Despite clearly recognized links between increased body mass and increased risk for various pathological conditions, therapeutic options to treat obesity are still very limited. The aim of the ...present study is to explore the effect of low-molecular-mass collagen fragments obtained from the scales of Antarctic wild marine fish on rats' visceral and subcutaneous white adipose tissue in a high-calorie diet-induced obesity model.
The study was conducted on outbred rats, which were divided into 3 experimental groups: (
) control, consuming standard food (3.81 kcal/g), (
) obese group, consuming a high-calorie diet (5.35 kcal/g), and (
) obese group, consuming a high-calorie diet (5.35 kcal/g) with intragastric administration of low-molecular-mass collagen fragments (at a dose 1 g/kg of body mass during 6 weeks). Low-molecular-mass collagen fragments were obtained by a procedure that included collagen extraction from fish scales and enzymatic hydrolysis with pepsin. Apart from hematoxylin and eosin staining, fibrosis level was assessed by histochemical Van Gieson's trichrome picrofuchsin staining, and mast cells were analysed by toluidine blue O staining.
Group treated with low-molecular-mass fragments of collagen exhibited decreased rate of mass gain, relative mass, area occupied by collagen fibre of both visceral and subcutaneous adipose tissue, and cross-sectional area of both visceral and subcutaneous adipocytes. Treatment with low-molecular-mass fragments of collagen reduced the infiltration of immune cells, number of mast cells and their redistribution back to the septa. This was also accompanied by a decreased number of the crown-like structures formed by the immune cells, which are markers of chronic inflammation that accompanies obesity.
This is the first study that reports the anti-obesity effect of low-molecular-mass fragments produced as a result of controlled hydrolysis of collagen from the scales of Antarctic wild marine fish in the
model. Another novelty of this work is the observation that the tested collagen fragments not only reduce the body mass, but also improve the morphological and inflammatory parameters (decrease in the number of crown-like structures, immune cell infiltration, fibrosis and mast cells). Altogether, our work suggests that low-molecular-mass collagen fragments are a promising candidate for amelioration of some comorbidities linked to obesity.
This study aimed to evaluate changes in beige adipocytes at different times of melatonin administration, in the morning (ZT01) or in the evening (ZT11), at 30 mg/kg daily by gavage for 7 weeks or ...continuously with drinking water in the term of high-calorie diet-induced obesity (HCD). Melatonin received at ZT11 or with drinking water resulted in an increased area of the browning zone in the subcutaneous white adipose tissue (sWAT), even in rats with HCD (compared with Control or HCD, respectively). The beige adipocyte and lipid droplet area after melatonin use were reduced compared to those with HCD and Control, in all administration modes (group ZT01 showed smaller changes compared to ZT11 or with drinking water groups). The fibrosis level decreased and significantly differed in HCD ZT01, HCD ZT11, and HCD water compared to that in HCD; moreover, the lowest value determined in HCD water, reached the control parameters. Furthermore, the IL-1b and IL-8 level was decreased in the HCD groups under melatonin treatment at ZT11 or with drinking water compared to that in HCD. The obtained results suggest that melatonin promotes sWAT browning in rats with diet-induced obesity and influences morphological signs of normal rats depending on the time of administration. Different functional activity of beige adipocytes was observed after melatonin was used depending on the time of administration, resulting in heat production and lipolysis (the relative mass of visceral fat was likewise diminished). More rapid browning was observed when melatonin treatment was performed at 1 h before lights-off (ZT11) or continuously via drinking water. Melatonin acted on beige adipocytes of obese rats through changing some parameters such as the area of adipocytes and lipid drops, the number of lipid drops, the relative area browning of sWAT, and the level of tissue fibrosis.
This study aimed to evaluate changes in beige adipocytes at different times of melatonin administration, in the morning (ZT01) or in the evening (ZT11), at 30 mg/kg daily by gavage for 7 weeks or ...continuously with drinking water in the term of high-calorie diet-induced obesity (HCD). Melatonin received at ZT11 or with drinking water resulted in an increased area of the browning zone in the subcutaneous white adipose tissue (sWAT), even in rats with HCD (compared with Control or HCD, respectively). The beige adipocyte and lipid droplet area after melatonin use were reduced compared to those with HCD and Control, in all administration modes (group ZT01 showed smaller changes compared to ZT11 or with drinking water groups). The fibrosis level decreased and significantly differed in HCD ZT01, HCD ZT11, and HCD water compared to that in HCD; moreover, the lowest value determined in HCD water, reached the control parameters. Furthermore, the IL-1b and IL-8 level was decreased in the HCD groups under melatonin treatment at ZT11 or with drinking water compared to that in HCD. The obtained results suggest that melatonin promotes sWAT browning in rats with diet-induced obesity and influences morphological signs of normal rats depending on the time of administration. Different functional activity of beige adipocytes was observed after melatonin was used depending on the time of administration, resulting in heat production and lipolysis (the relative mass of visceral fat was likewise diminished). More rapid browning was observed when melatonin treatment was performed at 1 h before lights-off (ZT11) or continuously via drinking water. Melatonin acted on beige adipocytes of obese rats through changing some parameters such as the area of adipocytes and lipid drops, the number of lipid drops, the relative area browning of sWAT, and the level of tissue fibrosis. KEY WORDS: Chronobiology; High-calorie diet; Fibrosis; IL-1b; Adipose tissue.
