Acute peripheral inflammation and post-traumatic sleep differ between sexes after experimental diffuse brain injury

Area of Science:

• Neuroscience
• Immunology
• Sleep Science

Background:

• Traumatic brain injury (TBI) can trigger peripheral and central inflammation, potentially affecting sleep patterns.
• Previous studies suggest TBI-induced inflammation increases sleep in male rodents, but this effect in females is largely unexplored.
• Understanding sex-specific responses to TBI is crucial for elucidating disease mechanisms and improving treatment strategies.

Purpose of the Study:

• To investigate sex differences in peripheral and central inflammation and sleep responses following diffuse TBI in mice.
• To test the hypothesis that TBI would increase inflammation and sleep in males more than in females.

Main Methods:

• Diffuse TBI was induced in C57BL/6J mice.
• Serial blood samples were collected to quantify immune cells and cytokines.
• Brains and spleens were harvested for immune cell analysis at 7 days post-injury (DPI).
• Sleep patterns were monitored and analyzed.
• Mixed-effects regression models were used for statistical analysis.

Main Results:

• Female TBI mice exhibited significantly higher IL-6 levels at 1 and 5 DPI compared to males.
• TBI reduced blood monocyte counts in both sexes, with a more pronounced decrease in TBI mice.
• Male TBI mice showed higher neutrophil counts in blood and spleen compared to females at various time points post-injury.
• TBI increased sleep duration in both sexes, with male TBI mice exhibiting greater sleep increases than females.

Conclusions:

• Sex and TBI interact to modulate peripheral inflammation profiles and sleep patterns.
• Observed sex differences in immune responses and sleep following TBI may contribute to differential disease progression.
• Further research into these sex-specific mechanisms is warranted to address discrepancies in TBI outcomes.