Resistance Exercise Training Improves Metabolic and Inflammatory Control in Adipose and Muscle Tissues in Mice Fed a High-Fat Diet.

This study investigates whether ladder climbing (LC), as a model of resistance exercise, can reverse whole-body and skeletal muscle deleterious metabolic and inflammatory effects of high-fat (HF) diet-induced obesity in mice. To accomplish this, Swiss mice were fed for 17 weeks either standard chow (SC) or an HF diet and then randomly assigned to remain sedentary or to undergo 8 weeks of LC training with progressive increases in resistance weight. Prior to beginning the exercise intervention, HF-fed animals displayed a 47% increase in body weight (BW) and impaired ability to clear blood glucose during an insulin tolerance test (ITT) when compared to SC animals.

Cold acclimation enhances UCP1 content, lipolysis, and triacylglycerol resynthesis, but not mitochondrial uncoupling and fat oxidation, in rat white adipocytes.

The objective of this study was to investigate whether cold-induced browning of the subcutaneous (Sc) inguinal (Ing) white adipose tissue (WAT) increases the capacity of this tissue to oxidize fatty acids through uncoupling protein 1 (UCP1)-mediated thermogenesis. To accomplish that, rats were acclimated to cold (4°C for 7 days). Subsequently, interscapular and aortic brown adipose tissues (iBAT and aBAT, respectively), epididymal (Epid), and Sc Ing WAT were used for adipocyte isolation.

Endothelial-specific FoxO1 depletion prevents obesity-related disorders by increasing vascular metabolism and growth.

Impaired angiogenesis is a hallmark of metabolically dysfunctional adipose tissue in obesity. However, the underlying mechanisms restricting angiogenesis within this context remain ill-defined. Here, we demonstrate that induced endothelial-specific depletion of the transcription factor Forkhead Box O1 (FoxO1) in male mice led to increased vascular density in adipose tissue.

Circulating fibroblast growth factor 21 is reduced, whereas its production is increased in a fat depot-specific manner in cold-acclimated rats.

This study investigated the effects of cold acclimation on circulating fibroblast growth factor 21 (FGF21) levels, as well as its production and signaling in classical brown and white adipose tissues. Male Wistar rats were cold (4°C) acclimatized for 7 days. Subsequently, liver, interscapular and aortic BAT (iBAT and aBAT), and the Sc Ing and epididymal (Epid) white adipose tissues were extracted.

Cold acclimation reduces hepatic protein Kinase B and AMP-activated protein kinase phosphorylation and increases gluconeogenesis in Rats.

This study investigated the molecular and metabolic responses of the liver to cold-induced thermogenesis. To accomplish that, male Wistar rats were exposed to cold (4°C) for 7 days. Livers were then extracted and used for the determination of glucose and fatty acid oxidation, glycogen content, the expression and content of proteins involved in insulin signaling, as well as in the regulation of gluconeogenesis and de novo lipid synthesis.

White and beige adipocytes: are they metabolically distinct?

The white adipose tissue (WAT) exhibits great plasticity and can undergo "browning" and acquire features of the brown adipose tissue (BAT), which takes place following cold exposure, chronic endurance exercise or β3-adrenergic stimulation. WAT that underwent browning is characterized by the presence of "beige" adipocytes, which are morphologically similar to brown adipocytes, express uncoupling protein 1 (UCP1) and are considered thermogenically competent. Thus, inducing a BAT-like phenotype in the WAT could promote energy dissipation within this depot, reducing the availability of substrate that would otherwise be stored in the WAT.

Cold acclimation causes fiber type-specific responses in glucose and fat metabolism in rat skeletal muscles.

This study investigated fiber type-specific metabolic responses and the molecular mechanisms that regulate glucose and fat metabolism in oxidative and glycolytic muscles upon cold acclimation. Male Wistar rats were exposed to cold (4 °C) for 7 days, and then glycogen synthesis and content, glucose and palmitate oxidation, and the molecular mechanisms underlying these metabolic pathways were assessed in soleus (Sol), extensor digitorum longus (EDL), and epitrochlearis (Epit) muscles. Cold acclimation increased glycogen synthesis, glycogen content, glucose oxidation, and reduced glycogen synthase (GS) phosphorylation only in Sol muscles.

High-fat diet induces skeletal muscle oxidative stress in a fiber type-dependent manner in rats.

This study investigated the effects of high-fat (HF) diet on parameters of oxidative stress among muscles with distinct fiber type composition and oxidative capacities. To accomplish that, male Wistar rats were fed either a low-fat standard chow (SC) or a HF diet for 8 weeks. Soleus, extensor digitorum longus (EDL), and epitrochlearis muscles were collected and mitochondrial HO (mtHO) emission, palmitate oxidation, and gene expression and antioxidant system were measured.

Antilipolytic and antilipogenic effects of the CPT-1b inhibitor oxfenicine in the white adipose tissue of rats.

Oxfenicine is a carnitine-palmitoyl transferase 1b (CPT-1b)-specific inhibitor that has been shown to improve whole body insulin sensitivity while suppressing fatty acid (FA) oxidation and increasing circulating FA. Because the white adipose tissue (WAT) is an organ that stores and releases FAs, this study investigated whether oxfenicine-induced inhibition of FA oxidation affected adiposity and WAT metabolism in rats fed either low (LF) or high-fat (HF) diets. Following 8 wk of dietary intervention, male Sprague-Dawley rats were given a daily intraperitoneal injection of oxfenicine (150 mg/kg body wt) or vehicle (PBS) for 3 wk.

Exercise-Mediated Effects on White and Brown Adipose Tissue Plasticity and Metabolism.

Exercise training increases the thermogenic capacity of white adipose tissue (WAT), an effect known as "browning" of the WAT. Here, we discuss how this affects whole-body energy homeostasis. We put forth the hypothesis that browning of the subcutaneous WAT allows the organism to adjust its metabolic rate according to energy availability while coping with increased heat production through exercise.

Lipolysis, lipogenesis, and adiposity are reduced while fatty acid oxidation is increased in visceral and subcutaneous adipocytes of endurance-trained rats.

This study examined the alterations in triglyceride (TG) breakdown and storage in subcutaneous inguinal (SC Ing) and epididymal (Epid) fat depots following chronic endurance training. Male Wistar rats were either kept sedentary (Sed) or subjected to endurance training (Ex) at 70-85% peak VO2 for 6 weeks. At weeks 0, 3, and 6 blood was collected at rest and immediately after a bout of submaximal exercise of similar relative intensity to assess whole-body lipolysis.