Impact of 5-week high-intensity interval training on indices of cardio metabolic health in men.

PURPOSE: To compare the acute and chronic effects of high-intensity intermittent training (HIIT) and moderate-intensity continuous training (MICT) on indices of cardio-metabolic health: (HDL-c, total cholesterol, triglycerides, heart ratio, and phase angle/PhA) in physically active men. METHODS: Twenty active men were randomly allocated to HIIT (n = 10), or MICT (n = 10) for 5 weeks, three times per week. HIIT consisted of running 5 km with 1-min at 100% of maximal aerobic speed interspersed by 1-min passive recovery while subjects in MICT group ran continuously the same 5 km at 70% of maximal aerobic speed. Blood samples were collected at different moments during the first and last exercise session. Before and after 5 weeks of both exercise training protocols, heart ratio (during exercise session) and PhA were measured pre and post-exercise training. RESULTS: Fasting HDL-c levels did not change after 5 weeks of HIIT or MICT. Perceptual variation of HDL pre and post training (fed state) tended to differ between HIIT and MICT (p = 0.09). All lipoproteins parameters (HDL-c, total cholesterol, triglycerides and non-HDL) were increased in post-acute exercise session compared to pre-exercise during the first and last training session, these being observed after both training protocols. PhA and heart rate measured at different times during the first and last training session were not affected in both training protocols. CONCLUSION: These results indicate that HIIT and MICT modify the post-exercise lipoprotein profile acutely. On the other hand, only HIIT tended to increase HDL-c levels chronically.

Two weeks of high-fat feeding disturb lipid and cholesterol molecular markers.

Metabolic disorders are often associated with liver steatosis and increased plasma cholesterol levels. However, the link between excessive lipid accumulation and impairments in cholesterol metabolism remains uninvestigated in the liver. Short term of high-fat diet (HFD) was previously shown to promote excessive lipid accumulation prior to the development of metabolic disorders. The present study intended to characterize how increases in liver fat alter the expression of several key regulators of hepatic cholesterol metabolism in response to a short-term HFD. Wistar rats were randomly submitted either to HFD (n = 8) or a regular chow diet (n = 8) for 14 days. Increases in triglycerides were highly significant (P < 0.01) in the liver but marginal in the plasma of HFD rats. In contrast, the HFD resulted in higher (P < 0.01) cholesterol levels in plasma but not in liver samples. Gene expression of key markers involved in cholesterol uptake (LDL particles) including low-density lipoprotein receptor-related protein-1 (LRP-1) and protein convertase subtilisin/kexin type 9 (PCSK9) along with ATP-binding cassette, superfamily G, member 5 (ABCG5) involved in cholesterol exportation via bile ducts was found to be higher (P < 0.05) in response to the HFD. In contrast, expression of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), involved in cholesterol synthesis, was downregulated in the liver. The data support the concept that excessive accumulation of lipids promptly alters the expression of key genes regulating cholesterol metabolism in the liver. On a clinical point of view, this indicates that increases in plasma cholesterol occur after a short-term HFD.

18F FDG positron-emission tomography findings of gliomatosis peritonei: A case report and review of the literature.

•Gliomatosis peritonei (GP) is a rare benign complication of ovarian teratomas that does not impact overall survival.•GP exhibits high 18-F FDG uptake unlike other non-malignant forms of mature teratoma.•The specific characteristics of GP on functional imaging may be used to follow it with active surveillance in select cases.

Loss of ovarian estrogens causes only mild deterioration of glucose homeostasis in female ZDF rats preventable by voluntary running exercise.

