Hydrogen inhalation alleviates nonalcoholic fatty liver disease in metabolic syndrome rats

Abstract

Hydrogen exhibits therapeutic and preventive effects against various diseases. The present study investigated the potential protective effect and dose‑dependent manner of hydrogen inhalation on high fat and fructose diet (HFFD)‑induced nonalcoholic fatty liver disease (NAFLD) in Sprague‑Dawley rats. Rats were randomly divided into four groups: i) Control group, regular diet/air inhalation; ii) model group, HFFD/air inhalation; iii) low hydrogen group, HFFD/4% hydrogen inhalation; and iv) high hydrogen group, HFFD/67% hydrogen inhalation. After a 10‑week experiment, hydrogen inhalation ameliorated weight gain, abdominal fat index, liver index and body mass index of rats fed with HFFD and lowered the total area under the curve in an oral glucose tolerance test. Hydrogen inhalation also ameliorated the increase in liver lipid content and alanine transaminase and aspartate transaminase activities. Liver histopathologic changes evaluated with hematoxylin and eosin as well as Oil Red O staining revealed lower lipid deposition in hydrogen inhalation groups, consistent with the decrease in the expression of the lipid synthesis gene SREBP‑1c. The majority of the indicators were affected following treatment with hydrogen in a dose‑dependent manner. In conclusion, hydrogen inhalation may play a protective role by influencing the general state, lipid metabolism parameters, liver histology and liver function indicators in the rat model of metabolic syndrome with NAFLD.

Figure 1.

Effects of H₂ inhalation on body weight gain and compositional changes. (A) Changes in food intake, (B) body weight, (C) BMI, (D) abdominal fat index, (E) liver index, and (F) kidney index of rats from Con (control group), HFFD (model group), HFFD + LH₂ and HFFD + HH₂ groups. *P<0.05, **P<0.01 and ***P<0.001 vs. the Con group; ^##P<0.01 vs. the HFFD group. n=10-12 per group. Con, control group; HFFD, high fat and fructose diet group; LH₂, low H₂ group; HH₂, high H₂ group.

Figure 2.

Effects of H₂ inhalation on OGTT and plasma biochemical values. (A) Curve of OGTT and (B) AUC of OGTT (n=10 per group). Concentrations of (C) plasma total triglycerides, (D) total cholesterol, (E) ALT, (F) AST and (G) LDH (n=8–12 per group). Data are shown as mean ± standard deviation. *P<0.05, **P<0.01 and ***P<0.001 vs. the Con group; ^#P<0.05 and ^###P<0.001 vs. the HFFD group. OGTT, Oral glucose tolerance test; AUC, area under the curve; ALT, aminotransferase; AST, aspartate aminotransferase; LDH, lactic dehydrogenase; Con, control group; HFFD, high fat and fructose diet group; LH₂, low H₂ group; HH₂, high H₂ group.

Figure 3.

Total and different species of cholesterol and triglycerides in the liver tissues from different groups. (A) total and cholesterol species of HFFD, HFFD + LH₂ and HFFD + HH₂ groups; (B) total and triacylglycerol species of HFFD, HFFD + LH₂ and HFFD + HH₂ groups. ^#P<0.05 vs. the HFFD group. n=8–10 per group. Con, control group; HFFD, high fat and fructose diet group; LH₂, low H₂ group; HH₂, high H₂ group; FC, free cholesterol; CE, cholesteryl ester; TG, triacylglycerol.

Figure 4.

Pathological examination by H&E staining and hepatic lipid accumulation analysis with Oil Red O staining in different groups. (A and E) Con, (B and F) HFFD group, (C and G) HFFD + LH₂ Group, (D and H) HFFD + HH₂ Group (n=10 per group; scale bars=200 µm). (I) Hepatic mRNA expression of SREBP-1c (n=4–6 per group). ***P<0.001 vs. the Con group; ^#P<0.05 and ^##P<0.01 vs. the HFFD group. H&E, hematoxylin and eosin; Con, control group; HFFD, high fat and fructose diet group; LH₂, low H₂ group; HH₂, high H₂ group.