Hepatic gene expression profile in persimmon peel extract administrated GK rat

Persimmon (Diospyros kaki L. f.) is a most popular fruit in Asian countries but its peels are totally wasted despite of containing a plenty of antioxidants such as carotenoids and polyphenols. We prepared a fat-soluble extract from a persimmon peel (PP) fraction and fed type 2 diabetic Goto-Kakizaki (GK) rats with a PP extract-containing AIN-93G diet (PP diet) for 12 weeks. Compared with the control AIN-93G diet, the feeding of the PP diet reduced the plasma glutamic-pyruvate transaminase activity significantly, with accumulation of ß-cryptoxanthin in the liver. A DNA microarray analysis revealed that the PP diet altered the hepatic gene expression profiles. In particular, insulin signaling pathway-related genes were significantly enriched in differentially expressed gene sets. Moreover, Western blotting analysis actually showed the promotion of IRß tyrosine phosphorylation. All these data suggest that the PP extract administration to the GK rats improves their insulin resistance.