Search

Objective. To analyze the changes in the size and shape of perikaryons and the degree of cytoplasm chromatophilia of the rat hippocampal and parietal cortex neurons at different periods after the modeling of total cerebral ischemia. Material and Methods. The experiments were performed on 42 male outbred white rats with an initial weight of 240 ± 20 g. Total cerebral ischemia in white outbred rats was modeled by decapitation. The material for further histological examination was taken at the 1st, 5th, 15th, 30th and 60th minutes, as well as 5 and 24 hours after decapitation. The study of histological preparations was carried out using an Axioscop 2 plus microscope, a digital video camera and the ImageWarp image analysis program. Among the total number, the cells were isolated by the intensity of cytoplasm staining (chromatophilia). After a preliminary check for the normal distribution of indicators, the data obtained were analyzed by non-parametric statistics. Results. With total cerebral ischemia, a decrease in the size of neurons and deformation of perikaryons were observed. Normochromic neurons completely disappeared at the 60th minute. The number of hyperchromic neurons increased, and then progressively decreased. Shrunken neurons made up the majority of cells in the studied cortical sections at the 30–60th minutes, and then, after 5 and 24 hours, cells with pericellular edema prevailed in the neuron population.Conclusion. The obtained data on histological changes in neurons of phylogenetically different parts of the cerebral cortex in the dynamics of total cerebral ischemia provide the basis for further detailed study of post-mortem changes of the brain as well as determining the time of death, thus creating a fundamental basis for studying the properties of neurons, including their transition from one functional state to another.

Background. Calbindin is a calcium-binding protein that supports calcium homeostasis for the normal functioning of neurons. Purpose. To study the distribution of immunoreactivity of calbindin-D28K in the structures of the developing cerebellum of the rat. Material and methods. The study was performed on 16 outbred white rats of different age groups: 2-, 7-, 15-days (early postnatal period), 45-days (puberty period). The cerebellum samples were taken and fixed in zinc-ethanol-formaldehyde for immunohistochemistry. Calbindin-D28K immunoreactivity was determined on paraffin sections using primary polyclonal rabbit antibodies. Results. In the cerebellar cortex, calbindin immunoreactivity was detected on the 2nd day after development of Purkinje cells (PC) in their perikaryons, and by the 15th day in their dendrites and it did not change by the 45th day. In all terms of the study in PC, it was detected not only in the cytoplasm, but also in their nucleus. In the granular layer, calbindin immunoreactivity decreased in rats in postnatal ontogenesis, however, in adult rats, some neurons were moderately immunopositive. Among them, from the 15th day after birth, the calbindin-immunoreactive afferent nerve fibers running in the white matter were detected. There were no significant differences in the distribution of calbindin between the lobes of the cerebellum of different phylogenetic age. Conclusions. Considering that the expression of сalbindin-D28k is detected throughout the entire period of development of Purkinje cells, as well as its physiological role in maintaining the function and homeostasis of calcium in them, it can be concluded that сalbindin-D28k is a valuable marker for the morphofunctional characteristics of PC in the developing and adult cerebellum of rats in normal and pathological conditions.

The aim of this study was to analyze and generalize the literature data on the structure and development of the rat hippocampus for the subsequent study of the developmental disorders of this section of the brain cortex and the extrapolation of the obtained experimental data to humans. Results: The information about morphofunctional organization of the rat hippocampus provides a basis for further study of this section of the brain cortex in norm and various pathologies and allows extrapolating the obtained experimental data to humans.

