Lymphocyte Index of Peripheral Blood in Rats at Different Stages of the Post-Stress Period under Conditions of Antigenic Exposure and Injection of Lipopolysaccharide.

Changes in the Shaganin lymphocyte index (ratio of the number of lymphocytes to segmented neutrophils) in the peripheral blood of rats after intraperitoneal administration of LPS (100 µg/kg) at the end of a single stress exposure in a model of 24-h restraint stress were studied. The lymphocyte index was analyzed 3 h later, on the 1st and 8th days after the stress load. Immobilization was accompanied by a decrease in this parameter 3 h after exposure. One day after the stress load, an increase in the lymphocyte index was noted, which remained on the 8th day of observation. LPS injection did not affect the changes in this parameter caused by 24-h immobilization on the 1st and 8th days of the study, but prevented a pronounced increase in the lymphocyte index on the 1st day after the stress load. The data obtained expand the existing scientific understanding of the specificity of the involvement of immunomodulatory substances in the implementation of adaptive-compensatory processes in mammals under conditions of emotional stress.

[Neurological status and structural changes in the tracheal lymphoid tissue in rats with different resistance to emotional stress of experimental hemorrhagic stroke]. / Nevrologicheskii status i strukturnye izmeneniya limfoidnoi tkani trakhei u krys s razlichnoi ustoichivost'yu k emotsional'nomu stressu pri eksperimental'nom gemorragicheskom insul'te.

OBJECTIVE: To study neurological status and structural changes in the tracheal lymphoid tissue in rats with different resistance to emotional stress in experimental hemorrhagic stroke. MATERIAL AND METHODS: Evaluation of neurological deficit on the Menzies scale and a histological study of structural features of tracheal lymphoid tissue were performed on days 1, 3 and 7 of experimental hemorrhagic stroke in 98 Wistar male rats with different resistance to emotional stress. Stroke simulation was preceded by animal testing to determine individual stress resistance. RESULTS AND CONCLUSION: Neurological disorders are more pronounced in non-stress-resistant animals during all periods of observation. Lymphoid nodules of the tracheal wall of rats react with destruction of lymphoid cells and depletion of small lymphocytes observed in stress-resistant rats already on the 1st day of a stroke. On the 3rd day, the neurological deficit and changes in the cellular composition of the lymphoid formations of the trachea are most pronounced in both groups of rats. By the 7th day, a positive trend towards the restoration of the structure of tracheal lymphoid tissue and normal neurological status is detected only in rats resistant to emotional stress.

State of Stress-Marker Organs in Rats after a Single Exposure to Long-Term Stress and Treatment with Lipopolysaccharide.

We studied the effect of LPS on the state of stress-marker organs in rats at various periods after a single exposure to long-term stress on the model of 24-h immobilization. The animals were intraperitoneally injected with LPS in a dose of 100 µg/kg immediately after the negative emotiogenic exposure. Changes in physiological parameters were evaluated 3 h, 1 day, and 8 days after immune stimulation. Acute stress was accompanied by a decrease in the weight of the thymus during all stages of the post-stress period. An increase in the relative weight of theadrenal glands in animals under these conditions was observed only on day 8 after restraint stress. The induction of immune reactions due to systemic treatment with LPS was shown to prevent involution of the spleen in the late stage after a single exposure to long-term stress (day 8). Hypertrophy of the adrenal glands, which serves as one of the typical reactions of mammals to negative emotiogenic factors, was not revealed during the post-stress period after antigenic stimulation. These data hold much promise for the development of new approaches to the use of immunoactive substances to prevent or reduce the severity of physiological changes after emotiogenic loads.

Neurological Deficit and Structural Changes in Lymphoid Structures of the Tracheal Wall in the Immediate Stage of Experimental Hemorrhagic Stroke in Rats with Different Behavioral Activity.

