impact on dynamics of main visual functions "Focus" is comparable with Picamilon, though it is better tolerated. Intake of vision correcting system "Focus" promotes visual functions improvement and prevents progressing of retinal degenerations.

[Prolactin-releasing peptide increases rat anxiety].

BACKGROUND: Prolactin-releasing peptide(Prl-RP), in addition to stimulating the production of prolactin, interacts with various parts of the central nervous system, participating in the implementation of many functions that are reflected in behavior. AIM: The effect of Prl-RP on the anxiety of white Wistar rats was studied since there were no data in the literature on the relationship between Prl-RP and anxiety. MATERIALS AND METHODS: Anxiety was assessed in two tests. In the elevated plus-maze (EPM), the time spent in the open arms and the number of edge reactions were recorded. In the social preference test, the time spent near a stranger, near a familiar individual, and in neutral territory were recorded. RESULTS: The administration of Prl-RP at a dose of 10-10 M with a volume of 10 µl in each nostril reduced the time spent by the animals in the open arms of the EPM, and the number of edge reactions. For testing the social interaction, animals were pre-selected for high or low levels of anxiety in the EPM. In rats with initially low levels of anxiety, Prl-RP reduced the time spent near a stranger, indicating an increase in anxiety levels. The behavior of rats with initially high levels of anxiety did not change after application of the Prl-RP. CONCLUSION: The results of our experiments indicate that the intranasal administration of Prl-RP increases the anxiety of rats.

[Social preference of white rats with high and low anxiety].

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.

Agonistic behavior during stress prevents the development of learned helplessness in rats.

Male Wistar rats were subjected to unavoidable electrical pain stimulation either in individual cages or in pairs. During the procedure, rats stressed in pairs fought. After 48 h, rats were tested in a shuttle box for the ability to develop active avoidance responses. The proportion of escape and avoidance responses was significantly lower in rats stressed individually as compared with intact animals and animals stressed in pairs. Plasma corticosterone was assayed one day later, at rest and after dexamethasone administration. There were no significant differences in resting corticosterone level between groups of animals. Administration of dexamethasone significantly reduced the plasma corticosterone level in intact rats and in animals stressed in pairs, but not in rats stressed individually. Thus, agonistic behavior during unavoidable stress prevents the development of pathological changes in adaptive behavior and the endocrine system.

The effects of stages of the estrous cycle on pain thresholds in female white rats.

The effects of stages in the estrous cycle on electrical pain thresholds were studied in white rats in conditions of chronic measurement. On recording day 3, females in the diestrus and estrus stages showed sharp increases in shudder and paw-shuffling thresholds. Females in proestrus and metestrus showed no change in thresholds as compared with those in the first days of recording. Starting from day 7, there were progressive decreases in electrical pain thresholds regardless of the stage of the estrous cycle. Data for all animals showed that regular measurement of pain thresholds induces a smooth two-fold increase in body resistance from day 1 to day 7. This was followed by a sharp drop on day 8, with parallel decreases in body resistance and electrical pain thresholds. Thus, chronic measurement of electrical pain thresholds and body resistance changed in a complex fashion, and threshold values depended on the stage of the estrous cycle.

[Effect of consumption of sucrose and saccharin on passive avoidance learning in female Wistar rats]. / Vliianie potrebleniia sakharozy i sakharina na obuchenie passivnomu izbeganiiu samok krys linii Vistar.

Influence of consumption of 32% sucrose or 0.1% saccharin solutions on passive avoidance acquisition in female Wistar rats was studied at different stages of estrous cycle. Under conditions of weak electrical shock, rats of the control and saccharin groups showed no acquisition at any stage of estrous cycle. Under the same conditions females of the sucrose group acquired the avoidance behavior if trained on the first day of diestrous and metestrous but not proestrous and estrous. The stage of estrous cycle on the second day did not influence the latency during testing session.

[The effect of different stages of the sex cycle on rat behavior in a plus maze]. / Vliianie razlichnykh stadii polovogo tsikla na povedenie krys v krestoobraznom labirinte.

Anxiety and motor activity of female white rats in the elevated plus-maze were studied at different stages of the reproduction cycle (estrus, diestrus, pregnancy and lactation). The level of anxiety was lower, and that of locomotor and exploratory activity was higher during estrus and lactation than during diestrus and pregnancy. Exposure to chronic pain of threshold intensity did not induce behavioral changes in pregnant rats. There was no difference between the control and experimental animals in the level of plasma corticosterone.

[Comparative analysis of the learning ability in Morris water test in rats with the various rate of active acquisition of the avoidance conditioned reflex]. / Sravnitel'nyi analiz sposobnosti k obucheniiu v vodnom teste Morrisa krys, razlichaiushchikhsia po skorosti vyrabotki uslovnogo refleksa aktivnogo izbeganiia.

