Multi-Method Quantification of Acetyl-Coenzyme A and Further Acyl-Coenzyme A Species in Normal and Ischemic Rat Liver.

Thioesters of coenzyme A (CoA) carrying different acyl chains (acyl-CoAs) are central intermediates of many metabolic pathways and donor molecules for protein lysine acylation. Acyl-CoA species largely differ in terms of cellular concentrations and physico-chemical properties, rendering their analysis challenging. Here, we compare several approaches to quantify cellular acyl-CoA concentrations in normal and ischemic rat liver, using HPLC and LC-MS/MS for multi-acyl-CoA analysis, as well as NMR, fluorimetric and spectrophotometric techniques for the quantification of acetyl-CoAs. In particular, we describe a simple LC-MS/MS protocol that is suitable for the relative quantification of short and medium-chain acyl-CoA species. We show that ischemia induces specific changes in the short-chain acyl-CoA relative concentrations, while mild ischemia (1-2 min), although reducing succinyl-CoA, has little effects on acetyl-CoA, and even increases some acyl-CoA species upstream of the tricarboxylic acid cycle. In contrast, advanced ischemia (5-6 min) also reduces acetyl-CoA levels. Our approach provides the keys to accessing the acyl-CoA metabolome for a more in-depth analysis of metabolism, protein acylation and epigenetics.

Protein intake in cancer: Does it improve nutritional status and/or modify tumour response to chemotherapy?

BACKGROUND: Combating malnutrition and cachexia is a core challenge in oncology. To limit muscle mass loss, the use of proteins in cancer is encouraged by experts in the field, but it is still debated due to their antagonist effects. Indeed, a high protein intake could preserve lean body mass but may promote tumour growth, whereas a low-protein diet could reduce tumour size but without addressing cachexia. Here we used a realistic rodent model of cancer and chemotherapy to evaluate the influence of different protein intakes on cachexia, tumour response to chemotherapy and immune system response. The goal is to gain a closer understanding of the effect of protein intake in cancer patients undergoing chemotherapy. METHODS: Female Fischer 344 rats were divided into six groups: five groups (n = 14 per group) with cancer (Ward colon tumour) and chemotherapy were fed with isocaloric diets with 8%, 12%, 16%, 24% or 32% of caloric intake from protein and one healthy control group (n = 8) fed a 16% protein diet, considered as a standard diet. Chemotherapy included two cycles, 1 week apart, each consisting of an injection of CPT-11 (50 mg/kg) followed by 5-fluorouracil (50 mg/kg) the day after. Food intake, body weight, and tumour size were measured daily. On day 9, the rats were euthanized and organs were weighed. Body composition was determined and protein content and protein synthesis (SUnSET method) were measured in the muscle, liver, intestine, and tumour. Immune function was explored by flow cytometry. RESULTS: Cancer and chemotherapy led to a decrease in body weight characterized by a decrease of both fat mass (-56 ± 3%, P < 0.05) and fat-free mass (-8 ± 1%, P < 0.05). Surprisingly, there was no effect of protein diet on body composition, muscle or tumour parameters (weight, protein content, or protein synthesis) but a high cumulative protein intake was positively associated with a high relative body weight and high fat-free mass. The immune system was impacted by cancer and chemotherapy but not by the different amount of protein intake. CONCLUSIONS: Using a realistic model of cancer and chemotherapy, we demonstrated for the first time that protein intake did not positively or negatively modulate tumour growth. Moreover, our results suggested that a high cumulative protein intake was able to improve moderately nutritional status in chemotherapy treated cancer rodents. Although this work cannot be evaluated clinically for ethical reasons, it nevertheless brings an essential contribution to nutrition management for cancer patients.

Nucleoside diphosphate kinases 1 and 2 regulate a protective liver response to a high-fat diet.

