ULTRASTRUCTURAL ORGANIZATION OF NEURONS OF THE LATERAL PREOPTIC NUCLEUS OF THE HYPOTHALAMUS OF OLD RATS UNDER VARIOUS LIGHT CONDITIONS

Purpose – to study the changes in the ultrastructure of neurons of the lateral preopticnucleus (LPON) of the hypothalamus of old rats under various light conditions.Material and methods. The experiments were carried out on 36 old white male rats.The material was fixed in a 2.5% solution of glutaraldehyde, prepared on the basisof phosphate buffer with a pH of 7.2–7.4. Then, postfixation was performed in a 1%solution of osmium tetraoxide and dehydrated in propylene oxide, after which it waspoured into a mixture of epoxy resins. Ultrathin sections made on an ultramicrotomeLKB-3 were contrasted with uranium acetate and lead citrate according to the Reynoldsmethod and studied under electron microscope TEM - 125 K.Results. Studies of LPON neurons under the standard light mode revealed nuclei withuneven contours. The nucleoli are quite large. The neuroplasm contains well-developedtubules of the rough endoplasmic reticulum (ER) and small cisternae of the Golgi complex(GC). Mitochondria are rounded, small, with moderately pronounced cristae. Underconditions of round-the-clock darkness, we have found that the cell nuclei are rounded,less often determined by the nucleoli. In the neuroplasm there are locally dilated tubulesof the ER and cisternae of the GC, mitochondria with enlightened matrix and fragmentedcristae. Under conditions of round-the-clock illumination, the nuclei of the rounded formwith uneven contours of a nuclear membrane forming deep intussusception are revealed.Nucleoli were rarely identified. In the hyaloplasm, locally dilated tubules of the ERare identified. Mitochondria are small in size with an enlightened matrix and reducedcristae.Conclusions. The obtained results of submicroscopic examination of LPON neuronsof the hypothalamus of old rats revealed their relatively increased functional activityin the dark period. Under conditions of round-the-clock lighting, more pronouncedhypertrophic and initial destructive changes of the nuclei and organelles of the neuronsof the LPON of the hypothalamic were revealed, compared with the animals that wereunder the conditions of round-the-clock darkness. This is confirmed by the change in theultrastructure of nerve cells at 2 am the appearance of "dark" cells.

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ONTOGENETIC ASPECTS OF MELATONIN RECEPTORS 1A DENSITY IN THE LATERAL PREOPTIC NUCLEUS OF THE HYPOTHALAMUS UNDER VARIOUS LIGHT CONDITIONS

Wiadomości Lekarskie ◽

10.36740/wlek202109131 ◽

2021 ◽

Vol 74 (9) ◽

pp. 2202-2206

Keyword(s):

Circadian Rhythm ◽

Immunohistochemical Staining ◽

Melatonin Receptors ◽

Polymeric System ◽

Light Deprivation ◽

Light Conditions ◽

Preoptic Nucleus ◽

Light Stimulation ◽

Old Rats

The aim: To find out density of melatonin receptors 1A in the neurons of the lateral preoptic nucleus of the hypothalamus in mature and old rats under various light conditions. Materials and methods: The study was carried out on 72 albino mature and old rats with light conditions appropriate for the experiment. To find out circadian differences of melatonin receptors 1A the material for the study was taken at 2 p.m. and 2 a.m. Visualization of primary antibodies against melatonin receptors 1A (Abcam) was conducted by means of the polymeric system Dako and diaminobenzidine staining under the microscope Delta Optical Evolution 100. The intensity of staining was assessed on the digital copies of images according to computer microdensitometry method. Results: Immunohistochemical examinations conducted enable to suggest that melatonin receptors 1A in the neurons of the lateral preoptic nucleus of the hypothalamus respond to different light conditions. In particular, intensity of immunohistochemical staining to melatonin receptors 1A under conditions of light deprivation increases both in mature and old rats, but it decreases under conditions of light stimulation. The parameter is higher at 2 a.m. as compared with 2 p.m. Intensity of immunohistochemical staining to melatonin receptors 1A in the neurons of the lateral preoptic nucleus of the hypothalamus is always lower in old rats than in mature ones. Conclusions: Density of melatonin receptors 1A in the neurons of the lateral preoptic nucleus of the hypothalamus is subordinated to the circadian rhythm: it increases at night and decreases in the daytime. At the same time, light stimulation results in disorders of the rhythm and development of desynchronization.