Studies on normoglycemic ovariectomized Sprague-Dawley rats have provided insights about the effects of estrogen deficiency on insulin resistance in lean individuals. It is not completely clear if subjects with pre-established obesity and insulin resistance are at greater risk of developing type 2 diabetes when ovarian estrogens are no longer secreted, and if physical activity can protect against this susceptibility. Contrasting with their male counterparts, obese and insulin resistant female ZDF (Zucker diabetic fatty) rats do not become hyperglycemic when fed a standard diet. The aim of the study was to evaluate the hypothesis that withdrawal of ovarian estrogens in insulin resistant female ZDF rats would trigger overt hyperglycemia, provided they remain physically inactive. Female ZDF rats underwent either an ovariectomy (OVX) or a simulated surgery (SHAM). Thereafter, OVX rats engaged either in voluntary wheel cage running (OVX-Active), or like the Sham rats, remained sedentary (OVX-Sed) for 6 weeks. Fasting glycemia, insulinemia, and glucose tolerance were not altered in OVX-Sed as compared to SHAM-Sed rats. However, OVX-Sed rats showed altered liver triglyceride and glycogen contents, increased pancreatic insulin content and reduced insulin-stimulated muscle pAKT as compared to SHAM-Sed rats. Physical activity in OVX rats lowered fasting glucose and insulin levels, improved glucose tolerance and insulin-stimulated skeletal muscle glucose uptake as compared to OVX-Sed rats. OVX-induced alterations in pancreatic insulin content and liver glycogen and triglyceride contents were significantly improved by physical activity. Loss of ovarian estrogens did not cause overt hyperglycemia in insulin-resistant female ZDF rats. Physical activity improved glucose homeostasis despite estrogen deficiency.

LDL receptor and Pcsk9 transcripts are decreased in liver of ovariectomized rats: effects of exercise training.

The aim of this study was to determine the effects of ovariectomy in rats on hepatic gene expression of key molecules involved in cholesterol metabolism and to verify if exercise training may play a role in preventing hypercholesterolemia in Ovx rats. Sprague-Dawley rats were ovariectomized (Ovx) or sham-operated (Sham) and were either trained (Tr) on treadmill or kept sedentary (Sed) for 8 weeks. Rats were divided into 5 groups: Sham-Sed, Sham-Tr, Ovx-Sed, Ovx-Tr and Ovx with 17ß-estradiol supplementation (Ovx-E2). Ovx animals had significantly (p<0.05) higher body weight, adiposity, liver total cholesterol (TC) content and hypercholesterolemia compared to Sham rats. In contrast, gene expression of hepatic low-density lipoprotein receptor (LDL-R), LDL receptor-related protein (Lrp1), proprotein convertase subtilisin/kexin type 9 (Pcsk9), sterol regulatory element binding protein 2 (SREBP-2) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCoA-r) were reduced (p<0.05) in Ovx compared to Sham rats. Hepatic mRNA levels of scavenger receptor class B member 1 (SR-B1) and ATP-binding cassette subfamily A member 1 (ABCA1) (hepatic and intestinal) were higher (p<0.05) in Ovx compared to Sham rats. All of these molecular changes were corrected in Ovx-E2. Exercise training, significantly reversed the effect of Ovx on adiposity, plasma triglyceride, TC and mRNA expression of SREBP-2 but had no effect on all other hepatic genes expression. These data indicate that hypercholesterolemia in Ovx rats is associated with a reduction of hepatic LDL-R and Lrp1 gene expression.

Satiety quotient linked to food intake and changes in anthropometry during menopause: a MONET Study.

OBJECTIVES: It is unknown whether the satiety quotient (SQ) differs across the menopausal transition, and whether changes in SQ are related to changes in anthropometric/body composition variables. The objective of this study was to evaluate the changes in SQ and its association with energy intake and changes in anthropometric/body composition variables across the menopausal transition. METHODS: At baseline, 102 premenopausal women (aged 49.9 ± 1.9 years, body mass index 23.3 ± 2.2 kg/m(2)) took part in a 5-year observational, longitudinal study. Body composition (DXA), appetite (visual analog scales), energy and macronutrient intakes (ad libitum lunch and 7-day food diary) were assessed annually. The SQ (mm/100 kcal) was calculated at 60 and 180 min post-breakfast consumption. RESULTS: Overall, the SQ increased at years 3 and 4 (p = 0.01-0.0001), despite no significant differences between menopausal status groups. Lower fullness, prospective food consumption and mean SQ values predicted overall increases in lunch energy and macronutrient intakes (p = 0.04-0.01), whereas only prospective food consumption and fullness SQ predicted energy intake and carbohydrate intake, respectively, when assessed with food diaries (p = 0.01). Delta SQs were negatively correlated with changes in waist circumference (p = 0.03-0.02), whereas delta SQs were positively (p = 0.04) and negatively (p = 0.02) associated with delta fat mass between years 1 and 5, and years 4 and 5, respectively. CONCLUSION: These results suggest that variations in SQ across the menopausal transition are related to energy and macronutrient intakes and coincide with changes in body composition and waist circumference.