The synthesis of fatty acids from acetyl-coenzyme A (AcCoA) is deregulated in diverse pathologies, including cancer. Here, we report that fatty acid accumulation is negatively regulated by nucleoside diphosphate kinases 1 and 2 (NME1/2), housekeeping enzymes involved in nucleotide homeostasis that were recently found to bind CoA. We show that NME1 additionally binds AcCoA and that ligand recognition involves a unique binding mode dependent on the CoA/AcCoA 3' phosphate. We report that Nme2 knockout mice fed a high-fat diet (HFD) exhibit excessive triglyceride synthesis and liver steatosis. In liver cells, NME2 mediates a gene transcriptional response to HFD leading to the repression of fatty acid accumulation and activation of a protective gene expression program via targeted histone acetylation. Our findings implicate NME1/2 in the epigenetic regulation of a protective liver response to HFD and suggest a potential role in controlling AcCoA usage between the competing paths of histone acetylation and fatty acid synthesis.

Relationships between food insecurity, physical activity, detachment from studies, and students' well-being: A prospective study.

OBJECTIVE: Research on students' well-being has shown that studies may have an impact on well-being. However, this relationship is complex and involves many other parameters (e.g., food security and physical activity). Therefore, the objective of the present study was to investigate the relationships between food insecurity (FI), physical activity (PA), and detachment from studies on the one hand, and student well-being, on the other. METHOD: A total of 4410 students (mean age = 21.55, 65 192% female) answered an online survey measuring FI, PA, detachment from studies, anxiety, burnout, depression, and satisfaction with life. RESULTS: A structural equation model (χ [18] = 585.739, RMSEA = 0.095, 90% CI [0.089; 0.102], comparative fit index [CFI] = 0.92, NNFI = 0.921) indicated that FI negatively predicted, and that detachment from studies and PA positively predicted, the latent variable of well-being. DISCUSSION: The results of the present study highlight that students' well-being is partly determined by FI, detachment from studies, and PA. Therefore, this study highlights the importance of looking at both the diets of students, as well as the activities and experiences they have outside their studies to gain a better understanding of the factors influencing student well-being and the action leverages to promote it.

Maternal training during lactation modifies breast milk fatty acid composition and male offspring glucose homeostasis in rat.

The perinatal exposome can modify offspring metabolism and health later in life. Within this concept, maternal exercise during gestation has been reported modifying offspring glucose sensing and homeostasis, while the impact of such exercise during lactation is little-known. We thus aimed at evaluating short- and long-term effects of it on offspring pancreatic function, assuming a link with changes in breast milk composition. Fifteen-week-old primiparous female Wistar rats exercised during lactation at a constant submaximal intensity (TR) or remained sedentary (CT). Male offspring were studied at weaning and at 7 months of age for growth, pancreas weight, glycemia and insulin responses. Milk protein content was determined by the bicinchoninic acid assay (BCA colorimetric method), and lipid content and fatty acid composition by gas chromatography. Mature milk from TR rats contained significantly less saturated (-7 %) and more monounsaturated (+18 %) and polyunsaturated (PUFA +12 %) fatty acids compared to CT rats, with no difference in total lipid and protein concentrations. In offspring from TR vs CT mothers, fasting glycemia was lower, pancreas weight was higher with a lower insulin content (-37 %) at weaning. Such outcomes were correlated with milk PUFA levels and indices of desaturase or elongase activities. These effects were no longer present at 7 months, whereas a more efficient muscle insulin sensitivity was observed. Maternal training during lactation led to a specific milk phenotype that was associated with a short-term impact on glucose homeostasis and pancreatic function of the male offspring.

Concomitant exposure to benzo[a]pyrene and triclosan at environmentally relevant concentrations induces metabolic syndrome with multigenerational consequences in Silurana (Xenopus) tropicalis.

Numerous studies suggest that amphibians are highly sensitive to endocrine disruptors (ED) but their precise role in population decline remains unknown. This study shows that frogs exposed to a mixture of ED throughout their life cycle, at environmentally relevant concentrations, developed an unexpected metabolic syndrome. Female Silurana (Xenopus) tropicalis exposed to a mixture of benzo[a]pyrene and triclosan (50 ng·L-1 each) from the tadpole stage developed liver steatosis and transcriptomic signature associated with glucose intolerance syndrome, and pancreatic insulin hyper secretion typical of pre-diabetes. These metabolic disorders were associated with delayed metamorphosis and developmental mortality in their progeny, both of which have been linked to reduced adult recruitment and reproductive success. Indeed, F1 females were smaller and lighter and presented reduced reproductive capacities, demonstrating a reduced fitness of ED-exposed Xenopus. Our results confirm that amphibians are highly sensitive to ED even at concentrations considered to be safe for other animals. This study demonstrates that ED might be considered as direct contributing factors to amphibian population decline, due to their disruption of energetic metabolism.

