The adaptive reactions in hemopoietic system of the irradiated mice of two lines, differing in the level of emotionally-stress reactions on the emotional stress

On lines of the mice genetically differing on the sensitivity on emotional stress (steady--of the mouse of the line C57BL/6 or sensitive--of the mouse of the line BALB/c), the research of the development of the adaptive reactions in the system of the blood on the emotional stress influencing animals on the background of the preliminary irradiation in a low dose (0.9 Gy) is carried out. The unirradiated mice of the line C57BL/6 adequately reacted on the stress, that was shown in a moderate behavioural reaction during the period of stress, and the development of high-grade adaptive reactions in the hemopoietic system. Among the mice of the line C57BL/6 in conditions of the combined influence of ionizing radiation and of the emotional stress was not revealed of the infringements of the adaptive reactions of the hemogenesis. As opposed to these data, among unirradiated mice of the line BALB/c the sharply expressed behavioural reactions during the stress were marked, that was accompanied by incomplete development of the adaptive reactions in the system of a blood on the stress. Under the influence of stress on the previously irradiated animal line BALB/c was observed the inhibition of the medullar hemopoiesis.     

Participation of angiotensin II in the establishment of negative emotional reactions

In waking rats and rabbits systemically injected angiotensin II was shown to participate predominantly in the mechanisms of negative emotional reactions. The effects of angiotensin II were observed at the behavioural level as well as at the neuronal one. Depending on the dose and the time of injection of angiotensin II and its specific antagonist saralasin they inhibited or facilitated elaboration and extinction of automatized conditioned active avoidance independently of arterial, pressure changes, the pain threshold being altered. Injection of angiotensin II abolished individual behavioural reactions of the animals in response to stress factors and increased their resistability to emotional stress. The negative emotional reactions were found to induce changes of chemosensitivity of neurones of the parafascicular complex of the medial thalamus and the midbrain reticular formation during microionophoretic application of angiotensin II. A supposition is made about the increase of angiotensin II brain synthesis under conditions of emotional stress.     

The Delta-Sleep Inducing Peptide in Cerebral Mechanisms of Emotional Stress

The problem of the anti-stressor effect of the delta-sleep inducing peptide (DSIP) and of its neurophysiological mechanisms of action is considered. Physiological data are exposed that indicate an intraventricular administration of DSIP in rats to results in an increase of resistance to emotional stress, according to behavioral and autonomous reactions, and in a decrease of excitability of the brain structures responsible for protective reaction. Radioimmunological evidence is presented for the resistance of animals to emotional stress to depend on the content in hypothalamus of certain oligopeptides, such as -endorphin, DSIP, and the substance P. It was shown that animals resistant to emotional stress had a higher content of these oligopeptides in hypothalamus than those predisposed to stress. The issue is discussed that the prolonged anti-stressor effects after the DSIP administration are determined by considerable changes of the content of other polypeptides and hormones in hypothalamus and blood, which are involved in the reaction under the effect of DSIP.     

Characteristics of free-radical oxidation and antiradical protection of the brain in adaptation to chronic stress

During the phase of long-lasting adaptation to chronic emotional painful stress three stages have been distinguished on the basis of physiological and neurobiochemical data. The first stage (1 week of stress)--transition from urgent to long-lasting adaptation--corresponds to labilization of vegetative indices, predominance of fear reactions and suppression of research behaviour in rats, inhibition of lipid peroxidation, activation of superoxide scavenging activity, decrease in cholesterol content in brain lipids. The second stage (2 weeks of stress)--long-lasting adaptation--is characterized by normalization of the behaviour, stabilization of high blood pressure, maximum brain antiradical activity and low level of lipid peroxidation. The third stage (3 weeks of stress)--transition from long-lasting adaptation to exhaustion--is characterized by blood pressure lowering, disturbed regulation of vegetative functions, behavioural hyperactivity in the open field, increased lipid peroxidation and decreased phospholipid content.     

Acute emotional stress and cyclic nucleotide content of the heart and blood plasma

The relationships between the changes in arterial pressure and the content of cyclic nucleotides in the heart and blood plasma were studied on rabbits exposed to acute emotional stress. During 3 hours of the stress program, there were changes in arterial pressure, namely an elevation within the first hour followed by a progressive fall during subsequent 2 hours and death of the animals. The content of cAMP in the heart rose to a greater degree than that of cGMP. The content of cAMP in the blood plasma considerably increased, while the level of cGMP remained unchanged. The data obtained attest to the predominance of activation of adrenergic structures over activation of cholinergic structures.     

