The effect of Corvitin on the content of bile acids in the liver of rats under conditions of chronic social stress

The article looks at recent research dealing with changes in the bile acid composition of the bile of outbred male rats under chronic social stress (social defeat in daily male confrontations, 14 days) when administered Corvitin (1 mg/kg, intragastrically, 7 days). Chronic social stress was created by daily agonistic interactions between animals. The main fractions of conjugated bile acids – taurocholic, taurohenodeoxycholic and taurodeoxycholic, glycocholic, glycochenodeoxycholic and glycodeoxycholic and free ones – cholic, chenodeoxycholic and deoxycholic were determined by the method of thin layer chromatography of bile. The conjugation index (ratio of the sum of conjugated cholates to the sum of free ones) and hydroxylation (ratio of the sum of trihydroxycholanic bile acids to the sum of dihydroxycholanic ones) of bile acids were calculated. The research showed that in the conditions of experimental social stress, Corvitin enhances the conjugation of bile acids with taurine and glycine, i.e. stimulates detoxification processes in hepatocytes. In the conditions of chronic social stress in male rats, the processes that had provided the flow of glycoconjugates of bile acids from hepatocytes to the bile ducts were further suppressed. The concentrations of glycocholic acid and glycochenodeoxycholic and glycodeoxycholic acids in the bile of male intruders were lower than the control values. But, as seen in the experiment, the use of Corvitin normalized these indicators. The experiment showed that in the conditions of chronic social stress, the content of cholic acid in the bile of intruder rats decreased, and when correcting the pathological condition using Corvitin, it reached the control values. The use of Corvitin simultaneously with the simulation of experimental social stress normalized the biliary secretory function of the liver, indicating the high potential of using Corvitin as a corrective factor in chronic social stress. Correction of stress-induced pathologies of liver bile-secretory function by Corvitin requires further thorough experimental studies.

Short-term fasting reshapes fat tissue

Intermittent fasting, which can effectively reduce obesity and improve the related metabolic syndrome has become an exciting research area in recent years. Adipose tissue is pivotal in regulating the metabolism and determining the occurrence of obesity. In the current study, we aimed to investigate the effects of acute fasting (AF) on fat tissue. Mice were subjected to AF for 36 h, receiving normal chow (low-fat diet [LFD]) or a high-fat diet (HFD), with free ad libitum access to drinking water, and those fed on free-diet counterparts without fasting serveding as controls. We found that AF obviously reshaped the morphology of fat tissue (WAT) and promoted the beiging of white adipose tissue in both LFD- and HFD-fed mice. AF principally improved the lipid metabolism, and increased the M2- polarization of macrophages in WAT white fat tissue of HFD-fed mice. Interestingly, we found that AF dramatically upregulated Sirt5 expression levels and fat tissue succinylation, suggesting that AF-induced beneficial effects on fat might occur via the regulation of Sirt5 levels and altered succinylation in fatty tissues. Our study clearly showed the remodeling function of adipose tissue during AF; in terms of mechanism, the regulation of succinylation levels by AF might provide new insights into the mechanism(s) underlying the improvement in fat metabolism by energy restriction.

(-)-Hydroxycitric Acid Alleviates Oleic Acid-Induced Steatosis, Oxidative Stress, and Inflammation in Primary Chicken Hepatocytes by Regulating AMP-Activated Protein Kinase-Mediated Reactive Oxygen Species Levels

Nonalcoholic fatty liver disease (NAFLD) is one of the most complex liver diseases in the world, which is characterized by hepatic steatosis, oxidative stress, inflammation, and apoptosis. (-)-Hydroxycitric acid [(-)-HCA] can regulate obesity in different animals, while whether this beneficial effect of (-)-HCA can alleviate the NAFLD and its mechanism is unclear. Hence, this study aimed to determine the potential actions and mechanisms of (-)-HCA on NAFLD in oleic acid (OA)-induced hepatocytes. We found that (-)-HCA effectively improved OA-induced hepatic steatosis by regulating the expression level of fat metabolism key factors, which was achieved by activating AMP-activated protein kinase (AMPK) signaling in hepatocytes. Importantly, activated AMPK alleviates mitochondrial disorder via the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α)-nuclear transcription factor 1 (NRF-1)-mitochondrial transcription factor A (TFAM) pathway, then reduces reactive oxygen species production, and blocks the activation of p38 MAPK-NF-κB pathway in OA-induced hepatocytes. These results not only provide a theoretical basis for the occurrence and development of NAFLD but also offer compelling evidence for prevention of NAFLD supplemental with (-)-HCA.

