Інтеграційні процеси в паливно-енергетичному комплексі як фактор забезпечення екологічної безпеки

Challenge tests stress homeostasis and may reveal deviations in health that remain masked under unchallenged conditions. Ideally, challenge tests are non-invasive and applicable in an early phase of an animal experiment. Oxygen restriction (OxR; based on ambient, mild normobaric hypoxia) is a non-invasive challenge test that measures the flexibility to adapt metabolism. Metabolic inflexibility is one of the hallmarks of the metabolic syndrome. To test whether OxR can be used to reveal early diet-induced health effects, we exposed mice to a low-fat (LF) or high-fat (HF) diet for only 5 days. The response to OxR was assessed by calorimetric measurements, followed by analysis of gene expression in liver and epididymal white adipose tissue (eWAT) and serum markers for e.g. protein glycation and oxidation. Although HF feeding increased body weight, HF and LF mice did not differ in indirect calorimetric values under normoxic conditions and in a fasting state. Exposure to OxR; however, increased oxygen consumption and lipid oxidation in HF mice versus LF mice. Furthermore, OxR induced gluconeogenesis and an antioxidant response in the liver of HF mice, whereas it induced de novo lipogenesis and an antioxidant response in eWAT of LF mice, indicating that HF and LF mice differed in their adaptation to OxR. OxR also increased serum markers of protein glycation and oxidation in HF mice, whereas these changes were absent in LF mice. Cumulatively, OxR is a promising new method to test food products on potential beneficial effects for human health

Preantral follicular atresia occurs mainly through autophagy, while antral follicles degenerate mostly through apoptosis

There is a general agreement that granulosa cell apoptosis is the cause of antral follicle attrition. Less clear is whether this pathway is also activated in case of preantral follicle degeneration, as several reports mention that the incidence of granulosa cell apoptosis in preantral follicles is negligible. Our objective is therefore to determine which cell-death pathways are involved in preantral and antral follicular degeneration.Atretic preantal and antral follicles were investigated using immunohistochemistry and laser-capture microdissection followed by quantitative real-time reverse transcription polymerase chain reaction. Microtubule-associated light-chain protein 3 (LC3), sequestosome 1 (SQSTM1/P62), Beclin1, autophagy-related protein 7 (ATG7), and cleaved caspase 3 (cCASP3) were used as markers for autophagy and apoptosis, respectively. P62 immunostaining was far less intense in granulosa cells of atretic compared to healthy preantral follicles, while no difference in LC3 and BECLIN1 immunostaining intensity was observed. This difference in P62 immunostaining was not observed in atretic antral follicles. mRNA levels of LC3 and P62 were not different between healthy and atretic (pre)antral follicles. ATG7 immunostaining was observed in granulosa cells of preantral atretic follicles, not in granulosa cells of degenerating antral follicles. The number of cCASP3-positive cells was negligible in preantral atretic follicles, while numerous in atretic antral follicles. Taken together, we conclude that preantral and antral follicular atresia is the result of activation of different cell-death pathways as antral follicular degeneration is initiated by massive granulosa cell apoptosis, while preantral follicular atresia occurs mainly via enhanced granulosa cell autophagy.</p

Temperature-flux induced metabolic adjustments in WAT

Mice have their lowest (basal) metabolic rate when housed at thermoneutrality, which starts above 29 degrees C. Although they eat less, and thus reduce their energy intake, their energy balance remains positive leading to an increased adiposity, especially when fed a high fat diet. However, almost all metabolic mouse studies are performed at standard room temperatures ranging between 20 and 22 degrees C. Previously, we showed that housing mice at thermoneutrality lead to massive increased adiposity, while metabolic dysfunction of white adipose tissue (WAT) was absent. Here, we studied whether an increased metabolic flux through WAT induces cellular stress and underlies tissue dysfunction leading to tissue inflammation. C57BL/6JOlaHsd wildtype male mice, aged 9 weeks, were fed purified low fat diet (BIOCLAIMS, Hoevenaars et al., Genes and Nutrition 2012) for 3 weeks to acclimatize, followed by 12 weeks a BIOCLAIMS high-fat diet (HFD), all at thermoneutrality (29 degrees C). Subsequently, mice were divided into different treatment groups: i) control group, which remained at thermoneutrality for 5 days, ii) 5 days normal housing temperature (22 C degrees) while housed continously in an indirect calorimetry system. At the end of the study, after 2 hours food removal at the start of the light phase, mice were killed immediately by decapitation after taking them out of the indirect calorimetry system. After sacrification, epididymal WAT was immediately dissected and snap frozen in liquid nitrogen. Total RNA was isolated, quantified and qualified, and subsequently used for global gene expression profiling using Agilent 8x60K microarrays

