Anxiety and depression
are among the major traumatic brain injury-induced
psychiatric disorders in survivors. The present study was undertaken
to investigate the beneficial effects of 6-Shogaol against depression-like
behavior and anxiety, induced by traumatic brain injury (TBI), in
mice. The mice were administered either fluoxetine, vehicle, or three
different doses (10, 20 and 30 mg/kg/day, i.p.) of 6-Shogaol after
10 days of impact-accelerated TBI. The treatment was continued for
14 consecutive days. Elevated plus maze test, marble burying test,
staircase test, and social interaction test were employed to investigate
the effect of 6-Shogaol on anxiety-like behavior. The impact of treatment
on depression-like behavior was assessed using hyper-emotionality
behavior or open-field exploration test. The expressions of brain-derived
neurotrophic factor (BDNF), tumor necrosis factor-α (TNF-α),
interleukin-1β (IL-1β), and malondialdehyde (MDA) levels
in brain tissue and brain water were measured to elucidate possible
mechanisms involved. 6-Shogaol treatment (higher dose) was able to
attenuate anxiety/depression-like behaviors in mice with TBI. 6-Shogaol
treatment also altered MDA formation and expressions of TNF-α
and IL-1β that act as major inflammation-inducing cytokines
in brain tissue. Additionally, brain BDNF levels were also affected
by 6-Shogaol treatment. Although the lower dose of 6-Shogaol was able
to rectify inflammation and BDNF expression in brain tissue, it was
unable to improve anxiety/depression-like behaviors. 6-Shogaol treatment
produced beneficial effects for TBI-induced anxiety/depression-like
behaviors in mice, which could be attributed to the reduction of lipid
peroxidation, inflammation, and enhanced BDNF expression.