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

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.

scholarly journals Age changes in the tigroid substance of neutrons of the lateral preoptic nucleus of hypothalamus under different light modes

2021 ◽  
Vol 11 (10) ◽  
pp. 269-274
Author(s):  
R. Bulyk ◽  
V. Yosypenko ◽  
M. Kryvchanska ◽  
K. Vlasova ◽  
Y. Lukan
Keyword(s):  
Optical Density ◽  
Histochemical Staining ◽  
Light Deprivation ◽  
Preoptic Nucleus ◽  
Age Changes ◽  
Light Stimulation ◽  
Experimental Conditions ◽  
Old Rats

The article presents analysis of the results of the original histochemical studies of tigroid substance of neurons of the lateral preoptic nucleus of  hypothalamus in mature and old rats under the influence of different light modes. In all observations, the tigroid substance was located in the cytoplasm of neurons of the lateral preoptic nucleus of hypothalamus in the form of individual granular formations of different sizes and shapes. The amount of tigroid substance of neurons of the lateral preoptic nucleus of hypothalamus in mature rats is greater than in older rats. At the same time, it should be noted that different experimental conditions significantly affected the amount of tigroid substance in neurons of the lateral preoptic nucleus of hypothalamus in old rats. In particular, under conditions of light deprivation, the optical density of specific histochemical staining for tigroid substance in neurons of the lateral preoptic nucleus of hypothalamus increased significantly (p<0,001), and under conditions of light stimulation, on the contrary, probably decreased (p<0,001).

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

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
V.R. Yosypenko ◽  
R.Ye. Bulyk ◽  
M.I. Kryvchanska ◽  
Y.R. Lukan
Keyword(s):  
Epoxy Resins ◽  
Dark Period ◽  
White Male ◽  
Ultrastructural Organization ◽  
Light Conditions ◽  
Preoptic Nucleus ◽  
Cell Nuclei ◽  
Light Mode ◽  
Old Rats ◽  
Ultrathin Sections

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.

New uses of Melatonin as a Drug, a Review

2022 ◽  
Vol 29 ◽  
Author(s):  
Miroslav Pohanka
Keyword(s):  
Cell Cycle ◽  
Circadian Rhythm ◽  
Sleep Disorder ◽  
Neurodegenerative Disorders ◽  
Melatonin Receptors ◽  
The Other ◽  
Basic Facts ◽  
Regulation Of Cell Cycle ◽  
Lifestyle Diseases

Abstract: Melatonin is a simple compound with a proper chemical name N-acetyl-5-methoxy tryptamine and known as a hormone controlling circadian rhythm. Humans produce melatonin at night which is the reason for sleeping in the night and awakening over the day. Melatonin interacts with melatonin receptors MT1 and MT2 but it was also revealed that melatonin is a strong antioxidant and it also has a role in regulation of cell cycle. Currently, melatonin is used as a drug for some types of sleep disorder but the recent research points to the fact that melatonin can also serve for the other purposes including prophylaxis or therapy of lifestyle diseases, cancer, neurodegenerative disorders and exposure to chemicals. This review summarizes basic facts and direction of the current research on melatonin. The actual literature was scrutinized for the purpose of this review.

Central adrenergic activity in the mediobasal hypothalamus is temporally related to surge outputs of gonadotrophins in oestrogen-stimulated infant female rats

1986 ◽  
Vol 109 (1) ◽  
pp. 45-51
Author(s):  
E. M. Clement ◽  
P. C. B. MacKinnon ◽  
R. Sheaves
Keyword(s):  
Circadian Rhythm ◽  
Temporal Relationship ◽  
Female Rats ◽  
Mediobasal Hypothalamus ◽  
Methyl Transferase ◽  
Similar Treatment ◽  
Adrenergic Activity ◽  
Old Rats ◽  
Baseline Levels ◽  
Radioenzymatic Assays

ABSTRACT In the mediobasal hypothalamus (MBH) of prooestrous rats or acutely ovariectomized oestrogentreated adults a marked but short-lived increase in adrenergic activity occurs at 16.00 h, 2 h before the oestrogen-dependent surge of gonadotrophins at 18.00 h. In this study oestrogen-stimulated (noon on day 1) 22-day-old female rats were used which are known to produce surge levels of prolactin at 18.00 h on day 2 and surges of both prolactin and LH at 18.00 h on day 3; although similar treatment of 18-day-old animals or oil-treated 22-day-old rats failed to produce these effects. Radioenzymatic assays of adrenaline concentrations and of the activity of its synthesizing enzyme (phenylethanolamine-N-methyl transferase; PNMT, EC 2.1.1.28) in the MBH of oestrogen-treated 22-day-old rats showed significant (P< 0·05–0·01) increases in both parameters at 16.00 h (i.e. 2 h before surge levels of gonadotrophins) on days 2 and 3 when compared with other times of day. Such effects were not seen in oil-treated 22-day-old animals or in oestrogen-treated 16-day-old rats. Noradrenaline and dopamine concentrations in the MBH of oestrogen-treated 22-day-old rats remained at baseline levels on days 2 and 3 with the exception of noradrenaline at 17.00 h on day 3 when levels appeared higher (P<0·05) than at either 15.00 or 16.00 h. Subsequent measurements of PNMT activity in oestrogen-treated 22-day-old rats at 4-hourly intervals throughout days 2 and 3 showed the presence of a clear circadian rhythm with peak levels occurring at 16.00 h. In conclusion, a temporal relationship (not necessarily specific) exists between increased adrenergic activity in the MBH of oestrogen-treated 22-day-old rats and a surge of gonadotrophins (LH and/or prolactin) 2 h later. This relationship apparently depends on an oestrogen-stimulated circadian rhythm of PNMT activity. J. Endocr. (1986) 109, 45–51

scholarly journals Effect of exogenous melatonin and flaxseed oil on the expression state of MT1 receptors in rat skin under light deprivation