Effects of the menopausal transition on dietary intake and appetite: a MONET Group Study.

BACKGROUND/OBJECTIVE: The purpose of this study was to investigate changes in dietary intake and appetite across the menopausal transition. SUBJECTS/METHODS: This was a 5-year observational, longitudinal study on the menopausal transition. The study included 94 premenopausal women at baseline (age: 49.9±1.9 years; BMI: 23.3±2.3 kg/m2). Body composition (dual-energy X-ray absorptiometry), appetite (visual analogue scale), eating frequency, energy intake (EI) and macronutrient composition (7-day food diary and buffet-type meal) were measured annually. RESULTS: Repeated-measures analyses revealed that total EI and carbohydrate intake from food diary decreased significantly over time in women who became postmenopausal by year 5 (P>0.05) compared with women in the menopausal transition. In women who became postmenopausal by year 5, fat and protein intakes decreased across the menopausal transition (0.05>P<0.01). Although a decrease in % fat intake was observed during the menopausal transition (P<0.05), this variable was significantly increased in the postmenopausal years (P<0.05). Spontaneous EI and protein intake also declined over time and were higher in the years preceding menopause onset (P<0.05). Desire to eat, hunger and prospective food consumption increased during the menopausal transition and remained at this higher level in the postmenopausal years (0.05>P<0.001). Fasting fullness decreased across the menopausal transition (P<0.05). CONCLUSION: These results suggest that menopausal transition is accompanied with a decrease in food intake and an increase in appetite.

Alternative fuel production by catalytic hydroliquefaction of solid municipal wastes, primary sludges and microalgae.

An alternative fuel production was investigated through catalytic hydroliquefaction of three different carbonaceous sources: solid municipal wastes (MW), primary sludges (PS), and microalgae (MA). The reaction was carried out under hydrogen pressure, at different temperatures (330, 380 and 450°C), with a Raney nickel catalyst and two different hydrogen donor solvents: a "fossil solvent" (tetralin) and a "green solvent" (2-methyl-hydro-furan). The feeds analyses (TDA-TGA, ICP-AES, lipids quantification) showed that MW and PS had similar characteristics and physico-chemical properties, but different from those of MA. The hydroliquefaction of these feeds allowed to obtain high oil yields, with a significant energetic value, similar to that of a bio-petroleum. 2-methyl-hydro-furan was more efficient than tetralin for the treatment of the strongly bio-degraded biomasses MW and PS, while better results were obtained with tetralin in the case of MA.

Effects of the menopausal transition on energy expenditure: a MONET Group Study.

OBJECTIVES: Factors that influence weight gain during the menopausal transition are not fully understood. The purpose of this study was to investigate changes in energy expenditure (EE) across the menopausal transition. METHODS: In all, 102 premenopausal women (age: 49.9 ± 1.9 years; body mass index: 23.3 ± 2.2 kg/m(2)) were followed for 5 years. Body composition (dual-energy X-ray absorptiometry), physical activity EE (accelerometer), resting EE and thermic effect of food (indirect calorimetry) were measured annually. RESULTS: Total EE decreased significantly over time in postmenopausal women (P<0.05), which was mostly due to a decrease in physical activity EE (P<0.05). Although average resting EE remained stable over time in postmenopausal women, a significant increase, over the 5-year period, was noted in women who were in the menopausal transition by year 5 (P<0.05). Finally, the time spent in moderate physical activity decreased and the time spent in sedentary physical activity increased during the menopausal transition (P<0.05). CONCLUSION: These results suggest that menopausal transition is accompanied with a decline in EE mainly characterized by a decrease in physical activity EE and a shift to a more sedentary lifestyle.

Effect of exercise training and isoflavones on hepatic steatosis in overweight postmenopausal women.

