The effects of dexamethasone on the behavior and neurotransmitters of asthmatic model mice

Patients with acute asthma frequently present with both neurological and psychological manifestations. Changes in neurotransmitter levels may provide objective indicators for assessing behavioral status. This study was conducted to investigate the effects of dexamethasone on motor behavior, neurotransmitter levels, and inflammatory mediators in a murine asthma model. Dopamine (DA), acetylcholine (ACh), γ-aminobutyric acid (GABA), tumor necrosis factor-α (TNF-α), and interleukin-4 (IL-4) were measured to assess neuroimmune interactions. Twenty-four C57 mice were randomly assigned to control, asthma, and treatment groups. Mice were initially sensitized with Der p1 and subsequently challenged with house dust mite (HDM) extract. Mice in the treatment group received dexamethasone (1 mg/kg) before challenge, after which motor behavior was evaluated using the open field test. ELISA was used to measure IL-4, TNF-α, GABA, and DA in plasma; IL-4 and TNF-α in bronchoalveolar lavage fluid (BALF); and TNF-α, GABA, DA, and ACh in brain tissue. Compared with the asthma group, the treatment group showed significantly reduced IL-4 and TNF-α levels in BALF (all P < 0.05). Plasma GABA and DA levels were increased, whereas plasma IL-4 and TNF-α levels were decreased (all P < 0.05). In brain tissue, ACh and TNF-α levels were decreased, whereas GABA and DA levels were increased (all P < 0.05). In the open field test, the total distance traveled, the proportion of time spent in the central area and speed in the peripheral area of the asthma group were all lower than those of the treatment group, while time spent in the peripheral area was higher than that of the treatment group (all P < 0.05). Correlation analysis showed that IL-4, TNF-α, and brain ACh levels were negatively correlated with total movement distance, time spent in the central area, mean speed in the central area, and mean speed in the peripheral area (all P < 0.05). Plasma DA levels were positively correlated with these behavioral indicators (all P < 0.05). Locomotor and exploratory behavior in asthmatic mice was improved by dexamethasone. The therapeutic effect of dexamethasone on asthma-associated behavioral changes may be associated with concurrent modulation of neurotransmitter levels and suppression of Th cell-related inflammatory mediators.