2021 ◽  
Vol 27 (2) ◽  
pp. 30-38
Author(s):  
I.S. Sobolevskaya ◽  
M.I. Krasnobaeva ◽  
O.D. Myadelets
Keyword(s):  
Flaxseed Oil ◽  
Hair Follicles ◽  
Melatonin Receptors ◽  
Male Rats ◽  
Target Cells ◽  
Special Role ◽  
Negative Consequences ◽  
Light Deprivation ◽  
Exogenous Melatonin ◽  
Corrective Effect

Most of the skin cells have their own autonomous functional circadian system, which is able to control physiological and biochemical processes in the general integument. A special role in these processes is assigned to the “clock” hormone of the pineal gland, melatonin, which acts on target cells through specific receptors (MT1, MT2, MT3 and RORα). Any disturbance of circadian rhythms can lead to rearrangements (disturbances) in the receptor apparatus of the cells of the general cover, which require a certain correction. Consequently, there is a need to search for effective and reliable drugs that will prevent the negative consequences caused by chronodestruction. In the present work, we studied the effectiveness of the effect of exogenous melatonin and flaxseed oil on the expression of MT1 receptors in the general coat of rats under light deprivation. An experimental study was carried out on 130 white outbred male rats (170-220 g), which were randomly divided into 5 groups: intact, light deprivation animals, light deprivation animals, which were injected intragastrically with flaxseed oil and melatonin. On days 7, 14 and 21, histological material was taken (fragments of the skin of the interscapular region of the back). For immunohistochemical studies, serial sections were stained using MTNR1A polyclonal antibodies. For morphometric data analysis, the Image Scope Color and ImageJ computer programs were used. All statistical data processing was performed using the Statistica 10.0 software. Differences were considered significant at a significance level of less than 0.01 (p <0.01). In the course of the experiment, it was found that light deprivation contributes to a change in the activity of expression of the MT1 melatonin receptors in the epidermis, sebaceous glands and hair follicles. Studies have shown that the administration of flaxseed oil, melatonin, and their combination to rats with desynchronosis is accompanied by the leveling of the adverse effect of desynchronosis on the studied parameters of MT1 receptors. The most pronounced corrective effect on the expression of MT1 receptors is observed with the introduction of exogenous melatonin on the 21st day of the experiment.

scholarly journals A Review of Silent Substitution Devices for Melanopsin Stimulation in Humans

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 121
Author(s):  
Vincent Conus ◽  
Martial Geiser
Keyword(s):  
Circadian Rhythm ◽  
Light Intensity ◽  
Cognitive Functions ◽  
Specific Response ◽  
Light Stimulation ◽  
Sleep Regulation ◽  
Human Relationships ◽  
Silent Substitution ◽  
Optical Setup ◽  
Year 2000

One way to study the specific response of the non-visual melanopsin photoreceptors of the human eye is to silence the response of cones and rods. Melanopsin photoreceptors (ipRGC), highlighted in the early 2000s, are intimately linked to the circadian rhythm and therefore to our sleep and wakefulness. Rest and sleep regulation, health and cognitive functions are all linked to ipRGC and play an important role in work and human relationships. Thus, we believe that the study of ipRGC responses is important.We searched and reviewed scientific articles describing instrumentation dedicated to these studies. PubMed lists more than 90,000 articles created since the year 2000 that contain the word circadian but only 252 with silent substitution. In relation to melanopsin, we found 39 relevant articles from which only 11 give a device description for humans, which is incomplete in most cases. We did not find any consensus for light intensity description, melanopsin contrast, sequences of melanopsin light stimulation and optical setup to expose the retina to the light.

scholarly journals Activity/inactivity circadian rhythm shows high similarities between young obesity-induced rats and old rats

2016 ◽  
Vol 103 (1) ◽  
pp. 65-74 ◽  
Author(s):  
R Bravo Santos ◽  
J Delgado ◽  
J Cubero ◽  
L Franco ◽  
S Ruiz-Moyano ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Old Rats

scholarly journals Diurnal rhythms of urine volume and electrolyte excretion in healthy young men under differing intensities of daytime light exposure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Isuzu Nakamoto ◽  
Sayaka Uiji ◽  
Rin Okata ◽  
Hisayoshi Endo ◽  
Sena Tohyama ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Light Exposure ◽  
Urine Volume ◽  
Bright Light ◽  
Random Order ◽  
Diurnal Rhythms ◽  
Light Conditions ◽  
Electrolyte Excretion ◽  
Daily Urine ◽  
Bright Light Exposure

AbstractIn humans, most renal functions, including urine volume and electrolyte excretions, have a circadian rhythm. Light is a strong circadian entrainment factor and daytime-light exposure is known to affect the circadian rhythm of rectal temperature (RT). The effects of daytime-light exposure on the diurnal rhythm of urinary excretion have yet to be clarified. The aim of this study was to clarify whether and how daytime exposure to bright-light affects urinary excretions. Twenty-one healthy men (21–27 years old) participated in a 4-day study involving daytime (08:00–18:00 h) exposure to two light conditions, Dim (< 50 lx) and Bright (~ 2500 lx), in a random order. During the experiment, RT was measured continuously. Urine samples were collected every 3 ~ 4 h. Compared to the Dim condition, under the Bright condition, the RT nadir time was 45 min earlier (p = 0.017) and sodium (Na), chloride (Cl), and uric acid (UA) excretion and urine volumes were greater (all p < 0.001), from 11:00 h to 13:00 h without a difference in total daily urine volume. The present results suggest that daytime bright light exposure can induce a phase shift advance in urine volume and urinary Na, Cl, and UA excretion rhythms.

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