OBJECTIVES: Postmenopausal women are particularly inclined to an increased risk of developing non-alcoholic hepatic steatosis. The purpose of this study was to investigate whether adding isoflavone supplementation to exercise training could reduce the risk. METHODS: In a 6-month, double-blind, randomized, controlled trial, 54 healthy overweight-to-obese (body mass index 28-40 kg/m2) postmenopausal women were randomly assigned to one of the following groups: (1) exercise and isoflavones (Ex-Iso; n = 26), (2) exercise and placebo (Ex-Pla; n = 28). Exercise training consisted of three weekly sessions of mixed training. We examined the plasma level of specific hepatic enzymes (alanine aminotransferase, aspartate aminotransferase, γ-glutamyltransferase, and alkaline phosphatase) as a reflection of fatty liver along with the calculation of the fatty liver index. All measures were obtained at baseline and after the 6-month intervention. RESULTS: Following the intervention, a lower fatty liver index (p <0.01; 29% in Ex-Iso, 18% in Ex-Pla) and plasma γ-glutamyltransferase (p <0.01; 22% in Ex-Iso, 16% in Ex-Pla) were observed in both groups, with a higher reduction in the Ex-Iso group. On the other hand, for all other hepatic enzymes, there was no change. CONCLUSIONS: Our results show that exercise training appears to bring favorable changes in the plasma level of hepatic enzymes, possibly due to the lowering of liver fat content. While postmenopausal women can benefit from this intervention to decrease the risk of developing non-alcoholic hepatic steatosis, it seems that the addition of isoflavones to exercise training provides some additional effects to those provided by exercise alone.

Ovariectomy stimulates hepatic fat and cholesterol accumulation in high-fat diet-fed rats.

This study was designed to determine how estrogens withdrawal during a high-fat (HF) diet regimen affects liver triacylglycerol (TAG) and cholesterol accumulation. Female Sprague-Dawley rats were submitted to a HF (42% energy as fat) or a standard (SD) diet for 6 weeks before being either ovariectomized (Ovx) or sham operated (Sham). Thereafter, Ovx and Sham rats were kept on the same diet for another 6 weeks leading to euthanasia. Liver TAG content was increased (p<0.01) in Ovx rats but not by the HF diet alone. However, the combination of HF diet and Ovx resulted in a greater liver TAG accumulation (p<0.06) than that observed in Ovx-SD/SD. Measurement of molecular markers of liver lipid metabolism revealed an increase in transcripts of markers of lipid oxidation (CPT-1 and PGC1; p<0.05) in rats fed the HF diet. This increase was, however, substantially less if HF fed rats were Ovx. Liver total cholesterol levels were increased (p<0.01) only in the Ovx-HF/HF rats while plasma cholesterol levels were increased in Ovx-SD/SD and in SHAM-HF/HF and Ovx-HF/HF rats. Transcripts of molecular markers of cholesterol metabolism suggest that biliary acids synthesis (CYP7a-1) was reduced in Ovx-SD/SD and Sham-HF/HF rats and even more so in Ovx-HF/HF rats. It is concluded that the effects of a HF diet on liver TAG accumulation are especially observed in Ovx rats possibly through a reduction in hepatic lipid oxidation. The combination of Ovx and HF diet also acts synergistically to favor liver cholesterol accumulation.

Conversion of lignin to aromatic-based chemicals (L-chems) and biofuels (L-fuels).

Conversion of lignin into chemicals and biofuels was performed using the commercial Kraft lignin, Indulin AT. Lignin was depolymerised in an aqueous alkaline solution using a continuous flow reactor generating four fractions. First is the gas fraction (mainly CO(2)), the second includes methanol, acetic acid and formic acid, thus defined as small organic compounds and third one (up to 19.1 wt.% of lignin) is mostly composed of aromatic monomers. The fourth fraction (45-70 wt.%) contains oligomers (polyaromatic molecules) and modified lignin. Pyrocatechol was the most abundant product at high severities (315°C) with selectivity up to 25.8%. (31)P NMR showed the loss of almost all aliphatic OH groups and apparition of catechol groups during depolymerisation.

Effects of high-intensity intermittent training on carnitine palmitoyl transferase activity in the gastrocnemius muscle of rats

We examined the capacity of high-intensity intermittent training (HI-IT) to facilitate the delivery of lipids to enzymes responsible for oxidation, a task performed by the carnitine palmitoyl transferase (CPT) system in the rat gastrocnemius muscle. Male adult Wistar rats (160-250 g) were randomly distributed into 3 groups: sedentary (Sed, N = 5), HI-IT (N = 10), and moderate-intensity continuous training (MI-CT, N = 10). The trained groups were exercised for 8 weeks with a 10% (HI-IT) and a 5% (MI-CT) overload. The HI-IT group presented 11.8% decreased weight gain compared to the Sed group. The maximal activities of CPT-I, CPT-II, and citrate synthase were all increased in the HI-IT group compared to the Sed group (P < 0.01), as also was gene expression, measured by RT-PCR, of fatty acid binding protein (FABP; P < 0.01) and lipoprotein lipase (LPL; P < 0.05). Lactate dehydrogenase also presented a higher maximal activity (nmol·min-1·mg protein-1) in HI-IT (around 83%). We suggest that 8 weeks of HI-IT enhance mitochondrial lipid transport capacity thus facilitating the oxidation process in the gastrocnemius muscle. This adaptation may also be associated with the decrease in weight gain observed in the animals and was concomitant to a higher gene expression of both FABP and LPL in HI-IT, suggesting that intermittent exercise is a "time-efficient" strategy inducing metabolic adaptation.

