Seasonal and diel transitions in physiology and behavior in the migratory dark-eyed junco

Body mass, fat stores, activities of lipogenic and lipolytic enzymes, and plasma corticosterone were measured throughout seasonal and diel transitions from fall through spring encompassing the non-migratory stages of early and mid winter, the prealternate molt, and the spring migratory stage in captive dark-eyed juncos to determine the physiological mechanisms underlying adaptations for migration. On a seasonal basis, lipid enzymes and corticosterone varied little throughout the stages even though the birds underwent dramatic alterations in mass, fat deposition, behavior, and activation of the reproductive axis. By contrast, diel changes were found in lipogenesis, lipolysis, muscle lipoprotein lipase, and plasma corticosterone when comparing birds in the two phases of spring migration--active flight and resting, as during times of stopover. In these two phases of migration, coordination of the lipogenic and lipolytic systems appear to maximize storage of fatty acids during rest and delivery/utilization during flight. Diel patterns of corticosterone revealed fairly consistent peaks during the night time (23:00) throughout the nonmigratory period. The profile of this pattern altered during the migratory period with variation between the flight and resting phases. In sum, the results from these captive studies offer a new approach for studying the regulation of migratory physiology in free-living birds.     

Potentiation of epinephrine-induced lipolysis in fat cells from estrogen-treated rats

We investigated concomitantly the effects of ethinyl-estradiol (EE₂) at low dose (1.2 μg/animal for 10 days) and high dose (120 μg/animal for 3 days) on body weight, weight of fat stores, triglyceridemia and fat cell lipoprotein lipase and hormone-sensitive lipase activities in female rats. At low dose, EE₂ increased triglyceridemia and lipoprotein lipase activity, whilst high dose decreased both parameters. At low and high doses, and regardless of whether triglyceridemia and lipoprotein lipase activity were increased and decreased, EE₂ caused depletion in fat stores. Fat cells isolated from depleted fat tissue elicited marked increases in the response of hormone-sensitivelipase to epinephrine. Taken together, the data suggest that the potentiation of epinephrine-induced lipolysis in fat cells is likely to represent a major cause to estrogen-induced fat depletion.     

Adrenalectomy Reduces Adiposity by Decreasing Feed Efficiency,Not Direct Effects on White Adipose Tissue

EDENS, N. K., A. MOSHIRFAR, G. M. POTTER, S. K. FRIED, AND T. W. CASTONGUAY. Adrenalectomy reduces adiposity by decreasing feed efficiency, not direct effects on white adipose tissue. Obes Res. Objective: This study was conducted to establish the effects of adrenalectomy (ADX) on adipose tissue metabolism in male Sprague—Dawley rats fed a standard chow diet. Research Methods and Procedures: The effects of adrenalectomy on adipose cell size, lipoprotein lipase activity, and basal and insulin-stimulated glucose conversion to lipid and lipolysis were measured. Results: ADX decreased body weight gain during the postoperative period in the absence of changes in food intake; feed efficiency was decreased significantly. ADX decreased adipocyte size by 30%. ADX increased adipocyte response to the effect of submaximal concentrations of insulin on lipid synthesis and lipolysis. ADX decreased maximally insulin-stimulated lipid synthesis, but this effect was accounted for by decreased adipocyte size. In contrast, ADX had no effect on maximally insulin-inhibited lipolysis. ADX did not affect heparin-releasable LPL. The small effect of ADX on residual extractable adipose tissue LPL activity was accounted for by decreased fat cell size. Discussion: ADX decreased adiposity in the absence of changes in food intake, lipoprotein lipase activity, and adipocyte lipid metabolism. The effect is best attributed to decreased feed efficiency.     