Partial replacement of glucose with galactose in the post-weaning diet positively affects markers of liver health

Previous research showed a beneficial programming effect of replacting glucose in the post-weaning diet with galactose on later life adiposity. Here, we studied the direct effect of the diets in the postweaning phase in female mice. In this study, female mice were fed a glucose diet (32 en% glucose; GLU) or a glucose+galactose diet (16 en% glucose and 16 en% galactose; GLU+GAL) postweaning for three weeks, from postnatal day (PN) 21 till PN42. We observed lower circulating insulin levels and lower hepatic triglyceride levels in the females on the GLU+GAL diet. The body weight, fat mass, liver weight and liver glycogen content did not differ between the groups. We next studied hepatic gene expression profiles, because of the altered hepatic triglyceride levels and since the liver is considered the primary site of galactose metabolism. However, detailed analyses including pathway analysis, showed mainly inflammation being reduced by the GLU+GAL treatment. This was confirmed by qPCR of liver tissues and focussed serum protein analysis

DFO-induced hypoxia leading to metabolic dysfunction in WAT

Metabolic dysfunction of white adipose tissue (WAT) is considered to be underlying the comorbidities in obesity, including insulin resistance and tissue inflammation. Moreover, due to the expansion of WAT, local tissue hypoxia has been reported. Whether local tissue hypoxia underlies the metabolic de-arrangements and is the first step in initiation inflammation is questioned here. Desferrioxamine (DFO) is a chemical compound trapping free iron, thus leading to a reduction in oxygen availability within the body, which mimics hypoxia. Therefore, C57BL/6JOlaHsd wildtype male mice, aged 9 weeks, were fed purified low fat diet (BIOCLAIMS, Hoevenaars et al., Genes and Nutrition 2012) for 3 weeks to acclimatize, followed by 12 weeks a BIOCLAIMS high-fat diet (HFD), all at thermoneutrality (29 degrees C) to induce massive expansion of WAT without metabolic dysregulation (Hoevenaars et al., Mol Nutr Food Res 2014). Subsequently, mice were divided into different treatment groups: i) control group, ii) 5 days Desferrioxamine (DFO) daily injections (100 mg/kg body weight). Mice were killed by decapitation at the end of the experiment after 2 hour food removal at the start of the light phase. After sacrification, epididymal WAT was immediately dissected and snap frozen in liquid nitrogen. Total RNA was isolated, quantified and qualified, and subsequently used for global gene expression profiling using Agilent 8x60K microarrays

Muscle mitochondrial stress-induced metabolic adaptations do not require FGF21 action

Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which was recently discovered as stress-induced myokine and common denominator of muscle mitochondrial disease. However, its precise function and pathophysiological relevance remains unknown. Here we demonstrate that white adipose tissue (WAT) is the major target of muscle mitochondrial stress-induced FGF21. Strikingly, substantial browning and metabolic remodeling of subcutaneous WAT, together with the reduction of circulating triglycerides and cholesterol are fully FGF21 dependent. Unexpectedly and in contrast to prior expectations, we found a negligible role of FGF21 in muscle stress-related improved glycemic control, obesity resistance and hepatic lipid homeostasis. Furthermore, we show that the protective muscle mitohormesis and metabolic stress adaptation does not require FGF21 action. Taken together, our data imply that although FGF21 drives WAT remodeling, this effect and FGF21 as stress hormone per se may not be essential for the adaptive response under muscle mitochondrial stress conditions

DFO-induced hypoxia leading to metabolic dysfunction in WAT

Metabolic dysfunction of white adipose tissue (WAT) is considered to be underlying the comorbidities in obesity, including insulin resistance and tissue inflammation. Moreover, due to the expansion of WAT, local tissue hypoxia has been reported. Whether local tissue hypoxia underlies the metabolic de-arrangements and is the first step in initiation inflammation is questioned here. Desferrioxamine (DFO) is a chemical compound trapping free iron, thus leading to a reduction in oxygen availability within the body, which mimics hypoxia. Therefore, C57BL/6JOlaHsd wildtype male mice, aged 9 weeks, were fed purified low fat diet (BIOCLAIMS, Hoevenaars et al., Genes and Nutrition 2012) for 3 weeks to acclimatize, followed by 12 weeks a BIOCLAIMS high-fat diet (HFD), all at thermoneutrality (29 degrees C) to induce massive expansion of WAT without metabolic dysregulation (Hoevenaars et al., Mol Nutr Food Res 2014). Subsequently, mice were divided into different treatment groups: i) control group, ii) 5 days Desferrioxamine (DFO) daily injections (100 mg/kg body weight). Mice were killed by decapitation at the end of the experiment after 2 hour food removal at the start of the light phase. After sacrification, epididymal WAT was immediately dissected and snap frozen in liquid nitrogen. Total RNA was isolated, quantified and qualified, and subsequently used for global gene expression profiling using Agilent 8x60K microarrays

