Energy Metabolism Changes and Dysregulated Lipid Metabolism in Postmenopausal Women

Aging women experience hormonal changes, such as decreased estrogen and increased circulating androgen, due to natural or surgical menopause. These hormonal changes make postmenopausal women vulnerable to body composition changes, muscle loss, and abdominal obesity; with a sedentary lifestyle, these changes affect overall energy expenditure and basal metabolic rate. In addition, fat redistribution due to hormonal changes leads to changes in body shape. In particular, increased bone marrow-derived adipocytes due to estrogen loss contribute to increased visceral fat in postmenopausal women. Enhanced visceral fat lipolysis by adipose tissue lipoprotein lipase triggers the production of excessive free fatty acids, causing insulin resistance and metabolic diseases. Because genes involved in β-oxidation are downregulated by estradiol loss, excess free fatty acids produced by lipolysis of visceral fat cannot be used appropriately as an energy source through β-oxidation. Moreover, aged women show increased adipogenesis due to upregulated expression of genes related to fat accumulation. As a result, the catabolism of ATP production associated with β-oxidation decreases, and metabolism associated with lipid synthesis increases. This review describes the changes in energy metabolism and lipid metabolic abnormalities that are the background of weight gain in postmenopausal women.

Correction to: Effects of acute hypoxia on human adipose tissue lipoprotein lipase activity and lipolysis

An amendment to this paper has been published and can be accessed via the original article.

Acute hypoxia induces hypertriglyceridemia by decreasing plasma triglyceride clearance in mice

Obstructive sleep apnea (OSA) induces intermittent hypoxia (IH) during sleep and is associated with elevated triglycerides (TG). We previously demonstrated that mice exposed to chronic IH develop elevated TG. We now hypothesize that a single exposure to acute hypoxia also increases TG due to the stimulation of free fatty acid (FFA) mobilization from white adipose tissue (WAT), resulting in increased hepatic TG synthesis and secretion. Male C57BL6/J mice were exposed to FiO2 = 0.21, 0.17, 0.14, 0.10, or 0.07 for 6 h followed by assessment of plasma and liver TG, glucose, FFA, ketones, glycerol, and catecholamines. Hypoxia dose-dependently increased plasma TG, with levels peaking at FiO2 = 0.07. Hepatic TG levels also increased with hypoxia, peaking at FiO2 = 0.10. Plasma catecholamines also increased inversely with FiO2. Plasma ketones, glycerol, and FFA levels were more variable, with different degrees of hypoxia inducing WAT lipolysis and ketosis. FiO2 = 0.10 exposure stimulated WAT lipolysis but decreased the rate of hepatic TG secretion. This degree of hypoxia rapidly and reversibly delayed TG clearance while decreasing [3H]triolein-labeled Intralipid uptake in brown adipose tissue and WAT. Hypoxia decreased adipose tissue lipoprotein lipase (LPL) activity in brown adipose tissue and WAT. In addition, hypoxia decreased the transcription of LPL, peroxisome proliferator-activated receptor-γ, and fatty acid transporter CD36. We conclude that acute hypoxia increases plasma TG due to decreased tissue uptake, not increased hepatic TG secretion.

Effect of 1,3,5,8-tetrahydroxyxanthone on carcass characteristics and meat quality traits in pigs

Angiopoietin-like protein 3 (Angptl3) may promote adipose formation. The present study investigated the beneficial effect of 1,3,5,8-tetrahydroxyxanthone (Xan), a naturally occurring polyphenol agent, on carcass characteristics and meat quality in pigs and the mechanisms involved. Forty-eight Duroc × Landrace × Yorkshire pigs (65.3 ± 7.8 kg) were randomly divided into four groups: control group, untreated high lipid diet (HLD) group and two groups of HLD with Xan (1 or 3%). Forty-two days later, Xan (1 or 3%) treatment significantly increased percentage lean, loin eye area, colour, expression and activity of adipose tissue lipoprotein lipase activity and decreased percentage fat, backfat thickness, total cholesterol concentration, triglyceride concentration, and Angptl3 mRNA expression. The present results suggest that the beneficial effect of Xan on carcass characteristics and meat quality may be related to decreased expression of Angptl3 in pig.