Simulation of migratory flight and stopover affects night levels of melatonin in a nocturnal migrant

Several species of diurnal birds are nocturnal migrants. The activation of nocturnal activity requires major physiological changes, which are essentially unknown. Previous work has shown that during migratory periods nocturnal migrants have reduced night-time levels of melatonin. Since this hormone is involved in the modulation of day-night rhythms, it is a good candidate regulator of nocturnal migratory activity. We studied whether melatonin levels change when nocturnally active blackcaps (Sylvia atricapilla) are experimentally transferred from a migratory to a non-migratory state. We simulated a long migratory flight by depriving birds of food for 2 days, and a refuelling stopover by subsequently re-administering food. Such a regimen is known to induce a reduction in migratory restlessness ('Zugunruhe') in the night following food reintroduction. The experiments were performed in both autumn and spring using blackcaps taken from their breeding grounds (Sweden) and their wintering areas (Kenya). In autumn, the food regimen induced a suppression of Zugunruhe and an increase in melatonin in the night following food reintroduction. In spring, the effects of the treatment were qualitatively similar but their extent depended on the amount of body-fat reserves. This work shows that the reduction of night-time melatonin during migratory periods is functionally related to nocturnal migration, and that fat reserves influence the response of the migratory programme to food deprivation.     

Regulation of Lipolysis and Lipoprotein Lipase after Weight Loss in Obese,Postmenopausal Women

Objective: To test the hypothesis that the greater β‐adrenoceptor (β‐AR)‐stimulated lipolysis and sensitivity (half‐maximal lipolytic response) in abdominal (ABD) adipocytes, greater gluteal (GLT) adipose tissue‐lipoprotein lipase (AT‐LPL) activity, and dyslipidemia associated with obesity in older women are modifiable by weight loss (WL) and are not due to menopause or aging. Research Methods and Procedures: The metabolic effects of 6 months of hypocaloric diet and low‐intensity walking WL program on the regional regulation of in vitro lipolysis and AT‐LPL activity in subcutaneous ABD and GLT adipocytes were measured in 34 obese (48.7 ± 0.7% body fat, mean ± SE) postmenopausal (59 ± 1 years) white women. Results: The lipolytic responsiveness to the β‐AR agonist isoproterenol and basal lipolysis in the presence of 1 U/mL adenosine deaminase‐uninhibited (lipolysis) were greater (p < 0.01) in ABD than GLT adipocytes before and after WL, but there were no regional differences in postreceptor (dibutyryl 3′, 5′‐cyclic adenosine monophosphate)‐stimulated lipolysis. β‐AR sensitivity was greater in ABD than GLT adipocytes before (p < 0.01) but not after WL. Regional AT‐LPL did not change after WL, but the change in the activity of ABD (but not GLT) AT‐LPL correlated with the baseline adenosine deaminase‐uninhibited lipolysis (r = 0.38, p = 0.03). There were no relationships between the declines in plasma triglyceride or increases in high‐density lipoprotein cholesterol associated with WL and the changes in regional fat cell metabolism. Discussion: Thus, despite improving lipoprotein lipid profiles in obese, postmenopausal women, WL does not affect the regulation of regional fat metabolism, and a greater tonic inhibition of basal lipolysis by endogenous adenosine may increase the activity of AT‐LPL after WL and predispose older women to develop ABD adiposity.     

The role of neutral lipases in human adipose tissue lipolysis

PURPOSE OF REVIEW: The aim of this article is to describe the relative roles of hormone sensitive lipase and adipose triglyceride lipase in human fat cell lipolysis. RECENT FINDINGS: Until recently, only hormone sensitive lipase was considered important for the regulation of lipolysis within fat cells. Recent rodent studies have suggested that adipose triglyceride lipase may, however, be more important. The few human adipose triglyceride lipase studies that have been published point to species differences between humans and rodents. Selective inhibition of hormone sensitive lipase in human fat cells completely counteracts hormone-activated lipolysis, though there is a considerable (>50%) residual nonhormonal (basal) lipolysis. In rodents, adipose triglyceride lipase enzyme activity is stimulated by a cofactor termed CGI-58. In the absence of CGI-58, lipase activity in fat cells is much higher for hormone sensitive lipase than adipose triglyceride lipase. Hormone sensitive lipase expression is regulated by obesity and body weight reduction (decreased and increased, respectively), but this is not the case for adipose triglyceride lipase. A role of adipose triglyceride lipase in human lipolysis is suggested by studies of gene polymorphisms. SUMMARY: Two lipases the 'old' hormone sensitive lipase and the 'new' adipose triglyceride lipase are of importance for the regulation of lipolysis in rodent fat cells. In humans, adipose triglyceride lipase seems essential for maintaining basal lipolytic activity, while hormone sensitive lipase is the enzyme most responsive to stimulated lipolysis.     