Maternal exercise before and during gestation modifies liver and muscle mitochondria in rat offspring.

It is now well established that the intrauterine environment is of major importance for offspring health during later life. Endurance training during pregnancy is associated with positive metabolic adjustments and beneficial effects on the balance between pro-oxidants and antioxidants (redox state) in the offspring. Our hypothesis was that these changes could rely on mitochondrial adaptations in the offspring due to modifications of the fetal environment induced by maternal endurance training. Therefore, we compared the liver and skeletal muscle mitochondrial function and the redox status of young rats whose mothers underwent moderate endurance training (treadmill running) before and during gestation (T) with those of young rats from untrained mothers (C). Our results show a significant reduction in the spontaneous H2O2 release by liver and muscle mitochondria in the T versus C offspring (P<0.05). These changes were accompanied by alterations in oxygen consumption. Moreover, the percentage of short-chain fatty acids increased significantly in liver mitochondria from T offspring. This may lead to improvements in the fluidity and the flexibility of the membrane. In plasma, glutathione peroxidase activity and protein oxidation were significantly higher in T offspring than in C offspring (P<0.05). Such changes in plasma could represent an adaptive signal transmitted from mothers to their offspring. We thus demonstrated for the first time, to our knowledge, that it is possible to act on bioenergetic function including alterations of mitochondrial function in offspring by modifying maternal physical activity before and during pregnancy. These changes could be crucial for the future health of the offspring.

Impact of maternal low-level cadmium exposure on glucose and lipid metabolism of the litter at different ages after weaning.

Cadmium (Cd) is a metal which may participate in the development of type II diabetes even if Cd exposure levels are mild. However, experimental studies focusing on daily environmentally relevant doses are scarce, particularly for glucose metabolism of the offspring of chronically exposed mothers. The aim is to measure the impact of maternal low level Cd exposure on glucose and lipid metabolism of offspring. Female rats were exposed to 0, 50 or 500 µg.kg-1.d-1 of CdCl2, 21 days before mating and during 21 days of gestation and 21 days of lactation. Pups exposure was organized in 3 groups (control, Cd1, Cd2) according to renal dams' Cd burden. Parameters of glucose and lipid metabolisms were measured for the pups on post-natal day 21, 26 and 60. Maternal Cd exposure led to significant amounts of Cd in the liver and kidney of pups. At weaning, insulin secretion upon glucose stimulation was unchanged, but the removal of circulating glucose was slower for pups born from the lowest impregnated dams (Cd1). Five days after, glucose tolerance of all groups was identical. Thus, this loss of insulin sensitivity was reversed, in part by increased adiponectin secretion for the Cd1 group. Furthermore, pups from dams accumulating the highest levels of Cd (Cd2) exhibited a compensatory increased insulin pancreatic secretion, together with increased circulating non-esterified fatty acids, indicating the establishment of insulin resistance, 2 months after birth. This study has demonstrated the influence of maternal exposure to low levels of Cd on glucose homeostasis in the offspring that might increase the risk of developing type II diabetes later in life.

Impact of chronic and low cadmium exposure of rats: sex specific disruption of glucose metabolism.