Temperature-flux induced metabolic adjustments in WAT

Mice have their lowest (basal) metabolic rate when housed at thermoneutrality, which starts above 29 degrees C. Although they eat less, and thus reduce their energy intake, their energy balance remains positive leading to an increased adiposity, especially when fed a high fat diet. However, almost all metabolic mouse studies are performed at standard room temperatures ranging between 20 and 22 degrees C. Previously, we showed that housing mice at thermoneutrality lead to massive increased adiposity, while metabolic dysfunction of white adipose tissue (WAT) was absent. Here, we studied whether an increased metabolic flux through WAT induces cellular stress and underlies tissue dysfunction leading to tissue inflammation. C57BL/6JOlaHsd wildtype male mice, aged 9 weeks, were fed purified low fat diet (BIOCLAIMS, Hoevenaars et al., Genes and Nutrition 2012) for 3 weeks to acclimatize, followed by 12 weeks a BIOCLAIMS high-fat diet (HFD), all at thermoneutrality (29 degrees C). Subsequently, mice were divided into different treatment groups: i) control group, which remained at thermoneutrality for 5 days, ii) 5 days normal housing temperature (22 C degrees) while housed continously in an indirect calorimetry system. At the end of the study, after 2 hours food removal at the start of the light phase, mice were killed immediately by decapitation after taking them out of the indirect calorimetry system. After sacrification, epididymal WAT was immediately dissected and snap frozen in liquid nitrogen. Total RNA was isolated, quantified and qualified, and subsequently used for global gene expression profiling using Agilent 8x60K microarrays

Partial replacement of glucose with galactose in the post-weaning diet positively affects markers of liver health

Previous research showed a beneficial programming effect of replacting glucose in the post-weaning diet with galactose on later life adiposity. Here, we studied the direct effect of the diets in the postweaning phase in female mice. In this study, female mice were fed a glucose diet (32 en% glucose; GLU) or a glucose+galactose diet (16 en% glucose and 16 en% galactose; GLU+GAL) postweaning for three weeks, from postnatal day (PN) 21 till PN42. We observed lower circulating insulin levels and lower hepatic triglyceride levels in the females on the GLU+GAL diet. The body weight, fat mass, liver weight and liver glycogen content did not differ between the groups. We next studied hepatic gene expression profiles, because of the altered hepatic triglyceride levels and since the liver is considered the primary site of galactose metabolism. However, detailed analyses including pathway analysis, showed mainly inflammation being reduced by the GLU+GAL treatment. This was confirmed by qPCR of liver tissues and focussed serum protein analysis

Metabolic adaptation of white adipose tissue to acute, short-term environmental oxygen restriction in mice [Mus musculus]

White adipose tissue (WAT) expansion during e.g. obesity reduces oxygen availability in WAT in mice. Little is known on the adaptation of WAT to mild environmental oxygen restriction (OxR). Therefore, we studied metabolic adaptation to acute OxR in fasted, diet-induced moderately obese mice that were exposed to mild hypoxic (12% O2) or normoxic (20.9% O2) conditions for only 6 hours. Adaptation was assessed by determination of amino acids and (acyl)carnitines levels in serum and WAT, and by whole genome expression analysis in WAT. Adaptation was also assessed during the exposure using indirect calorimetry. We found that OxR reduced mitochondrial oxidation at whole-body level, as shown by a reduction in whole-body oxygen consumption and an increase in serum long-chain acylcarnitine levels. WAT did not seem to contribute to this serum profile since only short-chain acylcarnitines were increased in WAT and gene expression analysis indicated an increase in mitochondrial oxidation, based on coordinate down-regulation of Sirt4, Gpam and Chchd3/Minos3. In addition, OxR did not induce oxidative stress in obese WAT, but increased molecular pathways involved in cell growth and proliferation. OxR increased levels of tyrosine, lysine and ornithine in serum and of leucine/isoleucine in WAT. This study shows that OxR limits oxidative phosphorylation at whole-body level, but in WAT compensatory mechanisms seem to operate. The down-regulation of the mitochondria-related genes Sirt4, Gpam, and Chchd3 may be considered as a biomarker profile for WAT mitochondrial reprogramming in response to acute exposure to limited oxygen availabilit