scholarly journals The influence of melatonin on stress-induced ultramicroscopic changes of the neurons of the supraoptic nuclei of the rat hypothalamus

2021 ◽  
Vol 25 (3 (99)) ◽  
pp. 25-32
Author(s):  
R. Bulyk ◽  
T. Bulyk ◽  
O. Smetanuik
Keyword(s):  
Immobilization Stress ◽  
Prolonged Exposure ◽  
Neurosecretory Cells ◽  
Ultrastructural Organization ◽  
Neurosecretory Granules ◽  
Electron Microscopic ◽  
Relative Improvement ◽  
White Rats ◽  
Hypothalamic Nuclei ◽  
Supraoptic Nuclei

The aim: to study the effect of melatonin on the ultrastructural state of the supraoptic nuclei of the hypothalamus of rats under immobilization stress.Materials and methods. The experiments were performed on non-linear male white rats weighing 200-220 g. The animals were divided into 3 study series, in each of which the biomaterial was collected at 2 p.m. and at 2 a.m. using electron microscopic method. Long immobilization stress was simulated by keeping rats in special plastic penal cages for 6 hours daily for 7 consecutive days. Melatonin (Sigma, USA, 99.5% purification degree) at a dose of 0.5 mg/kg, in 1.0 ml of solvent (0.9% ethanol solution on physiologic saline) was injected daily, intraperitoneally.Results. When the animals were kept under the standard light regime, the ultrastructural organization of the hypothalamic nuclei at 2 p.m. indicated their low functional activity in comparison with the studies carried out at 2 a.m. Prolonged exposure of rats to immobilization stress was reflected in a significant rearrangement of the ultrastructural organization of supraoptic nuclei of the hypothalamus. The established changes can be considered as a manifestation of neurosecretory activity suppression, a decrease in neurosecretase production by hypothalamic neurons. Melatonin injections against the background of immobilization stress resulted in relative normalization of ultrastructural state of neurons of supraoptic nuclei of the hypothalamus of animals. In particular, studies at 2 a.m. revealed light neurosecretory cells containing a large nucleus, it was pyknotically altered. Karyolema invaginations, euchromatin dominance in the nucleus were observed. Heterogeneous changes were observed on the part of mitochondria. Enlarged tubules of granular endoplasmic reticulum were seen. At the same time, a small number of ribosomes and few hormonal granules were noticeable in neuroplasm. The mentioned picture of neurosecretory cells reflects a relative improvement in their electron microscopic state, which is evidenced by the appearance of neurosecretory granules. However, the ultrastructure of other organelles of the studied neurons indicates a depleted state caused by prolonged immobilization.Conclusions. 1. In animals under standard photoperiod conditions, the structural organization of supraoptic neurons of the hypothalamic nuclei during the nighttime of the experiment reflects the intensity of intracellular synthesizing processes (at 2 a.m.). A decrease in the activity of the structures under study is noted during the daytime. 2. Under immobilization stress, the ultrastructural organization of the above neurons indicates a pronounced disturbance of reactive nature with the signs of decreased functional ability of the structures and the phenomena of edema and destruction during the period of observation. 3. Melatonin injections against the background of immobilization stress led to a relative improvement in the ultrastructural state of the animals’ hypothalamic nuclei neurons, which is evidenced by the appearance of neurosecretory granules. However, the ultrastructure of other organelles of the studied neurons indicated a depleted state caused by prolonged immobilization.

scholarly journals ELECTRON MICROSCOPIC LOCALIZATION OF ACID PHOSPHATASE AND THIAMINE PYROPHOSPHATASE ACTIVITY IN HYPOTHALAMIC NEUROSECRETORY CELLS OF THE RAT

1964 ◽  
Vol 21 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Joseph Osinchak
Keyword(s):  
Acid Phosphatase ◽  
Osmium Tetroxide ◽  
Neurosecretory Cells ◽  
Electron Microscopic ◽  
Vascular Perfusion ◽  
Dense Bodies ◽  
Thiamine Pyrophosphatase ◽  
Pyrophosphatase Activity ◽  
Supraoptic Nuclei ◽  
Electron Microscopic Localization

Supraoptic nuclei in the hypothalamus of rats were fixed for the electron microscope by vascular perfusion with solutions of glutaraldehyde followed by post fixation with osmium tetroxide. Cytochemical methods for detection of acid phosphatase and thiamine pyrophosphatase activity have been applied to glutaraldehyde-fixed frozen sections containing the neurosecretory cells. The enzyme activities have been localized to certain Golgi cisternae. Acid phosphatase activity is present in the large (0.4 µ to 1.0 µ) granules or dense bodies which are surrounded by a single limiting membrane; both features characterize these structures as lysosomes. Smaller (0.1 µ) granules also present in the perikarya are generally unreactive towards enzyme activity and resemble in form the neurosecretory granules in the neurohypophysis.

