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.

Blood Cytokine Concentration in Rats during Antigenic Treatment after a Single Long-Term Stress Exposure.

We studied changes in the blood cytokine profile of rats 3 h, 1 day, and 8 days after acute stress on the model of 24-h immobilization followed by LPS administration (100 µg/kg intraperitoneally). The concentration of proinflammatory cytokines (particularly of IL-1ß and TNFα) significantly decreased at the early stage after stress exposure and physiological saline injection, but increased in the follow-up period and practically did not differ or even surpassed the control level by the end of observations. Under these conditions, the blood content of anti-inflammatory cytokine IL-10 increased most significantly on day 1 of the post-stress period. Restraint stress followed by LPS administration was accompanied by a decrease in the level of proinflammatory cytokines at the early (IFNγ and TNFα) and late stages (IL-1ß) of the experiment. Directed modulation of the immune status in animals after acute stress was followed by a significant increase in the content of IL-10 on days 1 and 8, as well as by a tendency toward elevation of IL-4 concentration by the end of the study. The directionality and degree of changes in the cytokine profile of mammalian tissues depend on the type of extreme exposure, duration of the post-stress period, and specific effects of exogenous pathogenic factors in the whole body.

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.

Frequency conversion of mid-IR lasers into the long-wavelength domain of 12-20 µm with AgGaSe2, BaGa2GeSe6 and PbIn6Te10 nonlinear crystals.

Difference frequency generation under mixing of repetitively-pulsed CO- and CO2-laser radiation in AgGaSe2, BaGa2GeSe6 and PbIn6Te10 nonlinear crystals was studied. Efficiency and refractive indices were examined for this frequency conversion into the long-wave domain of ∼12-20 µm in the mid-IR. The highest frequency conversion efficiency of 10-4 was obtained for a relatively new PbIn6Te10 crystal, which is an order of magnitude higher than previous results.

Sum frequency generation of multi-line slab radio frequency discharge carbon monoxide laser system with intracavity nonlinear BaGa2GeSe6 crystal.

A compact repetitively pulsed broadband carbon monoxide (CO) laser system with intracavity frequency conversion, for which a nonlinear crystal was also used as an output coupler, was launched for the first time, to the best of our knowledge. The laser system simultaneously operated in two spectral ranges: CO laser fundamental band (4.9-6.0 µm) and its sum frequencies band (2.45-2.95 µm). Different designs of the laser cavity were considered. Peak powers of the fundamental and sum frequencies laser pulses were up to 2 kW and 10 W, respectively.

Frequency tunable CO laser operating on the highest vibrational transition with wavelength of 8.7 µm.

A carbon monoxide laser emitting on the highest ever observed vibrational transition with a wavelength of 8.7 µm was for the first time launched. An influence of gas mixture content on the CO laser spectrum and factors limiting the longest CO laser wavelength are discussed.

Broadband two-stage frequency conversion of CO laser in AgGaSe(2) crystal.

For the first time, to the best of our knowledge, a broadband two-stage frequency conversion of multiline CO laser radiation was theoretically and experimentally demonstrated in a single AgGaSe2 crystal. The first stage is sum frequency generation of CO laser radiation. The second stage is concurrent difference frequency generation within 4.3-4.9 µm spectral range when mixing sum frequency radiation with the pump radiation in the same AgGaSe2 crystal. Internal sum frequency generation efficiency of multiline CO laser was up to 1%, while internal difference frequency generation efficiency was up to 0.065%.

Nociceptive Reactions in Rats during Repeated Stress Exposure.

Changes in nociceptive sensitivity of rats with various behavioral patterns in the open-field test were studied after repeated stress exposure on the model of daily 4-h immobilization for 8 days. The tail-flick latency in response to light-heat stimulation in passive and active specimens decreased most significantly on days 2 and 7, respectively. However, this parameter did not differ from the baseline on day 8 of observations. Vocalization threshold during electrocutaneous stimulation in behaviorally active animals did not change over the first 7 days of repeated stress exposure, but increased significantly on day 8 of the study. The emotional component of nociception in passive animals increased on day 3, but decreased on days 4 and 6 of the experiment. Therefore, repeated stress exposure in rats is mainly accompanied by an increase in the perceptual component of nociception. Variations in the emotional component of nociceptive sensitivity after stress loads are manifested in the initial increase and subsequent decrease in this parameter. The observed changes are more pronounced in behaviorally passive rats than in active animals. These data illustrate the specifics of stress-induced changes in nociception of specimens with various individual and typological characteristics. Our results hold much promise for the development of new individual approaches to modulation of pain sensitivity in humans under conditions of negative emotiogenic exposures.