Background. Brain histaminergic neurons play an important role in regulating many body functions, systems, and reactions, and also in the pathogenesis of many pathological states and diseases. Histamine in the brain functions as a neurotransmitter and is located mainly in histaminergic neurons. All histaminergic neurons in the hypothalamus, in contrast to other types of neurons, have high monoamine oxidase type B (MAO B) activity, this being a key enzyme in histamine metabolism in the brain. Objective. Parallel assessment of MAO B activity and immunoreactivity in histaminergic neurons in the rat hypothalamus during postnatal ontogeny. Materials and methods. Experiments were run on hypothalamus specimens from 5-, 10-, 20-, 45-, and 90-day offspring of white rats (45 rat pups) in compliance with the "Guidelines for Studies Using Experimental Animals." Hypothalamus sections were processed histochemically to detect MAO B activity and immunohistochemically using antibodies to MAO B. Results. MAO B, the enzyme catalyzing the oxidative deamination of histamine and functioning as a marker enzyme for histaminergic neurons in the hypothalamus, showed no cytoplasmic activity or immunoreactivity on day 5 after birth, after which these measures increased in parallel from day 10 to day 90 of postnatal ontogeny. Conclusions. The synchronicity of postnatal development of the MAO B activity and immunoreactivity in histaminergic neurons in the brain is evidence of the parallel accumulation of MAO B protein in these cells and increases in its enzymatic activity, reflecting the establishment of their specific neurotransmitter metabolism. [ABSTRACT FROM AUTHOR]

Introduction. There are various physiological, experimental, and pathological conditions which can induce changes in the size, morphology, location, and number of nucleoli depending on functional and metabolic activity. One of these conditions is the postnatal development of cells, including neurons. Objective. To study the characteristics of the structural and functional establishment of nucleoli in histaminergic neurons in the rat brain during postnatal ontogeny. Materials and methods. Studies were carried out using mongrel white rats (12 individuals) aged 5, 20, and 45 days of postnatal ontogeny. The numbers and sizes of nucleoli in the nuclei of histaminergic neurons in nucleus E2 of the posterior hypothalamic area of the rat brain were studied by electron microscopy and morphometric methods and nonparametric statistics. Results. The number of nucleoli in the nuclei of histaminergic neurons in the posterior part of the hypothalamus decreased in rats from day 5 to day 45 of postnatal development, while their size increased; nucleoli were also displaced from the karyolemma to the center of the nucleus. Maturation of the animals was accompanied by a gradual transformation of relatively compact nucleoli into reticular nucleoli in histaminergic neurons, and this was accompanied by an increase in the quantities of the fibrillar and granular components, while the number of fibrillary centers increased and their sizes decreased. Furthermore, there were decreases in the cloud of migrating ribosomal subunits between the nucleolus and the karyolemma and in the quantity of nucleolus-associated heterochromatin. Conclusions. Hypothalamic nucleus E2 showed significant changes in the number, sizes, structure, and topography of nucleoli in the nuclei of histaminergic neurons in rats from day 5 to day 45 of postnatal ontogeny. [ABSTRACT FROM AUTHOR]

Objectives. To study structural and histochemical changes in neurons in the frontal cortex of the brain in rats after ligation of the common bile duct. Materials and methods. The cortex of the frontal lobe was studied in 72 mongrel adult white male rats weighing 200 ± 25 g. Ligation of the common bile duct and development of cholestasis (experimental group) and sham surgery (control group) was followed by histological and histochemical studies of microstructural changes in pyramidal neurons in all layers of the frontal cortex on days 2, 5, 10, 20, 45, and 90. Results. Ligation of the common bile duct in rats producing cholestasis led to profound histological and histochemical changes in neurons in the frontal cortex of the brain: changes in size and shape, and appearance of hyperchromic shrunken neurons and ghost cells. Impairments to energy and plastic metabolism in neurons led to the death of the experimental animals. The consequences of cholestasis in the brains of rats were apparent on days 2-5 and reached a maximum on days 10-20. In the later post-operative period (45-90 days), groups of survivors showed gradual reductions in these changes, though the consequences of cholestasis consisted of foci of neuron loss in all layers of the frontal cortex. Conclusions. It is suggested that survival of rats after ligation of the common bile duct is due to formation of bypass bile ducts, with elimination of cholestasis and the high adaptive potential of neurons. [ABSTRACT FROM AUTHOR]