scholarly journals SUBMICROSCOPIC TRANSFORMATIONS OF THE HYPOTHALAMUS STRUCTURE UNDER CONDITIONS OF 24-HOUR LIGHTING

2020 ◽  
Vol 19 (4) ◽  
pp. 5-9
Author(s):  
R. Bulyk ◽  
K. Vlasova
Keyword(s):  
Pineal Gland ◽  
Functional Activity ◽  
Ganglion Cells ◽  
Secretory Granules ◽  
Light Stress ◽  
Neurosecretory Cells ◽  
Free Access ◽  
Dense Matrix ◽  
White Rats ◽  
Supraoptic Nuclei

Light information that is perceived by the retinal photoreceptors is transmitted along the retinohypothalamic pathway (the retinal ganglion cells present in it) and supraoptic fibers, suprachiasmatic, paraventricular, arcuate nuclei of the hypothalamus, through the trunk of the upper thoracic region and lateral intermedial nuclei of the spinal cord, sym- pathic neurons of the superior cervical ganglion in the pineal gland. In the dark, signals from the suprachiasmatic nucleus enhance the synthesis and release of norepinephrine from sympathetic endings. The experiments were carried out on 40 sexually mature male outbred white rats weighing 0.15-0.18 kg. The animals were kept in cages at a constant temperature, air humidity and free access to water and food. Experimental animals were divided into two series, in each of which the biomaterial was taken at 14.00 and 02.00 h. The selected timing of the experiment is due to the different functional activity of the pineal gland in the indicated time periods of the day. Submicroscopic studies of the supraoptic nuclei of the hypothalamus of intact animals at 14:00 showed that the majority of neurosecretory cells are round-oval in shape with rare invaginations and nuclei of irregular shape with shallow invaginations of the karyolem. The karyoplasm contains lumps of chromatin and a dense osmiophilic nucleolus. Neuroplasm occupies a small volume, in it the tubules of the granular endoplasmic reticulum are tightly packed with a small lumen, where there are many ribosomes and polysomes, as well as a small amount of evenly distributed granules. In the Golgi complex, secretory granules of different sizes are formed. Mitochondria, small with a dense matrix, contain few cristae. Some of them are in an energetically stressed state, are able to hypertrophy and partially lose their cristae or die. The ultramicroscopic organization of neurosecretory cells of the supraoptic nuclei of the anterior hypothalamus of rats was investigated. Under the standard illumination mode (12.00C: 12.00T), the ultrastructure of neurons indicates a decrease in their functional activity during the light period of the day and growth - in the dark period of the day. Light stress (24.00C: 00T) leads to significant desynchronosis and causes destructive changes in the components of the structures under study, more pronounced at 02.00 h.

HISTOMETRIC AND ULTRASTRUCTURAL ORGANIZATION OF THE NERVIMUSCULAR TERMINALS OF SKELETAL MUSCLES AT A HYPOKINESIA

2019 ◽  
pp. 55-63
Author(s):  
Z. M. Yaschyshyn ◽  
S. L. Popel
Keyword(s):  
Skeletal Muscles ◽  
Structural Adjustment ◽  
Muscle Fibers ◽  
Electron Microscopic Examination ◽  
Nerve Fibers ◽  
Ultrastructural Changes ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Myelinated Nerve ◽  
Male Wistar Rats

The aim: to study the dynamics of histological and ultrastructural changes in muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia at different stages of ontogenesis. Methods. Studied skeletal muscles and their peripheral nervous apparatus of laboratory male Wistar rats aged 30 to 270 days. The restriction of motor activity was carried out in special canister cells for 30, 60, 90, and 240 days (5 animals for each term). To determine the type of muscle fiber, the Nahlas histochemical method was used, the Kulchitsky method was used to detect myelinated nerve fibers, the Bilshovsky-Gros method and the electron microscopic method to identify neuromuscular endings. Results. The data of histological and electron microscopic examination of skeletal muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia indicate their regular restructuring during the development of muscles, the formation of their synapses and structures that are associated with them at different stages of ontogenesis. Conclusion. The study provides an in-depth understanding of the relative frequency and nature of the disturbance of the neuromuscular endings during prolonged hypokinesia and its effect on the dynamics of structural adjustment of individual types of muscle fibers in ontogenesis.

