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Biomedical subjects

E P Vinogradova

Publications and source records attributed to E P Vinogradova.

At least 19 recordsLinked to original sources
PubMed2003

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.

Animals↗
PubMed2001

[Feedback in the stimulus-response system determines stress specifics].

The paper surveys controllability in the stress theory. Uncontrollable action is perceived by living organisms in a principally different way than the controllable one and induces persisting pathological changes. The controllability, i.e. presence of a feedback in the stimulus/response system, is determined by an interaction of the medium factors and a strategy of subject's behaviour. A passive strategy proves to be optimal for adaptation under the conditions when an animal cannot change unfavourable medium conditions. The authors base their theoretical statements on their own experimental studies as well as literature references analysis.

Adaptation, Physiological↗
PubMed2001

[Effect of estrous cycle phase on pain threshold in female white rats].

Pain thresholds and body resistance in female Wistar rats were determined during estrous cycle stages. The flinch and shuffle thresholds were increased on the 3rd day of measurement in diestrus and estrus but not in proestrus and metestrus as compared with the thresholds during the 1st day of recording. The thresholds decreased as of the 7th day to the 14th day. Daily threshold measurements raised the body resistance on the 7th day of recording. In contrast to the pain thresholds, the body resistance change had not a stage-dependent character.

Animals↗
PubMed1996

[Agonistic behavior during stress inhibits the development of learned helplessness in rats].

Male Wistar rats were exposed to inescapable shock in individual chambers (IS), or shocked in pairs (PIS). The latter rats were fighting during the shock administration. In 48 hrs, all the rats were subjected to escape/avoidance task in a shuttle-box. Failures increased significantly in the IS rats as compared with the PIS and intact rats. Dexamethasone administration decreased the plasma corticosterone level in the latter groups, but not in the IS rats. The findings suggest that an inescapable shock induces no learned helplessness in rats having an opportunity of agonistic interaction during the shock. The findings suggest also a stress-protective effect of agonistic contacts under averse conditions.

Agonistic Behavior↗
PubMed1978

[Responses of neurons in the cochlear nuclei of sharp-eared bats to presentation of simultaneous ultrasonic stimuli].

The single unit activity of cochlear nuclei in Verspertilionidae are studied by means of ultrasonic pure tonal and frequency-modulated stimuli. Most neurons (85%) had tonic reaction to combination tones f2-f1 and 2f1-f2 (f1, pulse frequency of the first tone, f2 pulse frequency of the second tone) as a result of the nonlinearity in the auditory system. The reaction to the combination tones depended upon pulse frequency and sound pressure level of each of the presented stimuli. Tonic reaction appeared in the case when the combination tone was equal to the best frequency of the neuron. The question about the role of the nonlinearity of the auditory system in the resolution of the complex signals is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

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.

Agonistic Behavior↗
PubMedDate not supplied

[The effect of different stages of the sex cycle on rat behavior in a plus maze].

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.

Animals↗
PubMedDate not supplied

[The differences between sexes and strains in the capacity to acquire a passive avoidance conditioned reflex in KLA- and KHA-strain rats].

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.

Animals↗
PubMedDate not supplied

[Comparative analysis of the learning ability in Morris water test in rats with the various rate of active acquisition of the avoidance conditioned reflex].

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.

Animals↗
PubMedDate not supplied

[Intersex and interspecies differences in sucrose consumption by rats with various behavioral strategies].

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.

Adaptation, Psychological↗
PubMedDate not supplied

[Rats with passive coping strategy have average, but not low social range].

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.

Adaptation, Psychological↗
PubMedDate not supplied

[Effect of consumption of sucrose and saccharin on passive avoidance learning in female Wistar rats].

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.

Animals↗
PubMedDate not supplied

[Patterns of maternal behavior of rats genetically selected for opposite coping styles].

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.

Adaptation, Psychological↗
PubMedDate not supplied

[Features of the reactions of neurons of the cochlear nuclei of the pointed-eared bat Myotis oxygnathus to ultrasonic stimuli].

Studies of the reactions of neurones in the cochlear nuclei in the bat Myotis oxygnathus to ultrasonic stimulation show that 61% of the investigated neurones in a frequency range 20-40 kHz change tonic response for repetitive bursts, this change being dependent on the filling frequency and the intensity of stimulation. It is suggested that peculiarities of the neuronal activity result from the effect of a special inhibitory system presented in bats which uses in echolocation a wide range frequency-modulated impulses.

Animals↗
PubMedDate not supplied

[Different anxiety levels in rats selected for their ability to acquire the conditioned reflex of active avoidance].

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.

Animals↗