Dietary-challenged mice with Alzheimer-like pathology show increased energy expenditure and reduced adipocyte hypertrophy and steatosis

New insights of acylation stimulating protein in modulating the pathological progression of metabolic syndromes

Obesity is associated with insulin resistance, hypertension, and coronary artery diseases which are grouped as metabolic syndrome. Rather than being a storage for energy, the adipocytes could synthesis and secret diverse hormones and molecules, named as adipokines. Under obese status, the adipocytes are dysfunctional with excessively producing the inflammatory related cytokines, such as interleukin 1 (IL-1), IL-6, and tumor necrosis factor α (TNF-α). Concerning on the vital role of adipokines, it is proposed that one of the critical pathological factors of obesity is the dysfunctional adipocytic pathways. Among these adipokines, acylation stimulating protein, as an adipokine synthesized by adipocytes during the process of cell differentiation, is shown to activate the metabolism of triglyceride (TG) by regulating the catabolism of glucose and free fatty acid (FFA). Recent attention has paid to explore the underlying mechanism whereby acylation stimulating protein influences the biological function of adipocyte and the pathological development of obesity. In the present review, we summarized the progression of acylation stimulating protein in modulating the physiological and hormonal catabolism which affects fat distribution. Furthermore, the potential mechanisms which acylation stimulating protein regulates the metabolism of adipose tissue and the process of metabolic syndrome were also summarized.

Combined exposure to lead and high-fat diet induced neuronal deficits in rats: Anti-neuroinflammatory role of SIRT1

INTRODUCTION

Lead (Pb) exposure and high-fat diet (HFD) trigger neurotoxicity, which may involve neuroinflammation. However, the mechanism by which combined Pb and HFD exposure induces nucleotide oligomerization domain-like receptor family pyrin domain 3 (NLRP3) inflammasome activation has not been fully elucidated.

MATERIAL AND METHODS

The Sprague-Dawley (SD) rat model of exposure to Pb and HFD was established to reveal the influence of co-exposure on cognition and identify signaling clues that mediate neuroinflammation and synaptic dysregulation. PC12 cells was treated with Pb and PA in vitro. Silent information regulator 1 (SIRT1) agonist (SRT 1720) was employed as intervention agent.

RESULTS

Our results showed that Pb and HFD exposure induced cognitive impairment and lead to neurological damage in rats. Meanwhile, Pb and HFD could stimulate the NLRP3 inflammasome assembly and activate caspase 1, releasing proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), further promoting neuronal cell activation and amplifying neuroinflammatory responses. Additionally, our findings suggest that SIRT1 plays a role in Pb and HFD induced neuroinflammation. However, the use of SRT 1720 agonists showed some potential in alleviating these impairments.

CONCLUSION

Pb exposure and HFD intake could induce neuronal damage through activation of the NLRP3 inflammasome pathway and synaptic dysregulation, while the NLRP3 inflammasome pathway may be rescued via activating SIRT1.

Impact of metabolic stress induced by diets, aging and fasting on tissue oxygen consumption

OBJECTIVE

Alterations in mitochondrial function play an important role in the development of various diseases, such as obesity, insulin resistance, steatohepatitis, atherosclerosis and cancer. However, accurate assessment of mitochondrial respiration ex vivo is limited and remains highly challenging. Using our novel method, we measured mitochondrial oxygen consumption (OCR) and extracellular acidification rate (ECAR) of metabolically relevant tissues ex vivo to investigate the impact of different metabolic stressors on mitochondrial function.

METHODS

Comparative analyses of OCR and ECAR were performed in tissue biopsies of young mice fed 12 weeks standard-control (STD), high-fat (HFD), high-sucrose (HSD), or western diet (WD), matured mice with HFD, and 2year-old mice aged on STD with and without fasting.

RESULTS

While diets had only marginal effects on mitochondrial respiration, respiratory chain complexes II and IV were reduced in adipose tissue (AT). Moreover, matured HFD-fed mice showed a decreased hepatic metabolic flexibility and prolonged aging increased OCR in brown AT. Interestingly, fasting boosted pancreatic and hepatic OCR while decreasing weight of those organs. Furthermore, ECAR measurements in AT could indicate its lipolytic capacity.

CONCLUSION

Using ex vivo tissue measurements, we could extensively analyze mitochondrial function of liver, AT, pancreas and heart revealing effects of metabolic stress, especially aging.