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. 2018 Jun 7;10(6):735.
doi: 10.3390/nu10060735.

Hepatoprotective Effects of Insect Extracts in an Animal Model of Nonalcoholic Fatty Liver Disease

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Free PMC article

Hepatoprotective Effects of Insect Extracts in an Animal Model of Nonalcoholic Fatty Liver Disease

A-Rang Im et al. Nutrients. .
Free PMC article

Abstract

Insects represent the largest and most diverse group of organisms on earth and are potential food and drug resources. Recently, we have demonstrated that a Forsythia viridissima extract prevented free fatty acid-induced lipid accumulation in an in vitro cellular nonalcoholic fatty liver disease (NAFLD) model. In this study, we aimed to evaluate the hepatoprotective effects of extracts of the insects Protaetia brevitarsis seulensis Kolbe, 1886 (PB), Oxya chinensis sinuosa Mishchenko, 1951 (OC), and Gryllus bimaculatus De Geer, 1773 (GB) in a high-fat diet (HFD)-induced NAFLD animal model, as well as to elucidate the underlying mechanisms. The effects of the supplementation with PB, OC, and GB extracts were evaluated histopathologically and histochemically. PB, OC, and GB extract supplementation inhibited the HFD-induced increase in body weight and body fat mass and ameliorated other adverse changes, resulting in decreased liver function parameters, lower serum triglyceride and cholesterol levels, and increased serum adiponectin levels. The expression of hepatic genes involved in lipid droplet accumulation and in fatty acid uptake also decreased upon treatment of HFD-fed mice with the extracts. These results provide evidence of the protective effects of the PB, OC, and GB extracts against HFD-induced fatty liver disease in an animal model.

Keywords: Gryllus bimaculatus; Oxya chinensis sinuosa; Protaetia brevitarsis seulensis; edible insect; hepatoprotection; nonalcoholic fatty liver disease.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Inhibition of free fatty acids (FFA)-induced lipid accumulation by Protaetia brevitarsis seulensis (PB), Oxya chinensis sinuosa (OC), and Gryllus bimaculatus (GB) extracts in HepG2 cells. HepG2 cells were cultured with 0.1% bovine serum albumin (BSA, control), 1 mM FFA mixture, or 1 mM FFA and PB, OC, and GB extracts (10, 50, and 100 μg/mL) for 24 h. (A) Cell viability after 24 h of treatment with PB, OC, and GB extracts. After 24 h, intracellular lipid accumulation was assessed by Nile red staining (B) and Oil Red O staining (C). The data are representative of three independent experiments. (D) Intracellular triglyceride (TG) content was measured, and absorbance readings were normalized to protein concentrations. Nor, normal. The data represent the mean ± SEM of at least three individual experiments; # p < 0.05 compared with the control group; * p < 0.05 versus FFA alone.
Figure 2
Figure 2
Effects of PB, OC, and GB extracts on mouse liver histology and body weight in a high-fat diet (HFD)-fed mouse model. (A) Photographs of the mouse liver. (B) Histopathological examination by hematoxylin and eosin (H&E) (liver and epididymis fat tissue) and Oil Red O (liver) staining and (C) body weights are shown for HFD-fed mice, with or without PB, OC, and GB extract supplementation. Liver weights (D), TG levels (E), and total cholesterol (TC) levels (F) in the liver tissues from the mice treated with the PB, OC, and GB extracts. MT, milk thistle. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 2
Figure 2
Effects of PB, OC, and GB extracts on mouse liver histology and body weight in a high-fat diet (HFD)-fed mouse model. (A) Photographs of the mouse liver. (B) Histopathological examination by hematoxylin and eosin (H&E) (liver and epididymis fat tissue) and Oil Red O (liver) staining and (C) body weights are shown for HFD-fed mice, with or without PB, OC, and GB extract supplementation. Liver weights (D), TG levels (E), and total cholesterol (TC) levels (F) in the liver tissues from the mice treated with the PB, OC, and GB extracts. MT, milk thistle. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 2
Figure 2
Effects of PB, OC, and GB extracts on mouse liver histology and body weight in a high-fat diet (HFD)-fed mouse model. (A) Photographs of the mouse liver. (B) Histopathological examination by hematoxylin and eosin (H&E) (liver and epididymis fat tissue) and Oil Red O (liver) staining and (C) body weights are shown for HFD-fed mice, with or without PB, OC, and GB extract supplementation. Liver weights (D), TG levels (E), and total cholesterol (TC) levels (F) in the liver tissues from the mice treated with the PB, OC, and GB extracts. MT, milk thistle. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 3
Figure 3
Effects of PB, OC, and GB extracts on body weight gain and body fat mass in HFD-fed mice: (A) abdominal subcutaneous fat, (B) kidney tissue, and (C) intestinal adipose tissue. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 4
Figure 4
Effects of PB, OC, and GB extracts on serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in HFD-fed mice. The serum ALT (A) and AST (B) levels were determined 14 weeks after PB, OC, and GB extracts treatment. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 5
Figure 5
Effects of PB, OC, and GB extracts on blood biochemistry parameters in HFD-fed mice. (A) Serum low-density lipoprotein (LDL) cholesterol, (B) serum high-density lipoprotein (HDL) cholesterol, (C) serum FFAs, (D) serum creatine, (E) fasting blood glucose, (F) serum adiponectin, and (G) serum IGF-1 levels. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 5
Figure 5
Effects of PB, OC, and GB extracts on blood biochemistry parameters in HFD-fed mice. (A) Serum low-density lipoprotein (LDL) cholesterol, (B) serum high-density lipoprotein (HDL) cholesterol, (C) serum FFAs, (D) serum creatine, (E) fasting blood glucose, (F) serum adiponectin, and (G) serum IGF-1 levels. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 6
Figure 6
Effects of PB, OC, and GB extracts on the mRNA expression of lipogenesis-related genes in the liver of HFD-fed mice, determined by RT-PCR. Expression of (A) leptin, (B) adiponectin, (C) sterol regulatory element-binding protein-1 (SREBP-1), (D) acetyl-CoA carboxylase (ACC), (E) adipocyte protein 2 (AP2), and (F) mitochondrial uncoupling protein (UCP2) in the liver. (G) Western blot analysis of the corresponding proteins in HFD-fed mice livers. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 7
Figure 7
Effects of PB, OC, and GB extracts on the expression of lipogenesis genes in HFD-fed mice livers, determined by RT-PCR. (A) Fit2/Fitm2, (B) PPARγ, and (C) Fsp27/Cidec expression in the livers. (D) Western blot analysis of the corresponding proteins in HFD-fed mice livers. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.
Figure 8
Figure 8
Effects of PB, OC, and GB extracts on the mRNA expression of inflammation-related genes in HFD-fed mice, determined by RT-PCR. (A) TNF-α, (B) IL-1β, and (C) IL-6 expression in the liver. Expression of (D) TNF-α and (E) IL-1β in the adipose tissue determined by ELISA assay. The data are presented as the mean ± SEM (n = 9); # p < 0.05 compared with the control group; * p < 0.05 compared with the HFD group.

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