Changes in fat metabolism of black-bone chickens during early stages of infection with Newcastle disease virus

Experiments were conducted to determine the effects of Newcastle disease on chicken fat metabolism. Thirty black-bone chickens were infected intraocularly with the Newcastle disease virus (NDV). Six birds were killed at 0, 12, 24, 48 and 72 h post infection, respectively. Results showed that the NDV infection decreased concentration of high-density lipoprotein cholesterol and increased concentrations of total cholesterol and low-density lipoprotein cholesterol in the plasma. Concentrations of triglycerides and free fatty acid were decreased after their initial increase. NDV infection also dramatically raised the activities of lipoprotein lipase (LPL), hepatic lipase and lipases in the serum. Furthermore, PCR results showed that the incipient infection up-regulated mRNA expression of LPL, adipose triglyceride lipase and nuclear factor peroxisome proliferator-activated receptor alpha (PPARα), but down-regulated them at later stage. Similarly, mRNA expression of fatty acid synthase, acetyl-CoA carboxylase and nuclear factor PPARγ, fatty acid transport protein 1 (FATP1), and 4(FATP4) decreased, whereas fatty acid translocase and fatty acid-binding protein increased initially. Data from Western blotting analysis showed that the changes in protein levels were consistent with mRNA expression. These results indicated that fat metabolism of the chicken was affected by the NDV infection. At the beginning of NDV infection, lipogenesis was inhibited, whereas lipolysis was strengthened. After lipolysis was strengthened, fat metabolism was found to be maximally depressed.     

Stable individual profiles of daily timing of migratory restlessness in European quail

Temporal characteristics of migratory behavior in birds are usually studied at the species and population levels, and rarely at the individual level. Variations among species and populations of the seasonal onset of migratory behavior have been widely investigated, but very little is known about its daily organization or whether birds are conservative in their behavior. The determination of intra- and inter-individual variability is important for the study of genetic variations and can reveal the existence of different adaptation capacities within populations. This laboratory study analyzed intra- and inter-individual variability of daily initiation and time course of nocturnal restlessness in partial-migrant European quail (Coturnix coturnix coturnix). Thirty-five quail were selected randomly from a captive stock, and their spring activity was recorded under natural daylenghs. Eighteen of the thirty-five quail presented behavioral profiles of migrant birds. Migrant birds initiated their nocturnal activity punctually, and the time courses of the nocturnal activity of 88% of them revealed intra-individual stability over six consecutive nights. All birds initiated their nocturnal activity after sunset and civil twilight, and they were more active at the beginning than the middle or end of the night, suggesting that their drive to migrate could be synchronized with particular skylight conditions. For the first time, stable individual profiles in the daily time course of migratory restlessness are shown. These results support previous findings concerning biological rhythms of quail and raise questions concerning the timing of migratory behavior.     

Tissue-specific responses of lipoprotein lipase to dietary macronutrient composition as a predictor of weight gain over 4 years

This study evaluated if the effect of dietary macronutrient composition on adipose tissue lipoprotein lipase (ATLPL) and skeletal muscle lipoprotein lipase (SMLPL) predicted the long-term (over 4 years) changes in body weight and composition in free-living adults. Using a crossover design, 39 healthy subjects (n = 24 normal weight, n = 7 overweight, n = 8 obese) each followed a 2-week isocaloric high-carbohydrate (HC; 55% CHO:25% fat) and high-fat (HF; 30% CHO:50% fat) diet. On day 15 of each diet, biopsies were performed in the fasted state and 6 h after a meal. Body weight and composition were measured annually over 4 years. The outcomes for body weight, fat mass and % body fat were assessed using a linear two-stage mixed model. The mean (±SEM) increase in body weight and fat mass over 4 years was 0.29 ± 0.15 kg/year (P = 0.063) and 0.31 ± 0.15 kg/year (P = 0.051), respectively. The most consistent predictors of future body weight and fat changes were the ΔATLPL and ΔSMLPL responses (0-6 h) to a HC diet/meal. For the HC diet/meal, the subjects who had an increase in ATLPL activity/cell gained more % body fat over 4 years (P = 0.006) whereas subjects who had a decrease in SMLPL activity/g also had an increase in fat mass (P = 0.021). No significant relationships were observed between fasting ATLPL and SMLPL or enzyme responses to meals and any of the outcomes following the HF diet. In free-living adults the variability in tissue-specific lipoprotein lipase (LPL) responsiveness to a HC diet/meal predicts longitudinal changes in body composition.     