An altered lipid metabolism characterizes Charcot-Marie-Tooth type 2B peripheral neuropathy

Charcot-Marie Tooth type 2B (CMT2B) is a rare inherited peripheral neuropathy caused by five missense mutations in the RAB7A gene, which encodes a small GTPase of the RAB family. Currently, no cure is available for this disease. In this study, we approached the disease by comparing the lipid metabolism of CMT2B-derived fibroblasts to that of healthy controls. We found that CMT2B cells showed increased monounsaturated fatty acid level and increased expression of key enzymes of monounsaturated and polyunsaturated fatty acid synthesis. Moreover, in CMT2B cells a higher expression of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), key enzymes of de novo fatty acid synthesis, with a concomitantly increased [1-¹⁴C]acetate incorporation into fatty acids, was observed. The expression of diacylglycerol acyltransferase 2, a rate-limiting enzyme in triacylglycerol synthesis, as well as triacylglycerol levels were increased in CMT2B compared to control cells. In addition, as RAB7A controls lipid droplet breakdown and lipid droplet dynamics have been linked to diseases, we analyzed these organelles and showed that in CMT2B cells there is a strong accumulation of lipid droplets compared to control cells, thus reinforcing our data on abnormal lipid metabolism in CMT2B. Furthermore, we demonstrated that ACC and FAS expression levels changed upon RAB7 silencing or overexpression in HeLa cells, thus suggesting that metabolic modifications observed in CMT2B-derived fibroblasts can be, at least in part, related to RAB7 mutations.

Decanoic Acid and Not Octanoic Acid Stimulates Fatty Acid Synthesis in U87MG Glioblastoma Cells: A Metabolomics Study

Medium-chain fatty acids (MCFA) are dietary components with a chain length ranging from 6 to 12 carbon atoms. MCFA can cross the blood-brain barrier and in the brain can be oxidized through mitochondrial β-oxidation. As components of ketogenic diets, MCFA have demonstrated beneficial effects on different brain diseases, such as traumatic brain injury, Alzheimer’s disease, drug-resistant epilepsy, diabetes, and cancer. Despite the interest in MCFA effects, not much information is available about MCFA metabolism in the brain. In this study, with a gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach, coupled with multivariate data analyses, we followed the metabolic changes of U87MG glioblastoma cells after the addition of octanoic (C8), or decanoic (C10) acids for 24 h. Our analysis highlighted significant differences in the metabolism of U87MG cells after the addition of C8 or C10 and identified several metabolites whose amount changed between the two groups of treated cells. Overall, metabolic pathway analyses suggested the citric acid cycle, Warburg effect, glutamine/glutamate metabolism, and ketone body metabolism as pathways influenced by C8 or C10 addition to U87MG cells. Our data demonstrated that, while C8 affected mitochondrial metabolism resulting in increased ketone body production, C10 mainly influenced cytosolic pathways by stimulating fatty acid synthesis. Moreover, glutamine might be the main substrate to support fatty acids synthesis in C10-treated cells. In conclusion, we identified a metabolic signature associated with C8 or C10 addition to U87MG cells that can be used to decipher metabolic responses of glioblastoma cells to MCFA treatment.

Brief daily access to cafeteria-style diet impairs hepatic metabolism even in the absence of excessive body weight gain in rats

Numerous nutritional approaches aimed at reducing body weight have been developed as a strategy to reduce obesity. Most of these interventions rely on reducing caloric intake or limiting calories access to a few hours per day. In this work, we analyzed the effects of the extended (24 hours/day) or restricted (1 hour/day) access to a cafeteria-style (CAF) diet, on rat body weight and hepatic lipid metabolism, with respect to control rats (CTR) fed with a standard chow diet. The body weight gain of restricted-fed rats was not different from CTR, despite the slightly higher total caloric intake, but resulted significantly lower than extended-fed rats, which showed a CAF diet-induced obesity and a dramatically higher total caloric intake. However, both CAF-fed groups of rats showed, compared to CTR, unhealthy serum and hepatic parameters such as higher serum glucose level, lower HDL values, and increased hepatic triacylglycerol and cholesterol amount. The hepatic expression and activity of key enzymes of fatty acid synthesis, acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS), was similarly reduced in both CAF-fed groups of rats with respect to CTR. Anyway, while in extended-fed rats this reduction was associated to a long-term mechanism involving sterol regulatory element-binding protein-1 (SREBP-1), in restricted-fed animals a short-term mechanism based on PKA and AMPK activation occurred in the liver. Furthermore, hepatic fatty acid oxidation (FAO) and oxidative stress resulted significantly increased in extended, but not in restricted-fed rats, as compared to CTR. Overall, these results demonstrate that although limiting the total caloric intake might successfully fight obesity development, the nutritional content of the diet is the major determinant for the health status.