HIF-1α- and HIF-2α-Immunopositive Neurons and Capillaries in the Prefrontal Cerebral Cortex of Rats with Experimental Myocardial Infarction.

The quantitative content of HIF-1α- and HIF-2α-immunopositive brain neurons in Wistar rats was studied 1, 15, and 30 days after modeling of myocardial infarction. In rats of the control group, the immunohistochemical markers HIF-1α and HIF-2α in the prefrontal cortex of the brain were determined in few pale-colored neurons and capillaries. One day after myocardial infarction simulation, the number of HIF-1α+ neurons increased, and on day 15 it reached the maximum level: the concentration of immunopositive neurons and capillaries increased by 24.7 and 18.4%, respectively, in comparison with the control. After 30 days, the number of HIF-1α+ structures decreased, but remained above the control values. The number of neurons and capillaries positively stained for HIF-2α peaked only on day 30 of the postinfarction period.

The Role of Carbon Monoxide in the Reactions of Arterial Branches of the Uterine Artery of Rats to Low-Intensity Irradiation with a Helium-Neon Laser.

Biomicroscopy was used to study order I-IV branches of the uterine artery in sexually mature female Wistar rats after a single 5- or 10-min direct exposure of the right broad ligament of the uterus to a helium-neon laser beam in the red band of the spectrum (λ=632.8 nm, output power 2 mW, intensity 20 mW/cm2). Under the influence of laser exposure, there was a significant increase in the diameter of small uterine branches and a weaker increase in large vessels with a well-developed muscular membrane. Preliminary administration of zinc IX protoporphyrin hemoxygenase blocker (30 mmol/kg) reduced reactivity of the vascular bed to laser irradiation, mainly of order I-II branches. It was concluded that carbon monoxide can act as an intermediary between the laser exposure and uterine vessels.

Reaction of Arterial and Venous Branches of the Broad Ligament of the Rat Uterus to Low-Intensity Red Laser Irradiation.

Using the biomicroscopy method, we studied the reaction of arterial and venous vessels of the broad ligament of the uterus in outbred female rats to irradiation with helium-neon laser (λ=632.8 nm; power output 2 mW). Small arteries were found to be most sensitive to laser irradiation. The veins of the broad ligament of the uterus demonstrated lower reactivity to laser irradiation of the same duration than arterial vessels, which can be explained by morphological, functional, and hemodynamic differences.

Dynamics of Organization of the Microcirculatory Bed and Mast Cells of the Uterus in Rats at Different Times of the Day.

Structural organization of the microcirculatory bed and mast cells in the uterus of mature female Wistar rats (n=60) were examined every 2 h over 24 h. During night hours, many vessels characterized by intensive reaction to NADPH-diaphorase and endothelial NO synthase were detected in the endometrium, and the density of these vessels and mast cells was quite high. During the day and evening hours, the capillaries with high levels of enzymes involved in NO synthesis and mast cells were less numerous. NO directly regulating the diameter of arteries and the intensity of transcapillary exchange can act as a signal molecule in the temporal dynamics of the vasoceptive action of estrogens and their receptors in the uterus.

Reaction of Mast Cells in the Zone of Polypropylene Mesh Implantation.

Reaction of mast cells of adult male Wistar rats (n=15) in the zone of polypropylene mesh fixation was studied by histochemical, immunohistochemical, and traditional morphological methods on days 1, 5, 10, and 30 after implantation. Immediately after the intervention, mast cells stimulated the processes aimed at wound healing. Secretion of mast cells was clearly regulatory. These cells migrated to the zone of injury for subsequent activation of their function. The number of cNOS+ mast cells near the polypropylene mesh was maximum on day 1 and the number of iNOS+ mast cells peaked on day 5 of the experiment, which probably represented a compensatory reaction. Presumably, stimulation of fibrillogenesis was largely due to the activatory effect of mast cells on the fibroblast function, but not to collagen production by these mast cells.

Effect of the Hemoxygenase-Carbon Monoxide (HO-CO) System on the Reactivity of Uterine Artery Branches in Rats.

First to fourth-order branches of the uterine artery in sexually mature female Wistar rats were studied by biomicroscopy. After administration of a CO donor hemin (60 mM), the diameters of large uterine branches with a well-developed muscle layer markedly increased, while the increase in diameter of small vessels with one often interrupted layer of smooth muscle cells increased insignificantly. Zinc protoporphyrin IX (30 mM) in all cases blocked this effect. However, zinc protoporphyrin IX does not affect NO-mediated reaction of the branches of the uterine artery caused by administration of L-arginine (60 mM), and L-NAME did not significantly affect reactivity of uterine artery branches associated with the hemoxygenase-CO system. In contrast to NO, CO produced less potent and rapid, but more sustained effect. The target for the hemoxygenase-CO system is mainly arteries with developed muscular layer, while the target for the NO synthase-NO is small vessels where endothelium plays a Rdecisive role in the regulation of vasomotor reactions.