Timing of nocturnal autumn migratory departures in juvenile European robins (Erithacus rubecula) and endogenous and external factors

Many passerine medium distance nocturnal migrants take off from stopover sites not only at the beginning of the night, but also in the middle and at the end of the night. In this paper, we tested two explanations for this phenomenon: (1) that departure time is governed by fuel stores, and (2) that departure time is influenced by the weather. The relationship of temporal distribution of migratory nocturnal departures with body condition and weather factors was studied in juvenile European robins (Erithacus rubecula) during autumn migration. The study was done on the Courish Spit on the Baltic Sea in 1997–2003 by retrapping 74 ringed birds in high mist nets during nocturnal migratory departure. Departure time was not related to fuel stores at arrival and departure, stopover duration, fuel deposition rate or progress of the season. Nor did the local weather at departure influence departure time. A possible reason was a large variation in the behaviour of the birds. European robins which made 1-day stopovers arrived and departed during better weather conditions than birds that stopped over for longer periods. In the former cohort, a significant model with four predictors explained 55% of variation in departure time. It is assumed that weather at the night of departure and during the previous night influenced the time of take-offs in these birds. In robins which made long stopovers, departure time is probably governed by their individual endogenous circadian rhythms of activity, which are related to the environment in a complex way.     

During stopover, migrating blackcaps adjust behavior and intake of food depending on the content of protein in their diets

During migration, birds undergo alternating periods of fasting and re-feeding that are associated with dynamic changes in body mass (m(b)) and in organ size, including that of the digestive tract. After arrival at a migratory stopover site, following a long flight, a bird must restore the tissues of its digestive tract before it can refuel. In the present study we examined how the availability of dietary protein influences refueling of migrating blackcaps (Sylvia atricapilla) during a migratory stopover. We tested the following predictions in blackcaps deprived of food and water for 1-2 days to induce stopover behavior: (1) birds provided with a low-protein diet will gain m(b), lean mass and fat mass, and increase in pectoral muscle size slower than do birds fed a high-protein diet; (2) since stopover time is shorter in spring, birds will gain m(b) and build up fat tissue and lean tissue faster than in autumn; and (3) if low dietary protein limits a bird's ability to gain m(b) and fat reserves, then birds that do not obtain enough protein will initiate migratory restlessness (Zugunruhe) earlier than will birds with adequate dietary protein. These predictions were tested by providing captured migrating blackcaps with semisynthetic isocaloric diets differing only in their protein content. Each day, we measured m(b), and food intake; also lean mass and fat mass were measured using dual energy X-ray absorptiometry. In addition, we monitored nocturnal activity with a video recording system. In both spring and autumn, birds fed diets containing either 3 or 20% protein increased in m(b), lean mass and fat mass at similar rates during the experiment. However, the group receiving 3% protein ate more than did the group receiving 20% protein. In support of our predictions, m(b), lean mass, fat mass, and intake of food all were higher in spring than in autumn. We also found that in spring all birds had higher levels of migratory restlessness, but birds fed 3% protein were less active at night than were birds fed 20% protein, possibly an adaptation conserving energy and protein. We conclude that protein requirements of migrating blackcaps during stopover are lower than expected, and that birds can compensate for low dietary protein by behavioral responses, i.e. hyperphagia and decreased migratory restlessness, that ensure rapid refueling.     