HISTOMETRIC AND ULTRASTRUCTURAL ORGANIZATION OF THE NERVIMUSCULAR TERMINALS OF SKELETAL MUSCLES AT A HYPOKINESIA

2019 ◽  
pp. 55-63
Author(s):  
Z. M. Yaschyshyn ◽  
S. L. Popel
Keyword(s):  
Skeletal Muscles ◽  
Structural Adjustment ◽  
Muscle Fibers ◽  
Electron Microscopic Examination ◽  
Nerve Fibers ◽  
Ultrastructural Changes ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Myelinated Nerve ◽  
Male Wistar Rats

The aim: to study the dynamics of histological and ultrastructural changes in muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia at different stages of ontogenesis. Methods. Studied skeletal muscles and their peripheral nervous apparatus of laboratory male Wistar rats aged 30 to 270 days. The restriction of motor activity was carried out in special canister cells for 30, 60, 90, and 240 days (5 animals for each term). To determine the type of muscle fiber, the Nahlas histochemical method was used, the Kulchitsky method was used to detect myelinated nerve fibers, the Bilshovsky-Gros method and the electron microscopic method to identify neuromuscular endings. Results. The data of histological and electron microscopic examination of skeletal muscle fibers and their neuromuscular endings under conditions of prolonged hypokinesia indicate their regular restructuring during the development of muscles, the formation of their synapses and structures that are associated with them at different stages of ontogenesis. Conclusion. The study provides an in-depth understanding of the relative frequency and nature of the disturbance of the neuromuscular endings during prolonged hypokinesia and its effect on the dynamics of structural adjustment of individual types of muscle fibers in ontogenesis.

scholarly journals Electron microscopic changes of lymph nodes during correction of sodium glutamate action by melatonin

2020 ◽  
Vol 26 (1) ◽  
pp. 59-64 ◽  
Author(s):  
T.V. Harapko
Keyword(s):  
Lymph Nodes ◽  
Monosodium Glutamate ◽  
Reproductive Age ◽  
Female Rats ◽  
Mesenteric Lymph Nodes ◽  
Electron Microscopic ◽  
Male And Female ◽  
White Rats ◽  
Mesenteric Lymph ◽  
Male And Female Rats

The effect of monosodium glutamate on lymphoid organs remains insufficiently studied. Also, no less relevant is the issue of correction of changes caused by the action of monosodium glutamate. The aim of the study was to study the electron microscopic changes in the parenchyma of the lymph nodes of rats under the action of monosodium glutamate for six weeks and during correction with melatonin. The experimental study was performed on 66 white male and female rats of reproductive age. The structure of mesenteric lymph nodes of white rats under the conditions of physiological norm at the electron microscopic level was studied in 10 intact animals. Experimental animals were divided into 4 groups, each with 10 animals. The control was 16 white rats, which instead of a high-calorie diet (HCD) received a standard diet of vivarium. HCD was achieved by adding to the diet of monosodium glutamate at a dose of 0.07 g/kg body weight of rats. The dose of melatonin was 10 mg/kg body weight of rats, administered orally daily at the same time in the afternoon. The electron microscopic structure of the mesenteric lymph nodes of male and female rats of reproductive age of the intact and control groups corresponds to the species norm. The study showed that monosodium glutamate causes changes in the parenchyma of the lymph nodes as in alimentary obesity. After six weeks of HCD, the number of apoptically altered lymphocytes increases. That part of lymphocytes, which has no signs of karyorrhexis or karyolysis, has a karyolemma with deep intussusception, the cytoplasm is enlightened, the tubules of the granular endoplasmic reticulum in cells with signs of edema, dilated, mitochondrial ridges swollen, damaged. There are profound destructive changes in the cellular composition of the organ and violations at the level of all parts of the vascular bed. After six weeks of melatonin correction, the number of macrophages and plasma cells decreased, in some lymphocytes the nucleolus is not clearly expressed, the karyolemma is uneven, the cytoplasm is enlightened, the number of osmophilic (fatty) inclusions decreases both in the intercellular space and in the cytoplasm of the cell. Therefore, the introduction of melatonin led to a significant restoration of the structural organization, and hence the function of this organ.