Specific features of neurological deficit and changes in the cellular composition of tracheal lymphoid structures during the immediate stage (day 1) of hemorrhagic stroke were studied in rats with various behavioral parameters. Modeling of hemorrhage in the left caudate nucleus of the brain was followed by the development of motor disturbances in the forelimb use asymmetry test and corner rotation paradigm. These animals preferred to use the left forelimb (ipsilateral to the side of hemorrhage) to lean on the cylinder wall. The frequency of using the right forelimb or both forelimbs was reduced under these conditions. The number of left-sided rotations increased, while the percentage of right-sided rotations decreased. The observed changes were accompanied by immune dysfunction. It was manifested in the depletion of lymphoid aggregates of the tracheal wall in lymphocytes and plasma cells. The severity of abnormal neurological symptoms and disturbances in immune homeostasis during the immediate stage of hemorrhagic stroke was greater in behaviorally passive rats than in active specimens.

Cellular Composition of the B- and T-Cell-Dependent Areas in the Small Intestine during the Post-Stress Period (Experimental Study).

A quantitative study of lymphoid cells in the B- and T-cell-dependent areas of intestinal lymphoid nodules and mesenteric lymph nodes in behaviorally passive and active rats was performed at various periods after acute stress on the model of 1-h immobilization with simultaneous electrocutaneous stimulation. Stress exposure is accompanied by a decrease in the number of lymphoid cells in immunogenic structures of the gastrointestinal tract. Post-stress changes in the cytoarchitectonics of B- and T-cell-dependent areas in mesenteric lymph nodes of animals are less pronounced than in lymphoid nodules. Quantitative changes in lymphoid cells of B-cell-dependent areas in the small intestine of rats are greater than in T-cell-dependent areas. Changes in the cellular composition of immunogenic structures in the digestive system are most significant at the early stages of the post-stress period (1st week). Passive rats are characterized by significant changes in the cytoarchitectonics of B- and Tcell-dependent areas in the small intestine after extreme exposure, which illustrates functional exhaustion of the lymphoid tissue in stress-predisposed specimens.

Effect of Coenzyme Q10 on Proteomic Profile of Rat Brain Amygdala during Acute Metabolic Stress.

Differences in the proteomic profiles of the brain amygdala in rats with different prognostic resistance to stress were found on the model of metabolic stress. Differential expression of tropomodulin-2, GTP-binding protein SAR1, peroxiredoxin-2, calcineurin B homologous protein 1, Ras-related protein Rab-14, glutathione S-transferase omega-1, Tcrb protein, and NADH dehydrogenase [ubiquinone] iron-sulfur protein 8 (mitochondrial) was shown to depend on the behavioral pattern of animals and stage of the study. Specific features were observed in the involvement of the amygdala in the stress response of specimens with various behavioral characteristics.

Effect of Acute Emotional Stress on Proteomic Profile of Selected Brain Areas and Lysosomal Proteolysis in Rats with Different Behavioral Activity.

We compared proteome profiles of selected brain areas (cortex, amygdala, hippocampus, and reticular formation) and measured cathepsins B and D activity in liver lysosomal fraction in rats with different behavioral activity under conditions of emotional stress. In passive rats, the expression of some proteins in various brain regions was changed and baseline cathepsin B activity was higher than in active animals. Taken together, the results attest to differences in the adaptive response formation in rats, depending on behavioral features.

[DYNAMICS OF CYTOKINE CONCENTRATION IN THE BLOOD OF RATS WITH VARIOUS BEHAVIORAL CHARACTERISTICS AFTER ACUTE EMOTIONAL STRESS].

This work was designed to study a change in cytokine content in the peripheral blood of behaviorally passive and active Wistar rats at various time intervals after acute stress on the model of night-time immobilization. A decrease in the concentration of most pro- and anti-inflammatory cytokines in passive animals was most pronounced immediately and, particularly, 3 days after stress exposure. Variations in the blood cytokine profile after experimental stress were lower in behaviorally active specimens. A statistically significant decrease was observed only in the amount of a proinflammatory cytokine IL-1α and anti-inflammatory cytokines IL-4 and IL-13. As differentiated from passive rats, these changes in active specimens were most pronounced 1 day after negative emotiogenic exposure. Our results illustrate a specific involvement of immunoactive substances in the systemic regulation of physiological functions and development of individual resistance to the negative consequences of stress.

State of Stress-Marker Organs in Rats with Various Behavioral Characteristics during Repeated Stress Exposures.