Effects of high-intensity intermittent training on carnitine palmitoyl transferase activity in the gastrocnemius muscle of rats.

We examined the capacity of high-intensity intermittent training (HI-IT) to facilitate the delivery of lipids to enzymes responsible for oxidation, a task performed by the carnitine palmitoyl transferase (CPT) system in the rat gastrocnemius muscle. Male adult Wistar rats (160-250 g) were randomly distributed into 3 groups: sedentary (Sed, N = 5), HI-IT (N = 10), and moderate-intensity continuous training (MI-CT, N = 10). The trained groups were exercised for 8 weeks with a 10% (HI-IT) and a 5% (MI-CT) overload. The HI-IT group presented 11.8% decreased weight gain compared to the Sed group. The maximal activities of CPT-I, CPT-II, and citrate synthase were all increased in the HI-IT group compared to the Sed group (P < 0.01), as also was gene expression, measured by RT-PCR, of fatty acid binding protein (FABP; P < 0.01) and lipoprotein lipase (LPL; P < 0.05). Lactate dehydrogenase also presented a higher maximal activity (nmol·min(-1)·mg protein(-1)) in HI-IT (around 83%). We suggest that 8 weeks of HI-IT enhance mitochondrial lipid transport capacity thus facilitating the oxidation process in the gastrocnemius muscle. This adaptation may also be associated with the decrease in weight gain observed in the animals and was concomitant to a higher gene expression of both FABP and LPL in HI-IT, suggesting that intermittent exercise is a "time-efficient" strategy inducing metabolic adaptation.

Liver fat accumulation may be dissociated from adiposity gain in ovariectomized rats.

OBJECTIVE: The purpose of the present study was to establish a model of rats prone and resistant to intra-abdominal fat accumulation in response to ovariectomy (Ovx-P and Ovx-R) and to determine its relationship with molecular biomarkers. DESIGN: Two experiments were conducted in which female rats were either sham-operated (Sham) or ovariectomized (Ovx). In the first experiment, ovariectomized rats were stratified into three tertiles based on intra-abdominal adipose tissue mass. To strengthen the Ovx-P/Ovx-R model, we conducted a second experiment in which the numbers of rats in each group were extended and in which different molecular markers were measured. At the end of a 6-8-week period, ovariectomized rats that displayed the lower abdominal fat accumulation (lower tertile) were labelled as Ovx-R and those in the upper tertile as Ovx-P. RESULTS: Ovx-R rats displayed similar abdominal fat gain to Sham rats whereas Ovx-P rats depicted abdominal fat mass twice as high as that of Sham and Ovx-R rats. Despite the difference in abdominal adiposity, liver fat content was ~50% higher (p < 0.01) in both Ovx-R and Ovx-P rats compared to Sham rats. In addition, both Ovx-R and Ovx-P rats depicted higher HOMA-IR scores (p < 0.05) and lower (p < 0.01) hepatic gene expression of leptin receptor-b and -e, microsomal transfer protein (MTP), and diacylglycerol acyltransferase-2 (DGAT-2) compared to Sham rats. CONCLUSION: The present findings indicate that estrogen withdrawal-induced hepatic steatosis and associated insulin resistance may be dissociated from abdominal fat accumulation and suggest that a decrease in leptin action through a down-regulation of leptin receptors and a decrease in very low density lipoprotein production through a down-regulation of MTP and DGAT-2 may be factors responsible for this observation in the absence of peripheral fat gain.

Hepatic VLDL-TG production and MTP gene expression are decreased in ovariectomized rats: effects of exercise training.