BACKGROUND: Several epidemiological and animal studies suggest a positive association between cadmium (Cd) exposure and incidence of type 2 diabetes, but the association remains controversial. Besides, the experimental data have mainly been obtained with relatively high levels of Cd, over various periods of time, and with artificial routes of administration. OBJECTIVES: Do environmental exposures to Cd induce significant disruption of glucose metabolism? METHODS: Adults Wistar rats were exposed for three months to 0, 5, 50 or 500 µg.kg-1.d-1 of CdCl2 in drinking water. Relevant parameters of glucose homeostasis were measured. RESULTS: Cd accumulated in plasma, kidney and liver of rats exposed to 50 and 500 µg.kg-1.d-1, without inducing signs of organ failure. In rats drinking 5 µg.kg-1.d-1 for 3 months, Cd exposure did not lead to any significant increase of Cd in these organs. At 50 and 500 µg.kg-1.d-1 of Cd, glucose and insulin tolerance were unchanged in both sexes. However, females exhibited a significant increase of both fasting and glucose-stimulated plasma insulin that was assigned to impaired hepatic insulin extraction as indicated by unaltered fasting C-peptide plasma levels. CONCLUSIONS: Glucose homeostasis is sensitive to chronic Cd exposure in a gender-specific way. Moreover, this study proves that an environmental pollutant such as Cd can have, at low concentrations, an impact on the glucose homeostatic system and it highlights the importance of a closer scrutiny of the underlying environmental causes to understand the increased incidence of type 2 diabetes.

Unexpected metabolic disorders induced by endocrine disruptors in Xenopus tropicalis provide new lead for understanding amphibian decline.

Despite numerous studies suggesting that amphibians are highly sensitive to endocrine disruptors (EDs), both their role in the decline of populations and the underlying mechanisms remain unclear. This study showed that frogs exposed throughout their life cycle to ED concentrations low enough to be considered safe for drinking water, developed a prediabetes phenotype and, more commonly, a metabolic syndrome. Female Xenopus tropicalis exposed from tadpole stage to benzo(a)pyrene or triclosan at concentrations of 50 ng⋅L-1 displayed glucose intolerance syndrome, liver steatosis, liver mitochondrial dysfunction, liver transcriptomic signature, and pancreatic insulin hypersecretion, all typical of a prediabetes state. This metabolic syndrome led to progeny whose metamorphosis was delayed and occurred while the individuals were both smaller and lighter, all factors that have been linked to reduced adult recruitment and likelihood of reproduction. We found that F1 animals did indeed have reduced reproductive success, demonstrating a lower fitness in ED-exposed Xenopus Moreover, after 1 year of depuration, Xenopus that had been exposed to benzo(a)pyrene still displayed hepatic disorders and a marked insulin secretory defect resulting in glucose intolerance. Our results demonstrate that amphibians are highly sensitive to EDs at concentrations well below the thresholds reported to induce stress in other vertebrates. This study introduces EDs as a possible key contributing factor to amphibian population decline through metabolism disruption. Overall, our results show that EDs cause metabolic disorders, which is in agreement with epidemiological studies suggesting that environmental EDs might be one of the principal causes of metabolic disease in humans.

Maternal exercise modifies body composition and energy substrates handling in male offspring fed a high-fat/high-sucrose diet.

KEY POINTS: Maternal training during gestation enhances offspring body composition and energy substrates handling in early adulthood. Offspring nutrition also plays a role as some beneficial effects of maternal training during gestation disappear after consumption of a high-fat diet. ABSTRACT: Maternal exercise during gestation has been reported to modify offspring metabolism and health. Whether these effects are exacerbated when offspring are receiving a high-fat diet remains unclear. Our purpose was to evaluate the effect of maternal exercise before and during gestation on the offspring fed a high-fat/high-sucrose diet (HF) by assessing its body composition, pancreatic function and energy substrates handling by two major glucose-utilizing tissues: liver and muscle. Fifteen-week-old nulliparous female Wistar rats exercised 4 weeks before as well as during gestation at a constant submaximal intensity (TR) or remained sedentary (CT). At weaning, pups from each group were fed either a standard diet (TRCD or CTCD) or a high-fat/high-sucrose diet (TRHF or CTHF) for 10 weeks. Offspring from TR dams gained less weight compared to those from CT dams. Selected fat depots were larger with the HF diet compared to control diet (CD) but significantly smaller in TRHF compared to CTHF. Surprisingly, the insulin secretion index was higher in islets from HF offspring compared to CD. TR offspring showed a higher muscle insulin sensitivity estimated by the ratio of phosphorylated protein kinase B to total protein kinase B compared with CT offspring (+48%, P < 0.05). With CD, permeabilized isolated muscle fibres from TR rats displayed a lower apparent affinity constant (Km ) for pyruvate and palmitoyl coenzyme A as substrates compared to the CT group (-46% and -58%, respectively, P < 0.05). These results suggest that maternal exercise has positive effects on young adult offspring body composition and on muscle carbohydrate and lipid metabolism depending on the nutritional status.

