Nutr Res Pract.  2020 Dec;14(6):568-579. 10.4162/nrp.2020.14.6.568.

Standardized rice bran extract improves hepatic steatosis in HepG2 cells and ovariectomized rats

• Lim DW
• Jeon H
• Kim M
• Yoon M
• Jung J
• Kwon S
• Cho S
• Um MY

• KMID: 2508791
• DOI: http://doi.org/10.4162/nrp.2020.14.6.568

Abstract

BACKGROUD/OBJECTIVES: Hepatic steatosis is the most common liver disorder, particularly in postmenopausal women. This study investigated the protective effects of standardized rice bran extract (RBS) on ovariectomized (OVX)-induced hepatic steatosis in rats.
MATERIALS/METHODS
HepG2 cells were incubated with 200 µM oleic acid to induce lipid accumulation with or without RBS and γ-oryzanol. OVX rats were separated into three groups and fed a normal diet (ND) or the ND containing 17β-estradiol (E2; 10 µg/kg) and RBS (500 mg/kg) for 16 weeks.
RESULTS
RBS supplementation improved serum triglyceride and free fatty acid levels in OVX rats. Histological analysis showed that RBS significantly attenuated hepatic fat accumulation and decreased hepatic lipid, total cholesterol, and triglyceride levels. Additionally, RBS suppressed the estrogen deficiency-induced upregulation of lipogenic genes, such as sterol regulatory element-binding protein 1 (SREBP1), acetyl-CoA carboxylase 1, fatty acid synthase, glycerol-3-phosphate acyltransferase, and stearoyl-CoA desaturase 1.
CONCLUSIONS
RBS and γ-oryzanol effectively reduced lipid accumulation in a HepG2 cell hepatic steatosis model. RBS improves OVX-induced hepatic steatosis by regulating the SREBP1-mediated activation of lipogenic genes, suggesting the benefits of RBS in preventing fatty liver in postmenopausal women.

Keyword

Oryza; Oryza; menopause; menopause; fatty liver; fatty liver; lipogenesis; lipogenesis

Figure

• 

  Fig. 1 HPLC chromatograms of RBS detected at ultraviolet 315 nm. A standard chromatogram of γ-oryzanol (A) was compared with the chromatogram of RBS (B) and contents of the compounds were calculated based on the standard.RBS, rice bran extract.

• 

  Fig. 2 Effects of RBS and γ-oryzanol on intracellular lipid accumulation in OA-stimulated HepG2 cells. After treatment with 200 µM OA with or without RBS and γ-oryzanol for 24 h, the cells were stained with ORO solution and intracellular lipid accumulation was visually observed under a light microscope (magnification, ×200). Data are expressed as mean ± SD.RBS, rice bran extract; ORO, oil red O; CONT, not-treated cells; OA, oleic acid; ORY, γ-oryzanol; RBS, rice bran extract.###P < 0.001 compared to untreated cells. *P < 0.05, **P < 0.01, and ***P < 0.001 compared to OA only treated cells.

• 

  Fig. 3 Effect of RBS on hepatic lipid levels in OVX rats. (A) Histological changes (original magnification, ×200) and (B) hepatic lipid, triglyceride, and total cholesterol levels in rats. Data are expressed as mean ± SD.RBS, rice bran extract; OVX, ovariectomized; E2, 17β-estradiol; SHAM, sham-operated controls.#P < 0.05 and ###P < 0.001 compared to the SHAM group. *P < 0.05, **P < 0.01, and ***P < 0.001 compared to the OVX group.

• 

  Fig. 4 RBS suppresses the mRNA expression of lipogenic genes. Relative mRNA levels were measured by qRT-PCR and normalized against that of β-actin. Data from three independent experiments are presented as the mean ± SD.RBS, rice bran extract; qRT-PCR, quantitative reverse transcription polymerase chain reaction; SHAM, sham-operated controls; OVX, ovariectomized; E2, 17β-estradiol; SREBP1, sterol regulatory element-binding protein 1; ACC1, acetyl-CoA carboxylase 1; FAS, fatty acid synthase; SCD1, stearoyl-CoA desaturase 1; GPAT, glycerol-3-phosphate acyltransferase.#P < 0.05, ##P < 0.01 compared to the SHAM group. *P < 0.05, **P < 0.01, and ***P < 0.001 compared to the OVX group.

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