Fat mass and obesity associated protein (Fto) is a nucleic acid demethylase, with a preference for thymine or uracil, according to the recent structural data. This fact suggests that methylated single-stranded RNA, rather than DNA, may be the primary Fto substrate. Fto is abundantly expressed in all hypothalamic sites governing feeding behavior. Considering that selective modulation of Fto levels in the hypothalamus can influence food intake, we set out to investigate the effect of 48 h fasting on the Fto expression in lateral hypothalamic area, paraventricular, ventromedial and arcuate nucleus, the regulatory centres of energy homeostasis. We have demonstrated that 48 h fasting causes not only an increase in the overall hypothalamic levels of both Fto mRNA and protein, but also alters Fto intracellular distribution. This switch happens in some neurons of paraventricular and ventromedial nucleus, as well as lateral hypothalamic area, resulting in the majority of the enzyme being localized outside the cell nuclei. Interestingly, the change in the Fto intracellular localization was not observed in neurons of arcuate nucleus, suggesting that fasting did not universally affect Fto in all of the hypothalmic sites involved in energy homeostasis regulation. Both Fto mRNA and catechol-O-methyltransferaze mRNA were upregulated in the identical time-dependent manner in fasting animals. This fact, combined with the knowledge of the Fto substrate preference, may provide further insight into monoamine metabolism in the state of disturbed energy homeostasis.

SUMMARYThermal stressors such as low and high ambient temperature elicit an abundance of neuroendocrine responses including activation of the hypothalamo-pituitary-adrenal (HPA) axis and arginine vasopressin (AVP) release. The exposure to heat is a particularly interesting model for studying AVP action because this kind of stressor represents not only an unpleasant experience but also a threat to osmotic homeostasis. As AVP has long been recognized as a hormone involved in the modulation of HPA axis activity, the aim of this study was to elucidate the role of AVP in acutely heat-exposed rats using Nelivaptan, a selective vasopressin 1b receptor (V1bR) antagonist. Rats were exposed to high ambient temperature (38°C) for 60min. The circulating hormones were determined by ELISA or chemiluminescence, and intrapituitary adrenocorticotropic hormone (ACTH) and V1bR level were determined by western blot. The results obtained show that V1bR blockade negatively affected the increase in blood ACTH caused by heat exposure. This treatment alone, or in combination with Nelivaptan, decreased intrapituitary V1bR levels while circulating AVP concentration was increased under the same conditions. Furthermore, a strong correlation was observed between blood ACTH and corticosterone concentration. In conclusion, our results directly confirm the positive role of AVP in the regulation of ACTH secretion from the pituitary in animals exposed to heat. Moreover, the results suggest that AVP from the general circulation influences pituitary V1bR.

One of the useful properties of probiotic bacteria is their capacity to bind different targets, thus eliminating them through feces. It is supposed that one of these targets could be cadmium, a widespread environmental toxicant that causes various disturbances in biological systems. This study examined the protective effects of probiotic supplementation against cadmium-induced toxicity in the rat. The experiment was conducted in the course of 5 weeks. Animals were divided into four groups: (1) controls, (2) probiotics treated, (3) cadmium treated, and (4) probiotics + cadmium treated. The cadmium concentration was measured in the blood, liver, kidney, and feces, as well as the blood alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as biomarkers of the liver function. Histomorphological changes in the liver and kidney were also determined. Our results revealed that probiotics combined with cadmium increase this metal concentration in feces. As a result, blood, liver, and kidney Cd levels, as well as blood ALT and AST activities were lessened compared to the rat group treated with cadmium only. Besides, probiotics consumed simultaneously with cadmium attenuated histomorphological changes in the liver and kidney caused by cadmium. The rise in lactobacilli number in feces of rats treated simultaneously with cadmium and probiotics results in strong correlation with the increase of Cd concentration in their feces and the decrease of Cd concentration in their blood. We speculate that probiotics actively contribute to cadmium excretion through feces, probably, by its binding to their bacterial cell wall.

