Brown Rice and Its Component, γ-Oryzanol, Attenuate the Preference for High-Fat Diet by Decreasing Hypothalamic Endoplasmic Reticulum Stress in Mice

Abstract

Brown rice is known to improve glucose intolerance and prevent the onset of diabetes. However, the underlying mechanisms remain obscure. In the current study, we investigated the effect of brown rice and its major component, γ-oryzanol (Orz), on feeding behavior and fuel homeostasis in mice. When mice were allowed free access to a brown rice–containing chow diet (CD) and a high-fat diet (HFD), they significantly preferred CD to HFD. To reduce hypothalamic endoplasmic reticulum (ER) stress on an HFD, mice were administered with 4-phenylbutyric acid, a chemical chaperone, which caused them to prefer the CD. Notably, oral administration of Orz, a mixture of major bioactive components in brown rice, also improved glucose intolerance and attenuated hypothalamic ER stress in mice fed the HFD. In murine primary neuronal cells, Orz attenuated the tunicamycin-induced ER stress. In luciferase reporter assays in human embryonic kidney 293 cells, Orz suppressed the activation of ER stress–responsive cis-acting elements and unfolded protein response element, suggesting that Orz acts as a chemical chaperone in viable cells. Collectively, the current study is the first demonstration that brown rice and Orz improve glucose metabolism, reduce hypothalamic ER stress, and, consequently, attenuate the preference for dietary fat in mice fed an HFD.

Marked augmentation of PLGA nanoparticle-induced metabolically beneficial impact of γ-oryzanol on fuel dyshomeostasis in genetically obese-diabetic ob/ob mice

“…Preference for dietary fat was evaluated in the two-foods (chow versus HFD) choice tests as previously described (Kozuka et al, 2012). Briefly, the mice were allowed free access to the chow and the HFD.…”

“…Gene expression was examined as described (Kozuka et al, 2012) (Supplemental Methods and Supplemental Table 1). All of mRNA samples were collected at 4 weeks after starting the treatment.…”

Effects of Ginseng-Added Brown Rice Cookie on the Regulation of Hepatic Glucose Metabolism Mediated through the Insulin Signaling Pathway in <i>db/db</i> Obese Mice

“…The bioactive compounds in red ginseng, such as ginsenosides, might augment the insulin sensitivity, given that Ginsenoside Re was shown to exhibit plasma glucose-lowering effects in diabetic rats [15] and Ginsenoside Rh2 improved insulin sensitivity in fructose-rich chow-fed rats [31]. Brown rice decreased the postprandial blood glucose and insulin levels and body weights of mice with the metabolic syndrome, compared to the levels in subjects that had been fed white rice, indicating that insulin sensitivity and body weight are closely related [32]. Furthermore, FOS has demonstrated a serum insulin-lowering effect in obese rats [33].…”

Hypolipidemic Effects of Starch and γ-Oryzanol fromwx/aeDouble-Mutant Rice on BALB/c.KOR-ApoeshlMice

“…13,14) It also has anti-inflammatory and antioxidative properties and attenuates the preference to dietary fat in mice. 15,16) Most -oryzanol in the rice grains is located in the bran and some in the endosperm. 17,18) Spontaneously hyperlipidemic (shl) mice developed by inbreeding Japanese wild mice (Mus musculus molossinus) have high concentrations of plasma and hepatic lipids due to disruption of the apolipoprotein E (apoE) gene.…”