C-type Natriuretic Peptide Inhibits L-type Ca2+ Current in Rat Magnocellular Neurosecretory Cells by Activating the NPR-C Receptor

2005 ◽  
Vol 94 (1) ◽  
pp. 612-621 ◽  
Author(s):  
Robert A. Rose ◽  
Madhu B. Anand-Srivastava ◽  
Wayne R. Giles ◽  
Jaideep S. Bains
Keyword(s):  
Natriuretic Peptide ◽  
Action Potentials ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Neurosecretory Cells ◽  
Mediated Effects ◽  
Inhibitory G Protein ◽  
Whole Cell Recordings ◽  
Supraoptic Nuclei

Magnocellular neurosecretory cells (MNCs), of the paraventricular and supraoptic nuclei of the hypothalamus, secrete the hormones vasopressin and oxytocin. As a result, they have an essential role in fundamental physiological responses including regulation of blood volume and fluid homeostasis. C-type natriuretic peptide (CNP) is present at high levels in the hypothalamus. Although CNP is known to decrease hormone secretion from MNCs, no studies have examined the role of the natriuretic peptide C receptor (NPR-C) in these neurons. In this study, whole cell recordings from acutely isolated MNCs, and MNCs in a coronal slice preparation, show that CNP (2 × 10−8 M) and the selective NPR-C agonist, cANF (2 × 10−8 M), significantly inhibit L-type Ca2+ current ( ICa(L)) by ∼50%. This effect on ICa(L) is mimicked by dialyzing a Gi-activator peptide (10−7 M) into these cells, implicating a role for the inhibitory G protein, Gi. These NPR-C–mediated effects were specific to ICa(L). T-type Ca2+ channels were unaffected by CNP. Current-clamp experiments revealed the ability of CNP, acting via the NPR-C receptor, to decrease (∼25%) the number of action potentials elicited during a 500 ms depolarizing stimulus. Analysis of action potential duration revealed that CNP and cANF significantly decreased 50% repolarization time (APD50) in MNCs. In summary, our findings show that CNP has a potent and selective inhibitory effect on ICa(L) and on excitability in MNCs that is mediated by the NPR-C receptor. These data represent the first electrophysiological evidence of a functional role for the NPR-C receptor in the mammalian hypothalamus.

scholarly journals A light, scanning electron and transmission electron microscopic study of a Fetal mouse Skin Dendritic Cell line (FSDC)

2009 ◽  
Vol 15 (S3) ◽  
pp. 35-36 ◽  
Author(s):  
A. M. Dinis ◽  
M. T. Cruz ◽  
M. C. Lopes ◽  
M. T. Batista
Keyword(s):  
Electron Microscopy ◽  
T Cell ◽  
Cell Line ◽  
Mouse Skin ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Peripheral Tissues ◽  
Fetal Mouse ◽  
Transmission Electron ◽  
Scanning Electron

AbstractDendritic cells (DC) are major players in initiating immune responses by activating T-lymphocytes. They act as sentinels in peripheral tissues, continuously scavenging for antigens in their immediate surroundings. Their involvement in T-cell responses consists of a linear progression of events starting with capture of antigens in peripheral tissues, such as the skin, followed by migration to draining lymphoid organs and presentation of antigen-derived peptides to induce T-cell priming. In the last years, a number of DC lines have been generated and the electron microscopy has been used to define their characteristics, thus contributing to their formal validation. A cell line with features of early DC precursors was previously established from fetal mouse skin (FSDC), but its ultrastructural organization was not fully investigated. Here we report such investigation using light (LM), scanning electron (SEM) and transmission electron microscopy (TEM). The goal is to use FSDC as a model system to evaluate the safety and effectiveness of selected plant extracts, fractions and isolated polyphenols against inflammatory processes. Our preliminary results with these cells showed anti-inflammatory activity for some of the extracts we are currently investigating.

scholarly journals Paraganglioma of the Filum Terminale

1978 ◽  
Vol 5 (2) ◽  
pp. 257-260 ◽  
Author(s):  
Réal Lagacé ◽  
Claude Delage ◽  
François Gagné
Keyword(s):  
Clinical Data ◽  
Cell Types ◽  
Vascular Network ◽  
Filum Terminale ◽  
Neurosecretory Granules ◽  
Electron Microscopic ◽  
Dark Cells ◽  
Microscopic Studies ◽  
Glomus Coccygeum

SUMMARY:An unusual tumor arising in the filum terminale is described. The clinical data revealed an extensive and slowly growing lesion. The histologic picture was characterized by a proliferation of lobules and sheets of regular cells within a rich vascular network. Electron microscopic studies showed light and dark cells with sustentacular extensions. Typical neurosecretory granules were obsen'ed in both cell types, establishing the diagnosis of para-ganglioma. The glomus coccygeum could be the site of this tumor.

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