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There are individual differences in the tolerance to hypoxia and stress. Stress can contribute to the development of various diseases, including inflammatory bowel disease. It was found that inflammatory bowel diseases in animals susceptible to hypoxia runs more severe course than in tolerant animals. We studied morphofunctional changes in the colon under conditions of modeled cold stress in male C57BL/6 mice susceptible and tolerant to hypoxia. The animals were daily subjected to cold stress (20 min at -20°C) for 2 weeks. Cold stress was followed by an increase in the volume fraction of goblet cells in the colon and production of mucins by these cells in mice tolerant to hypoxia and an increase in cell content in the lamina propria of the colon mucous membrane in animals susceptible to hypoxia. The number of serotoninproducing endocrine cells increased in both groups, but these changes were more pronounced in mice susceptible to hypoxia.

Introduction. Doxorubicin (Dox) in the composition of poly(lactic-co-glycolic acid, 50:50) (PLGA) – nanoparticles has high antitumor efficacy in rats with glioblastoma 101.8. However, the toxic effect of Dox-PLGA is not well understood. The aim of the study was morphological and biochemical evaluation of the hepatotoxic and cardiotoxic effects of doxorubicin and Dox-PLGA in the glioblastoma 101.8 treat-ment in Wistar rats. Materials and methods. The study was performed on 24 male Wistar rats with glioblastoma: no treatment (n=7), treated with doxorubicin (n=9) or Dox-PLGA (n=8) intravenously at a dose of 1.5 mg/kg on days 2, 5 and 8 after tumor implantation. On the 14th day of the experiment, morphological changes in the myocardium and liver were examined. Hematological and biochemical blood tests were performed. Results.When treating rats with experimental glioblastoma 101.8, Dox-PLGA in comparison with doxorubicin has less pronounced cardiotoxic and hepatotoxic effects according to the morphological, hematological and biochemical tests. Inflammatory changes in the myocardium of the animals treated with Dox-PLGA were less pronounced and widespread than the ones treated with doxorubicin. The activities of total and cardiac creatine phosphokinase (CPK) isoforms and AST were statistically significantly lower in Dox-PLGA group than in animals with glioblastoma without treatment and receiving doxorubicin. The hepatotoxic effects of Dox-PLGA were minimal. Unlike animals treated with doxorubicin, they had mild hepatocyte dystrophy. ALT activity in all groups did not differ from the reference values. Conclusion. Compared with doxorubicin, the nanosomal form of Dox-PLGA in the experimental glioblas-toma 101.8 treatment has less pronounced cardio- and hepatotoxic effects. Keywords: rat glioblastoma 101.8, doxorubicin, PLGA-nanoparticles, toxic effect, liver, myocardium, morphology, biochemistry

The morphological and functional peculiarities of the immune system are studied in adult male and female Wistar rats with high and low hypoxic resistance. Sex-specific differences in the subpopulation composition of the peripheral blood lymphocytes, not depending on the hypoxic resistance of animals, are detected: the males have lower absolute counts of T helpers and higher percentage of regulatory T cells than the females in the diestrus phase. Comparison of the morphofunctional status of the immune system in male and female (diestrus) rats with high resistance to hypoxia has shown a better developed subcapsular zone of the thymus, higher levels of anti-inflammatory cytokine TGF-β, and lower absolute counts of cytotoxic T lymphocytes in the peripheral blood in the males. Males with low hypoxic resistance have higher counts of phase II thymic bodies in comparison with low-resistant females. Hence, morphofunctional differences in the immune system of male and female rats with different hypoxic resistance are detected, which can determine the course of inflammatory diseases.