Changes in the level of oxygen tension in different brain structures of rats in positive and negative emotional states

Changes of oxygen tension (pO2) level in various brain structures were studied in rats in positive and negative emotional states. It is established that pO2 level changes depend on the character of behavioural reactions: "active" type of behaviour (emotionally positive orienting-investigatory, actively defensive) is accompanied by pO2 level increase, and "passive" type of behaviour ("freezing" reaction)--by a decrease of pO2 level. Changes of oxidative brain metabolism observed at "active" and "passive" types of behaviour indicate, respectively, adaptive and nonadaptive character of these behavioural reactions.     

Bone marrow hemopoiesis at emotional stress reactions of various intensity upon a background of exposure to low dose ionizing radiation

Rats preliminary exposed to 0.9 Gy of ionizing radiation showed disturbances in the development of adaptive reactions of blood system to emotional stress, compensatory capacity of the blood system being decreased. A degree of the disturbances directly depended on the duration and intensity of the emotional stress: at the prolonged intensive emotional stress a sharp decrease in the adaptive and compensatory capacity of blood system was found; at short intensive or moderate stress the changes in the adaptive and compensatory capacity of hemopoiesis were less pronounced. A combined action of low-dose ionizing radiation and short weak emotional stress did non affect the adaptive and compensatory capacity of hemopoietic system.     

Effect of stress experienced during pregnancy on the rate of lipid peroxidation in erythrocytes and brain tissue of newborn rat pups

The rate of lipid peroxidation (LPO) in erythrocytes and brain homogenate has been assessed by the accumulation of malondialdehyde, the degree of erythrocyte autohemolysis, the content of hydrogen peroxide and catalase activity observed in newborn rats aged 1 hour, 1, 15, 20 and 30 days. Pregnant rats were exposed to emotional stress (aggressive interaction of two pregnant rats in an unavoidable conflict situation provoked by nociceptive irritation. Significant age-dependent differences in the rate of LPO (both in erythrocytes and cerebral tissue) have been found. The highest rate was noted in rats 15 days of age. The emotional stress of pregnant females resulted in the changes of behavioural reactions of newborn rats and LPO activity that was characterized by the increase in LPO rate in 1-hour- and 1-day-old rats and by slowing of LPO rate in 15-day-old rats. These phenomena were observed in erythrocytes and brain tissues of test animals.     

Neurophysiological analysis of the development of endocrine and hypertensive reactions in long-term emotional stress

A study was made of the effect of chronic emotional stress on the formation of hypertension in animals. This was shown to be related to dynamic changes in the function of the CNS, particularly in the hypothalamic apparatus of the neuroendocrine control. The above changes played a role in the formation of hypertensive vascular reactions accompanied by a high hormonal secretion of the adrenal cortex and thyroid. During stabilization of high arterial blood pressure at the late stages of the "after-effect", the hormonal secretion returns to normal.     

The prediction of resistance to emotional stress based on the individual testing of behavior

On the basis of the elaborated experimental model for testing of emotional interaction of animals individual typification of behaviour was established according to which all experimental male rats of August line were subdivided into groups: I--rats manifesting behaviour of avoidance, "victims" of electrocutaneous stimulation; II--without definite behaviour with respect to the "victim" rat; III--rats, preferring the behaviour determining electrocutaneous stimulation of the "victim" rat. All typified animals were subjected to emotional stress with the use of the elaborated experimental model of aggressive-conflict behaviour. Stability against emotional stress of each group of animals was studied. Significant differences were established of stability degree to emotional stress of the rats of three groups manifesting different types of behavioural reaction in conditions of emotional interaction. The most stable were rats of the I group, the least--of the III group; rats of the II group were in the middle position. Typification on the basis of testing of emotional interaction of animals allows to prognosticate individual stability against emotional stress.     

