Objective To investigate the effects of ketogenic amino acid ( KAA) replacement diet on insulin resistance in mice fed with high fat diet(HFD) and to analyze the possible mechanism. Methods C57BL mice were fed with a control diet, HFD, and KAA-fortified HFD(HFDKAAR)from the age of 8 weeks, and 8 weeks after HFD initiation, the HFD-fed mice were divided into two groups:one group of mice were fed the same HFD, the other group were fed HFDKAAR ( HFD→HFDKAAR ) . The metabolic evaluations were performed at the end of 16 weeks. Blood glucose levels were measured at 0, 15, 30, 60, 90, and 120 min after the injection of glucose ( 1 g/kg BW intraperitoneal glucose tolerance test, ipGTT) . The insulin,β-hydroxybutyrate, and acetoacetate levels in the plasma were measured via ELISA. The insulin resistance index ( IRI) and area under curve ( AUC) were calculated. The expression of hepatic LKB1 ( liver kinase B1 ) , AMP-activated protein kinase ( AMPK ) , and mTOR ( Mammalian target of rapamycin ) protein, and mcp-1 mRNA were measured by western blot and real-time PCR respectively. Results HFD-fed group of mice displayed significantly heavier body weight,heavier intra-abdominal fat weight, and significant deterioration of glucose tolerance at the end of 16 weeks in addition to higher insulin levels( all P<0. 05), HFDKAAR-fed mice exhibited significantly ameliorated high fat diet-induced obesity and glucose intolerance compared to the HFD-fed mice, which was associated with decreased insulin levels, IRI, AUC, and mcp-1 mRNA expression (all P<0. 05). HFD suppressed hepatic LKB1 and AMPK phosphorylation expression, and increased mTOR phosphorylation levels compared to the control diet-fed mice(all P<0. 05). In contrast, treatment with the HFDKAAR diet increased LKB1and p-AMPK expression, which was associated with suppressed p-mTOR levels compared to the HFD-fed mice(all P<0. 05). Conclusion KAA may ameliorate high fat diet-induced obesity, glucose intolerance, via normalizing the hepatic LKB1-AMPK-mTOR nutritional signal passageway. KAA replacement diet seems to be a potential nutritional intervention for the treatment for patients with metabolic defects, such as obesity, glucose intolerance, as well as metabolic syndrome.

To investigate the effects of short-chain fatty acids(SCFAs)on oxidative stress and inflammation in cultured glomerular mesangial cells(GMCs)under high glucose.SV-40 MES 13 mouse GMCs were exposed to 30 mmol/L glucose, exogenous SCFAs or their specific G-protein coupled receptor 43(GPR43)agonist were used individually as an intervention.GPR43 expression was suppressed by transfection with GPR43-specifc siRNA.The oxidative stress-related factors reactive oxygen species and malondialdehyde were detected and the expression of GPR43,monocyte chemotactic protein 1(MCP-1),and interleukin-1β(IL-1β)were observed.GPR43 expression were significantly down-regulated,but reactive oxygen species and malondialdehyde production and MCP-1 and IL-1β releases were induced by high glucose(all P<0.05),treatment with SCFAs or GPR43 agonist reversed high glucose-induced oxidative stress and inflammation in a dose-dependent manner(all P<0.05).However, these SCFAs-mediated effects were blunted by siRNA-mediated knockdown GPR43(all P<0.05).SCFAs mitigates high glucose-induced oxidative stress and inflammatory injury in part via GPR43 signaling pathway,suggesting a likely mechanism for SCFAs-induced therapeutic effect in diabetic kidney disease.

Objective: To investigate the role of sweet taste receptors(STRs)in the activation of reactive oxygen species (ROS)-NLRP3 inflammasome signaling in diabetic kidney disease(DKD). Methods: DKD mouse were established by high-fat diet and streptozotocin. After mouse glomerular mesangial cells(GMCs)were exposed to high glucose, STRs(T1R2/T1R3)and associated signaling components and NLRP3 inflammasome signaling components expressions were detected. After GMCs were treated with STRs inhibitor lactisole, the production of ROS was detected and the role of STRs in the activation of NLRP3 signaling was investigated. Results: Under high glucose condition, the expressions of T1R2, T1R3, Gα-gustducin, phospholipase C-β2, and TRPM5 were significantly decreased in vivo and in vitro(all P<0.05)and ROS-NLRP3 signaling was activated(all P<0.05). Lactisole significantly mitigated the production of ROS and the activation of NLRP3 inflammasome signaling stimulated by high glucose in GMCs(all P<0.05). Conclusion The STRs(T1R2/T1R3)-mediated signaling pathway may be involved in the regulation of ROS-NLRP3 inflammatory signaling, suggesting that STRs may act as new therapeutic targets of DKD. (Chin J Endocrinol Metab, 2018, 34: 587-593)