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Aim. To update the study on morphological changes in the hippocampal structure and blood supply in conditions of persistent arterial hypertension with a focus on the cognitive sphere state. Materials and methods. The authors independently searched and selected scientific literature for a systematic review in the PubMed, Scopus, and Cochrane databases using the following keywords “arterial hypertension”, “cognitive functions”, “morphological and functional state of the hippocampus” in full-text articles in English and Ukrainian based on the study results with a level of evidence I–III. Results. The authors have conducted a systematic review of articles and scientific publications in PubMed, Scopus and Cochrane databases. The information of the hippocampal structure, blood supply, functions and importance for the generation of human cognitive performance in health and in conditions of persistent arterial hypertension has been processed. Conclusions. The current research results allow asserting that the hippocampus plays an important role in combining environmental signals and creating an integral and unified perception in the spatial and temporal domains. The performance efficiency depends on cellular signaling and stability, adequate blood supply, neurotransmitter balance, and the character of a receptor landscape. Experimental studies and clinical observations show cerebral arteriole reconstruction and constriction as well as decreased NO bioavailability in the hippocampus induced by chronic arterial hypertension to compensate for excessive pressure and increased blood flow pulsatility and to protect microvessels from damage. Increased vasoconstriction results in hypoperfusion and neuronal damage, which is most obvious in the hippocampal CA1 and CA3 areas and visualized as a reduced number of chaotically scattered cells with cytoplasmic vacuoles, nuclear pyknosis and nucleolysis.

Aim. The paper aimed to update the study on accelerated biological aging as a complication of cancer therapy with a focus on diagnosing and prognosing the disease course. The authors independently searched scientific literature for the systematic review within databases PubMed, Scopus and Cochrane in the period from 2018 to 2024, using combinations of keywords “cancer”, “biological aging”, “replicative aging”, “antitumor therapy”, “markers of cellular senescence”, “coronary artery calcium” and selected full-text publications written in English and Ukrainian with level 1–3 evidence. People affected by cancer grow old faster. This could be related to malignant growth biology as well as to methods of anticancer therapy received. Cytostatics, targeted, hormonal and immune drugs damage not only malignant, but also benign cells, which leads to violations of replication with sustained cell cycle arrest and other phenotypic signs – macromolecular damage, metabolic changes, production of a specific senescence-associated secretome. Clinically, this is manifested by reduced work capacity, weakness, chronic organ dysfunction, cardiovascular disorders, progression of coronary atherosclerosis, hypertension, diabetes, dyslipidemia, sarcopenia, cognitive disorders, a de novo development of tumors and premature death. Biological markers of cellular senescence include the expression of lipofuscin, Ki67, p21 WAF1/Cip1 or p16 INK4a. A clinical marker of aging is the deposition of calcium salts within coronary arteries based on the Agatston score detected using multidetector computed tomography. Conclusions. A better understanding of the cancer consequences associated with accelerated biological aging might suggest new therapeutic strategies and improve the quality of life among cancer survivors. Rehabilitation measures through changes in diet, caloric restriction, aerobic exercises and pharmacological senolytic therapy should be a part of a patient’s daily routine after completion of radical cancer treatment.