The present study was designed to investigate the effects of estrogen withdrawal and exercise training on hepatic very low density lipoprotein-triglyceride (VLDL-TG) production and on expression of genes involved in hepatic VLDL synthesis in response to lipid infusion. Female Sprague-Dawley rats underwent ovariectomy (Ovx), sham surgery (Sham), and Ovx with 17ß-estradiol supplementation (OvxE2) before being subdivided into sedentary (Sed) and trained (Tr) groups for 8 weeks. Exercise training consisted of continuous running on a rodent treadmill 5 times/wk. At the end of the 8-week period, all rats in the fasted state were intravenously infused with a 20% solution of Intralipid for 3-h followed by an injection of Triton WR-1339 to block lipoprotein lipase activity. Plasma TG accumulation was subsequently measured during 90 min to estimate VLDL-TG production. An additional control group consisting of Sham-Sed rats was infused with saline (0.9% NaCl). Estrogen withdrawal resulted in higher (p<0.01) liver fat accumulation concomitantly with lower (p<0.01) VLDL-TG production and lower mRNA and protein content of hepatic microsomal triglyceride transfer protein (MTP). All of these effects in Ovx rats were corrected with estrogen supplementation. Training in Ovx rats reduced (p<0.01) liver fat accumulation and further reduced (p<0.01) hepatic VLDL-TG production along with gene expression of MTP and diacylglycerol acyltransferase-2 (DGAT-2). It is concluded that VLDL-TG synthesis and/or secretion is decreased in Ovx rats probably via MTP regulation and that this decrease may constitute one of the factors involved in hepatic fat accumulation. The training effect on reducing VLDL production was independent of the estrogenic status.

Does exercise training prior to ovariectomy protect against liver and adipocyte fat accumulation in rats?

OBJECTIVE: To determine whether a training state protects against the metabolically deleterious effects of ovariectomy on liver and adipocyte fat accumulation in rats. DESIGN: Female rats were randomly assigned to each group (n = 8 rats/group). The animals were first either exercise-trained (Tr) for 6 weeks or kept sedentary (Sed) before being sham-operated (Sham), ovariectomized (Ovx), or ovariectomized with 17beta-estradiol supplementation (OvxE2). Following surgery, sedentary rats either remained sedentary (Sed-Sed) or undertook exercise training for 6 weeks (Sed-Tr) while exercise-trained rats either became sedentary (Tr-Sed) or resumed exercise training (Tr-Tr). RESULTS: Body weight and energy intake along with intra-abdominal and subcutaneous fat pad weights and homeostasis model assessment of insulin resistance (HOMA-IR) were significantly (p < 0.01) increased in the Ovx group compared to the Sham and OvxE2 groups. Rats kept in a sedentary state after surgery showed the higher (p < 0.05) values for all of these variables whether they were trained or not before surgery (Sed-Sed and Tr-Sed), indicating no protective effect of a previous exercise-trained state. On the other hand, training conducted after surgery resulted in a lowering of fat mass and HOMA-IR whether rats had been trained or not before surgery (Sed-Tr and Tr-Tr), indicating the effectiveness of exercise training even initiated after surgery. These responses were independent of surgery. Interestingly, liver triacylglycerol concentrations followed a pattern of responses identical to fat mass with the exception that all of the responses were observed only in the Ovx group (p < 0.05). CONCLUSION: There is no protective effect of a previous exercise-training state on ovariectomy-induced liver and adipocyte fat accumulation if rats remain sedentary after ovariectomy. However, training conducted concurrently with estrogen withdrawal has protective effects, especially on liver fat accumulation, whether or not rats were previously trained.

Comparison between several insulin sensitivity indices and metabolic risk factors in overweight and obese postmenopausal women: a MONET study.

