Hydrogen inhalation alleviates nonalcoholic fatty liver disease in metabolic syndrome rats.

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.