The aim of the work was to define the nature of changes in morpho-densitometric parameters of magnocellular neurons of the hypothalamic paraventricular nucleus in rats at 6, 15 and 21 weeks of restricted living space. Materials and methods. A total of 55 male Wistar rats aged 6-10 months were used and divided into 4 groups (1 – intact control, 10 rats; 2, 3 and 4 – experimental groups of 15 rats each, which were in conditions of restricted environmental space for 6, 15 and 21 weeks, respectively). Morpho-densitometric analysis of 5-μm-thick rat brain sections was performed after preliminary standard histological processing and 48 hours of halocyanine-chrome staining by Einarson using an AxioImager-M2 microscope (Carl Zeiss, Germany). Images of magnocellular neurons of the hypothalamic paraventricular nuclei (PVN), which were topographically identified according to the stereotaxic atlas of the rat brain, were captured using a highly sensitive AxioCam-ERc 5s video camera (Carl Zeiss, Germany) and recorded as a computer file using AxioVision 40 V 4.8.2.0 software (license number 3005339). Quantitative data on the area of neurons, their nuclei and nucleoli, the content of heterogeneous DNA and RNA in the cell cytoplasm, nuclei and nucleoli were obtained in a semi-automatic mode using the open source software ImageJ (National Institutes of Health, USA). Results. Chronic stress condition modelled in rats for 6, 15, and 21 weeks (limited living space, inactivity, and complicated communications) resulted in a decrease in the area of cytoplasm and nuclei of magnocellular neurons of the hypothalamic PVN. The decrease was directly proportional to restrain stress duration: cytoplasm and nuclei by 18 % and 9 % at week 6 and by 40 % and 25 % at week 21, respectively, and only cytoplasm by 23 % at 15 weeks. On the contrary, the area of neuronal nuclei was increased by 31 % at 6 weeks of stress and 33 % at 15 weeks, and by 15 % at 21 weeks of stress compared to the control. The content of nucleic acids in the cytoplasm of magnocellular neurons of the hypothalamic PVN in the group of rats with 6-week restriction was 39 % less than in the control group, 34 % less than that in the group with 15-week restriction, and 42 % less than that in the group of 21-week restrain stress. In the nuclei of cells after 6 and 15 weeks of restriction, the content was decreased approximately equally by 37 % and 35 %, respectively, and long-term restriction (21 weeks) contributed to a 41 % decrease. In the neuron nucleoli, the content of nucleic acids was changed similarly: in the group of 6 weeks, a decrease of 40 % was characteristic, after 15 weeks – by 39 %, and after 21 weeks – by 43 %. Conclusions. Changes in the morphometric parameters of magnocellular neurons of the hypothalamic PVN in rats with long-term limitation of living space are characterized by time dependence and multidirectionality, which is related to the functional features of the neuron structural components (cytoplasm, nucleus and nucleoli). There is a progressive decrease in the cytoplasmic area of PVN neurons and their nuclei, while the nucleolar area increases with increasing length of living space limitation. The content of nucleic acids in the studied structures of the hypothalamic PVN magnocellular neurons after prolonged stress at each time point (6, 15, 21 weeks) becomes less than the control values by more than a third. Comparison of nucleic acid content in the neuron cytoplasm, nuclei, and nucleoli shows a narrow range of variations in the parameters of the experimental group rats between different periods.

Aim of the study was to characterize the locomotor and cognitive aspects of the behavior of experimental rats under intracerebroventricular colchicine administration in the open field test and the 8-arm radial maze, as well as identify a set of behavioral features of experimental animals that emerged during the study. Materials and methods. The study was conducted in two stages on 20 male Wistar rats aged 10–11 months. The first stage involved assessment of initial locomotor activity and cognitive functions in all intact rats. At the next stage, the rats were divided into two experimental groups (n = 10): the first group with intracerebroventricular injection of physiological NaCl solution, and the second group with intracerebroventricular injection of colchicine. In 14 days after the surgery, repeated recording of locomotive and cognitive activity indicators was performed. Results. The locomotor activity characteristics did not statistically differ between the animals before the surgical procedures and the rats of the first group. However, in the second group, the activity indicators were significantly higher than in the respective pre-surgery rats. In the intergroup comparison of the rats that entered the second stage of the experiment, it was found that among all the investigated parameters, only the indicator of high activity duration was significantly higher in the second group compared to the first group. At the same time, the animals in the second group showed significant cognitive impairments compared to the first group, as indicated by significantly lower memory index values, the number of correct entries into the maze arms, and a significantly longer time to make the first correct entry into the maze arm. Conclusions. Intracerebroventricular administration of colchicine to experimental rats is accompanied by increased locomotor activity and impairment of cognitive functions. The administration of a physiological solution is not accompanied by a statistically significant increase in locomotor activity, but it demonstrates a clear tendency to increase, which may indicate a certain influence of the procedure itself. The applied pharmacological model of neurodegeneration with subsequent comprehensive assessment of animal behavior in an open field and an 8-arm radial maze is legitimate and can be used to study the early development of neuroinflammation, neuroapoptosis, and synaptogenesis disorders in the experiment.

