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

Integrated analysis of restraint stress in rat serum using ATR-FTIR and Raman spectroscopy with Machine learning

In forensic practice, accurately determining whether an individual has been subjected to prolonged restraint or assessing injuries resulting from restraint can be challenging. To address this, we explored a novel approach using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and Raman spectroscopy combined with machine learning to jointly identify restraint stress. We randomly assigned rats into three experimental groups: a restraint stress group (subjected to fasting and water deprivation), a control group (subjected to fasting and water deprivation without restraint), and a normal group. After collecting the serum spectra of the animals, a principal component analysis (PCA) model was established to explore the separation trends among the groups and to identify relevant characteristic peaks. Subsequently, a random forest (RF) model was established to compare the restraint stress group with the other two groups. The analysis identified key substances that indicated the presence of restraint stress: 1161 cm-1, 1167 cm-1 (anti-symmetric C-O-C stretch) and 980 cm-1, 976 cm-1, 974 cm-1 (-N+(CH3)3, antisymmetric stretch). And the RF model was used to compare the restraint stress groups at different time points, revealing substances that may help determine the duration of restraint stress: 1747 cm-1 (ester carbonyl band), 1626 cm-1 (β-pleated sheet), 1211 cm-1 (Amide III, -N+(CH3)3, antisymmetric stretch), 1180 cm-1 (phosphodiester), 1128 cm-1 (-C-C-), 1024 cm-1 (C-O stretching coupled with C-O bending) and 1389 cm-1, 1335 cm-1, 1321 cm-1 (Trp, α helix, phospholipids), 710 cm-1 (Polysaccharides), 1266 cm-1 (Amide Ⅲ), 1015 cm-1 (β-carotene). These findings suggest that ATR-FTIR and Raman spectroscopy together, when combined with machine learning, has significant potential as a powerful tool for analyzing and characterizing restraint stress, offering new insights and directions for future research in this area.

Effect of Plant Extracts Combinations on TNF-α, IL-6 and IL-10 Levels in Serum of Rats Exposed to Acute and Chronic Stress

Oxydative stress, anxiety and depression are associated with changes in cytokine levels. Natural products, including individual and combined plant extracts, have the potential to be used in the treatment of neuropsychiatric disorders. The goal of this study is to investigate the effects of two combined plant extracts, rich in flavonoids, on the levels of the cytokines TNF-α, IL-6, and IL-10 in rats subjected to models of acute cold stress and chronic unpredictable stress. The study utilized common medicinal plants such as Valeriana officinalis, Melissa officinalis, Crataegus monogyna, Hypericum perforatum, and Serratula coronata, which were combined in two unique combinations-Antistress I and Antistress II. The compositions of the used extracts were determined by HPLC methods. Pro- and anti-inflammatory cytokines in rats' serum were measured with Enzyme-linked immunosorbent assay. The results from the acute stress model revealed that the individual extract of Crataegus monogyna decreased levels of TNF-α, while Serratula coronata, Hypericum perforatum, and Valeriana officinalis effectively reduced IL-6 levels. Both combinations, Antistress I and Antistress II, were effective in reducing TNF-α and IL-6 levels, with Antistress II also increasing IL-10 levels. In the chronic stress model, Hypericum perforatum extract decreased the levels of the pro-inflammatory cytokines TNF-α and IL-6, whereas extracts of Serratula coronata and Valeriana officinalis only reduced TNF-α levels. The two combined extracts, Antistress I and Antistress II, decreased TNF-α and IL-6 levels, while Antistress I also reduced the levels of the anti-inflammatory cytokine IL-10. The combinations of plant extracts used in our experiment have not been previously studied or documented in the available literature. However, based on our own experimental results, we can draw the conclusion that the combinations exhibit a more pronounced effect in reducing cytokine levels compared to the individual plant extracts.