Acute renal ischemia/reperfusion (I/R) injury is a clinical condition that is challenging to treat. Meldonium is an anti-ischemic agent that shifts energy production from fatty acid oxidation to less oxygen-consuming glycolysis. Thus, in this study we investigated the effects of a four-week meldonium pre-treatment (300 mg/kg b.m./day) on acute renal I/R in male rats (Wistar strain). Our results showed that meldonium decreased animal body mass gain, food and water intake, and carnitine, glucose, and lactic acid kidney content. In kidneys of animals subjected to I/R, meldonium increased phosphorylation of mitogen-activated protein kinase p38 and protein kinase B, and increased the expression of nuclear factor erythroid 2-related factor 2 and haeme oxygenase 1, causing manganese superoxide dismutase expression and activity to increase, as well as lipid peroxidation, cooper-zinc superoxide dismutase, glutathione peroxidase, and glutathione reductase activities to decrease. By decreasing the kidney Bax/Bcl2 expression ratio and kidney and serum high mobility group box 1 protein content, meldonium reduced apoptotic and necrotic events in I/R, as confirmed by kidney histology. Meldonium increased adrenal noradrenaline content and serum, adrenal, hepatic, and renal ascorbic/dehydroascorbic acid ratio, which caused complex changes in renal lipidomics. Taken together, our results have confirmed that meldonium pre-treatment protects against I/R-induced oxidative stress and apoptosis/necrosis.

The protective effect of probiotic bacteria against cadmium (Cd)-induced genotoxicity was studied in rat hepatocytes in vivo and in vitro. Male Wistar rats, Rattus norvegicus, were treated for five weeks with (i) CdCl2 (70 ppm in the drinking water), (ii) a mixture of lyophilized probiotic bacteria Lactobacillus rhamnosus, L. acidophilus and Bifido-bacterium longum (5×108 cfu/g of food), or (iii) CdCl2 and probiotic bacteria. In addition, single cells obtained from the untreated rat liver were exposed to CdCl2 (70 ppm), probiotic bacteria (1.28 mg/ml), or CdCl2 and probiotic bacteria, for 15 min at 22°C in the dark. The level of Cd-induced DNA damage in hepatocytes was determined by the comet assay. The obtained results show that probiotic bacteria significantly reduced Cd-induced genotoxicity, both in vivo and in vitro (20% and 48%, respectively). Moreover, the toxicity of Cd to lactobacilli in the gastrointestinal tracts of rats was significantly decreased in the probiotic-treated animals. The binding of Cd2+ to probiotic bacteria was proposed as the most probable protection mechanism. [Acknowledgments. This research was financially supported by the Ministry of Education and Science of the Government of Serbia, projects No 172058 and 173023

Rats have the ability to synthesize vitamin C in the liver. In the present work, we tested whether its additional intake improves antioxidative protection of the tissue. Thus, we studied the liver’s oxidative status in rats given two supplements of ascorbic acid over a four-week period of time. Our results confirmed that the additional intake of ascorbate improves the liver’s antioxidative defense in a dose-dependent manner. The explanation for the disproportion between the ratio of employed doses of vitamin C and their effects on the studied parameters probably lies in the mechanism of tissue accumulation of ascorbate and balance of its alimentary and endogenous availability

Abstract:The increased ambient temperature affects the function of hypothalamic-pituitary-adrenal (HPA) axis. Since the correlation among vasopressin (VP), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) responses to various stressors have been long recognized, the aim of this study was to reveal the aforementioned hormones production and morphology of the pituitary gland after exposure to acute heat. Rats were exposed to high ambient temperature (38°C) for 20 or 60 minutes. The circulating hormones were determined by an ELISA test or chemiluminescence's method. The results obtained show the elevation in ACTH and CORT secretion depending on the duration of heat exposure. The VP concentration increased only after prolonged exposure to heat (60 min). The pituitary morphology was examined by routine and fluorescent immunohistochemistry as well as electron microscopy. Observed changes in the anterior and posterior pituitary well corresponded to circulating hormones, regarding the volume density of ACTH-immunopositive cells, percentage of ACTH immunopositive area v. total area and number of VP-immunopositive containing varicose fibers per total area. Acute heat exposure also induced changes in shapes of ACTH-immunopositive cells. Cells appeared stellate with numerous slender cytoplasmic processes and degranulated, which is the most obvious after 20 min. In addition, immunopositivity of endothelial and anterior pituitary cells for VP suggests its influence on ACTH secretion.

The gut microbiota is composed of a diverse population of obligate and facultative anaerobic microorganisms which are shown to influence host metabolism and immune homeostasis. This study investigated the effects of virgin coconut oil on the weekly fasting glycaemia, daily food and water intake and weekly body mass gain over 16 weeks, as well as the changes in composition of gut microbiota in both non-diabetic and alloxan-induced diabetic rats. Although the intake of virgin coconut oil did not decrease the diabetes-induced hyperglycemia, it affected the secondary parameters, such as food and water intake and average body mass gain. Furthermore, its potential to positively affect the fecal microbiome was proved, since it significantly increased the abundance of probiotic bacteria, such as Lactobacillus, Allobaculum and Bifidobacterium species.