We studied morphological changes in the prostate ventral lobe, proliferative activity of the epithelium in prostate acini, and the levels of prolactin and prostate-specific antigen in the blood serum of Sprague-Dawley rats after repeated injections of sulpiride in a dose of 40 mg/ kg over 30 and 60 days and in 10 and 30 days after withdrawal. Morphological and morphometrical analysis of hyperplastic changes in the prostate ventral lobe was performed. Ki-67+ proliferating epithelial cells in the acini were counted. The dynamics of serum concentrations of prolactin and prostate-specific antigen was evaluated by ELISA. Morphological and morphometrical analysis and evaluation of the content of Ki-67+ cells demonstrated epithelium hyperplasia in the prostate ventral lobe after sulpiride treatment for 30 or 60 days and in 10 days after withdrawal, but serum level of prostate-specific antigen did not differ from the control. After 60-day sulpiride treatment and in 30 days after withdrawal, pronounced hyperplastic changes of prostate and elevated concentrations of prostate-specific antigen (but not prolactin) were observed. Thus, administration of sulpiride (40 mg/kg) to Sprague-Dawley rats for 60 days allows, by morphological criteria and serum level of prostate-specific antigen, to model stable hyperplastic changes in the prostate corresponding to benign prostatic hyperplasia in humans.

Introduction. Stress is one of the factors contributing to the gastrointestinal tract diseases development and exacerbating the course of diseases of the gastrointestinal tract. The cold factor is the most common stress factor in Russia. Therefore, the aim of our work was to characterize the immune responses and colon morphological and functional changes during cold stress in male and female C57BL/6 mice. Materials and methods. We studied alterations in the subpopulation composition of peripheral blood lymphocytes and morphofunctional changes in the thymus, spleen, and colon in response to a course intermittent cold exposure during 35-minute sessions for 14 days at –20° in adult male and female C57BL/6 mice. Results. The volume fraction of the PALS zone of the spleen and the content of endocrine cells in the colon decreased in animals of both sexes in the cold stress conditions. In females, the number of platelets and leukocytes in the peripheral blood increased, the width of the subcapsular zone of the thymus decreased, and the volume fraction of the red spleen pulp increased. In males, in the peripheral blood, the absolute and relative content of T-regulatory lymphocytes decreased, and the relative content of activated T-helpers increased, the volume fraction of the light centers of lymphoid nodules in the spleen decreased, the length of the crypts increased in the colon. A number of differences between males and females of control groups were also revealed: in the peripheral blood, males had more platelets and the absolute content of T-regulatory lymphocytes and less absolute content of T-cytotoxic. In the colon of males, the content of proliferating epithelial cells in the colon was higher than the one in females, and the bulk density of goblet cells was lower in males. Conclusion. Under the cold stress factor exposure in animals, physiological stress develops. Immune reactions and colon morphofunctional changes in the colon during cold stress differ between males and females. Keywords:cold stress, sex differences, colon, immune system

Hypoxia tolerance of the organism depends on many factors, including age. High newborn organisms tolerance and high level of oxidative stress throughout aging were demonstrated by many studies. However, there is lack of investigations reflecting the expression of key hypoxia-inducible factor HIF in different age organisms in correlation to levels of pro-inflammatory and anti-inflammatory cytokines. Liver is a sensitive to hypoxia organ, and is an important organ in providing an acute reaction to infections – it synthesizes acute inflammation phase proteins, in particular, C-reactive protein. The aim of study was to determine relationship between age-related tolerance to hypoxia and HIF-1 and PHD2 (prolyl hydroxylase domain protein) expression levels in the liver and the production of cytokines in the spleen in newborn, prepubertal and adult Wistar rats. Newborn rats are characterized by high mRNA Hif-1α expression level in the liver, accompanied by a low content of HIF-1 protein and high level of PHD2. The growth in HIF-1α protein level throughout age is accompanied by the growth of pro-inflammatory cytokines level. Prepubertal animals are the least hypoxia resistant and their HIF-1α mRNA expression level was higher than in adult animals. The PHD2 activity in prepubertal animals was significantly reduced in comparison to newborn rats, and the HIF-1α protein level did not change. Further studies require the identification of additional mechanisms, determining the regulation of the HIF-1α level in prepubertal animals., Hypoxia tolerance, HIF-1, PHD2, Age-related differences, Newborn, Prepubertal age.

