Effects of linalyl acetate and 1, 8-cineole inhalation on PTSD-like symptoms in mice

To explore the effects of inhaling and smelling linalool acetate (LA) and 1, 8 eucalyptol (EO) on post-traumatic stress disorder (PTSD) like symptoms in mice.

Male C57BL/6J mice were randomly divided into the control group, model group, sertraline hydrochloride (Ser) positive control group, LA group, EO group, and LA+EO group (n=8). A PTSD mouse model was established using a brief electric shock method. The inhalation doses for LA and EO were detected by portable VOC analyzer respectively, while the oral dose for Ser was 10 mg/kg. On days 13, 16, and 18 after modeling, the anxiety-like and depression-like behaviors were assessed using the open field test, elevated plus maze, and forced swim test, respectively. Hematoxylin-eosin (HE) staining, biochemical colorimetric assays, and enzyme-linked immunosorbent assays (ELISA) were adopted to detect changes in the structure of hippocampal tissues, inflammatory factors of brain tissues, and oxidative stress levels, respectively.

Compared with the model group, the durations of freezing and immobility in LA, EO, and LA+EO groups were significantly reduced, along with a marked increase in total travel distance in the open field test. The percentage of time spent in the open arms of the elevated plus maze was also significantly elevated. Histological examination revealed an increase in the number of neuronal layers, with more organized arrangement and clearer cellular contours. Furthermore, significant reductions in neuroinflammation and effective alleviation of oxidative stress were observed in brain tissues. Among all the intervention groups, the EO group was the most pronounced in terms of improvement.

Both individual and alternating inhalation of LA and EO can significantly ameliorate PTSD-like symptoms in mice. Specifically, anxiolytic and antidepressant effects in the EO group are stronger than in the other two intervention groups, but the alternating inhalation of EO and LA produces no synergistic effect.