Despite the lipolysis-lipogenesis cycle being a fundamental process in adipocyte biology, very little is known about the morphological changes that occur during this process. The remodeling of lipid droplets to form micro lipid droplets (mLDs) is a striking feature of lipolysis in adipocytes, but once lipolysis ceases, the cell must regain its basal morphology. We characterized mLD formation in...

This study determined the role of intramuscular triglyceride (IMTG) and adipose lipolysis in the elevated fat oxidation during exercise caused by a high-fat diet. In four separate trials, six endurance-trained cyclists exercised at 50% peak O2 consumption for 1 h after a two-day control diet (22% fat, CON) or an isocaloric high-fat diet (60% fat, HF) with or without the ingestion of acipimox, a...

Tumor necrosis factor-alpha (TNF alpha) is a cytokine with multiple biological functions which, in mammals, has been shown to modulate muscle and adipose tissue metabolism. In fish, TNF alpha has been identified in several species. However, few studies have examined the role of TNF alpha in fish outside the immune system. In this study, we assessed the effects of human recombinant TNF alpha and...

Rapid oscillations of visceral lipolysis have been reported. To examine the putative role of the CNS in oscillatory lipolysis, we tested the effects of beta(3)-blockade on pulsatile release of FFAs. Arterial blood samples were drawn at 1-minute intervals for 120 minutes from fasted, conscious dogs (n = 7) during the infusion of saline or bupranolol (1.5 micro g/kg/min), a high-affinity beta(3)-...

The calorigenic action of norepinephrine in isolated brown adipocytes was selectively mimicked by theophylline, dibutyryl cyclic AMP, and the principal fatty acids known to be present in the acyl moieties of brown adipose tissue triglycerides (palmitic, oleic, and linoleic acids). The stimulatory effects of fatty acids were entirely reversible, occurred at physiological concentrations, and were...

Prolyl hydroxylase enzymes (PHDs) sense cellular oxygen upstream of hypoxia-inducible factor (HIF) signaling, leading to HIF degradation in normoxic conditions. In this study, we demonstrate that adipose PHD2 inhibition plays a key role in the suppression of adipocyte lipolysis. Adipose Phd2 gene ablation in mice enhanced adiposity, with a parallel increase in adipose vascularization associated...

Hypoglycemia, a major side effect of intensive glucose-lowering therapy, was recently linked to increased cardiovascular risk in patients with diabetes. Whether increased circulating free fatty acids (FFA) owing to catecholamine-induced lipolysis affect myocardial energy metabolism and thus link hypoglycemia to cardiac vulnerability is unclear. Therefore, this study investigated the impact of h...

Effects of dietary cimaterol (5 mg/kg) on adipose tissue metabolism of wether lambs were studied. Lipogenesis, lipolysis, fatty acid composition and adipocyte size and number were measured. Cimaterol feeding increased lipogenesis; however, this effect was not statistically significant. Insulin (1,000 microU/ml) stimulated lipogenesis of adipose tissue from control sheep. However, this elevated ...

HIV protease inhibitors (HPIs) are potent antiretroviral agents clinically used in the management of HIV infection. Recently, HPI therapy has been linked to the development of a metabolic syndrome in which adipocyte insulin resistance appears to play a major role. In this study, we assessed the effect of nelfinavir on glucose uptake and lipolysis in differentiated 3T3-L1 adipocytes. An 18-h exp...

Though two isoforms of nitric oxide synthase, iNOS and eNOS, were reported in adipocytes, the role of NO in adipose tissue is still ambiguous. The aims of the present study were 1) to follow the effect of bacterial lipopolysaccharide (LPS), on 24 h-lipolysis in rat epididymal adipocyte culture in relation to iNOS stimulation; 2) to compare LPS-induced NO effects with exogenously NO, delivered a...