Pharmacological and genetic increases in liver NADPH levels ameliorate NASH progression in female mice.

Non-alcoholic steatohepatitis (NASH) is one of the fastest growing liver diseases worldwide, and oxidative stress is one of NASH main key drivers. Nicotinamide adenine dinucleotide phosphate (NADPH) is the ultimate donor of reductive power to a number of antioxidant defences. Here, we explored the potential of increasing NADPH levels to prevent NASH progression. We used nicotinamide riboside (NR) supplementation or a G6PD-tg mouse line harbouring an additional copy of the human G6PD gene. In a NASH mouse model induced by feeding mice a methionine-choline deficient (MCD) diet for three weeks, both tools increased the hepatic levels of NADPH and ameliorated the NASH phenotype induced by the MCD intervention, but only in female mice. Boosting NADPH levels in females increased the liver expression of the antioxidant genes Gsta3, Sod1 and Txnrd1 in NR-treated mice, or of Gsr for G6PD-tg mice. Both strategies significantly reduced hepatic lipid peroxidation. NR-treated female mice showed a reduction of steatosis accompanied by a drop of the hepatic triglyceride levels, that was not observed in G6PD-tg mice. NR-treated mice tended to reduce their lobular inflammation, showed a reduction of the NK cell population and diminished transcription of the damage marker Lcn2. G6PD-tg female mice exhibited a reduction of their lobular inflammation and hepatocyte ballooning induced by the MCD diet, that was related to a reduction of the monocyte-derived macrophage population and the Tnfa, Ccl2 and Lcn2 gene expression. As conclusion, boosting hepatic NADPH levels attenuated the oxidative lipid damage and the exhausted antioxidant gene expression specifically in female mice in two different models of NASH, preventing the progression of the inflammatory process and hepatic injury.

Glucosamine Supplementation Improves Physical Performance in Trained Mice.

INTRODUCTION: d-Glucosamine (GlcN) is one of the most widely consumed dietary supplements and complementary medicines in the world and has been traditionally used to attenuate osteoarthritis in humans. GlcN extends life span in different animal models. In humans, its supplementation has been strongly associated with decreased total mortality and improved vascular endothelial function. GlcN acts as a suppressor of inflammation, and by inhibiting glycolysis, it can activate the metabolism of stored fat and mitochondrial respiration. METHODS: The conventional human GlcN dose is 1500 mg·d-1, but extensive evidence indicates that much higher doses are well tolerated. GlcN is one of the supplements that has experienced a greater use in the last years in elite athletes mainly because of its potential chondroprotective effects that may promote cartilage health. However, the possibility of it being an ergogenic aid has not been explored. We aimed to study the potential beneficial effects of GlcN on mitochondrial content, physical performance, and oxidative stress in mice that were aerobically trained and supplemented with three different doses of glucosamine (250, 500, and 1000 mg·kg-1) for 6 wk. We measured exercise performance (grip strength, motor coordination, and running capacity) before and after the training period. Proteins involved in mitochondrial biogenesis (AMPK, PGC-1, NRF-1, SIRT-1, cytochrome c, citrate synthase), markers of oxidative stress (GSSG/GSH) or damage (malondialdehyde, carbonylated proteins), antioxidant enzymes (NRF-2, SOD1, SOD2, catalase, and PRDX6), and MAPKs (p38 and ERK1/2 were also determined in skeletal muscle. RESULTS AND CONCLUSIONS: Our results show that GlcN supplementation in aerobically trained mice, at doses equivalent to those conventionally used in humans, increases the protein levels of mitochondrial biogenesis markers, improves motor coordination, and may have a synergistic effect with exercise training on running distance.