Repeated mild traumatic brain injury in the juvenile brain: Investigations on synaptic plasticity in the hippocampus

Abstract

Traumatic Brain Injury (TBI) occurs when an impulsive force is transmitted to the head and affects the brain. Up to 75% of all brain injuries are classified as “mild” TBI (mTBI; also known as concussion). There is growing evidence that during a life time repeated mTBI (rmTBI) can produce cumulative structural damage and long‐term changes in behaviour. The juvenile brain is in a period of robust synaptic reorganization and myelination, making this a particularly vulnerable time to incur either mTBI or rmTBI. Although most children recover from mTBI incidents, a significant proportion experience learning and memory impairments after rmTBI. Memory formation is closely dependent on the capacity of the brain to regulate long‐lasting changes in neuronal communication (synaptic plasticity) with the hippocampus being an essential structure for this process. Therefore, we hypothesize that rmTBI causes learning and memory deficits through its effects on hippocampal synaptic plasticity.Using the Awake Closed‐Head Injury (ACHI) model we examined how male and female Long‐Evans rats (25–28 days of age) responded after 8 episodes of ACHI over a four day period in. Animals were assessed for changes in their state of consciousness and sensorimotor abilities immediately following each ACHI, allowing us to examine the acute effects of each injury. Synaptic plasticity was assessed using in vitro electrophysiology either one day or seven days post‐ACHI.Our results show that rmTBI impacts sensorimotor abilities and impairs hippocampal synaptic plasticity in both males and female subjects. These data suggest that learning and memory deficits from rmTBI may be due to impairments in hippocampal synaptic plasticity.Support or Funding InformationSupport or Funding Information Canadian Institutes of Health Research (CIHR) Natural Sciences and Engineering Research Council of Canada (NSERC) CP funded by Fundació Universitaria Agustí Pedro PonsThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.