Effect of Repeated Stress Exposures on the Blood Cytokine Profile in Rats with Different Behavioral Parameters

Changes in the blood cytokine profile were studied in rats with different behavioral patterns in the open-field test during chronic stress on the model of daily 4-h immobilization over 8 days. The level of proinflammatory cytokines IL-1α and IFNγ in behaviorally active and passive animals changed insignificantly under these experimental conditions. Repeated stress exposures were accompanied by a progressive decrease in the plasma level of IL-2 and IL-5 in passive rats; these changes were most pronounced on day 8 of the study. Active animals were characterized by a tendency toward reduction of IL-2 content, but significant decrease in IL-5 concentration on days 3 and 8 of restraint stress. Blood levels of IL-1β and IL-6 in rats remained practically unchanged after single immobilization, but progressively increased during further stress exposures and reached maximum on day 8 of stress. The content of the anti-inflammatory cytokine IL-4 in rats was constant, but blood concentration of IL-10 increased during repeated stress exposures. These changes were most pronounced on day 8 in passive animals and on days 3 and 8 of restraint stress in active animals. These data indicate that the direction of variations in the blood cytokine profile of rats under conditions of chronic stress depends on the baseline parameters of behavior and frequency of stress exposures.

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.

Correlation of Physiological Parameters in Rats after Stress Exposure under Conditions of Antigenic Stimulation with Lipopolysaccharide Administration

We studied correlation dependences between physiological parameters in rats in 3 h, 1 day, and 8 days after administration of LPS (100 μg/kg) at the end of 24-h immobilization stress. In 3 h after LPS administration against the background of stress exposure, significant correlations of metabolic parameters with the relative weight of the adrenal glands and the perceptual component of nociception in rats were revealed. A direct relationship between the concentration of the proinflammatory cytokine TNFα and anti-inflammatory IL-4 was also found in these animals. On the first day after LPS injection, correlations were revealed, predominantly positive, only between the indicators of the cytokine blood profile. In the late post-stress period after antigenic exposure, no correlations between the studied physiological parameters were found. It can be hypothesized that immune modulation through systemic administration of LPS prevents persistent excessive stress of physiological functions at the later stages after stress exposure.

Dysregulation of miR-15a-5p, miR-497a-5p and miR-511-5p Is Associated with Modulation of BDNF and FKBP5 in Brain Areas of PTSD-Related Susceptible and Resilient Mice

Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder occurring in susceptible individuals following a traumatic event. Understanding the mechanisms subserving trauma susceptibility/resilience is essential to develop new effective treatments. Increasing evidence suggests that non-coding RNAs, such as microRNAs (miRNAs), may play a prominent role in mediating trauma susceptibility/resilience. In this study, we evaluated the transcriptional expression of two key PTSD-related genes (FKBP5 and BDNF) and the relative targeting miRNAs (miR-15a-5p, miR-497a-5p, miR-511-5p, let-7d-5p) in brain areas of PTSD-related susceptible and resilient mice identified through our recently developed mouse model of PTSD (arousal-based individual screening (AIS) model). We observed lower transcript levels of miR-15a-5p, miR-497a-5p, and miR-511a-5p in the hippocampus and hypothalamus of susceptible mice compared to resilient mice, suggesting that the expression of these miRNAs could discriminate the two different phenotypes of stress-exposed mice. These miRNA variations could contribute, individually or synergically, to the inversely correlated transcript levels of FKBP5 and BDNF. Conversely, in the medial prefrontal cortex, downregulation of miR-15a-5p, miR-511-5p, and let-7d-5p was observed both in susceptible and resilient mice, and not accompanied by changes in their mRNA targets. Furthermore, miRNA expression in the different brain areas correlated to stress-induced behavioral scores (arousal score, avoidance-like score, social memory score and PTSD-like score), suggesting a linear connection between miRNA-based epigenetic modulation and stress-induced phenotypes. Pathway analysis of a miRNA network showed a statistically significant enrichment of molecular processes related to PTSD and stress. In conclusion, our results indicate that PTSD susceptibility/resilience might be shaped by brain-area-dependent modulation of miRNAs targeting FKBP5, BDNF, and other stress-related genes.