[Changes in spatial relationships between catecholamine- and nitroxidergic neurons in the nuclei of the caudal brain stem in the development of hypertension]. / Izmenenie prostranstvennykh vzaimootnoshenii katekholamin- i nitroksidergicheskikh neironov v iadrakh kaudal'noi chasti stvola mozga pri razvitii arterial'noi gipertenzii.

AIM: To obtain the data on the spatial relationships between catecholamine (TH-positive) and nitroxidergic (nNOS-positive) neurons in vasomotor nuclei of the medulla in different periods of hypertension development. MATERIAL AND METHODS: The experiment was performed on male Wistar rats (n=45) with induced renovascular hypertension (RVH). TH and nNOS in neurons of solitary tract nuclei, reticular small-and giant cell nuclei were detected using immunohistochemical methods. RESULTS AND CONCLUSION: The most early and severe changes in the intensity of reaction and amount of nNOS-positive neurons were noted in the solitary tract nucleus. Significant changes in the quantitative parameters of TH-positive neurons in RVH were identified only in the reticular giant cell nucleus but they appeared later and were less expressed compared to nNOS-positive cells. This resulted in the changes of spatial relationships between two types of neurons and remodeling of the bulbar region of the cardiovascular center.

Immunolocation of Heme Oxygenases in the Walls of Cerebral Arteries of Various Diameters in Rats.

The distribution of two enzymes involved in the formation of carbon monoxide, heme oxygenases 1 and 2, in the pial branches of orders I-V of the middle cerebral artery basin and in intracerebral vessels was studied in adult Wistar rats. Immunohistochemical studies detected hemeoxygenase-2 in the endothelium of the small pial and intracerebral arterioles and in myocytes of pial branches I-III. Heme oxygenase 1, an inducible form of the enzyme, is normally not expressed in the cerebral vessels, but the enzyme is expressed in response to sodium metaarsenite. In this case, heme oxygenase markers are detected in myocytes of pial arteries I-II and in the endothelium of small pial and intracerebral vessels. Sodium meta-arsenite is inessential for immunolocation and quantitative distribution of heme oxygenase 2 in the vessels.

Age-Specific Characteristics of CO-Mediated Reaction of the Pial Arteries of Various Diameters in Rats.

First-fourth order pial branches of the median cerebral artery were studied by biomicroscopy in male Wistar rats aged 1 and 12 months. Irrespective of age, CO-mediated mechanisms are involved in the regulation of the basal tone of pial vessels of various diameters (more so of arteries with well-developed muscular tunic). Injection of hemin confirmed that endogenous production of CO maintained vasodilatation and this effect was most pronounced in large pial branches of young animals, while zinc protoporphyrin IX blocked this effect in all cases. On the other hand, zinc IX protoporphyrin did not modify NO-mediated reaction caused by injection of L-arginine, while hemin compensated (though not completely) vasoconstriction induced by NO synthase blocker L-NAME. In contrast to NO, the effect of CO on blood vessels was not so rapid and potent, but more lasting. Other targets for CO were arteries with well-developed muscular tunic, while targets for NO were small vessels. The vasomotor effects of both gas transmitters were more pronounced in young animals.

Topochemistry of Internuclear and Intranuclear Interneurons of the Vasomotor Area in the Medulla Oblongata of Hypertensive Rats.

Immunohistochemical examination with the antiserum against neuronal NO synthase and cystathionine ß-synthase was used to study the following two pools of interneurons in Wistar rats at various periods after the development of renovascular hypertension: intranuclear interneurons (lying in the projection of the solitary nucleus, reticular gigantocellular nucleus, and parvocellular nucleus) and 2 groups of internuclear interneurons (small interneurons, area 50-300 µ(2); and large interneurons, area above 350 µ(2)). Intranuclear and internuclear interneurons probably play a role in the central mechanisms of hemodynamics regulation. These interneurons differ by not only in topochemical parameters, but also functional properties (different resistances to BP changes). Intranuclear interneurons are characterized by high sensitivity of the gas transmitter systems to a continuous increase in BP, which results in remodeling and dysfunction of the bulbar part of the cardiovascular center. Large internuclear interneurons demonstrate a strong reaction to BP rise, which confirms their involvement into hemodynamics regulation. By contrast, small internuclear interneurons retain their characteristics in arterial hypertension and probably perform an integrative function.

