Silymarin sex-dependently improves cognitive functions and alters TNF-α, BDNF, and glutamate in the hippocampus of mice with mild traumatic brain injury

Aims Mild traumatic brain injury (mTBI) is an important risk factor for cognitive impairment. Despite intense efforts to develop efficient treatments, the current therapies are not often effective and far from satisfactory. Silymarin has been suggested as a therapeutic agent in the treatment of traumatic brain injury. This study aimed to determine whether silymarin can exert neuroprotective effects on memory impairment following mTBI in mice. Main methods After mTBI induction, mice were treated with silymarin once daily for 20 consecutive days by oral gavage. To investigate cognitive functions, animals were subjected to Y-maze, novel-object recognition, and Morris-water maze. Levels of tumor necrosis factor (TNF)-α, glutamate, and brain derived neurotrophic factor (BDNF) were measured in the hippocampus. Key findings Our findings showed that mTBI resulted in a significant decline in memory in the Y-maze and Morris-water maze in both sexes, whereas only impaired cognitive function in males in the novel-object recognition. We found notable increases in TNF-α and glutamate levels in the hippocampus of both sexes, while there was only a significant decrease in hippocampal BDNF in mTBI-induced females. In addition, silymarin treatment improved cognitive impairments in mTBI-induced males but not in females. Silymarin significantly reduced TNF-α and glutamate levels, and increased BDNF levels in the hippocampus of mTBI-induced male but not in female mice. Significance This study demonstrates that silymarin treatment sex-dependently improves cognitive impairment in mTBI-induced mice, and suggests that silymarin may be a therapeutic agent for cognitive decline following mTBI in males. Further studies are needed to establish the validity of these findings in humans.