The interaction of immunological system, thyroid and pineal gland was studied in 5-week old males of Gallus domesticus. Several morphometrical parameters in pineal and thyroid glands were measured ...after bird immunization with human red blood cells and/or treatment with melatonin or seduxen, melatonin receptor blocker. The peak of the thyroid activity was found on Day 7 after immunization. The immune system appears to directly activate the thyroid gland only in the presence of certain level of melatonin. We suggest that the melatonin mechanism of action includes the enhancement of thyroid gland sensitivity to immune factors. Seduxen prevented the stimulatory influence of the immune system on the thyroid gland.
Male Japanese quails were treated with melatonin alone or melatonin combined with D1 and D2 dopamine receptor blockers. Following the treatment, hypothalamus, pituitary glands and testes were ...analyzed morphometrically. The results suggest the existence of an interaction between melatonin and dopaminergic system in the brain in the regulation of reproductive processes in immature birds. The character of this interaction alters according to the time of the treatment (morning, afternoon, evening, night).
Pozadina istraživanja. Usprkos jasno utvrđenoj povezanosti povećane tjelesne mase s većim rizikom razvoja različitih patoloških oboljenja, mogućnosti liječenja pretilosti su još uvijek vrlo ...ograničene. Svrha je ovoga rada bila ispitati učinak fragmenata kolagena male molekularne mase, dobivenih iz ljuski morskih riba s područja Antarktika, na visceralno i potkožno masno tkivo štakora s dijabetesom uzrokovanim visokokaloričnom prehranom.
Eksperimentalni pristup. Istraživanje je provedeno na nesrođenim sojevima štakora, podijeljenim u tri eksperimentalne skupine: (i) kontrolna skupina, koja je primala standardnu prehranu (3,81 kcal/g), (ii) pretila skupina koja je primala visokokaloričnu prehranu (5,35 kcal/g), i (iii) pretila skupina koja je primala visokokaloričnu prehranu (5,35 kcal/g) i intragastrično fragmente kolagena male molekularne mase (1 g po kg tjelesne mase tijekom 6 tjedana). Fragmenti kolagena male molekularne mase dobiveni su ekstrakcijom kolagena iz ljusaka ribe i njegovom enzimskom hidrolizom pomoću pepsina. Stupanj fibroze masnog tkiva je, osim bojenjem hematoksilin eozinom, utvrđen Van Giesonovim bojenjem, a mastociti su ispitani bojenjem toluidinskim modrilom.
Rezultati i zaključci. Skupina štakora koja je primala fragmente kolagena male molekularne mase sporije je dobivala na masi i relativnoj masi, a kolagenska vlakna su zauzimala manju površinu njihovog visceralnog i potkožnog masnog tkiva te presjeka visceralnih i potkožnih adipocita. Intragastričnom primjenom fragmenata kolagena male molekularne mase smanjili su se infiltracija imunoloških stanica, broj mastocita i njihova redistribucija u septe. Također se smanjio broj krunastih struktura koje tvore makrofagi, a koje su markeri kronične upale povezane s pretilošću.
Novina i znanstveni doprinos. Ovo je prvo istraživanje in vivo o utjecaju fragmenata kolagena dobivenih kontroliranom hidrolizom ljusaka morskih riba iz područja Antarktika na smanjenje tjelesne mase. Još jedna novina ovoga rada je opažanje da ispitani fragmenti kolagena nisu samo smanjili tjelesnu masu, već i poboljšali morfološke i upalne parametre (smanjili su se broj krunastih struktura, infiltracija imunostanica, fibroza i broj mastocita). Zaključno, rad je pokazao da fragmenti kolagena male molekularne mase mogu ublažiti neke komorbiditete povezane s pretilošću.
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