Hence, we Fig 4. eNOS in adipocytes is important for protecting against NASH progress. (A) Livers of HFD-fed WT and eNOS-/- mice ended up stained with Sirius pink, 8-OHdG, or CD68. order JNJ-26481585 Arrows point out parts of fibrosis stained by Sirius pink. Scale bar, 100 m. (B) Expression of fibrosis-related or inflammatory genes in the livers of HFD-fed WT and eNOS-/- mice that have been sacrificed in a non-fasted state. Expressions have been measured by quantitative genuine-time RT-PCR assays and normalized to -actin expression in each and every sample (signify SE n = 3). Statistically GLYX-13 considerable variations among WT and eNOS-/- are indicated (p < 0.05). (Tgfb1, transforming growth factor1 Col4a1, collagen type IV1 Mcp1, monocyte chemoattractant protein 1 Il6, interleukin 6 Il1, interleukin 1). (C) Results of insulin tolerance test in HFD-fed WT and eNOS-/- mice (n = 3). (D) HFD-fed WT and eNOS-/- mice were fasted overnight and administered insulin (5U) by intravenous injection. Activation of Akt in the liver was examined by immunoblot analysis.believe that the development of NASH in eNOS-/- mice might be due to the increase in hepatic de novo lipogenesis as a result of the excess lipolysis in adipose tissue.We next focused on the molecular mechanisms underlying the regulation of eNOS expression in adipocytes. Because eNOS expression was up-regulated during adipocyte differentiation, we focused on PPAR, the master regulator of adipocyte differentiation [19]. Ciglitazone, a PPAR agonist, promoted adipocyte differentiation and reduced the size of lipid droplets in adipocytes (Fig 4A). To our surprise, pretreatment of 3T3L1 adipocytes with PPAR agonists such as ciglitazone and troglitazone either abolished or markedly attenuated the induction of eNOS expression (Fig 5A and 5B and S4B Fig). We also found that ciglitazone significantly reduced eNOS promoter activity (Fig 5C). Consistent with these findings, eNOS expression was increased by pretreatment with the PPAR antagonist GW9662 (Fig 5D). Taken together, these data suggest a negative regulatory role of PPAR in adipocyte eNOS expression. Finally, to examine the regulatory role of PPAR in adipose eNOS expression in vivo, we administered GW9662 to WT mice on HFD. While there was no difference in food intake between vehicle- and GW9662-treated mice (not shown), treatment with GW9662 prevented the time-dependent increase in weight on HFD (S4C Fig). As shown in Fig 5E, HFD significantly down-regulated eNOS expression in the adipose tissues of vehicle-treated mice while it was preserved in the adipose tissues of mice treated with GW9662. Consistent with this preserved eNOS expression in adipose tissue, the HFD-induced excess liver TG deposition was also prevented by GW9662 (Fig 5F). Accordingly, we observed an inverse relationship between the adipose eNOS level and liver TG content, suggesting that preserving adipocyte eNOS expression with the use of GW9662 may contribute to the mechanism of its prevention of HFD-induced fatty liver disease.