Frequency conversion of mode-locked and Q-switched CO laser radiation with efficiency up to 37%.

Frequency conversion of CO laser radiation was experimentally studied in ZnGeP(2) and GaSe nonlinear crystals. To enhance conversion efficiency, we applied a CO laser system "master oscillator power amplifier" with concurrent mode locking and Q switching. The laser system emitted ∼1-µs train of ns pulses. Internal efficiency of frequency doubling reached 37% in ZnGeP(2) crystal and 5% in GaSe crystal. Two-stage frequency conversion (including second-harmonic and difference-frequency generation) in ZnGeP(2) crystal under optical pumping by a selective two-spectral line CO laser was studied.

Dynamics of changes in nociceptive reactions of rats after peripheral administration of lipopolysaccharide.

The type of changes in nociceptive reactions of rats was studied at various time intervals after intraperitoneal injection of LPS in a dose of 30 µg/kg. The perceptual component of nociception in animals was evaluated from the tail-flick latency in response to light-heat stimulation. The emotional component of nociception in rats was determined from the vocalization threshold during electrocutaneous stimulation of the tail. The tail-flick latency of animals under conditions of light-heat stimulation was shown to decrease 1 day after peripheral administration of LPS, which illustrates an increase in the perceptual component of nociception at the relatively early stage of antigenic stimulation. A significant decrease in the tail-flick latency and vocalization threshold in rats in response to nociceptive stimulation was observed on day 7 after LPS injection. These changes demonstrate an increase in the perceptual and emotional components of nociception at the late period after antigen exposure. Our results indicate that antigenic stimulation due to peripheral administration of LPS is followed by the increase in nociceptive sensitivity of rats. LPS-induced variations in the emotional and perceptual components of nociception in animals suggest the existence of specific mechanisms for systemic regulation of pain. They probably depend on the period of study and type of immune reactions during antigenic stimulation.

Cytokine levels in rat blood and brain structures after administration of lipopolysaccharide.

We compared cytokine profile of rat serum and brain structures after immune status modulation by LPS (30 µg/kg intraperitoneally). The content of inflammatory (IL-1α, IL-1ß, IL-2, IL-6, IFN-γ, and TNF-α) and anti-inflammatory (IL-4 and IL-10) cytokines in biological samples of animals was measured on days 1 and 7 after antigenic stimulation. LPS administration reduced the levels of both inflammatory and anti-inflammatory cytokines in the peripheral blood of the rats, especially on the 1st day. LPS administration was also accompanied by specific changes in cytokine content in the dorsal hippocampus and anterior cingulate cortex. Antigenic stimulation increased the level of anti-inflammatory cytokines IL-4 and IL-10 in the examined brain tissues, the changes were most pronounced on day 1 after LPS injection. No significant changes in the levels of proinflammatory cytokines in the brain tissue of animals were found at the above terms after LPS injection. Thus, peripheral LPS administration to rats shifts the balance between the inflammatory and anti-inflammatory cytokines in the CNS structures towards the latter.

Nociceptive thresholds in rats in response to lipopolysaccharide injection into the specific nuclei of the thalamus of the brain.

Microinjections of LPS into the specific nuclei of rat thalamus (ventrobasal thalamic nuclei VPL and VPM) slightly increased perceptual component and significantly decreased emotional component of systemic nociceptive response.

Nociceptive sensitivity and lymphocytic index of peripheral blood in rats with different behavioral activity in model of inflammatory pain provoked by injection of freund's complete adjuvant and bovine serum albumin.

