Prevention of NAFLD development in rats with obesity via the improvement of pro/antioxidant state by cerium dioxide nanoparticles

Abstract

Background: One of the pathogenic mechanisms of the nonalcoholic fatty liver disease (NAFLD) is the accumulation of reactive oxygen species, which in turn aggravates the disease progress. We have investigated novel cerium dioxide nanoparticles (nCeO2) due to their promising antioxidant auto-regenerative ability and low toxicity.

Methods: 30 white male Wistar rats were divided into 3 groups: control, monosodium glutamate (MSG)-induced obesity and MSG treated with nCeO2 (MSG+nCeO2) groups. Newborn rats of control group were injected with saline (control). MSG- and MSG+nCeO2 groups were injected with MSG (4 mg/g concentration, 8 μl/g volume) between the 2nd and the 10th days of life subcutaneously [13]. At the age of 1 month, rats of group II were administered water 2.9 ml/kg orally, MSG+nCeO2 group received 1 mM solution of nCeO2 1 mg/kg orally. 4-months rats were sacrificed and the liver was harvested for histological and biochemical analysis. To assess the morphological changes in the liver we used NAS (NAFLD activity score). The content of lipid peroxidation products and enzymatic activity of superoxide dismutase (SOD) and catalase in the liver were studied by standard biochemical methods [Refs].

Results: In 4-month rats we found significantly lower total score (1.3±0.26 vs 3.6±0.34, p<0.001), degree of steatosis (1.1±0.18 vs 2.1±0.18, p<0.001), manifestation of lobular inflammation (0.2±0.13 vs 1.2±0.2, p<0.001) and ballooning degeneration (0.0±0.0 vs 0.3±0.15, p=0.034) due to NAS in the nCeO2 group compared to the MSG-group. nCeO2 significantly decreased lipid peroxidation in the liver tissue, namely it reduced the conjugated dienes content by 27% (p<0.05), TBA-products - by 43% (p<0.05) and Schiff bases - by 21% (p<0.05).

Conclusions: Due to its antioxidant properties nCeO2 significantly reduces the incidence of NASH and improves the main NAFLD histological features.

Keywords: Wistar rats; lipid peroxidation; nanoparticles; non-alcoholic fatty liver disease; reactive oxygen species.

Figure 1

Light microscopic micrographs of the liver tissue of MSG-group rats stained with hematoxylin and eosin, ×400. A - pronounced total microvesicular steatosis; B - microvesicular steatosis with perivascular leukocyte infiltration in zone 3 (mild lobular inflammation); C - focal necrosis as a result of hepatocytes ballooning degeneration – lack of nuclei (center).

Figure 2

Light microscopic micrographs of the liver tissue of MSG+nCeO2 rats stained with hematoxylin and eosin, ×400. A - single perivascular lobular lymphocytes infiltration; B - focal mild microvesicular steatosis; C - mainly normal histological structure of hepatocytes.

Figure 3

Lipid peroxidation in the rat liver under conditions of MSG-obesity and nCeO2 (1 mg/kg) treatment. A, B, C – content of conjugated dienes, TBA-products and Schiff basis in the liver, correspondingly. * – p<0.05 compared to control rats without obesity, # – p<0.05 compared to rats with MSG-obesity. Data are presented as the M ± SEM. One-way ANOVA with post hoc Tukeys test for multiple comparisons were performed for data analysis.

Figure 4

Antioxidant enzymes activity in the rat liver under conditions of MSG-obesity and nCeO2 (1 mg/kg) treatment. A, B – enzymatic activity of superoxide dismutase and catalase in the liver, correspondingly. * – p<0.05 compared to control rats without obesity, # – p<0.05 compared to rats with MSG-obesity. Data are presented as the M ± SEM. One-way ANOVA with post hoc Tukeys test for multiple comparisons were performed for data analysis.