Changes in the relative weight of stress-marker organs in rats with various behavioral patterns in the open-field test were studied after repeated stress exposures on the model of daily 4-h immobilization over 8 days. Involution of the thymus and spleen in behaviorally passive specimens was found after single stress, as well as under conditions of 3- and 8-fold immobilizations. The weight of these organs in active animals remained practically unchanged after acute stress, but decreased on day 3 and particularly on day 8 of repeated stress exposures. As differentiated from passive rats (open-field test), behaviorally active specimens were characterized by hypertrophy of the adrenal glands after single and 3-fold stress procedures. Our results complement the data on individual features of the peripheral and central mechanisms for the stress response in mammals. These data illustrate the importance of individual approach to studying systemic organization of physiological functions under normal conditions and during negative emotiogenic exposures.

[Effect of melatonin on antioxidant enzyme activities in blood erythrocytes of rats during acute emotional stress].

The effect of the epiphyseal hormone melatonin on the activity of antioxidant enzymes, glutathione peroxidase (GPx), glutathione reductase (GR), and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) was studied in peripheral blood erythrocytes of behaviorally passive and active Wistar rats. Acute emotional stress was modeled by immobilization of animals for1 h with simultaneous electrocutaneous stimulation. Basal activity of antioxidant glutathione enzymes in erythrocytes of behaviorally passive rats was higher than that in active animals. Administration of melatonin (2 mg/kg, intraperitoneally) was accompanied by a decrease in the activity of GPx and GR in erythrocytes from non-stressed passive animals. After experimental stress, passive rats demonstrated a significant increase in the activity of Cu/Zn-SOD and GPx in peripheral blood erythrocytes. The absence of stress-induced changes in functional activity of antioxidant defense enzymes in the blood of behaviorally active animals suggests a relatively constant oxidative status of tissues in these animals under stress conditions. Melatonin administration had little effect on stress-induced changes in functional activity of the erythrocyte antioxidant system in passive rats. Active specimens pretreated with melatonin before stress exposure were characterized by activation of study antioxidant enzymes. Quantitative parameters of the erythrocyte antioxidant defense enzymes did not differ in behaviorally active and passive rats subjected to experimental stress after melatonin injection. Thus, exogenous melatonin abolishes differences in the activity of study antioxidant enzymes in erythrocytes of animals with different behavioral parameters under basal conditions and after experimental stress. In passive rats melatonin mainly reduced the initial tension of oxidative processes. By contrast, administration of this hormone to active specimens is followed by an increase in functional activity of the antioxidant enzyme system under conditions of acute stress.

Effect of interleukin-4 on peripheral blood leukocytes in rats with various behavioral characteristics during acute stress.

We studied the effect of anti-inflammatory cytokine IL-4 (5 µg/kg intraperitoneally) on peripheral blood leukocytes in Wistar rats with various behavioral characteristics during acute emotional stress (1-h immobilization with simultaneous subthreshold electrocutaneous stimulation). IL-4 reduced the differences in blood leukocyte count in rats with various behavioral characteristics, which was related to a significant decrease in this parameter in active animals. IL-4 injection to active animals was accompanied by changes in the leukogram (development of neutrophilia, monocytopenia, and lymphopenia) and had a modulatory effect on leukocyte indexes of cell reactivity. Blood leukocyte count in cytokine-treated animals did not change after stress exposure. IL-4 prevented shifts in leukocyte indexes of cell reactivity, which was found after acute stress exposure. Our results expand current notions on the specific involvement of endogenous immunomodulatory compounds in the realization of adaptive and compensatory processes in mammals during negative emotiogenic exposures.

Dynamics of locomotor activity and heat production in rats after acute stress.

The dynamics of locomotor activity and heat production were studied in rats demonstrating passive and active behavior in the open field test at different time after exposure to acute emotional stress caused by 12-h immobilization during dark hours. The most pronounced changes in behavior and heat production followed by disturbances in circadian rhythms of these parameters were detected within the first 2 days after stress. In contrast to behaviorally active rats, the most significant decrease in locomotor activity and heat production of passive animals subjected to emotional stress was observed during dark hours. Circadian rhythms of behavior and heat production in rats tended to recover on day 3 after immobilization stress. These data illustrate the specificity of metabolic and behavioral changes reflecting the shift of endogenous biological rhythms in individuals with different prognostic resistance to stress at different terms after exposure to negative emotiogenic stimuli.