Place learning in Morris place navigation task was studied in male rats of KHA (Koltushi High Avoidance) and KLA (Koltushi Low Avoidance) rat strains. These strains were selected for different rate of acquisition of active avoidance in a shuttle box. At the initial stages of learning and after changing the experimental conditions, the performance of KLA rats was significantly better than that of KHA. Analysis of individual escape latency showed that the latency of the platform finding in the first trial had a significant effect on successful performance in the second trial. This effect was different in KHA and KLA rats. As distinct from KLA, the KHA rats demonstrated more rigid strategy in spatial orientation, the clear-cut thigmotropism was characteristic for their behavior in water.

[Changes in the level of anxiousness in female white rats during the estrous cycle and depending on handling]. / Izmenenie urovnia trevozhnosti u samok belykh krys v techenie éstral'nogo tsikla i v zavisimoti ot khéndlinga.

Experiments were carried out in naive and handled female white rats at the oestrus and dioestrus stages. The elevated plus-maze was used for anxiety measurements. Handled female rats, as compared with the naive ones at the same stage, showed much lower anxiety scores and higher general level of activity. No statistically significant effect of the oestrus cycle was observed in the naive rats, and the handled ones showed significant decrease of anxiety and increase of general level of activity during the oestrus stage.

[Changes in the higher nervous activity of the progeny of alcoholized male white rats]. / Izmenenie vysshei nervnoi deiatel'nosti u potomstva alkogolizirovannykkh samtsov belykh krys.

Some forms of behaviour of the offsprings of male rats, which within a period more than 1 month gave preference to 20% ethanol solution over water (I group), were compared with behaviour of the offsprings of males, in which alcoholic motivation had been interrupted after a period of preferential consumption of ethanol during 1 month (II group), and behaviour of the offsprings of intact males (III group). Exploratory and locomotor activity in the animals of the I group was lower, and the level of anxiety was higher, than in the animals of the II group; there were no distinctions between the animals of the II and the III groups (by testing in elevated plus-maze). Memory traces in a test of avoidance by swimming retained worse in the females of the I group, than in the females of the II group; there were no distinctions between males. Capability for bilateral active avoidance conditioning was higher in the animals of the I group, but at the same time the number of animals, which demonstrated non-escape reaction, increase. Forced alcoholization of males of the I and the II groups was carried out beginning from the age of 7 months. Within 2.5 months after the beginning of alcoholization 2/3 of the rats of the I group demonstrated ethanol preference during a testing period of 1 month. Such preference retained only in 14.3% of the animals of the II group. It is supposed that the main factor, which determines predisposition of the offsprings to alcohol consumption, is alcohol consumption by parents rather than their own predisposition.

[Different anxiety levels in rats selected for their ability to acquire the conditioned reflex of active avoidance]. / Razlichnaia trevozhnost' u krys, selektirovannykh po sposobnosti k vyrabotke uslovnogo refleksa aktivnogo izbeganiia.

Experiments were carried out in rat strains selected for high (KHA) and low (KLA) rates of active avoidance conditioning in a shuttle box. The elevated plus-maze was used for anxiety measurements. Naive KHA rats, as compared with KLA ones, demonstrated much higher anxiety scores. Inescapable electric footshock had opposite effects on anxiety levels in KHA and KLA rats, i.e., it increased anxiety scores in KLA rats and decreased in KHA. The results point to the role of anxiety in adaptive behaviour, e.g., in learning abilities.

[Patterns of maternal behavior of rats genetically selected for opposite coping styles]. / Materinskoe povedenie u krys s razlichnoi strategiei prisposobleniia.

Maternal behavior of Koltushi High- and Low-avoidance (KHA and KLA) rats strains was assessed over the prewealing period (days 6-21). Ten litters of each strain were observed during the light phase of the light/dark cycle. In a series of experiments, rat pups were taken from the maternal nest and placed into the opposite corner of the cage. The following parameters of the maternal behavior were recorded: the latency of the first contact with the pups, pup licking, latency of carrying/retrieval of the first pup back to the nest, time of returning to the nest of the whole litter, and mother's spontaneous behavior (grooming and locomotion time) over the course of 10 min of observation. KLA mothers stayed with their pups and took care of them more frequently than KHA mothers during the light phase of the circadian cycle. Time of self-grooming was significantly higher in KHA rats. The highest levels of self-grooming of mothers was registered on the first day of testing. The latency of the first coming to pups after their removal from the nest was lower in KHA rats, but they needed more time to returned all pups to the nest. The experimental evidence suggests that the KHA but not KLA rats with the active coping style and higher stress reactivity display disorders in maternal behavior in a novel situation.

[The differences between sexes and strains in the capacity to acquire a passive avoidance conditioned reflex in KLA- and KHA-strain rats]. / Mezhpolovye i mezhlineinye razlichiia sposobnosti k vyrabotke uslovnogo refleksa passivnogo izbeganiia u krys linii KLA i KHA.

The interstrain differences in passive avoidance conditioning were studied in male and female KHA (Koltushi High Avoidance) and KLA (Koltushi Low Avoidance) rats. These strains were selected for the rate of acquisition of active avoidance in a shuttle box. It was shown that the passive avoidance was substantially better acquired in the KLA strain than in the KHA. In females KHA rats the capability for passive avoidance conditioning depended on the estrus phase: the conditioning was impossible in proestrus.