The aim of the work was to define the pattern of changes and pathogenetic mechanisms of glycemic curve shape during a glucose tolerance test in rats at 6, 15, and 21 weeks of environmental space restriction. Materials and methods. A total of 55 male Wistar rats aged 6–10 months were used and divided into 4 groups (1 – intact control, 10 rats; 2, 3 and 4 of 15 rats each, which were in conditions of restricted environmental space for 6, 15 and 21 weeks, respectively). Fasting plasma levels of glucose (test strips Test Strip II on a Glucocard glucometer (ARKRAY Inc., Japan)), insulin and corticosterone (by an immunoenzymatic method using commercial kits for rats from Monobind, USA) were measured, glucose tolerance tests (GTT) were performed, the HOMA index and the insulin/corticosterone ratio were calculated. Results. The 6-week environmental space restriction, immobility and complex communication relations resulted in a hypoinsulinemic-hypoglycemic type of the glycemic curve with high tissue glucose sensitivity in animals which were in the conditions described (the HOMA index was significantly decreased to 0.21 versus 0.55 in the control), the characteristic delayed hyperglycemic peak at the 30th min of the test slowly returned to the euglycemic level by only the 90th min against the 30th min in the controls. The 15-week restriction caused a hypoinsulinemic curve with preserved tissue glucose sensitivity (the HOMA index 0.33 versus 0.55 in the controls). Alterations in postprandial glucose absorption were manifested by the highest glucose concentration at the 15th min of the test, a very slow decrease in the glucose level in the post-absorption period not being restored to baseline values by the 90th min. The 21-week restriction shaped a diabetic type of the glycemic curve, impaired tissue glucose sensitivity (a substantial and significant increase in the calculated HOMA index from 0.55 in the controls to 0.95) and resulted in the development of insulin resistance. Conclusions. The environmental space restriction, immobility and complex communication relations gradually induce a range of disorders in animals and change the glycemic response shape to glucose load, impair prandial insulin secretion, augment hyperglycemic effects of counterinsular hormones (corticosterone), and realize dysfunctional manifestations of prandial/postprandial glycemia. 6 weeks of restrictions and challenges shape the hypoinsulinemic-hypoglycemic type of the glycemic curve with high tissue glucose sensitivity, while 15 weeks result in the hypoinsulinemic curve with preserved tissue glucose sensitivity. 21 weeks show the diabetic type of the glycemic curve with impaired tissue glucose sensitivity and the development of insulin resistance.