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Ultrastructural Organization and Biochemical Characterization of Chromatin . RNA . Protein Complexes Isolated from Mammalian Cell Nuclei

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1975.tb02379.x ◽

1975 ◽

Vol 58 (2) ◽

pp. 327-337 ◽

Cited By ~ 67

Author(s):

Jean-Pierre BACHELLERIE ◽

Edmond PUVION ◽

Jean-Pierre ZALTA

Keyword(s):

Mammalian Cell ◽

Biochemical Characterization ◽

Protein Complexes ◽

Ultrastructural Organization ◽

Cell Nuclei ◽

Rna Protein Complexes

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Microwave Polymerization of Embedding Resins for Biological/Biomedical Elecron Microscopy

MRS Proceedings ◽

10.1557/proc-189-347 ◽

1990 ◽

Vol 189 ◽

Cited By ~ 3

Author(s):

B.L. Giammara ◽

D.J. Birch ◽

D.O. Harper

Keyword(s):

Epoxy Resins ◽

Polyester Resin ◽

Unsaturated Polyester ◽

Polymerization Time ◽

Diagnostic Pathology ◽

Rapid Methods ◽

Convection Oven ◽

Microwave Polymerization ◽

Semithin Sections ◽

Ultrathin Sections

ABSTRACTThe use of microwave energies for polymerization of epoxy and other commercially available resins, used routinely in electron microscopy methodologies, shows promise for diagnostic pathology where rapid methods can be crucial. Many desirable embedment properties, such as specimen infiltration, color, hardness, rough trimming, and ability to stain, are necesssary. The properties necessary for cutting 1 micron semithin sections and 700 Angstrom ultrathin sections (that can withstand pentration by a 100 kV electron beam for image formation) must be maintained.In this study, six epoxy resins and one unsaturated polyester resin were used, the latter in a variety of recipes. Each formulation was subjected to microwave power levels from 400 to 700 W for 1 to 15 minutes. Selected specimen embedments tested well and significantly reduced traditional convection oven polymerization time from two days to a few minutes.

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Aging and arteriosclerosis. I. Development of myointimal hyperplasia after endothelial injury.

Journal of Experimental Medicine ◽

10.1084/jem.164.4.1171 ◽

1986 ◽

Vol 164 (4) ◽

pp. 1171-1178 ◽

Cited By ~ 66

Author(s):

R J Hariri ◽

D R Alonso ◽

D P Hajjar ◽

D Coletti ◽

M E Weksler

Keyword(s):

Vascular Injury ◽

Experimental Models ◽

Endothelial Injury ◽

Vascular Lesions ◽

Fischer 344 Rats ◽

Cell Nuclei ◽

Fischer 344 ◽

Endothelial Denudation ◽

Old Rats ◽

Intimal Thickness

Old Fischer 344 rats are more susceptible to vascular lesions after arterial endothelial injury than are young animals. Thus, 20-26-mo-old Fischer 344 rats developed greater and more persistent intimal proliferative lesions than did 2-5-mo-old rats after aortic endothelial denudation. 3 d after deendothelialization, intimal thickness was increased two-fold in both old and young animals. However, 14 d after endothelial injury, intimal thickness had increased nearly five times in old animals, but had regressed to normal in young animals. Intimal thickness of young aortic grafts transplanted into young recipients did not differ significantly from adjacent host aorta or autotransplanted aortic segments 6 wk after surgery. In contrast, intimal thickness of old grafts transplanted into young recipients was eight times greater than adjacent young host aorta 6 wk after surgery. The density of cell nuclei in the intima of old grafts was also much greater than that in young grafts. Thus, in two experimental models of vascular injury, old rats have consistently had greater myointimal hyperplasia than young rats. The increased proliferative response of aortic smooth muscle cells after vascular injury of old animals may contribute to the increased prevalence of vascular disease with age.

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Cytochemical localization of chloride in the leaves of Ruppia maritima L

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162910 ◽

1996 ◽

Vol 54 ◽

pp. 90-91

Author(s):

A. D. Barnabas

Keyword(s):

Silver Chloride ◽

Chloride Ions ◽

Ruppia Maritima ◽

Light Conditions ◽

Salt Glands ◽

Cytochemical Localization ◽

Glass Slides ◽

Transmission Electron ◽

Ultrathin Sections ◽

Edx Microanalysis

Ruppia maritima L. is a submerged halophyte which occurs frequently in estuaries where sodium chloride is the dominant salt. Unlike terrestrial halophytes, R. maritima does not possess any specialized salt-secreting structures such as salt glands. Knowledge of salt tolerance mechanisms in this plant is important to our understanding of its biology. In the present study, the subcellular distribution of chloride ions in leaf blade epidermal cells of R. maritima was determined.Chloride ions in the cells were localized by precipitation with silver, resulting in the formation of silver chloride (AgCl2) deposits. Leaf samples were fixed in a mixture of osmium and silver acetate under red safe light conditions to prevent reduction of silver by light. The material was dehydrated and embedded in a chloride-free resin. Leaf samples fixed only in osmium were used as controls. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) microanalysis using a Joel 6100 SEM with a Noran Voyager 2100 EDX microanalyser, were used to study AgCl2 distribution. Ultrathin sections for TEM were examined unstained. EDX microanalysis was performed on thick sections of resinembedded material mounted on glass slides.

