Krskova Katarina, Balazova Lucia, Dobrocsyova Viktoria, Olszanecki Rafal, Suski Maciej, Chai Siew Yeen, Zorad Štefan
Institute of Experimental Endocrinology, Biomedical Research Center, Department of Endocrine Regulations and Psychofarmacology, Slovak Academy of Sciences, Bratislava, Slovakia.
Department of Pharmacology, Jagiellonian University Medical College, Cracow, Poland.
Front Mol Biosci. 2020 Dec 4;7:586225. doi: 10.3389/fmolb.2020.586225. eCollection 2020.
The aim of our study was to determine the influence of inhibition of insulin-regulated aminopeptidase/oxytocinase (IRAP) on glucose tolerance and metabolism of skeletal muscle and visceral adipose tissue in obese Zucker rats. Obese Zucker rats administered with IRAP inhibitor-HFI-419 at a dose of 29 μg/100 g BW/day by osmotic minipumps implanted subcutaneously for 2 weeks. Two-hour intraperitoneal glucose tolerance test (ipGTT) was performed in fasting rats. Plasma oxytocin levels were measured by enzyme immunoassay after plasma extraction. In the musculus quadriceps and epididymal adipose tissue, the expression of factors affecting tissue oxidative status and metabolism was determined by real-time qPCR and/or Western blot analysys. The plasma and tissue enzymatic activities were determined by colorimetric or fluorometric method. Circulated oxytocin levels in obese animals strongly tended to increase after HFI-419 administration. This was accompanied by significantly improved glucose utilization during ipGTT and decreased area under the curve (AUC) for glucose. In skeletal muscle IRAP inhibitor treatment up-regulated enzymes of antioxidant defense system - superoxide dismutase 1 and 2 and improved insulin signal transduction pathway. HFI-419 increased skeletal muscle aminopeptidase A expression and activity and normalized its plasma levels in obese animals. In epididymal adipose tissue, gene expression of markers of inflammation and adipocyte hypertrophy was down-regulated in obese rats after HFI-419 treatment. Our results demonstrate that IRAP inhibition improves whole-body glucose tolerance in insulin-resistant Zucker fatty rats and that this metabolic effect of HFI-419 involves ameliorated redox balance in skeletal muscle.
我们研究的目的是确定抑制胰岛素调节氨肽酶/催产素酶（IRAP）对肥胖Zucker大鼠葡萄糖耐量以及骨骼肌和内脏脂肪组织代谢的影响。通过皮下植入渗透微型泵，以29μg/100g体重/天的剂量给肥胖Zucker大鼠施用IRAP抑制剂-HFI-419，持续2周。对禁食大鼠进行两小时腹腔内葡萄糖耐量试验（ipGTT）。血浆提取后，通过酶免疫测定法测量血浆催产素水平。在股四头肌和附睾脂肪组织中，通过实时定量PCR和/或蛋白质印迹分析确定影响组织氧化状态和代谢的因子的表达。通过比色法或荧光法测定血浆和组织酶活性。施用HFI-419后，肥胖动物的循环催产素水平强烈倾向于升高。这伴随着ipGTT期间葡萄糖利用率的显著改善以及葡萄糖曲线下面积（AUC）的降低。在骨骼肌中，IRAP抑制剂治疗上调了抗氧化防御系统的酶——超氧化物歧化酶1和2，并改善了胰岛素信号转导途径。HFI-419增加了肥胖动物骨骼肌氨肽酶A的表达和活性，并使其血浆水平正常化。在附睾脂肪组织中，HFI-419治疗后肥胖大鼠炎症标志物和脂肪细胞肥大的基因表达下调。我们的结果表明，IRAP抑制改善了胰岛素抵抗的Zucker肥胖大鼠的全身葡萄糖耐量，并且HFI-419的这种代谢作用涉及骨骼肌中氧化还原平衡的改善。