The aim of the work is to ascertain the character of changes in the hormonal profile (concentrations of corticosterone, insulin, and adrenocorticotropic hormone) in conjunction with metabolic alterations and elevated blood pressure, which are induced in rats by restraint stress at 6th, 15th and 21st weeks of environmental space restriction. Materials and methods. A total of 55 normotensive male Wistar rats, aged 6–10 months, were assigned into 4 experimental groups (1 – intact control (10 rats); 2, 3 and 4 (15 rats each exposed to restricted space allowance)). All the animals were subjected to blood pressure (BP), blood glucose level and body weight measurements twice: at the stage of forming groups and at the 6th, 15th and 21st weeks. Plasma hormone concentrations (insulin, corticosterone, and ACTH) were examined by the immunoenzymatic method using commercial kits (Monobind, USA). Results. The body weight of the animals was significantly reduced by 20.72 % after 6 weeks of space allowance restriction, it was restored to baselines by the 15th week and exceeded control values by 26.1 % at the 21st week. BP levels showed an increasing trend, a dynamic increase in systolic pressure by 7 %, 17 % and 26 % was detected, respectively, as well as diastolic from the 15th week to the 21st week by 21.4 % and 37.0 %, respectively. Glucose concentration was within the euglycemic range. Changes in the hormonal profile showed an increase in the concentration of ACTH by more than 50 % and a decrease in insulin – by 34 % at the 6th week with a subsequent twofold decrease in the insulin concentration (at week 15) and a further more than twofold increase in ACTH at the 21st week. As for changes in the concentration of corticosterone, a peak increase of 3.77 times was noticed at the 15th week, followed by a decrease and restoration to the normative values by the 21st week. Conclusions. Even minor and unremarkable continuously acting stressors, which cannot be coped, become important triggers for hormonal profile and carbohydrate metabolism alterations as well as for a persistent increase in blood pressure, which manifest first by hypoinsulinemia, an increase in the level of ACTH, and a constant concentration of corticosterone. Long-term stress exposure contributes to a transient “peak” increase in the corticosterone level, a significant increase in insulin and a sustained increase in ACTH. Multidirectional changes in the levels of the studied hormones occur amidst a gradual increase in blood pressure and a stable increase in the level of glycemia.

Intermittent hypoxia has been studied for many years as a promising non-pharmacological method of cardiovascular disease prevention. Hypoxic effects are accompanied by structural and functional changes in the myocardium. There is a direct link between the duration of hypoxic exposures and the severity of left ventricular myocardial remodeling. A range of histochemical markers of myocardial remodeling (cardiotrophin-1, titin, collagen type 1, annexin V) characterizing parenchymal-stromal relationships in the myocardium has shown high informativeness and prognostic value. The aim of the study was to examine cardiotrophin-1, titin, collagen type 1, annexin V and the morphofunctional state of the left ventricle of the heart in experimental rats exposed to intermittent 15-day (IH15) and 60-day hypoxia (IH60). Materials and methods. Intermittent hypoxia was modeled using 30 normotensive male Wistar rats, 7–8 months old, which were randomly assigned to 3 experimental groups of 10 animals each: 1) INT – a control group – intact animals (196.3 ± 6.8 g); 2) IH15 – 15-day hypoxia (205.6 ± 4.1 g); 3) IH60 – 60-day hypoxia (201.1 ± 5.5 g). The study compared the effects of intermittent hypoxia of varying duration: 15-day and 60-day hypoxia. Experimental modeling of intermittent hypoxia of 2 terms revealed a number of differences between the effects dependent on this factor duration through functional (blood pressure measurement, echocardiography) and immunofluorescent studies. Results. Blood pressure in rats of both groups was in the normotensive range, but an increase in systolic by 10 % and diastolic by 19 % was found in IH60 group compared to IH15 group (p < 0.05). In IH15 group, there was a significant decrease in end-diastolic dimension by 20 %, end-systolic dimension by 22 %, an increase in the thickness of left ventricular posterior wall by 44 % and interventricular septum by 33 % as well as left ventricular mass by 12 %, indicating concentric remodeling of the left ventricle, the development of which was confirmed by a 76 % increase in relative wall thickness compared to that in the control group (p < 0.05). Along with these changes, a decrease in end-diastolic volume by 47 %, end-systolic volume by 48 %, stroke volume by 49 % and cardiac output by 50 % with preserved ejection fraction was revealed (p < 0.05). While the parameters of IH60 rats were characterized by an increase in the thickness of interventricular septum by 33 % and left ventricular posterior wall by 17 %, as well as left ventricle mass by 23 %, relative left ventricular wall thickness was 15 % higher than the control value (p < 0.05). At the same time, diastolic volume was 9 % decreased and systolic volume was 24 % increased (p < 0.05). Also, cardiac output was increased by 58 % compared to that in 15-day hypoxic rats with an 8 % decrease in ejection fraction (p < 0.05). The concentrations of markers in IH60 group exceeded those in IH15, namely: cardiotrophin-1 by 39 %, titin by 70 %, collagen type 1 by 60 % and annexin V by 130 % (p < 0.05). Conclusions. 15-day hypoxia forms concentric left ventricular hypertrophy according to echocardiography findings; the study of marker profile of myocardial remodeling has revealed the development of moderate hypertrophy with increased resilient-elastic properties and decreased intensity of cardiomyocyte death. Remodeling caused by 60-day hypoxia is characterized by the eccentric pattern of changes with severe hypertrophy, significant fibrosis associated with apoptosis of cardiomyocytes. Such morphofunctional state of the myocardium may indicate the initial stages of maladaptation, increasing the risk of heart failure development.

