Citation

Ogier M, Belmeguenai A, Lieutaud T, Georges B, Bouvard S, Carre E, Canini F, Bezin L. J. Neurotrauma 2016; 34(8): 1645-1657.

Affiliation

Institute for Epilepsy, IDEE, Bron, France ; Laurent.bezin@univ-lyon1.fr.

Copyright

(Copyright © 2016, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2016.4741

PMID

27901414

Abstract

Traumatic brain injury (TBI) is common in both military and civilian populations, and often results in neurobehavioral sequelae that impair quality of life in both patients and their family. Although individuals who are chronically exposed to stress are more likely to experience TBI, it is still unknown whether pre-injury stress influences the outcome after TBI. The present study tested whether behavioral and cognitive long-term outcome after TBI in rats is affected by prior exposure to an innate stress stimulus. Young adult male Sprague-Dawley rats were exposed to the predator odor 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) or to water (WAT); exposure was repeated 8 times at irregular intervals over a 2-week period. Rats were subsequently subjected to either mild-to-moderate bilateral fluid percussion (LFP) brain injury or sham surgery (Sham). Four experimental groups were studied: Sham-WAT, Sham-TMT, LFP-WAT and LFP-TMT. Compared to Sham-WAT rats, LFP-WAT rats exhibited transient locomotor hyperactivity without signs of anxiety, minor spatial learning acquisition and hippocampal long-term potentiation deficits, and lower baseline activity of the hypothalamic-pituitary-adrenal axis with slightly stronger reactivity to restraint stress. Exposure to TMT had only negligible effects on Sham rats whereas it exacerbated all deficits in LFP rats except for locomotor hyperactivity. Early brain inflammatory response (8 hours post-trauma) was aggravated in rats pre-exposed to TMT, suggesting that increased brain inflammation may sustain functional deficits in these rats. Hence, these data suggest that pre-exposure to stressful conditions can aggravate long-term deficits induced by TBI, leading to severe stress response deficits, possibly due to dysregulated inflammatory response.

Language: en