## 4 Discussion
Ferulic acid in rice germ was previously shown to suppress the activities of G6 PC and PEPCK, both of which are involved in liver gluconeogenesis, highlighting the potential of this phenolic compound in T2 DM [34; 35]. To explore the involvement of ferulic acid in glycolysis and gluconeogenesis, we measured the expression of genes related to glucose metabolism in the liver. GK plays an important role in the regulation of glycolysis. Increased \(Gk\) expression decreases blood glucose levels by storing glucose in the form of glycogen or utilizing glucose. In contrast, G6 pc and PEPCK are major enzyme regulators of gluconeogenesis. A decrease in \(G6 pc\) and \(Pepck\) expression indicates reduced glucose synthesis in the liver, subsequently resulting in lower blood glucose levels [34; 36; 37]. We observed that \(Gk\) expression was significantly upregulated in FA, RG_30E, and RG_50E mice. In particular, \(Gk\) expression in the RG_50E group increased to a similar degree as in db/+ mice, which were non-diabetic controls. According to [PERSON] et al., mice fed ferulic acid were reported to regulate the hepatic glucose production by engaging in the activities of GK, G6 PC, and PEPCK [34]. The result of this study also confirmed that ferulic acid significantly reduced the expression of the hepatic \(Gk\) gene. \(G6 pc\) expression was significantly decreased in FA and RG_50E mice, while \(Pepck\) expression was lower in the FA, RG_30E, and RG_50E groups. These results indicate that the fermented rice germ extract regulates the expression of \(G6 pc\) and \(Pepck\), thereby inhibiting glucose synthesis. Ferulic acid has both antihyperglycemic and antioxidant properties. It has been shown to alleviate hyperglycemia and oxidative stress by maintaining the redox balance and inhibiting mitochondrial apoptosis pathways [18; 38; 39]. Ferulic acid removes the free radicals present in aromatic rings, thus acting as an antioxidant and reducing MDAlevels. The decrease in antioxidant enzyme activity in tissues promotes ROS-mediated lipid peroxidation and protein oxidation. As one such antioxidant enzyme, SOD inhibits ROS generation by converting superoxide anions into hydrogen peroxide [40; 41]. We observed that ferulic acid and fermented rice germ extracts reduced MDA levels and improved catalase and SOD activity, confirming previous observations. While no effect on hepatic catalase activity was observed (Figure 4c), MDA levels in erythrocytes and the liver were significantly decreased in the FA and RG_50E groups, indicative of decreased lipid peroxidation (Figure 4a,b). Further, hepatic SOD activity was significantly increased in the FA, RG_30E, and RG_50E groups (Figure 4d). Thus, RG_50E significantly reduced MDA levels and enhanced SOD activity, exhibiting a greater antioxidant effect than RG_30E. The db/db mice, which are animal models of type 2 diabetes, have mutation in the leptin receptor involved in dietary intake regulation and homeostasis [23]. In this study, compared to the db/db group, FA, RG_30E, and RG_50E did not confirm the tendency of a decrease in body weight. This is a limitation of this study. GABA is one of the compounds in rice germ [42]. [PERSON] et al. reported that GABA was expressed in a subpopulation of neuropeptide Y (NPY) neurons involved in feed stimulation [43]. In particular, it was suggested that GABA and NPY interact to regulate of feeding. The relationship between GABA in rice germ and NPY must be a further study confirming the effect of weight loss by controlling food intake. [PERSON] et al. reported that rice germ contains large amounts of vitamin E and \(\gamma\)-oryzanol [44]. \(\gamma\)-oryzanol is a mixture of ferulic acid esters of phytosterols and triterpenoids [45]. Therefore, this study focused on ferulic acid which was known compound as hydrolyzed compound of \(\gamma\)-oryzanol, and it was conducted based on the study that antioxidants such as ferulic acid have antidiabetic effects [46; 47].