Fatty liver of growing rats fed excess lysine and its prevention by adenine or allopurinol

Specific biological responses following dextran-coated ultra-small superparamagnetic particles of iron oxides administration

Aim: The potential bio-related risks of dextran-coated ultra-small superparamagnetic particles of iron oxides (D-USPIO) were assessed. Materials & methods: Metabolic responses of D-USPIO in BALB/C mice were obtained using ¹H-NMR-based metabolomic strategy combined with the traditional biochemical assay. Results: The metabolomic analyses of biological fluids (plasma and urine) and organs (liver, kidney and spleen) indicated that the disturbance, impairment and recovery of the physiological functions were related to the metabolic response to D-USPIO. The correlations between the biofluids and tissue metabolomes described the specific metabolic information of D-USPIO on their in vivo transportation, absorption, biodistribution and excretion. Conclusion: Metabolomic analysis provides preliminary validation for the use of D-USPIO in clinical medicine, and the results help to understand the potential adverse effects of the similar bio-nanomaterials further serve to their synthesis optimization and biocompatibility improvement.

Reactive oxygen species-induced TXNIP drives fructose-mediated hepatic inflammation and lipid accumulation through NLRP3 inflammasome activation

AIMS

Increased fructose consumption predisposes the liver to nonalcoholic fatty liver disease (NAFLD), but the mechanisms are elusive. Thioredoxin-interacting protein (TXNIP) links oxidative stress to NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation and this signaling axis may be involved in fructose-induced NAFLD. Here, we explore the role of reactive oxygen species (ROS)-induced TXNIP overexpression in fructose-mediated hepatic NLRP3 inflammasome activation, inflammation, and lipid accumulation.

RESULTS

Rats were fed a 10% fructose diet for 8 weeks and treated with allopurinol and quercetin during the last 4 weeks. Five millimolars of fructose-exposed hepatocytes (primary rat hepatocytes, rat hepatic parenchymal cells [RHPCs], HLO2, HepG2) were co-incubated with antioxidants or caspase-1 inhibitor or subjected to TXNIP or NLRP3 siRNA interference. Fructose induced NLRP3 inflammasome activation and pro-inflammatory cytokine secretion, janus-activated kinase 2/signal transducers and activators of transcription 3-mediated inflammatory signaling, and expression alteration of lipid metabolism-related genes in cultured hepatocytes and rat livers. NLRP3 silencing and caspase-1 suppression blocked these effects in primary rat hepatocytes and RHPCs, confirming that inflammasome activation alters hepatocyte lipid metabolism. Hepatocellular ROS and TXNIP were increased in animal and cell models. TXNIP silencing blocked NLRP3 inflammasome activation, inflammation, and lipid metabolism perturbations but not ROS induction in fructose-exposed hepatocytes, whereas antioxidants addition abrogated TXNIP induction and diminished the detrimental effects in fructose-exposed hepatocytes and rat livers.

INNOVATION AND CONCLUSIONS

This study provides a novel mechanism for fructose-induced NAFLD pathogenesis by which the ROS-TXNIP pathway mediates hepatocellular NLRP3 inflammasome activation, inflammation and lipid accumulation. Antioxidant-based interventions can inhibit the ROS-TXNIP pathway.

Ammonia: its effects on biological systems, metabolic hormones, and reproduction

The physical, chemical properties of ammonia, its sources and detoxification, its effects in biological systems, its influence upon insulin action and glucose metabolism, and its possible effects on reproduction are discussed. Present chemical methods do not distinguish nonionic from ionic forms. At physiological pH, nonionic ammonia concentrations remain low but are primarily responsible for toxic effects. Thus, biologically significant changes of ammonia concentrations may not be revealed by determinations of ammonia in blood plasma. For these and other reasons the subacute toxicity of ammonia often is unrecognized, and its effects on intermediary metabolism and the hormonal milieu in normal and disease states remain poorly understood. Effects of ammonia may be stimulatory at low concentrations and inhibitory as concentrations rise or exposure is extended. Extensive experiments in eight ureotelic species, including man, show that urinary excretion of orotic acid becomes significantly elevated when the quantity of ammonia presented to the liver exceeds the capacity for normal detoxification. Present evidence with arginine and other intermediates of the urea cycle suggest that these substances influence glucose metabolism and insulin action. Recent studies of dairy cattle provide speculative evidence that high protein feeding or forms of protein that lead to elevated ammonia concentrations in tissue decrease conception rates and increase the calving to conception interval of dairy cows. Limited data concerning luteinizing hormone concentrations and steroid hormone metabolism are insufficient to establish whether differences in reproductive performance are due to changes of hormonal physiology, intrauterine environment, or metabolism.