[Intersex and interspecies differences in sucrose consumption by rats with various behavioral strategies]. / Mezhpolovye i mezhlineinye razlichiia v potreblenii sakharozy krysami s razlichnoi strategiei povedeniia.

Sucrose consumption by male and female rats during active avoidance acquisition was measured in two rat strains: KLA (Koltushi low avoidance) and KHA (Koltushi high avoidance) selected for divergent performance in a shuttlebox. Under resting condition, there were no interstrain difference in sucrose consumption by males, but KHA females consumed significantly less sucrose than KLA females. Active avoidance acquisition during five consecutive days decreased sucrose consumption in KLA males and did not change sucrose consumption in KHA males. Within a week after exposure to the stress, the sucrose consumption by KLA males returned to its normal values, and KHA males consumed significantly more sucrose. The active avoidance conditioning did not affect sucrose consumption in females of both strains. Substitution of 32% solution for 4% produced on the first day a sharp decrease in sucrose consumption in males of both strains, while females sharply increased consumption of the diluted solution over the next four days of observation. During this time, males returned to consumption of the same volume of the solution despite its decreased concentration. The findings suggest that the exposure to the escapable stress induces the negative affect only in KLA males.

[Rats with passive coping strategy have average, but not low social range]. / Krysy s passivnoi strategiei prisposobleniia obladaiut srednim, a ne nizshim sotsial'nym rangom.

Social ranks were determined in rats with different degrees of activity-passivity in coping style. The dominance status of rats was assessed by their behavior during social interaction and during competition for food and water. Coping styles were determined during initial trials of acquisition of active avoidance in a two-way shuttle box. Animals with passive behavior in a shuttle box had average scores of social ranks. Both dominant and subordinate rats displayed significantly more active behavior than subdominant animals. In additional experiment, the rats were caged as a one male-one female pairs. Two weeks later, the social ranks of males were determined during agonistic interactions. Males were caged in triads, and corticosterone levels were assayed in blood samples taken from the tail veins during the first five days. The corticosterone level was significantly higher in subdominants than in dominants. There was no significant difference between the dominants and subordinates in corticosterone levels. The obtained evidence suggests the passive coping in subdominant rats, whereas the dominant and subordinate animals were more "active" under aversive stimulation.

[The effect of stress on the anxiety level in female white rats at different stages of the estrous cycle]. / Vliianie stressa na uroven' trevozhnosti u samok belykh krys v razlichnye stadii éstral'nogo tsikla.

Locomotor activity in the elevated plus-maze was studied in female white rats following chronic stress induction (measuring pain threshold in the course of 15-20 days). Anxiety and plasma corticosterone levels were determined. In control experiments in intact rats anxiety was lower and locomotor activity was higher in proestrus than in diestrus. There were no differences in anxiety and locomotor activity between diestrus and proestrus in rats exposed to chronic stress. In intact rats plasma corticosterone levels were the same in proestrus and diestrus. Following chronic stress plasma corticosterone level was significantly higher in proestrus than in diestrus.

[The effect of stress in pregnant rats on the anxiety level in their offspring]. / Vliianie stressa beremennykh krys na uroven' trevozhnosti potomstva.

The anxiety level was studied in offsprings of dams stressed during pregnancy. Increased number of resorptions and stillbirths was mentioned. The experimental pups (1 month old) had lower locomotion and higher anxiety levels as compared to the control animals. There were no differences in anxiety and locomotion levels in males (4 months old) between the experimental and control groups. In experimental females of this age anxiety was decreased and locomotion increased. Aggressive behavior was more expressed in the experimental animals of both sexes.

[The effect of prenatal "pain" and "emotional" stresses on the learning characteristics of rats]. / Vliianie prenatal'nogo "bolevogo" i "émotsional'nogo" stressov na kharakteristiki obucheniia krys.

Behaviour was studied of the offsprings of female rats which were exposed to pain (P) and emotional (PSY) stress during the last 9 days of pregnancy. The P group received 5 electrical foot shocks (shuffle threshold, 50 Hz, 3 sec). PSY rats were placed in the compartment adjacent with the grid-floor box, thus they could watch, hear and smell the mate exposed to P. Pups of the intact rats served as a control (C). At 7-8 weeks of age the offsprings were tested in a modified Morris maze. Performance was significantly better in the P group than in the PSY and C groups. Acquisition of avoidance in a one-way shuttle-box at 10-12 weeks was higher in the P group than in the PSY and C animals. Two weeks later, the C rats were more successful in acquisition in a two-way shuttle-box than the PSY and P rats. At the age of 4-5 months a trend was revealed to higher capacity for learning in female P and C offsprings than in males while in the PSY group capacity for learning was sex-independent. The findings suggest that the pain and emotional stress during pregnancy exert different effects on behaviour of the offsprings.