The aim of the work is to review the professional literature sources from the scientific database PubMed mainly for the last 20 years analyzing the modern view on approaches to experimental modeling of cognitive impairment. Materials and methods. A review of the scientific literature over the past 20 years was performed. The lack of requisite knowledge about the pathogenesis of cognitive impairment and the wide range of risk factors for these conditions continue to be major challenges in the development of guidelines on early diagnosis and treatment. The literary analysis suggests that all modeling approaches to experimental cognitive impairment are currently divided into two groups: cell culture and animal models. Conclusions. Experimental modeling of cognitive impairment remains important in addition to clinical and population-based studies. In recent years, the problem of selecting an adequate model to study cognitive impairment, which is a central clinical manifestation of various neurological diseases (Alzheimer’s and Parkinson’s diseases, traumatic brain injury, vascular, demyelinating, and infectious diseases, metabolic aberrations and hormonal imbalance, neurodegenerative diseases of the central nervous system) is becoming increasingly relevant. The choice of model and experimental material – animals or cultures (invertebrate and mammalian cells) is based on a clear understanding of the study design and depends on the ultimate goal of research.

The aim of this study was to characterize the nitric oxide isoforms profile in rats’ nucleus tractus solitarii (NTS) and dorsal motor nucleus (DMN) of vagus nerve in arterial hypertension (AH) of various origin (essential (EAH) – rats of SHR line, and endocrine-salt AH). Materials and methods. The study was performed on 30 aged male rats. Among them, 20 Wistar rats were divided into two groups – control (10 rats) and 10 rats with simulated endocrine-salt AH (ESAH) and 10 SHR rats. An immunohistochemical method was used to study the of nitric oxide synthase isoforms expression features in DMN and NTS. The following parameters were determined: the content of immunoreactive material (IRM) for the studied peptides (Uif), the relative area of the IRM (%) and the IRM concentration in 1 μm2 (Uif/μm2). Results. It was found that in rats with both models of AH, the expression indices of all three nitric oxide synthase (NOS) isoforms in the studied structures increased. In our opinion, this is due to the activation of the studied structures in AH conditions. This must be considered as an important element of high blood pressure compensating. It is achieved through the implementation by a complex of mechanisms like reducing of the sympathetic tone and increasing of the parasympathetic tone by activating a system of secondary messengers; improving neurotrophy due to the high activity of constitutive NOS isoforms; iNOS-mediated NO overproduction, as a factor in compensating for its bioavailability in conditions of local ischemia in AH. Conclusions. Regardless of the AH etiopathogenesis in both experimental groups, the expression of all three NOS isoforms increases in the DMN and NTS structures. In rats with EAH in the DMN and NTS structures, the expression indices of NOS isoforms have their own characteristics. So in the first structure, the largest changes in the indices of the immunoreactive material content and concentration are observed for eNOS, and the relative area for iNOS. At the same time, in the NTS structure, the largest changes in the content indices are observed for iNOS, and the concentration and relative area for eNOS. In rats with ESAH in the DMN structure, the highest changes in the indices of IRM content and concentration are observed for the endothelial isoform of NOS, and the relative area – for inducible. In the NTS structure, the IRM content changed the most for nNOS, and the concentration and relative area for iNOS.