Two pools of interneurons in the bulbar region of the cardiovascular center of rats.

Wistar rats were subjected to renovascular hypertension. Then, we studied two pools of neurons: intranuclear neurons located in projection area of the solitary tract nucleus and reticular, magnocellular, and parvicellular nuclei; and two groups of internuclear neurons, which included both small neurons 50-300 µm(2) in size and large neurons more than 350 µm(2) in size. Immunohistochemical methods with antisera against neuronal nitric oxide synthase, cystathionine-ß-synthase, and heme oxygenase-2 were used. The studies were performed 8, 16, and 24 weeks after the development of renovascular hypertension. We have found that at least two pools of interneurons, intra- and internuclear cells, may be involved in the mechanisms of regulation of hemodynamics. These pools of interneurons differ in some topochemical and functional features, including different resistances to an increased blood pressure.

Norepinephrinergic and nitroxidergic neurons of vasomotor nuclei in hypertensive rats.

The distributions of norepinephrinergic and nitroxidergic neurons in solitary tract nucleus, locus coeruleus, and in the small-celled and gigantocellular reticular nuclei were examined in sham-operated and experimental Wistar rats with induced renovascular hypertension. In control rats, the greatest population of norepinephrinergic cells was revealed in the projections of locus coeruleus and reticular gigantocellular nuclei, while the larger number of nitroxidergic neurons were observed in the solitary tract and the small-celled nuclei. During renovascular hypertension, the earliest and the most pronounced changes in luminescence intensity and the number of nitroxidergic neurons were observed in the solitary tract nucleus, while the changes in locus coeruleus were minimal. The significant changes in similar parameters of norepinephrinergic neurons were documented only in reticular gigantocellular nucleus and locus coeruleus, but they were delayed and less pronounced in comparison with the changes of nitroxidergic neurons.

[Topochemistry of internuclear interneurons in the human brain stem in arterial hypertension].

OBJECTIVE: To study the internuclear interneurons (IN) involved in the metabolism of nitric oxide, hydrogen sulfide and carbon monoxide in the caudal brainstem in healthy people and those with lifetime hypertension. MATERIAL AND METHODS: The study was performed on postmortem material of 8 healthy men and 19 men, aged 18-44 years, with lifetime arterial hypertension. Immunohistochemistry methods for nNOS, HO-2, CBS and histochemical method for NADPH-diaphorase were used to study IN groups located between the giant and small cell reticular nuclei (IN1), small cell reticular nucleus and the nucleus of the solitary tract (IN2) surrounded by the lateral reticular nucleus (IN3). RESULTS: IN differ in size, shape, length and structure of sprouts as well as the nature of relationships formed and intensity of immunohistochemical reaction. The intensity of MN response to the high blood pressure depends on the cell size: qualitative and quantitative changes among the most small MN are mild. In contrast, in many major MN, structural changes, a significant reduction in the proportion of these cells, concentration and reaction rate are noted. More significant changes in quantitative indicators are found among nNOS-positive neurons. The reduction in the quantitative indicators depends on the localization of cells. In IN1, where there are many large IN, changes are more pronounced than in IN3 and IN2, which do not contain so many such cells. CONCLUSION: Central mechanisms of hemodynamic control include, at least, two groups of interneurons: intranuclear and internuclear. However, among the latter, only large IN are responsive to increases in blood pressure that confirms their participation in the regulation of hemodynamics, Small IN maintain a relatively small organization and perform a stable, obviously, integrating function.

[Interneurons Brainstem of the Human].

OBJECTIVE: To conduct a comparative study of the structural organization of internuclear interneurons involved in the metabolism of nitrogen monoxide, hydrogen sulphide and carbon monoxide in the caudal brain stem humans. METHODS: The cross-sectional study was performed. We used histochemical and immunohistochemical methods to study the internuclear interneurons expressing neuronal nitric oxide synthase, cystathionine ß-synthase and heme oxygenase-2 which are located between the giant and small cell reticular nuclei (cell group 1), small cell reticular nucleus and the nucleus of the solitary tract (cell group 2) or is surrounded by reticular lateral nucleus (cell group 3). RESULTS: The work was carried out on the corpses of 6 men 18-44 years old who died from causes unrelated to the damage of the central nervous system. We revealed the differences between internuclear organization and intranuclear interneurons and local structural features of internuclear interneurons that are more clearly visible between the cell group 1 including a relatively large number of large neurons and cell groups 2 and 3 (p < 0.001). In the latter two groups small cells with high concentrations of the neuronal nitric oxide synthase and heme oxygenase-2 dominated. CONCLUSION: Despite the fact that the number of internuclear interneurons significantly is less than the number of intranuclear cells, they have structural prerequisites to control integration processes in the brain. Internuclear interneurons produce gasotransmitters and classical mediators of nerve impulse, form a local chain of interneurons between vasomotor nuclei, share many links with the above and the lower parts of the brain.