Hypoxia tolerance and the intensity of systemic inflammatory response during endotoxemia were examined in newborn, prepubertal, and mature Wistar rats. To assess the sensitivity to hypoxia, the rats were placed into a pressure chamber simulating an altitude of 11,500 m. The systemic inflammatory response was provoked by intraperitoneal injection of LPS from E. coli O26:B6. Serum concentrations of HIF-1α, neopterin, C-reactive protein, and endotoxin were measured. In histological sections of the liver, the area of necrosis was assessed. The smallest tolerance of the prepubertal males to hypoxia correlated with the greatest manifestations of hepatic inflammation and elevated endotoxin, neopterin, and C-reactive protein. Elevation of serum HIF-1α in 3 h after LPC injection was observed in only prepubertal rats. The data obtained should be taken into account during the development of therapeutic strategy for prepubertal children with infectious and inflammatory diseases.

Purpose The aim of the study was to characterize the severity of the systemic inflammatory response induced by lipopolysaccharide (LPS) in animals with different resistance levels to hypoxia. Materials and methods Two to three months old male Wistar rats (220-240 g) were divided according to hypoxia tolerance in a hypobaric chamber. After a month, they were injected intraperitoneally with Escherichia coli LPS at a dose of 1.5 mg/kg. After 3, 6 and 24 hours of LPS injection, we studied the levels of IL-1β, C-reactive protein (CRP) and TGF-β in the serum, the expression of Hif-1α and Nf-kb in the liver, morphological disorders in the lung and ex vivo production of IL-10 by splenic cells activated by ConA. Results In the early periods after the injection of LPS, increase in Nf-kb expression in the liver was observed only in the rats susceptible to hypoxia. After 6 hours of LPS injection, the number of neutrophils in the interalveolar septa of the lungs of rats susceptible to hypoxia was higher than in tolerant rats. This points to the development of more pronounced LPS-induced inflammation in the rats susceptible to hypoxia and is accompanied by increased expression of Hif-1α in the liver after 6 hours of LPS administration, serum IL-1β level after 3 hours and CRP level after 24 hours. The production of the anti-inflammatory cytokine IL-10 by the spleen was significantly decreased after 6 hours of LPS injection only in the animals tolerant to hypoxia. After 24 hours of LPS injection, a significant decrease in serum TGF-β level occurred in the rats tolerant to hypoxia in comparison with the control group, which improved the survival rates of the animals. Conclusion We have demonstrated the differences in the severity of the LPS-induced inflammatory response in male Wistar rats with different resistance levels to hypoxia. Rats susceptible to hypoxia are characterized by a more pronounced inflammatory response induced by LPS.

It is a common fact, that the content of sex hormones in humans and animals varies in different age periods. The functional state of the immune system also changes with age. However, sex differences studies of inflammatory and immune responses during puberty prevail in literature. Investigation of immune responses to LPS peculiarities in prepubertal females and males may contribute to the development of more effective immunotherapy and minimize side effects of children vaccination. Therefore, the aim of this work was to investigate the LPS-induced SIRS sex differences in prepubertal Wistar rats. Despite the absence of sex differences in estradiol and testosterone levels, LPS-induced inflammatory changes in liver and lungs are more pronounced among males. Males demonstrate the increasing neopterin, corticosterone levels and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Not less important is that in females, demonstrating less morphological changes in liver and lungs, endotoxin level is tenfold higher, and corticosterone level decreases. Thus, endotoxin cannot be used as a marker of the severity of multiple organ failure in prepubertal period. The LPS-induced immune reactions in females and males are similar and are characterized by immunosuppression. Both females and males have decreased production of cytokines (IL-2, IL-4, TNF-α, TGF-β) and the absolute number of CD3 + and CD3 + CD8 + lymphocytes in blood. The acute atrophy of thymus and apoptosis of thymic cells are revealed in animals of both sexes. However, the number of CD3 + CD4 + T-helpers and CD4 + CD25 + Foxp3 + T-cells decreases only in females with SIRS, and in males there was a decrease of CD45R + B-cells. The least expressed sex differences in immune responses in the prepubertal period can be determined by the low levels of sex steroids and the absence of their immunomodulatory effect. Further studies require the identification of mechanisms, determining the sex differences in the inflammatory and immune responses in prepubertal animals.