BACKGROUND AND AIMS: The purpose of this study was to compare the relationship of several insulin sensitivity indices with cardiometabolic risk factors in overweight and obese postmenopausal women. METHODS AND RESULTS: This was a cross-sectional study involving 137 overweight and obese postmenopausal women (age: 57.7+/-4.8 yrs; body mass index: 32.4+/-4.6 kg/m(2); body fat: 38.6+/-9.2 kg). Insulin sensitivity was determined by the euglycaemic-hyperinsulinemic (EH) clamp technique as well as by oral glucose tolerance test (OGTT) derived indices (Stumvoll, Matsuda and SI(is)) and fasting surrogate indices (HOMA, QUICKI). Cardiometabolic risk factors included: body composition and visceral fat that were measured using dual energy X-ray absorptiometry and computed tomography, respectively. Peak oxygen consumption, lower body muscle strength (using weight training equipment), physical activity energy expenditure (doubly labeled water), plasma lipids and C-reactive protein were also measured. Correlations of insulin sensitivity indices with metabolic risk factors showed some similarities, however, a wide range of variations were also observed. Furthermore, our results showed that visceral fat was the primary predictor for surrogate and OGTT indices, explaining 15-28% of the variance and the triglycerides/HDL-C ratio was the primary predictor for the EH clamp indices, explaining 15-17% of the variance. CONCLUSION: The present study indicates that the different methods of measuring and/or expressing insulin sensitivity display variations for associations with cardiometabolic risk factors. Therefore, interpretations of relationships between insulin sensitivity indices and cardiometabolic risk factors should take into account the method used to estimate and express insulin sensitivity.

Fatty acid oxidation is decreased in the liver of ovariectomized rats.

Estrogen-deficient states are associated with hepatic steatosis. Based on previous findings obtained at the molecular and enzymatic levels, it has been suggested that estradiol exerts its lipid-lowering effects in liver through partitioning of triacylglycerols into oxidative pathways. However, information on relevant physiological response was lacking. Therefore, the purpose of the present study was to assess fatty acid oxidation rate in the liver of intact and ovariectomized rats. Tritiated water released from liver slices incubated with 9,10-[ (3)H]palmitate was measured as a reflection of in vivo fatty acid metabolism. Fatty acid oxidation rate was lowered by 34% (p<0.05), associated with 114% higher (p<0.01) hepatic triacylgylcerol content in the liver of ovariectomized as compared to intact rats. Estrogen replacement prevented all of these changes. Fatty liver has been linked with hepatic leptin resistance in obese male rats. Since leptin stimulates fatty acid oxidation in liver, we hypothesized that increased liver triacylglycerol content and decreased fatty acid oxidation might be associated with leptin resistance in ovariectomized rats. To this end, acute leptin delivery was performed. The 120-min intravenous leptin infusion increases fatty acid oxidation by 23% in the liver of ovariectomized rats, which was coupled with 24% lower hepatic triacylglycerol content. We conclude that fatty acid oxidation is decreased in the liver of ovariectomized rats, which is likely to contribute to hepatic steatosis development. Furthermore, our results suggest that leptin sensitivity is not completely lost in the liver of rats ovariectomized for 5 weeks.

Effects of exercise training on hepatic microsomal triglyceride transfer protein content in rats.

Microsomal triglyceride transfer protein (MTP) is a protein that exerts a central regulatory role in very-low-density lipoprotein (VLDL) assembly and secretion. The purpose of the study was to investigate the effects of an exercise-training program on hepatic content of MTP and its relation to hepatic VLDL-triglyceride (VLDL-TG) production in response to lipid infusion. Female rats either fed a standard (SD) or an obesity-induced high-fat (HF; 43% as energy) diet for 8 weeks were subdivided into sedentary (Sed) and trained (Tr) groups. Exercise training consisted of continuous running on a motor-driven rodent treadmill 5 times/week for 8 weeks. At the end of this period, all rats in the fasted state were intravenously infused with a 20% solution of Intralipid for 3 h followed by an injection of Triton WR1339 to block lipoprotein lipase. An additional control group consisting of Sed rats fed the SD diet was infused with saline (0.9% NaCl). Plasma TG accumulation was thereafter measured during 90 min to estimate VLDL-TG production. Under HF diet, hepatic MTP content and plasma TG accumulation after Triton blockade (thus reflecting VLDL-TG synthesis and secretion) were not changed in Sed rats, whereas liver TG content was highly increased (approximately 90%; p<0.01). On the other hand, training reduced liver MTP protein content in both SD (-18%) and HF (-23%) fed rats (p<0.05). Plasma VLDL-TG accumulation was also lower (p<0.05) in Tr than in Sed rats fed the HF diet. This effect was not observed in SD fed rats. Furthermore, the exercise training-induced decrease in VLDL-TG production in HF rats was associated with a decrease in liver TG levels. It is concluded that in addition to a reduction in liver TG content, exercise training reduces VLDL synthesis and/or secretion in HF fed rats probably via MTP regulation.