Repeated Mild TBI in Adolescent Rats Reveals Sex Differences in Acute and Chronic Behavioral Deficits

Area of Science:

• Neuroscience
• Behavioral Science
• Sports Medicine

Background:

• Repetitive mild traumatic brain injury (TBI) in adolescents, common in contact sports, can lead to cognitive and emotional deficits.
• Sex-based differences in TBI outcomes are observed, with boys potentially facing more cognitive issues and girls reporting depression and anxiety.

Purpose of the Study:

• To investigate the effects of repetitive mild TBI on memory and behavior in adolescent male and female rats.
• To compare the temporal patterns of cognitive and emotional deficits between sexes following TBI.

Main Methods:

• Adolescent male and female Sprague-Dawley rats underwent repetitive mild TBI or sham injury.
• Cognitive function was assessed using object location, spatial working memory, and object recognition memory tasks at 1 and 4 weeks post-injury.
• Depressive-like and anxiety-like behaviors were evaluated at 5 weeks, followed by histological analysis of brain tissue.

Main Results:

• Male rats showed immediate and persistent impairments in both hippocampal-dependent and -independent memory tasks.
• Female rats exhibited memory impairments only at the 4-week mark.
• Depressive-like behaviors were observed in female rats at 5 weeks post-injury, but not anxiety-like behaviors in either sex.
• Histological analysis revealed increased astrocyte and microglia reactivity in specific brain regions, including the hippocampus, in both sexes.

Conclusions:

• Repetitive mild TBI in adolescent rats results in sex-specific temporal patterns of behavioral deficits.
• Female rats may be more susceptible to chronic post-traumatic cognitive and emotional deficits.
• These findings highlight the importance of considering sex in TBI research and clinical management.