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Ultrastructural Organization of Plant Cell Nuclei

The Cell Nucleus ◽

10.1016/b978-0-12-147601-4.50011-7 ◽

1974 ◽

pp. 149-185 ◽

Cited By ~ 29

Author(s):

Jean-G. Lafontaine

Keyword(s):

Plant Cell ◽

Ultrastructural Organization ◽

Cell Nuclei

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Growth hormone-releasing hormone activates sleep regulatory neurons of the rat preoptic hypothalamus

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00494.2009 ◽

2010 ◽

Vol 298 (1) ◽

pp. R147-R156 ◽

Cited By ~ 21

Author(s):

Zoltan Peterfi ◽

Dennis McGinty ◽

Erzsebet Sarai ◽

Ronald Szymusiak

Keyword(s):

Growth Hormone ◽

Dark Period ◽

Nrem Sleep ◽

Gabaergic Neurons ◽

Growth Hormone Releasing Hormone ◽

Saline Injection ◽

Preoptic Nucleus ◽

Releasing Hormone ◽

Cell Counts ◽

Sleep Amount

We examined whether growth hormone-releasing hormone (GHRH) may promote non-rapid eye movement (NREM) sleep via activation of GABAergic neurons in the preoptic area. Male Sprague-Dawley rats were implanted with EEG, EMG electrodes and a unilateral intracerebroventricular cannula. Groups of rats received injections (3 μl icv) with gonadotropin-releasing hormone (GHRH) (0.1 nmol/100 g body wt) or equal volume of physiological saline at the onset of the dark period and were permitted spontaneous sleep for 90 min. Separate groups of rats were sleep deprived by gentle handling for 90 min, beginning at the time of GHRH or saline injection, at the onset of the dark period. Other groups of rats received intracerebroventricular octreotide (somatostatin analog OCT) injections, intracerebroventricular injection of one of two doses of competitive GHRH antagonist, or intracerebroventricular saline injection at light onset and were then permitted 90 min spontaneous sleep-waking. Rats were killed immediately after the 90-min sleep/wake monitoring period. Brain tissue was processed for immunohistochemistry for c-Fos protein and glutamic acid decarboxylase (GAD). Single c-Fos and dual Fos-GAD cell counts were determined in the median preoptic nucleus (MnPN), and in the core and the extended parts of the ventrolateral preoptic nucleus (cVLPO and exVLPO). Intracerebroventricular GHRH elicited a significant increase in NREM sleep amount. Double-labeled Fos+GAD cell counts were significantly elevated after GHRH injection in the MnPN and VLPO in both undisturbed and sleep-deprived groups. OCT and GHRH antagonist significantly decreased NREM sleep amount compared with control rats. OCT injection increased single c-Fos-labeled cell counts in the MnPN, but not in the VLPO. Double-labeled cell counts were significantly reduced after OCT and the high dose of GHRH antagonist injection in all areas examined. These findings identify GABAergic neurons in the MnPN and VLPO as potential targets of the sleep-regulatory actions of GHRH.

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Respiration of soybean plants in relation to their physiological conditions. II. Effects of preceding light conditions on the time course change of respiration in the following dark period.

Japanese Journal of Crop Science ◽

10.1626/jcs.58.114 ◽

1989 ◽

Vol 58 (1) ◽

pp. 114-118

Author(s):

Junko YAMAGISHI ◽

Ryuichi ISHII ◽

Atsuhiko KUMURA

Keyword(s):

Time Course ◽

Dark Period ◽

Light Conditions ◽

Physiological Conditions ◽

Soybean Plants

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Diel periodicity in spermatophore formation in the house cricket, Acheta domesticus (L.)

Canadian Journal of Zoology ◽

10.1139/z68-097 ◽

1968 ◽

Vol 46 (4) ◽

pp. 695-698 ◽

Cited By ~ 14

Author(s):

J. E. McFarlane

Keyword(s):

Dark Period ◽

Continuous Light ◽

Light Period ◽

Acheta Domesticus ◽

Diel Periodicity ◽

Light Conditions ◽

House Cricket ◽

Male House

Male house crickets reared individually at 28 °C developed a diel periodicity in spermatophore formation, which consisted in loss of the spermatophore during the dark period and secretion during the light period. The periodicity became established only after most of the insects had formed at least two spermatophores in a random way with respect to light conditions. When periodicity was established, rearing the insects in continuous light resulted in the retention of the spermatophore by nearly all insects. Stridulation began in all experiments at the time of first spermatophore formation.

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