Immunolocation of cystationine ß-synthase in cerebral pontile nuclei in humans.

The immunolocation of cystationine ß-synthase in the motor, sensitive, and autonomic nuclei of the cerebral pons was studied on the material from 8 healthy men aged 18-44 years dead from traumas not involving the CNS. The motor nuclei contained numerous large intensely stained cells, while the sensitive and autonomic nuclei contained many small neurons with low levels of cystationine ß-synthase marker. However, cells with intense reaction were found among small neurons. They were located mainly at the nuclear periphery, between the nuclei or between the nuclei and conduction tracts. The content of immunopositive neurons in the studied nuclei varied from 2 to 14%. The level of these cells in motor nuclei was 3-4-fold higher than in sensitive and autonomic nuclei.

Distribution of H2S synthesis enzymes in the walls of cerebral arteries in rats.

The distribution of two enzymes involved in H(2)S synthesis, cystationine ß-synthase (CBS) and cystationine γ-liase (CSE), was studied in the walls of the internal carotid artery, order I-V branches of the middle cerebral artery basin, and intracerebral vessels of adult Wistar rats. Immunohistochemical staining showed the presence of CBS in the endothelium of small pial arteries (order IV-V branches) and intracerebral arterioles and in the capillary walls, neurons, and vascular nerves. As for CSE, in the internal carotid artery and large (order I-II) pial branches it was found mainly in the tunica media myocytes, in order III-IV vessels in myocytes and endothelium, and in smaller pial and intracerebral vessels in the endothelium. Along with enzyme-positive vessels, many pial and intracerebral arteries contained no these enzymes in the walls.

Changes in inducible NO synthase in the pial arteries of different diameters in hypertensive rats.

Biomicroscopy of pial arteries of branching orders 1-5 in Wistar rats with induced renovascular hypertension revealed a common trend to vasoconstriction. Up to week 4 of arterial hypertension the diameters decreased mainly in arterial branches of orders 1-2, while at weeks 8-10 the reaction was significantly more manifest in branches of orders 4-5. During weeks 12-16, vessels with solitary club deformations or several alternating dilated and stenosed portions appeared in rats with renovascular hypertension. Immunocytochemical studies of the vessels showed hyperexpression of inducible NO synthase in these deformations. The enzyme activity was also detected in leukocytes in the vascular lumen and in perivascular tissue, as well as in cells fixed to the inner endothelial surface.

Changes in neurons of medulla oblongata nuclei under conditions of chronic NO-synthase inhibition.

Nucleus tractus solitarius and giant-cell and lateral reticular nuclei were studied using the reaction to NADPH-diaphorase in 7-, 10-, 14-, 30-, 45-, 60-day-and 3- and 6-month-old rats receiving L-NAME (50 µg/kg, 2 times a day) on days 1-6 of life. In 7-14-day-old rats, the compound reduced NO-synthase activity in the majority of NO-neurons and the total number and to a lesser degree the relative number of these neurons, while cell cross-section areas remained practically unchanged. The differences in the corresponding quantitative parameters between the control (D-NAME administration) and experimental groups decreased with time after the last L-NAME injection and became undetectable starting from the age of 30-45 days. In the nucleus tractus solitarius, the changes in metric parameters after exposure to NO-synthase inhibitor were more pronounced than in the reticular formation nuclei.

Nitroxidergic nerve fibers of intracerebral vessels.

Light and electron histochemical methods were used to study the structure and distribution of neurons containing NADPH diaphorase and their processes in the parietal area of the cortex in rats. Most neurons were found to be characterized by tight associations with intracerebral vessels. The smallest distances between the axon plasmalemma and the smooth myocytes of intracerebral arteries in the cerebral cortex were at least 0.3-0.5 microm. Neuron bodies were located at functionally important locations of vessels (sites at which subsidiary vessels branched off, the origins of arterioles), and their processes accompanied vessels, densely entwining the vessels with their branches. Neurons whose dendrites contacted the bodies or process of above- or below-lying neurons often sent nerve conductors to arteries, veins, or capillaries. Thus, nitroxidergic neurons or groups of these neurons may monitor the state of the circulation at different points in the vascular bed, functioning as local nerve centers.