Anxiolytic- and antidepressant-like effects of Silymarin compared to diazepam and fluoxetine in a mouse model of mild traumatic brain injury

Clinical and experimental studies have shown that mild traumatic brain injury (mTBI) is associated with increased anxiety- and depression-related behaviors and inflammation in the brain. Unfortunately, there are no specific therapies for long-term behavioral consequences of mTBI. This study set out to determine whether silymarin treatment compared to diazepam (DZP) and fluoxetine (FLX) can reduce neuroinflammation, anxiety- and depression-like behaviors after mTBI induction in mice. We used open field, elevated plus maze, light-dark box, zero maze, sucrose preference, forced swim, and tail suspension tests to assess anxiety and depression-like behaviors in mTBI-induced mice. The levels of tumor necrosis factor (TNF)-α protein, a marker of inflammation, in the prefrontal cortex and hippocampus was also measured. This study identified that the long-term treatment with DZP, FLX or SIL results in decreased anxiety and depression-like behaviors in mTBI-induced mice. The results also showed that these drugs reduced TNF-α levels in the prefrontal cortex and hippocampus. In addition, there were no significant differences between the effects of SIL and DZP or SIL and FLX on behavioral and cytokine levels in mTBI-induced mice. Our findings support the idea that mTBI could be a risk factor for anxiety- and depression-related disorders and neuroinflammation in the brain. Taken together, this study demonstrates that DZP, FLX or SIL can significantly reduce anxiety- and depression-like symptoms, and neuroinflammation after mTBI induction in mice.