Tissue-Specific Lipoprotein Lipase: Relationships to Body Composition and Body Fat Distribution in Normal Weight Humans

Twenty-six normal weight subjects (22 female, 4 male) were studied to determine the relationships of fasting levels of lipoprotein lipase in gluteal adipose tissue (ATLPL) and skeletal muscle (SMLPL) to body composition and body fat distribution. No relationship was found between fasting gluteal ATLPL and percent (%) body fat There was, however, an inverse relationship between fasting SMLPL (from the vastus lateralis) and %body fat (p=0.005). A strong inverse correlation was also seen between fasting ATLPL and waist/hip ratio (p=0.0006), a measurement of body fat distribution. These relationships existed with or without the male subjects included. The tissue-specific relationships of lipoprotein lipase to body composition and body fat distribution could relate to the development of obesity or the maintenance of normal body weight by the effects of the lipase on the partitioning of lipoprotein triglyceride fatty acids.     

Lipogenesis and lipoprotein lipase in human adipose tissue: reproducibility of measurements and relationships with fat cell size

Lipogenesis from glucose and lipoprotein lipase activity were investigated in humans. The reliability of measurements was quantified and correlations with fat cell weight were assessed. Twenty-four subjects (7 women, 17 men) were studied twice within a 2-week period, along with 17 additional male subjects who were studied once and used only in the correlation analyses. All subjects were not regularly involved in an exercise-training program and were between 18 and 30 years of age. Following an overnight fast, adipose tissue specimens were obtained by suprailiac biopsy and fat cells were collagenase isolated. Mean fat cell weight was obtained from 400 to 500 cell diameter determinations per subject. Basal and insulin-stimulated fat cell lipogenesis from glucose were determined using D-[U-14C]glucose and were reported in nanomoles of glucose per hour per 10(6) cells. Adipose tissue heparin-releasable lipoprotein lipase activity was also determined and expressed in micromoles of free fatty acids per hour per gram of tissue and per 10(6) cells. Fat cell weight, basal and insulin-stimulated lipogenesis and lipoprotein lipase activity per gram showed high reliability of measurement, interclass and intraclass coefficients being 0.83 and over. Lipoprotein lipase activity per 10(6) cells showed a somewhat lower degree of reliability, interclass and intraclass coefficients being, respectively, 0.69 and 0.81. On the other hand, fat cell weight was positively correlated with lipoprotein lipase activity (r = 0.80), while no significant correlation was observed between basal lipogenesis and fat cell weight. Moreover, basal lipogenesis presented no significant correlation with lipoprotein lipase activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dietary fish oil reverse epididymal tissue adiposity, cell hypertrophy and insulin resistance in dyslipemic sucrose fed rat model small star, filled

The present work was designed to assess the possible benefits of (7% w/w) dietary fish oil in reversing the morphological and metabolic changes present in the adipose tissue of rats fed an SRD for a long time. With this purpose, in the epididymal fat tissue, we investigated the effect of dietary fish oil upon: i) the number, size and distribution of cells, ii) the basal and stimulated lipolysis, iii) the lipoprotein lipase (LPL) and the glucose 6-phosphate dehydrogenase activities, and iv) the antilipolytic action of insulin. The study was conducted on rats fed an SRD during 120 days with fish oil being isocaloric substituted for corn oil for 90-120 days in half the animals. Permanent hypertriglyceridemia, insulin resistance and abnormal glucose homeostasis were present in the rats before the source of fat in the diet was replaced. The major new findings of this study are the following: i) Dietary fish oil markedly reduced the fat pads mass, the hypertrophy of fat cells and improved the altered cell size distribution. ii) The presence of fish oil in the diet corrected the inhibitory effect of high sucrose diet upon the antilipolytic action of insulin, reduced the "in vitro" enhanced basal lipolysis and normalized isoproterenol-stimulated lipolysis. Fat pads lipoprotein lipase activity decreased reaching values similar to those observed in age-matched controls fed a control diet (CD). These effects were not accompanied by any change in rat body weight. All these data suggest that the dyslipemic rats fed a moderate amount of dietary fish oil constitute a useful animal model to study diet-regulated insulin action.     

