The effect of constant illumination as a stress factor on the state of the "early response" c-fos gene in the lateral magnocellular subnuclei of the paraventricular nucleus (lmPVN) of the hypothalamus of rats at different time intervals (day and night) has been studied. To identify c-Fos in histological sections of the hypothalamus, a secondary (indirect) immunofluorescence method is used. Expression of the product of this gene, the c-Fos protein, in animals kept under normal conditions of alternation of illumination and darkness, shows a clear-cut circadian character. There was a significant decrease in the area of the immunopositive sites of structures at night by 19.4% compared to daytime measurements. The average values of the areas of such immunopositive subnuclei sites varied also in subgroups of rats under light stimulation conditions, in which samples of lmPVN were selected for study at 2 pm and 2 am, but the differences between groups did not reach the level of reliability. Under conditions of light stress, the c-Fos concentration index decreased by 29.4% during the day, and by 16.5% at night in relation to similar values in the intact group. In animals that were in the standard light mode, the c-Fos protein concentration index was significantly higher during the day than at night. In the intact group, the night value of the c-Fos concentration index averaged only 71.5% of the daily value. In rats subjected to constant illumination, the day and night values of the c-Fos concentration index did not differ reliably. To correct stress-induced changes in the activity of the "early response" c-fos gene in the rat hypothalamus, melatonin (0.5 mg/kg body weight of the animal) was used. Injections of melatonin to rats exposed to constant illumination normalized the circadian rhythm of the area of the material immunoreactive to c-Fos, compared to the group of animals that did not receive melatonin. When using melatonin against the background of constant illumination, a sharp increase of the protein concentration in the lmPVN subnuclei of hypothalamus in daytime and less pronounced at night intervals was detected. Injections of melatonin to animals were also reflected in the daily dynamics of the index of c-Fos protein content in the lmPVN subnuclei under conditions of constant illumination. In the daytime observation period, the index was almost twice the experimental data on stressed animals without the introduction of the hormone, bringing it closer to normal. Prospects for further research in this sphere will allow us to better understand the place and role of subnuclei of paraventricular nuclei of the hypothalamus in the mechanisms of the formation of circadian rhythms of the rat brain.
Urinary tract infections (UTIs) remain an urgent issue in clinical pediatrics. Empirical selection of antibacterial therapy becomes more complicated, and antibacterial drug indication is not always clinically substantiated. This study aimed to compare the antibacterial susceptibility pattern of the main group of urinary tract infectious agents from 2009–2016 with intermediate results from 2020–2021, during the COVID-19 pandemic, among children in the Chernivtsi region. Urine samples were collected from 3089 children (0–17 years old) treated at the health care institutions in the Chernivtsi region (2009–2016). The clinical-laboratory examination of 177 children (0–17 years old) was carried out from 2020 to 2021. The children received specialized medical care at the Department of Nephrology. Preliminary data of regional monitoring (2020–2021) are not considerably different from the previous regional susceptibility of antibiotics: to penicillin (p<0.01), ІІ-ІІІ generation cephalosporin (p<0.01); an increased resistance to levofloxacin (χ2=4,338; p<0.01), tetracycline – χ2=7,277; p<0.01; doxycycline – χ2=5,309; p<0.01) and imipenem – χ2=5,594; p<0.01). The data obtained did not explain an increased resistance to fluoroquinolones completely (ofloxacin, pefloxacin, ciprofloxacin), except for levofloxacin (χ2=4,338; p<0.01). A reliable difference of susceptibility of tetracycline group was registered (tetracycline – χ2=7,277; p<0.01; doxycycline – χ2=5,309; p<0.01). Furthermore, there was a regional increase in some UTI-pathogen strains resistant to carbapenems (imipenem – χ2=5,594; p<0.01). The use of antibiotics from the group of penicillins and II-III generation cephalosporins as the starting antibacterial therapy for STIs during the COVID-19 pandemic should be justified. A regional increase (2020–2021) of some uropathogenic strains resistant to carbapenems administered to treat severe bacterial infections requires their exclusively designated purpose in everyday pediatric practical work.
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.
We studied the morphologic and histochemical organization of neurons of the hypothalamic supraoptic nucleus in rats exposed to different durations of photoperiod and injection of melatonin. Morphometric and histochemical analyses of neurons were performed after staining brain histological sections for RNA. Prolonged illumination leads to more pronounced changes in the parameters of hypothalamic structures at 2 a.m. than at 2 p.m., particularly decreasing the concentration of RNA in the cell nuclei. The use of exogenous melatonin does not normalize the revealed changes in the parameters of the studied structures of the neurons of the supraoptic nucleus of the hypothalamus caused by the prolonged stay of rats under conditions of constant illumination.
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