Effect of interleukin-1ß on peripheral blood leukocytes in rats with various behavioral characteristics during acute stress.

We studied the effect of a pro-inflammatory cytokine IL-1ß (5 µg/kg intraperitoneally) on blood leukocytes in Wistar rats various behavioral characteristics during acute emotional stress (1-h immobilization with simultaneous delivery of subthreshold electrocutaneous stimulation). Stress exposure was accompanied by a decrease in the total number of peripheral blood leukocytes in rats. Active animals were characterized by the increase in neutrophil count during stress. The number of eosinophils in passive specimens was shown to decrease under these conditions. Emotional stress was followed by a decrease in the lymphocyte index (by Shaganin) of active rats and increase in the leukocyte intoxication index (according to Kalf-Kalif) of passive specimens. Stress-induced changes in leukocytes differed after pretreatment with IL-1ß. The number of blood leukocytes increased in animals receiving a cytokine injection before stress exposure. Exogenous IL-1ß inverted (in active rats) or prevented (in passive specimens) a change in the percentage of various types of blood leukocytes, which was found after stress exposure. These data contribute to the understanding of peripheral mechanisms for the involvement of immunomodulatory cytokines in the systemic organization of physiological functions in specimens with different prognostic resistance to a similar stress exposure.

Cytokine profile of peripheral blood in rats with various behavioral characteristics during acute emotional stress.

The cytokine profile of peripheral blood plasma was studied in rats with various behavioral characteristics after acute emotional stress (1-hour immobilization with simultaneous electrocutaneous stimulation). Under basal conditions the concentrations of pro-inflammatory (IL-1α, IL-1ß, IL-2, IFN-γ, and granulocyte-monocyte CSF) and anti-inflammatory cytokines (IL-4 and IL-10) in the blood of active animals were higher than in passive specimens. Acute stress was accompanied by a decrease in the level of plasma cytokines in behaviorally active rats. Stressed passive specimens were characterized by the accumulation of a pro-inflammatory cytokine IL-1ß and anti-inflammatory cytokine IL-4 in the peripheral blood. The observed differences in the cytokine profile of the blood in behaviorally passive and active rats under basal conditions and after a negative emotiogenic exposure can be related to the specifics of immune reactions and metabolic processes in animals with different prognostic resistance to similar stress factors.

Melatonin effects on serum cytokine profiles of rats with different behavioral parameters in acute emotional stress.

The effects of melatonin (epiphyseal neurohormone) on the serum cytokine profiles of rats with different behavioral characteristics were studied after acute emotional stress. One-hour immobilization of animals with simultaneous electrocutaneous stimulation of subthreshold intensity served as the stress model. Acute stress exposure of animals with active behavior led to reduction of the peripheral blood concentrations of pro-inflammatory (IL-1α, IL-1ß, IL-2, IFN-γ, granulomonocytic CSF) and anti-inflammatory (IL-4, IL-10) cytokines. Passive rats exposed to emotional stress developed a pronounced increase of pro-inflammatory IL-1ß concentration. Reduction of pro-inflammatory cytokine levels in active rats exposed to stress was less pronounced after intraperitoneal preinjection of melatonin (2 mg/kg). In passive animals, exogenous melatonin inverted the poststress changes in the serum levels of pro-inflammatory IL-2 cytokine and of anti-inflammatory IL-4 and IL-10 cytokines. The modulatory effect of melatonin on the cytokine profiles of rats with different behavioral parameters seemed to contribute to adaptation of animals to emotional stress exposure.

[Effect of melatonin on lipid peroxidation in the blood of rats with various behavioral characteristics during acute emotional stress].

