Longitudinal effects of mild traumatic brain injury on the gut microbiome and acoustic startle response in male and female rats

The current study used a multi-modal longitudinal design to examine overall and sex-specific changes in the gut microbiome and ASR following mTBI. The aim of this study was to examine: 1) overall and sex-specific differences in the gut microbiome and taxa in response to mTBI and 2) associations between the gut microbiome and sensorimotor processing. This longitudinal study included twenty-six male (mTBI, n = 14; sham, n = 12) and twenty-eight female (mTBI, n = 16; sham, n = 12) Sprague Dawley rats. The animals were approximately 3-months of age at the start of the study, housed individually in a room with a 12-h reverse light cycle. All rats went through the same experimental and surgical procedures except for the mild lateral fluid percussion injury (mLFPI) procedure, which only mTBI groups experienced. Fecal pellets were collected directly from each rat prior to injury and post-injury on days 1, 2, 3, 4, 7, 10, 15, 20 and 30. A multi-intensity ASR protocol was used to assess differences in startle sensitivity and responsivity pre-injury, 7 days post-injury and 30 days post-injury using the SR-Lab Startle Response System.