Effects of Arachis hypogaea nutshell extract on lipid metabolic enzymes and obesity parameters

The aim of the present study was to assess the effects of peanut (Arachis hypogaea L.) shell extracts (PSE) on lipases and to evaluate its potential development for the treatment of obesity. The peanut shells were extracted in 95% ethanol, and the extracts were screened for inhibitory effects on pancreatic lipase (PL) and lipoprotein lipase (LPL) activities as well as on lipolysis of 3T3-L1 adipocytes. We also examined in vivo whether PSE could prevent the body weight gain induced by feeding a high-fat diet to male Wistar rats for 12 weeks. PSE inhibits a number of lipases, including PL, LPL and, possibly, hormone sensitive lipase (HSL). PSE-treated Wistar rats showed increased fecal lipid excretion respect to the control group. Body weight and body weight gain, and liver size, were significantly lower in rats fed the high-fat diet with 1% of PSE (w:w diet) than in those fed the high-fat diet alone. The rats treated with PSE showed reduced triacylglycerol content in the liver, as well as the serum glucose and insulin. The inhibitory activity of PSE on the lipid metabolic enzymes and the increase in fecal fat excretion suggests that PSE might be useful as a treatment to reduce the dietary fat absorption. The observed reduction in intracellular lipolytic activity of cultured 3T3-L1 adipocytes may reduce the levels of circulating free fatty acids. The observed effects are likely induced by more than one bioactive component of PSE. The PSE actions may, at least in part, be attributed to the inhibition of fat absorption in the digestive tract and the reduction of the adipocyte lipolysis.     

Triglyceride with medium-chain fatty acids increases the activity and expression of hormone-sensitive lipase in white adipose tissue of C57BL/6J mice

We have previously shown that medium-chain triglyceride (MCT) resulted in significantly less body fat mass than long-chain triglyceride (LCT) did in hypertriglyceridimic subjects. The possible mechanism for this was investigated by measuring and analyzing changes in the body fat, blood lipid profile, enzymatic level and activity of hormone-sensitive lipase (HSL) and its mRNA expression, and levels of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in white adipose tissue (WAT) of C57BL/6J mice fed for 16 weeks on an MCT or LCT diet. MCT induced lower body weight and body fat, and an improved blood lipid profile than LCT did. The enzymatic level and activity of HSL and its mRNA expression, and the levels of cAMP and PKA were significantly higher in WAT of mice fed with the MCT diet. No significant differences in the levels of lipoprotein lipase and peroxisome proliferator-activated receptor-γ in WAT were apparent between the effects of MCT and LCT. It is concluded that lipolysis by the increased level and activity of HSL, which was induced by the activation of cAMP-dependent PKA in WAT, was partially responsible for the lower fat accumulation in C57BL/6J mice fed with MCT.     

The 20-kD human growth hormone reduces body fat by increasing lipolysis and decreasing lipoprotein lipase activity

AIM: The aim of this study was to estimate the lipolytic activity of the human growth hormone variant, 20-kD human growth hormone (20K-hGH). METHODS: Obese KV-A(y) mice were given daily subcutaneous injections of 20K-hGH (0.25, 0.5, 1.0 mg/kg), 22K-hGH (0.25 mg/kg) or saline as a control for 2 weeks. Body composition (fat, water and protein), lipolysis and lipoprotein lipase (LPL) activity were measured 24 h after the final injection. RESULTS: Both growth hormone isoforms significantly reduced relative fat pad and whole body lipids. In addition, 20K-hGH produced an inhibition of LPL activity in adipose tissue and stimulated lipolysis in adipocytes. CONCLUSION: These data strongly suggest that inhibition of LPL activity in adipose tissue and stimulation of lipolysis in adipocytes by 20K-hGH treatment reduce adipose tissue mass, resulting in body fat reduction.     

Skeletal muscle adiposity is associated with serum lipid and lipoprotein levels in Afro‐Caribbean men

