Additive effect of clove essential oil combined with hydrogen inhalation improves psychological harm caused by lipopolysaccharide in mice.

Background: Psychological anxiety and depression, as well as memory impairment, are frequently linked to inflammation. Clove essential oil (CEO) administration and hydrogen (H₂) inhalation have been proven to have anti-inflammatory and alleviating effects on related psychological disorders in the past. The current study investigated the potential to improve anxiety-like behaviors and cognitive function by a combination of CEO and H₂ treatment.

Methods: The mice were administered lipopolysaccharide (LPS) to induce inflammation and oxidative stress response and cause psychological disorders. Using this animal model, we conducted experiments to test whether essential oil and H₂ inhalation could improve the psychological damage in behavior caused by LPS. Subsequently, elevated plus maze (EPM), forced swimming test (FST), and passive avoidance (PA) test were performed for evaluation of mice anxiety, depression, and response to electric shock, respectively. Furthermore, the biochemical analysis was used to examine the expression levels of inflammatory and oxidative stress markers.

Results: Our results showed that CEO administration and H₂ inhalation alone or in combination positively improved inflammation-induced anxiety, depression, and cognitive memory deficits in the mice. In the single treatment groups, CEO demonstrated better results than H₂ inhalation in the elevated plus maze, forced swimming, and passive avoidance tests, while combined treatment with both provided a further improved enhancement effect. Biochemical analysis of the cerebral cortex revealed that CEO and H₂ therapy reversed the LPS-induced inflammation and oxidative stress response.

Conclusions: Our results suggest that a combination of CEO and H₂ has the potential to treat psychological disorders or neuropsychiatric disorders.