Synergistic effects of citrulline supplementation and exercise on performance in male rats: evidence for implication of protein and energy metabolisms.

Background: Exercise and citrulline (CIT) are both regulators of muscle protein metabolism. However, the combination of both has been under-studied yet may have synergistic effects on muscle metabolism and performance. Methods: Three-month-old healthy male rats were randomly assigned to be fed ad libitum for 4 weeks with either a citrulline-enriched diet (1 g·kg-1·day-1) (CIT) or an isonitrogenous standard diet (by addition of nonessential amino acid) (Ctrl) and trained (running on treadmill 5 days·week-1) (ex) or not. Maximal endurance activity and body composition were assessed, and muscle protein metabolism (protein synthesis, proteomic approach) and energy metabolism [energy expenditure, mitochondrial metabolism] were explored. Results: Body composition was affected by exercise but not by CIT supplementation. Endurance training was associated with a higher maximal endurance capacity than sedentary groups (P<0.001), and running time was 14% higher in the CITex group than the Ctrlex group (139±4 min versus 122±6 min, P<0.05). Both endurance training and CIT supplementation alone increased muscle protein synthesis (by +27% and +33%, respectively, versus Ctrl, P<0.05) with an additive effect (+48% versus Ctrl, P<0.05). Mitochondrial metabolism was modulated by exercise but not directly by CIT supplementation. However, the proteomic approach demonstrated that CIT supplementation was able to affect energy metabolism, probably due to activation of pathways generating acetyl-CoA. Conclusion: CIT supplementation and endurance training in healthy male rats modulates both muscle protein and energy metabolisms, with synergic effects on an array of parameters, including performance and protein synthesis.

Middle Iron-Enriched Fructose Diet on Gestational Diabetes Risk and on Oxidative Stress in Offspring Rats.

Gestational diabetes mellitus (GDM) is associated with increased insulin resistance and a heightened level of oxidative stress (OS). Additionally, high iron consumption could also increase insulin resistance and OS, which could aggravate GDM risk. The aim of this study is to evaluate a high fructose diet (F) as an alternative experimental model of GDM on rats. We also have evaluated the worst effect of a fructose iron-enriched diet (FI) on glucose tolerance and OS status during pregnancy. Anthropometric parameters, plasma glucose levels, insulin, and lipid profile were assessed after delivery in rats fed an F diet. The effects observed in mothers (hyperglycemia, and hyperlipidemia) and on pups (macrosomia and hypoglycemia) are similar to those observed in women with GDM. Therefore, the fructose diet could be proposed as an experimental model of GDM. In this way, we can compare the effect of an iron-enriched diet on the metabolic and redox status of mother rats and their pups. The mothers' glycemic was similar in the F and FI groups, whereas the glycemic was significantly different in the newborn. In rat pups born to mothers fed on an FI diet, the activities of the antioxidant enzyme glutathione peroxidase (GPx) and glutathione-S-transferase in livers and GPx in brains were altered and the gender analysis showed significant differences. Thus, alterations in the glycemic and redox status in newborns suggest that fetuses are more sensitive than their mothers to the effect of an iron-enriched diet in the case of GDM pregnancy. This study proposed a novel experimental model for GDM and provided insights on the effect of a moderate iron intake in adding to the risk of glucose disorder and oxidative damage on newborns.