The aim of our study was to determine the characteristics of the BNP and AT II expression in the LC structure of rat brain stem with experimental (genetically determined essential and secondary endocrine-salt) arterial hypertension and to give a comparative description of the expression pattern of these peptides in etiologically different types of arterial hypertension. Materials and methods. The study was carried out on adult 30 male rats. 20 Wistar animals were divided into two groups – control (10 rats) and 10 rats with simulated endocrine-salt AH (ESAH) and 10 rats of the SHR line with essential AH (EAH). The expression parameters of neuropeptides, such as the content, concentration, and relative area of the immunoreactive material, were studied using an immunohistochemical method. Results. It was found that from all BNP expression parameters in the locus coeruleus structure, only relative area increased significantly in both groups. The concentration did not significantly change, and the content of immunoreactive material increased significantly only in animals with ESAH. At the same time, all parameters of angiotensin II expression increased significantly in both experimental groups. Thus, in rats with experimental arterial hypertension in the locus coeruleus structure, more pronounced changes in expression parameters are characteristic for angiotensin II, rather than for BNP. There is a discrepancy between levels of pressor angiotensin II expression and depressor BNP expression in the direction of angiotensin II expression increasing during the arterial hypertension formation. The nature and peculiarities of these neuropeptides expression in the LC structure depend on the key link of the pathogenesis of the modeled arterial hypertension. Conclusions. In rats of the control group with normal blood pressure in LC structure, AT II is more represented. The content and concentration of IRM to AT II are 2.32 and 2.19 times higher than the corresponding BNP values. Prevalence of AT II in the LC structure of the brainstem remains even when arterial hypertension is formed, regardless of its etiology. However, the etiopathogenetic mechanisms of arterial hypertension development impose their own characteristics. In EAH, the content and concentration of AT II is higher than BNP by 4.58 and 3.59 times; in ESAH – by 2.16 and 2.83 times. In the pathogenesis of essential arterial hypertension formation an important role is played by a change in the central control of blood pressure regulation. It is characterized by a significant predominance of the pressor component AT II over the depressor BNP in the brainstem LC structure.

The aim of our study was to establish the morphodensitometric features of locus coeruleus (LC) neurons nuclei in the brain stem of rats with arterial hypertension of various origin (essential – SHR and endocrine-salt hypertension (ESH)). Matherials and methods: the study was carried out on 30 mature male rats: 10 control Wistar rats, 10 Wistar rats with modeled endocrine-salt AH (ESH) and 10 spontaneously hypertensive rats (SHR) with genetically determined hypertension. The histochemical method of staining with gallocyanine-chrome alum by Einarson was used for the evaluation of morphodensitometric characteristics of the neurons nuclei: the nucleus area, the content and concentration of nucleic acids (NA) in the nucleus. Results: it was found that the highest indices were observed in rats of the SHR line while in rats with ESH the content, RNA concentration and nucleus area decreased. In SHR rats with essential hypertension high synthetic activity was observed in the LC neurons with an increase of the content and concentration of NA. Conclusions. Morphometric and densitometric characteristics of the of the brain stem LC in AH depend on the etiological factor and pathogenesis of hypertension. In essential AH of SHR there is a high synthetic activity in the brainstem LC neurons nuclei along with an increase in the content and concentration of NA. In symptomatic AH in rats with ESH, on the contrary, the structure activity is decreased and characterized by the reduction in nucleus size and NA content in it.