Objective: When compared with other ethnic groups, African ancestry individuals have lower triglycerides and higher High‐density lipoprotein cholesterol (HDL‐C) levels, although the mechanisms for these differences remain unclear. A comprehensive array of factors potentially related to fasting serum lipid and lipoprotein levels in African ancestry men was evaluated. Design and Methods: Men (1,821) underwent dual‐energy X‐ray absorptiometry measures of total body fat and quantitative computed tomography assessments of calf skeletal muscle adiposity [subcutaneous and intermuscular adipose tissue (AT), and muscle density as a measure of intra‐muscular AT]. Results: Multivariable linear regression analysis identified age (?), total body fat (+), subcutaneous AT (?), fasting glucose (+), fasting insulin (+), diastolic blood pressure (+), and non‐African ancestry (+) as independent correlates of triglycerides (all P < 0.05). Total body fat (+), intra‐muscular AT (?), and diastolic blood pressure (+) were independent correlates of Low‐density lipoprotein cholesterol (LDL‐C) (all P < 0.001). Age (+), waist circumference (?), fasting insulin (?), physical activity (+), and alcohol intake (+) were independent correlates of HDL‐C (all P < 0.05). Conclusions: A novel relationship between skeletal muscle adiposity and serum lipid and lipoprotein levels in African ancestry men, independent of total and central adiposity was illuminated. In African ancestry populations, genetic factors are likely a significant determinant of triglycerides levels.     

Gluten-free diet reduces adiposity,inflammation and insulin resistance associated with the induction of PPAR-alpha and PPAR-gamma expression

Gluten exclusion (protein complex present in many cereals) has been proposed as an option for the prevention of diseases other than coeliac disease. However, the effects of gluten-free diets on obesity and its mechanisms of action have not been studied. Thus, our objective was to assess whether gluten exclusion can prevent adipose tissue expansion and its consequences. C57BL/6 mice were fed a high-fat diet containing 4.5% gluten (Control) or no gluten (GF). Body weight and adiposity gains, leukocyte rolling and adhesion, macrophage infiltration and cytokine production in adipose tissue were assessed. Blood lipid profiles, glycaemia, insulin resistance and adipokines were measured. Expression of the PPAR-α and γ, lipoprotein lipase (LPL), hormone sensitive lipase (HSL), carnitine palmitoyl acyltransferase-1 (CPT-1), insulin receptor, GLUT-4 and adipokines were assessed in epidydimal fat. Gluten-free animals showed a reduction in body weight gain and adiposity, without changes in food intake or lipid excretion. These results were associated with up-regulation of PPAR-α, LPL, HSL and CPT-1, which are related to lipolysis and fatty acid oxidation. There was an improvement in glucose homeostasis and pro-inflammatory profile-related overexpression of PPAR-γ. Moreover, intravital microscopy showed a lower number of adhered cells in the adipose tissue microvasculature. The overexpression of PPAR-γ is related to the increase of adiponectin and GLUT-4. Our data support the beneficial effects of gluten-free diets in reducing adiposity gain, inflammation and insulin resistance. The data suggests that diet gluten exclusion should be tested as a new dietary approach to prevent the development of obesity and metabolic disorders.     

Medium‐Chain Oil Reduces Fat Mass and Down‐regulates Expression of Adipogenic Genes in Rats

Objective: To test the hypothesis that adipose tissue could be one of the primary targets through which medium‐chain fatty acids (MCFAs) exert their metabolic influence. Research Methods and Procedures: Sprague‐Dawley rats were fed a control high‐fat diet compared with an isocaloric diet rich in medium‐chain triglycerides (MCTs). We determined the effects of MCTs on body fat mass, plasma leptin and lipid levels, acyl chain composition of adipose triglycerides and phospholipids, adipose tissue lipoprotein lipase activity, and the expression of key adipogenic genes. Tissue triglyceride content was measured in heart and gastrocnemius muscle, and whole body insulin sensitivity and glucose tolerance were also measured. The effects of MCFAs on lipoprotein lipase activity and adipogenic gene expression were also assessed in vitro using cultured adipose tissue explants or 3T3‐L1 adipocytes. Results: MCT‐fed animals had smaller fat pads, and they contained a considerable amount of MCFAs in both triglycerides and phospholipids. A number of key adipogenic genes were down‐regulated, including peroxisome proliferator activated receptor γ and CCAAT/enhancer binding protein α and their downstream metabolic target genes. We also found reduced adipose tissue lipoprotein lipase activity and improved insulin sensitivity and glucose tolerance in MCT‐fed animals. Analogous effects of MCFAs on adipogenic genes were found in cultured rat adipose tissue explants and 3T3‐L1 adipocytes. Discussion: These results suggest that direct inhibitory effects of MCFAs on adiposity may play an important role in the regulation of body fat development.