Atrial Natriuretic Peptide Induces Postprandial Lipid Oxidation in Humans

OBJECTIVE—Atrial natriuretic peptide (ANP) regulates arterial blood pressure. In addition, ANP has recently been shown to promote human adipose tissue lipolysis through cGMP-mediated hormone-sensitive lipase activation. We hypothesized that ANP increases postprandial free fatty acid (FFA) availability and energy expenditure while decreasing arterial blood pressure

Is metabolic flexibility altered in multiple sclerosis patients?

OBJECTIVES: Metabolic flexibility is defined as ability to adjust fuel oxidation to fuel availability. Multiple sclerosis (MS) results in reduced muscle strength and exercise intolerance. We tested the hypothesis that altered metabolic flexibility contributes to exercise intolerance in MS patients. METHODS: We studied 16 patients (all on glatiramer) and 16 matched healthy controls. Energy expenditure (EE), and carbohydrate (COX) and lipid oxidation (LOX) rates were determined by calorimetry, before and after an oral glucose load. We made measurements either at rest (canopy device) or during 40 min low-grade (0.5 W/kg) exercise (metabolic chamber). We also obtained plasma, and adipose tissue and skeletal muscle dialysate samples by microdialysis to study tissue-level metabolism under resting conditions. RESULTS: At rest, fasting and postprandial plasma glucose, insulin, and free fatty acid levels did not differ between patients and controls. Fasting and postprandial COX was higher and LOX lower in patients. In adipose, fasting and postprandial dialysate glucose, lactate, and glycerol levels were higher in patients vs. controls. In muscle, fasting and postprandial dialysate metabolite levels did not differ significantly between the groups. During exercise, EE did not differ between the groups. However, COX increased sharply over 20 min in patients, without reaching a steady state, followed by an immediate decrease within the next 20 min and fell even below basal levels after exercise in patients, compared to controls. CONCLUSIONS: Glucose tolerance is not impaired in MS patients. At rest, there is no indication for metabolic inflexibility or mitochondrial dysfunction in skeletal muscle. The increased adipose tissue lipolytic activity might result from glatiramer treatment. Autonomic dysfunction might cause dysregulation of postprandial thermogenesis at rest and lipid mobilization during exercise

Metabolic response to daytime dry fasting in Bahá'í volunteers -- results of a preliminary study

Each year in March, adherents of the Bahá'í faith abstain from eating and drinking from sunrise to sunset for 19 days. Thus, Bahá'í fasting (BF) can be considered as a form of daytime dry fasting. We investigated whether BF decreased energy expenditure after a meal and whether it improved anthropometric measures and systemic and tissue-level metabolic parameters. This was a self-controlled cohort study with 11 healthy men. We measured anthropometric parameters, metabolic markers in venous blood and pre- and postprandial energy metabolism at systemic (indirect calorimetry) and tissue (adipose tissue and skeletal muscle microdialysis) level, both before and during BF. During BF, we found reduced body weight, body mass index, body fat and blood glucose. Postprandial increase in energy expenditure was lower and diet-induced thermogenesis tended to be lower as well. In adipose tissue, perfusion, glucose supply and lipolysis were increased. In skeletal muscle, tissue perfusion did not change. Glucose supply and lipolysis were decreased. Glucose oxidation was increased, indicating improved insulin sensitivity. BF may be a promising approach to losing weight and improving metabolism and health. However, outside the context of religiously motivated fasting, skipping a meal in the evening (dinner cancelling) might be recommended, as metabolism appeared to be reduced in the evening

The Region Specific Influence of Estradiol on In-Vivo Lipolysis in Subcutaneous Adipose Tissue in Overweight-to-Moderately-Obese Premenopausal Women

Premenopausal women demonstrate preferential accumulation of adiposity in the gynoid region, a distribution which shifts towards the abdominal region after the menopausal transition. Although estrogen is implicated as a major player in determining body fat distribution the mechanisms behind estrogenic action(s) in adipose tissue of women are still unclear. The global aim of this project was to determine if local estrogen influences regional adiposity in premenopausal women. Specifically, we investigated the influence of local estradiol on adipose tissue lipolysis as well as estrogen receptor content and adipocyte size in abdominal and gluteal subcutaneous adipose tissue of overweight-to-moderately-obese premenopausal women.    Eighteen overweight-to-moderately-obese Caucasian (CA, n=9) and African American (AA, n=9) women were recruited. Between 15 and 17 of these women took part in each of the three studies. We found the influence of estradiol on lipolysis to be adipose tissue depot specific and treatment dependent, with estradiol perfusion blunting the response to lipolytic stimulation under some conditions while potentiating this response in others. Furthermore, we found differences in abdominal and gluteal estrogen receptor alpha and estrogen receptor beta protein content, potentially revealing region specific actions of estrogen through these estrogen receptors in adipose tissue. Finally, we found racial differences in adipose tissue morphology, as indicated by variations in adipocyte diameter populations in CA and AA women (higher proportion of medium size adipocytes in abdominal and gluteal subcutaneous adipose tissue of CA and higher proportion of small adipocytes in gluteal region of AA) which could underlie the increased chronic disease risk in AA compared to CA women for a given body mass index (BMI).   Our findings indicate depot specific influence of estradiol on lipid mobilization may play a role in the predominant gluteal-femoral body fat distribution of premenopausal women. It is possible that depot specific effects of estradiol may be a result of regional differences in estrogen receptor content. Racial divergence in adipocyte morphology is an adipose tissue characteristic potentially underlying differing disease risk between CA and AA women of similar BMI. The integration of these results provides insight towards a more complete understanding of regional adiposity in overweight-to-obese premenopausal women, but future studies must be conducted to uncover the interaction between estrogen receptor content and local estrogen action as well as the direct physiological consequences of these findings.  Ph.D