Nociceptive thresholds decreased in rats at the early stage of inflammatory reaction induced by subcutaneous injection of BSA and complete Freund's adjuvant. At the later stage of this reaction, there was a trend of restoring nociceptive parameters in behaviorally passive rats in contrast to active animals, which demonstrated further decrease in the nociceptive thresholds. During the late inflammatory period, the lymphocytic index (by Shaganin) changed unidirectionally in the rats with different behavioral parameters. Probably, the changes in nociceptive thresholds were not triggered by the shift in lymphocyte/segmented neutrophil ratio, but resulted from production of yet not established biologically active agents with proalgesic and analgesic nature.

Nociceptive thresholds of the response to lipopolysaccharide injection into the limbic structures of the brain in rats.

Microinjections of LPS into the limbic structures of rat brain (dorsal hippocampus and caudal compartment of the cingulate fascicle) caused opposite effects on the nociceptive thresholds: injection into the dorsal hippocampus enhanced perception and reduced the emotional affective perception of pain, while injection into the cingulate fascicle reduced the perceptual and enhanced the emotional components of the nociceptive reaction. These results indicated specific involvement of these limbic structures in nociception modulation during induction of the immune response in CNS.

Cascaded carbon monoxide laser frequency conversion into the 4.3-4.9 µm range in a single ZnGeP2 crystal.

Collinear cascaded mid-IR frequency conversion in a single nonlinear optical crystal was accomplished. Concurrent collinear generation of the sum frequency of multiline fundamental band carbon monoxide laser radiation as a first frequency conversion cascade resulted in collinear difference frequency generation within the 4.3 to 4.9 µm spectral range when mixing this sum frequency radiation with the fundamental one as the second cascade in the same ZnGeP(2) nonlinear optical crystal.

Role of caudomedial portion in left and right cingulum bundle in perceptual and emotional components of nociception in rats.

The effects of electrocoagulation of caudomedial portion of the left and right cingulum bundles on tail-flick latency and vocalization threshold were examined on rats. We revealed a tendency to a decrease in the tail-flick latency and more pronounced elevation of the vocalization threshold after destruction of the right cingulum bundle. These findings indicate functional asymmetry of the cingulum bundle in the realization of the emotional nociceptive reaction.

Comparative study of macrophage response in mice after DNA immunization and infection with herpes simplex virus type 1.

Functional activity of macrophages and intensity of T cell immune response in mice were studied after intravaginal and intraperitoneal infection with herpes simplex virus type 1 and DNA vaccination in combination with adjuvant treatment (recombinant granulocyte-macrophage colony-stimulating factor and glucosaminylmuramyl dipeptide). DNA vaccination induced a virus-specific T cell immune response with no macrophagic inflammatory reaction. Infection with herpes simplex virus type 1 was accompanied by sustained inflammation, but not by the T cell immune response.

Nociceptive reactions during stimulation of immunity in rats with different individual sensitivities to stress.

Different nociceptive reactions and individual resistance were studied in rats in the initial state and in conditions of stimulation of immune processes by various methods. The aims were to study the effect of the preparation Imunofan, an immune stimulator, on various behavioral manifestations of pain reactions in animals with different individual resistances to stress and to compare the results with similar data in a natural model of immune activation. Detection of the central, immune-dependent component of the regulation of nociceptive reactions was addressed using intracerebroventricular administration of the study compound. Studies were performed on 43 male Wistar rats. Individual resistance to stress was assessed by recording the free behavior of the animals in an open field test. The following nociceptive reactions were assessed: 1) the tail withdrawal reaction using the standard tail flick method; and 2) running, twitching, jumping, and vocalization reactions to electrical stimulation of the limbs. These studies demonstrated that i.m. administration of Imunofan (10 microl of 0.005% solution) suppressed the active behavior of the animals in the open field and produced hyperalgesia, with decreases in the thresholds of nociceptive reactions. Hyperalgesia in stress-sensitive rats were significantly greater than in resistant animals. Similar results were obtained in conditions of natural activation of immunity produced by the operative intervention needed for injection of the agent into the cerebral ventricle. Intracerebroventricular administration of Imunofan was accompanied by more marked and complex changes in pain sensitivity.