scholarly journals Peroxisome proliferator-activated receptor-δ induces insulin-induced gene-1 and suppresses hepatic lipogenesis in obese diabetic mice

Hepatology ◽  
2008 ◽  
Vol 48 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Xiaomei Qin ◽  
Xuefen Xie ◽  
Yanbo Fan ◽  
Jianwei Tian ◽  
Youfei Guan ◽  
...  
2002 ◽  
Vol 364 (2) ◽  
pp. 361-368 ◽  
Author(s):  
Mary C. SUGDEN ◽  
Karen BULMER ◽  
Geoffrey F. GIBBONS ◽  
Brian L. KNIGHT ◽  
Mark J. HOLNESS

The aim of the present study was to determine whether peroxisome-proliferator-activated receptor-α (PPARα) deficiency disrupts the normal regulation of triacylglycerol (TAG) accumulation, hepatic lipogenesis and glycogenesis by fatty acids and insulin using PPARα-null mice. In wild-type mice, hepatic TAG concentrations increased (P<0.01) with fasting (24h), with substantial reversal after refeeding (6h). Hepatic TAG levels in fed PPARα-null mice were 2.4-fold higher than in the wild-type (P<0.05), increased with fasting, but remained elevated after refeeding. PPARα deficiency also impaired hepatic glycogen repletion (P<0.001), despite normal insulin and glucose levels after refeeding. Higher levels of plasma insulin were required to support similar levels of hepatic lipogenesis de novo (3H2O incorporation) in the PPARα-null mice compared with the wild-type. This difference was reflected by corresponding changes in the relationship between plasma insulin and the mRNA expression of the lipogenic transcription factor sterol-regulatory-element-binding protein-1c, and that of one of its known targets, fatty acid synthase. In wild-type mice, hepatic pyruvate dehydrogenase kinase (PDK) 4 protein expression (a downstream marker of altered fatty acid catabolism) increased (P<0.01) in response to fasting, with suppression (P<0.001) by refeeding. Although PDK4 up-regulation after fasting was halved by PPARα deficiency, PDK4 suppression after refeeding was attenuated. In summary, PPARα deficiency leads to accumulation of hepatic TAG and elicits dysregulation of hepatic lipid and carbohydrate metabolism, emphasizing the importance of precise control of lipid oxidation for hepatic fuel homoeostasis.


2020 ◽  
Vol 21 (17) ◽  
pp. 6243 ◽  
Author(s):  
Yohei Tomita ◽  
Deokho Lee ◽  
Yukihiro Miwa ◽  
Xiaoyan Jiang ◽  
Masayuki Ohta ◽  
...  

Diabetic retinopathy (DR) is one of the leading causes of blindness globally. Retinal neuronal abnormalities occur in the early stage in DR. Therefore, maintaining retinal neuronal activity in DR may prevent vision loss. Previously, pemafibrate, a novel selective peroxisome proliferator-activated receptor alpha modulator, was suggested as a promising drug in hypertriglyceridemia. However, the role of pemafibrate remains obscure in DR. Therefore, we aimed to unravel systemic and retinal changes by pemafibrate in diabetes. Adult mice were intraperitoneally injected with streptozotocin (STZ) to induce diabetes. After STZ injection, diet supplemented with pemafibrate was given to STZ-induced diabetic mice for 12 weeks. During the experiment period, body weight and blood glucose levels were examined. Electroretinography was performed to check the retinal neural function. After sacrifice, the retina, liver, and blood samples were subjected to molecular analyses. We found pemafibrate mildly improved blood glucose level as well as lipid metabolism, boosted liver function, increased serum fibroblast growth factor21 level, restored retinal functional deficits, and increased retinal synaptophysin protein expression in STZ-induced diabetic mice. Our present data suggest a promising pemafibrate therapy for the prevention of early DR by improving systemic metabolism and protecting retinal function.


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