Long-term abdominal adiposity activates several parameters of cardiac energy function

Abdominal obesity increases the incidence of cardiac events but reduces mortality when one of these events occurs. The phenomenon called obesity paradox might be related to myocardial energetics. This study was aimed at determining whether long-term abdominal adiposity alters cardiac energy function. Two groups of male Wistar rats were fed a standard or a Western-type (WD) diet for 8 months. The ex vivo coronary reactivity and mechanical function as well as the mitochondrial oxidative phosphorylation (mOxPhos) and hydrogen peroxide release (mH2O2r) were determined. Abdominal adiposity was augmented by the WD. This was also the case for the coronary reactivity to acetylcholine, but the rate pressure product remained roughly stable despite a reduction of the left ventricle-developed pressure partly compensated by a slight increase in heart rate. The prolonged WD administration resulted in an improvement of mOxPhos, but the mH2O2r was exaggerated which was confirmed in the whole cell by a reduced aconitase to fumarase ratio. This did not modify the plasma oxidative stress due to an increased plasma antioxidant status. In conclusion, long-term WD administration improved the cardiac fitness and might predispose the organism to the obesity paradox. Conversely, the increased mitochondrial mH2O2r can precipitate the heart toward cardiomyopathy if the WD is maintained for a longer duration (AU)

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Short-term and long-term effects of submaximal maternal exercise on offspring glucose homeostasis and pancreatic function.

Only a few studies have explored the effects of maternal exercise during gestation on adult offspring metabolism. We set out to test whether maternal controlled submaximal exercise maintained troughout all gestational periods induces persistant metabolic changes in the offspring. We used a model of 15-wk-old nulliparous female Wistar rats that exercised (trained group) before and during gestation at a submaximal intensity or remained sedentary (control group). At weaning, male offspring from trained dams showed reduced basal glycemia (119.7 ± 2.4 vs. 130.5 ± 4.1 mg/dl, P < 0.05), pancreas relative weight (3.96 ± 0.18 vs. 4.54 ± 0.14 g/kg body wt, P < 0.05), and islet mean area (22,822 ± 4,036 vs. 44,669 ± 6,761 µm(2), P < 0.05) compared with pups from control dams. Additionally, they had better insulin secretory capacity when stimulated by 2.8 mM glucose + 20 mM arginine compared with offspring from control dams (+96%, P < 0.05). At 7 mo of age, offspring from trained mothers displayed altered glucose tolerance (AUC = 15,285 ± 527 vs. 11,898 ± 988 mg·dl(-1)·120 min, P < 0.05) and decreased muscle insulin sensitivity estimated by the phosphorylated PKB/total PKB ratio (-32%, P < 0.05) and tended to have a reduced islet insulin secretory capacity compared with rats from control dams. These results suggest that submaximal maternal exercise modifies short-term male offspring pancreatic function and appears to have rather negative long-term consequences on sedentary adult offspring glucose handling.

Cinnamon intake alleviates the combined effects of dietary-induced insulin resistance and acute stress on brain mitochondria.

Insulin resistance (IR), which is a leading cause of the metabolic syndrome, results in early brain function alterations which may alter brain mitochondrial functioning. Previously, we demonstrated that rats fed a control diet and submitted to an acute restraint stress exhibited a delayed mitochondrial permeability transition pore (mPTP) opening. In this study, we evaluated the combined effects of dietary and emotional stressors as found in western way of life. We studied, in rats submitted or not to an acute stress, the effects of diet-induced IR on brain mitochondria, using a high fat/high fructose diet (HF(2)), as an IR inducer, with addition or not of cinnamon as an insulin sensitizer. We measured Ca(2+) retention capacity, respiration, ROS production, enzymatic activities and cell signaling activation. Under stress, HF(2) diet dramatically decreased the amount of Ca(2+) required to open the mPTP (13%) suggesting an adverse effect on mitochondrial survival. Cinnamon added to the diet corrected this negative effect and resulted in a partial recovery (30%). The effects related to cinnamon addition to the diet could be due to its antioxidant properties or to the observed modulation of PI3K-AKT-GSK3ß and MAPK-P38 pathways or to a combination of both. These data suggest a protective effect of cinnamon on brain mitochondria against the negative impact of an HF(2) diet. Cinnamon could be beneficial to counteract deleterious dietary effects in stressed conditions.

Long-term abdominal adiposity activates several parameters of cardiac energy function.