Adrenocortical and thyroid systems of rats at the initial stage of nociceptive influence

There are two phases in the initial period of formation of adrenocortical response to sharp nociceptive influence. The first phase (within 10-15 sec.) involves emergency mobilization of "basal" reserves of hormone active substances. It is characterized by reduction of corticoliberine activity in hypothalamic and extrahypothalamic structures of the rat brain with a parallel increase of corticotrophin concentration in plasma, devastation of corticosteroid reserves in adrenal glands; a decrease in the level of corticosteroids in blood against the background of accumulating hormone in bodies-targets. In the second phace: the phase of hypercompensation, the progressive increase of credit of the substances under study was quite obvious. The authentic changes in a level of aldosterone in adrenal glands and blood took place only in 2.5 minutes after the stress. The nociceptive influence was also biphasic when acting upon the reorganization of thyroid status number. However, unlike the initial adrenocortical response to stress in the first phase of thyroid reaction, the elevation of plasma thyroxine and tri-iodothyronine level was obvious. At the second stage, selective decrease in concentration of thyroxine to normal amounts occurred.     

Electroencephalographic Correlates of Mental Performance of Emotional Personal and Scenic Situations: I. Characteristics of Local Synchronization

An electroencephalogram (EEG) was recorded in 19 standard derivations in two groups of subjects (student actors and nonactors) during emotionally positive and negative mental recalls of personal experiences (test 1) or mental reproduction of scenic situations (test 2), as well as during mental count of time. Statistical comparison of EEG spectral power estimations in the frequency bands , , ₁, ₂, ₁, and ₂ showed that the induction of emotionally positive and emotionally negative states led to statistically significant changes in the EEG absolute power (local synchronization) simultaneously in many derivations and frequency bands. Analysis of all possible comparisons and changes in frequency bands showed that bilateral prefrontal and temporal cortical areas are most active during the internal induction of emotional states. Emotionally positive states were characterized, predominantly, by higher local EEG power than emotionally negative states. The EEG power changes accompanying internal induction of emotionally negative and positive states were of the same order in the case of reproduction of a presented situation (scenic material), whereas, in the case of recall of personal experience, emotionally negative states were accompanied by substantially weaker EEG spectral changes than emotionally positive states. The internal induction of emotional states on the basis of scenic material was accompanied by a pronounced increase in the power of the EEG range over the whole cortical surface. EEG reactions to induction of emotional states were generally stronger in actors than in nonactors. In case of emotional induction on the basis of scenic material, qualitative differences in the EEG reactions were also revealed between the groups. The findings are discussed in comparison with known data of investigations into regional cerebral blood flow during internal emotional induction and EEG studies of internal and external emotional induction.     

Individual Variation in Behavioural Reactions to Unfamiliar Conspecific Vocalisation and Hormonal Underpinnings in Male Chimpanzees

It has been established that various species exhibit personality, defined as intra‐individual consistency and inter‐individual variation in behavioural phenotypes. For example, certain individuals may demonstrate consistently greater behavioural reactions and elevated stress responses. We conducted playback experiments and hormonal analyses on male chimpanzees (Pan troglodytes) in captivity to investigate the patterns and proximate mediators of individual variations in behavioural reactions. We found intra‐individual consistency and inter‐individual variation in behavioural reactions (intensive vigilance towards the direction of speakers) to vocalisations by unfamiliar chimpanzees. This behavioural reaction was positively correlated with changes in salivary cortisol concentration, suggesting that stress is a proximate factor mediating the variation in behavioural reactions. The males who were highly responsive to the conspecific vocalisation also exhibited high behavioural reactions towards the neutral broadcast stimulus (the jungle crow’s Corvus macrorhynchos ‘ka’ vocalisation). This observation is consistent with the notion that male chimpanzees vary in intrinsic behavioural tendency to different stimuli.     

Disruptions in the blood system upon exposure to low-dose ionizing radiation depending on duration of emotional stress

In experiments on rats, disturbances in the development of blood system adaptive reactions on emotional stress were found. Under the combined effect of preliminary (before stress) exposure to 0.8 Gy of gamma-radiation and the emotional stress of various duration (2, 4 and 8 days), a compensatory capability of the blood system decreased. The degree of the disturbances directly depended on the duration of the emotional stress.     