This work was designed to study the effect of melatonin on lipid peroxidation in the peripheral blood of behaviorally passive and active Wistar rats. Immobilization of rats with simultaneous electrocutaneous stimulation (1 h) served as a model of acute stress. After intraperitoneal injection of melatonin (2 mg/kg) the intensity of lipid peroxidation in the blood plasma remained practically unchanged in passive specimens, but increased in active animals. Stress exposure was followed by specific variations in free radical processes in the blood (passive rats, inhibition; active specimens, no changes). Administration of melatonin contributed to a decrease in the intensity of lipid peroxidation in the blood of stressed rats (as compared to control specimens receiving this neurohormone). Therefore, the effect of melatonin on free radical processes depends on the initial behavioral characteristics and physiological state of animals. These data illustrate the importance of an individual approach to studying the systemic mechanisms for organization of functions in mammals. Key words: melatonin, emotional stress, lipid peroxidation, blood plasma, rats with various behavioral characteristics.

Effect of interleukin-4 on antioxidant protection of the brain in rats during acute emotional stress.

We studied the effect of IL-4 on antioxidant enzyme activity in brain structures (hypothalamus, sensorimotor cortex, and amygdala) in behaviorally passive and active rats. One-hour immobilization of animals with simultaneous delivery of subthreshold electrocutaneous stimulation was used as the model of acute stress. Intraperitoneal injection of IL-4 (5 µg/kg) was followed by an increase in activities of glutathione peroxidase and Cu/Zn SOD in the hypothalamus of non-stressed rats. Activities of glutathione peroxidase and Cu/Zn SOD in the amygdala were shown to decrease. Administration of IL-4 was accompanied by activation of glutathione peroxidase (active and passive rats), glutathione reductase (passive rats), and Cu/Zn SOD (active rats) in the sensorimotor cortex. These data indicate that the efficiency of antioxidant protection increases in the hypothalamus and sensorimotor cortex, but decreases in the amygdala of rats receiving IL-4. Pretreatment with IL-4 abolished a poststress increase in glutathione peroxidase activity in the sensorimotor cortex of passive animals.

Antistress effect of Semax in the course of recovery of spleen lymphoid structures after the stress in rats with different behavioral activity.

We studied the effect of antistress peptide Semax, an ACTH4-10 analogue, on the cellular composition of spleen lymphoid structures in Wistar rats with different stress tolerance in the course of post-stress recovery (days 1, 3, 14, and 30). Preliminary administration of Semax alleviates stress-induced proliferation of macrophages and destructive processes in functionally active zones of the rat spleen on days 1, 3, and 14 after the stress exposure, which attests to its capacity to reduce the adverse effects of 1-h stress load on proliferation of macrophages and destructive processes in functionally active zones of this organ.

Antioxidant protection of the brain in rats during acute stress and administration of interleukin-1ß.

We studied the effect of IL-1ß on antioxidant enzyme activity in emotiogenic structures of the brain (hypothalamus, sensorimotor cortex, and amygdala) in behaviorally passive and active rats with different sensitivity to stress. One-hour immobilization of animals with simultaneous electrocutaneous stimulation was used as a model of stress. An intraperitoneal injection of IL-1ß (5 µg/kg) was followed by the decrease in glutathione reductase activity in the hypothalamus of rats. Behaviorally active animals of the IL-1ß group were characterized by an increase in the activities of Cu/Zn superoxide dismutase and glutathione peroxidase in the sensorimotor cortex and amygdala, respectively. IL-1ß administration was accompanied by activation of Cu/Zn superoxide dismutase and glutathione peroxidase in the amygdala of passive rats. Pretreatment with IL-1ß abolished the poststress changes in enzyme activity in the hypothalamus and sensorimotor cortex of active and passive rats, respectively. These data illustrate the specific effects of IL-1ß on antioxidant protection of CNS tissues in rats with various behavioral characteristics.

Morphological features of the lymphoepithelial structures of the jejunum after the stress in rats.

We studied the effect of acute emotional stress on functional status of lymphoid epithelial structures of the jejunum in rats with different behavioral activity. Morphological and functional characteristics of lymphoid tissue were assessed using morphometric, histological and electron microscopic methods. In behaviorally active and passive rats, reduction in villus height, area of the epithelium and lymphoid tissue of the jejunum was recorded on the third day after acute emotional impact. At that, the largest number of destructively modified lymphoid cells was identified by comparison with the other time points. Moreover, destruction of the apical part of the jejunal villi was observed on days 3 and 7 after stress exposure. Recovery of the lymphoepithelial structures of the jejunum after acute stress exposure was detected on day 14.