Abdominal obesity increases the incidence of cardiac events but reduces mortality when one of these events occurs. The phenomenon called obesity paradox might be related to myocardial energetics. This study was aimed at determining whether long-term abdominal adiposity alters cardiac energy function. Two groups of male Wistar rats were fed a standard or a Western-type (WD) diet for 8 months. The ex vivo coronary reactivity and mechanical function as well as the mitochondrial oxidative phosphorylation (mOxPhos) and hydrogen peroxide release (mH2O2r) were determined. Abdominal adiposity was augmented by the WD. This was also the case for the coronary reactivity to acetylcholine, but the rate pressure product remained roughly stable despite a reduction of the left ventricle-developed pressure partly compensated by a slight increase in heart rate. The prolonged WD administration resulted in an improvement of mOxPhos, but the mH2O2r was exaggerated which was confirmed in the whole cell by a reduced aconitase to fumarase ratio. This did not modify the plasma oxidative stress due to an increased plasma antioxidant status. In conclusion, long-term WD administration improved the cardiac fitness and might predispose the organism to the obesity paradox. Conversely, the increased mitochondrial mH2O2r can precipitate the heart toward cardiomyopathy if the WD is maintained for a longer duration.

Functional changes of the coronary microvasculature with aging regarding glucose tolerance, energy metabolism, and oxidative stress.

This study was aimed at characterizing the functional progression of the endothelial (ECs) and smooth muscle cells (SMCs) of the coronary microvasculature between youth and old age, as well as at determining the mechanisms of the observed changes on the basis of the glucose tolerance, mitochondrial energy metabolism, and oxidative stress. Male rats were divided into four age groups (3, 6, 11, and 17 months for the young (Y), young adult (YA), middle-aged (MA), and old (O) animals). The cardiac mechanical function, endothelial-dependent dilatation (EDD) and endothelial-independent dilatation (EID) of the coronary microvasculature were determined in a Langendorff preparation. The mitochondrial respiration and H2O2 production were evaluated and completed by ex vivo measurements of oxidative stress. EDD progressively decreased from youth to old age. The relaxation properties of the SMCs, although high in the Y rats, decreased drastically between youth and young adulthood and stabilized thereafter, paralleling the reduction of mitochondrial oxidative phosphorylation. The ECs dilatation activity, low at youth, was stimulated in YA animals and returned to their initial level at middle age. That parameter followed faithfully the progression of the amount of active cardiac endothelial nitric oxide synthase and whole body glucose intolerance. In conclusion, the progressive decrease in EDD occurring with aging is due to different functional behaviors of the ECs and SMCs, which appear to be associated with the systemic glucose intolerance and cardiac energy metabolism.

Acute stress delays brain mitochondrial permeability transition pore opening.

Since emotional stress elicits brain activation, mitochondria should be a key component of stressed brain response. However, few studies have focused on mitochondria functioning in these conditions. In this work, we aimed to determine the effects of an acute restraint stress on rat brain mitochondrial functions, with a focus on permeability transition pore (PTP) functioning. Rats were divided into two groups, submitted or not to an acute 30-min restraint stress (Stress, S-group, vs. Control, C-group). Brain was removed immediately after stress. Mitochondrial respiration and enzymatic activities (complex I, complex II, hexokinase) were measured. Changes in PTP opening were assessed by the Ca(2+) retention capacity. Cell signaling pathways relevant to the coupling between mitochondria and cell function (adenosine monophosphate-activated protein kinase, phosphatidylinositol 3-kinase, glycogen synthase kinase 3 beta, MAPK, and cGMP/NO) were measured. The effect of glucocorticoids was also assessed in vitro. Stress delayed (43%) the opening of PTP and resulted in a mild inhibition of complex I respiratory chain. This inhibition was associated with significant stress-induced changes in adenosine monophosphate-activated protein kinase signaling pathway without changes in brain cGMP level. In contrast, glucocorticoids did not modify PTP opening. These data suggest a rapid adaptive mechanism of brain mitochondria in stressed conditions, with a special focus on PTP regulation. In a rat model of acute restraint stress, we observed substantial changes in brain mitochondria functioning. Stress significantly (i) delays (43%) the opening of permeability transition pore (PTP) by the calcium (Ca(2+) ), its main inductor and (ii) results in an inhibition of complex I in electron transport chain associated with change in AMPK signaling pathway. These data suggest an adaptive mechanism of brain mitochondria in stressed condition, with a special focus on PTP regulation.