The aim of this work is to determine the features of the neurotensin content in the hypothalamic ARC in Wistar rat and SHR strains in arterial hypertension of different etiology: endocrine-salt and essential. Materials and methods. The study was performed on 24 adult male rats at the age of 13–14 months, weight of 250–270 g, which were divided into three experimental groups of 8 animals each. The 1st group (control) – Wistar rats with normal BP indices (Psys / Pdias = 110/75 ± 5 mm Hg), the 2nd – Wistar rats with endocrine-salt model of hypertension (Psys/Pdias = 145/110 ± 10 mm Hg); the 3rd – SHR with spontaneous arterial hypertension (Psys/Pdias = 150/110 ± 10 mm Hg). An immunohistochemical method was used to study the content of neurotensin in the arcuate nucleus, analyzed by digital processing with Image J and EXCEL-7.0. Results. Persistent increase in BP is accompanied by an increase in the content and concentration of neurotensin in the hypothalamic ARC, does not depend on the etiology of hypertension and has a compensatory character. In SHR with essential hypertension there is a higher expression of neurotensin in the hypothalamic ARC in comparison with the endocrine-salt model of hypertension, but the number of neurons involved in the synthesis and accumulation of the neurohormone is significantly lower, which characterizes the morphological features of cellular populations in the hypothalamus of the animals of this strain and can play a role in the development and progression of hypertension.

Modern biomedical research conducted in scientific laboratories is a basis not only for studying the pathogenetic mechanisms of diseases formation and progression, today they are widely used for highly informative diagnostic methods development, new medicines creation, and the study of newly developed pharmaceutical compounds influence on the organism with their potential effectiveness assessment. The article highlights new approaches and possibilities for the functional state of small laboratory animals assessing, taking into account modern international requirements for research conduction and findings interpretation.

The regulation of the paraventricular (PVN) and supraoptic (SON) nuclei’s activity is carried out with a great amount of different neurotransmitters, in particular, with nitric oxide. In order to get clear understanding of the local NO effects in hypothalamus in normal condition and different models of hypertension it is necessary to study all isoforms of NOS in PVN and SON. Our purpose was to find out the features of the inducible nitric oxide synthase (iNOS) expression in magnocellular SON and PVN in SHR and endocrine-saline model of hypertension in rats. Materials and methods. For all rats the mean blood pressure (mBP) was measured. In Wistar rats mBP was stable during the experiment. In SHR mBP was higher than normal. In animals of the 3rd group with ESM the first measurement (before the modelling) demonstrated normal rates of mBP. Since the 7th day of modelling mBP started increase and became steadily increased from the 21st day. We obtained the frontal slices of hypothalamus and performed the assessment of iNOS expression using immunofluorescence assay. The results showed the presence of the constitutive expression of iNOS in the magnocellular neurons of hypothalamus in Wistar rats as well as in both groups of experimental hypertension. The level of iNOS expression in magnocellular nuclei was dependent both on type of hypertension and topography of magnocellular neurons in hypothalamus. In SHR there was high expression of iNOS in PVN and low one in SON, whereas in endocrine-saline model there was high expression in SON and there were no substantial changes of the iNOS expression in PVN. Conclusions. We believe the alteration of iNOS expression in magnocellular nuclei of hypothalamus could participate in development and/or adaptation to hypertension.

Aim. The purpose was to evaluate the features of the neuronal and endothelial nitric oxide synthase expression pattern in supraoptic and magnocellular part of paraventricular nuclei of the hypothalamus in different models of hypertension. Materials and methods. The study was carried out on 20 Wistar male rats and 10 SHR male rats. There were two experimental models of hypertension used: the genetically predisposed to age-related hypertension SHR and rats with endocrine-saline model of hypertension (ESM). The object was the hypothalamus of rats. The immunohystochemical assay was used to determine the expression of NOS isoforms. Results showed the imbalance of constitutive NOS isoforms in SON and PVN of hypothalamus in both of SHR and ESM. The eNOS and nNOS expression pattern is dependent on etiological factor, topographical peculiarities of the nuclei and their functions. Conclusions. We believe the imbalance of constitutive NOS isoforms take part in the hypertension development, its progression and the formation of complications.