The features of B16 melanoma progression in male C57BL/6 mice with initially high and low resistance to hypoxia were studied. To assess the resistance to hypoxia, the mice were placed in a low-pressure chamber at a simulated altitude of 10,000 m. One month after testing, B16 melanoma was inoculated to high- and low-resistant animals. In 19 days after melanoma transplantation, the severity of melanoma progression was assessed by morphological and immunofluorescent methods. The expression of vegf-a and hif-1a in the liver of melanomabearing and control mice was evaluated by real-time PCR. Tumor growth progression was more pronounced in low-resistant mice, which was seen from high weight of the primary tumor node, relative necrosis area, proliferation rates (mitotic index and number of Ki-67+ cells), and expression of vegf-a gene in the liver. In high-resistant to hypoxia animals, the number of caspase-3+ cells dying by apoptosis was higher. The data on more rapid melanoma progression in mice with low resistance to hypoxia should be considered during the search of new prognostic markers and methods for therapy of malignant neoplasms.

On the model of the systemic inflammatory response (SIRS), induced by lipopolysaccharide (LPS), the morphological and functional changes in the thymus and spleen and the subpopulation composition of peripheral blood lymphocytes of rats differing in resistance to hypoxia were studied. It was demonstrated that the level of endotoxin in blood serum after 3 hours of LPS administration in susceptible-to-hypoxia rats was 64 times higher than in the control group, while in tolerant-to-hypoxia animals it was only 8 times higher in 6 hours. After 24 hours of LPS injection, only in susceptible-to-hypoxia rats did the level of C-reactive protein in blood serum increase. There is a difference in the dynamics of morphological changes of lymphoid organs after LPS injection in tolerant- and susceptible-to-hypoxia animals. After 3 hours of LPS administration, the tolerant-to-hypoxia rats showed no changes in the thymus, spleen, and subpopulation composition of lymphocytes in peripheral blood. After 6 hours there was only a decrease in B-lymphocytes and increase in cytotoxic T-lymphocytes and NK cells. After 1 day of LPS injection, the tolerant-to-hypoxia rats had devastation in PALS of the spleen. After 3 hours of LPS injection the susceptible-to-hypoxia animals had reactive changes in the lymphoid organs: decrease of the thymus cortex, narrowing of the marginal zones of spleen lymphoid follicles, widening of their germinal centers, and a decrease in the absolute number of cytotoxic T-lymphocytes, NK cells, and B-lymphocytes. After 24 hours of LPS injection the tolerant-to-hypoxia animals had a greater absolute number of T-lymphocytes and NK cells in comparison with the susceptible rats. Thus, in animals with different resistance to hypoxia the LPS-induced SIRS is characterized by different dynamics of morphological and functional changes of the thymus and spleen. The obtained data will serve as a basis for the development of new individual approaches to the prevention and treatment of infectious and inflammatory diseases.

We studied the expression of Hif-1α, Nf-κb, and Vegf genes in the liver and serum levels of HIF-1α, erythropoietin, VEGF, TGF-β, 8-isoprostane, and corticosterone in Wistar rats with different resistance to hypoxia in 5 and 90 min after acute exposure to hypobaric hypoxia. In 5 min after hypoxic exposure, Hif-1α expression in the liver and serum levels of erythropoietin, VEGF, and TGF-β in high-resistant rats were higher than in low-resistant animals. In highresistant rats, the increment in expression of Nf-κb gene responsible for the control over the inflammatory processes was more pronounced than in low-resistant animals. In 90 min after hypoxic exposure, the serum levels of HIF-1α, erythropoietin, VEGF, and TGF-β returned to normal in high-resistant rats, while in low-resistant animals, an increase in 8-isoprostane and TGF-β concentrations was observed. The rats with different resistance to hypoxia were characterized by different changes in biomolecular parameters determining predilection to inflammatory diseases.