Change in the cholesterol and triglyceride content in the blood in self-stimulation and avoidance reactions]

The changes in the blood serum cholesterol and triglyceride content were studied or rabbits of both sexes during reactions of self-stimulation and avoidance. Self-stimulation was accompanied by a significant decrease in the blood serum cholesterol and triglyceride content. During the reaction of avoidance the character of the cholesterol changes varied. The reaction of avoidance of the "agression" type was accompanied by elevated blood serum cholesterol content, whereas the reaction of the "fear" type was associated with a decrease in its content. The maximal changes in the cholesterol and triglyceride content as compared to the initial level were observed in all types of the reactions 15--30 minutes following stimulation.     

Nature of changes in the level of steroid hormones and their precursors in peripheral blood of Papio monkeys under stress]

The radioimmunological method was applied to determination of changes in the peripheral blood plasma level of 12 steroids in male Papio hamadryas under immobilization and surgical stress. Androgen content decreased, and the concentration of steroid hormone precursors and hydrocortisone blood plasma content rose in response to stress. These changes were in contraphase with the circadian steroid rhythms. The most objective and sensitive criteria of the stress situation evaluation were decrease of testosterone and dihydrotestosterone level, increase of pregnenolone concentration, as well as of 17-alpha-hydroxypregnenolone, 17alpha-hydroxyprogesterone in the blood plasma.     

Correlations of central nervous system and thyroid function under chronic emotional stress

Experiments on cats exposed to chronic emotional stress induced during one week by 4-hour immobilization of the animals in conjunction with aperiodic electrocutaneous stimulation were made to study correlations of the time course of changes in the EEG of the cortical and subcortical structures and the content of thyroxin in the peripheral blood at varying time of the experiments. It was demonstrated that in the course of stress, the EEG manifests the cycles of "burst" activity of slow waves, which are first recorded in the posterior hypothalamus and then get generalized. This is accompanied by a significantly high thyroxin secretion. As the stress exposures are repeated, the EEG changes become dominant, also corresponding with high thyroxin secretion. After the experiments are over, the cycles of "burst" activity accompanied by enhanced thyroid function are still recordable over several days.     

Features of the behavior of the rat with hereditarily determined arterial hypertension

The behaviour of spontaneously hypertensive rats (SHR strain), rats with inherited stress induced arterial hypertension (ISIAH, a new developed strain), and of their normotensive Wistar progenitors was studied. The open-field arena and a device for measuring the total activity in the home cage were used in the behavioural studies. The SHR were much more active in the open--field and home cage tests than the Wistar and ISIAH rats. The basal locomotor activity of the ISIAH strain was lower than that of the Wistar rats, but the ISIAH strain had an index of behavioural reactivity 2.7 fold higher than the Wistar or SHR strains. These behavioural characteristics corresponded to the hypertension patterns of the strains compared. Enhanced spontaneous locomotion of the SHR rats was associated with spontaneous increase in arterial blood pressure. The ISIAH rats showed low spontaneous locomotor activity, but high behavioural and blood pressure reactivity under conditions of mild emotional stress.     

Effect of dipeptide vilon on emotional stress resistance in rats

Effects of synthetic thymomimetic vilon on open field behaviour, immediate early gene c-Fos expression in paraventricular hypothalamus properties of organs sensitive to emotional stress, and characteristics of albumin in the blood plasma in male Wistar rats, were investigated and are discussed in the article. It is shown that intraperitoneal vilon injection rises the resistance against emotional stress according to prognostic indexes open field behaviour. Vilon administration also inhibits hypertrophy of the adrenals, involution of the thymus, and elevates concentration of albumin in the blood plasma. The number of Fos-immunoreactive neurons in the paraventricular hypothalamus was lower after vilon administration especially in rats resistant against emotional stress.     

Delta sleep-inducing peptide in the blood and hypothalamus of rats with various resistance to emotional stress

Enzyme immunoassay was used to study delta-sleep peptide content in blood and hypothalamus in rats of Wistar lines under acute emotional stress. It was found that the content of delta-sleep peptide in blood and hypothalamus of stable rats was higher as compared with rats predisposed to emotional stress. After 1.5-hour emotional stress the content of delta-sleep peptide increased in blood and hypothalamus both in stable rats and predisposed ones. After 3-hour stress there was an increase in delta-sleep peptide content in hypothalamus, and contrary to its decrease in blood in both stable and predisposed animals. It is supposed that delta-sleep peptide along with other oligopeptides is one of the factors determining individual animal resistance to emotional stress, which is supported by significant delta-sleep peptide increase in hypothalamus in stable rats.