Hippocampal N-acetylaspartate levels before trauma predict the development of long-lasting posttraumatic stress disorder-like symptoms in mice.
BACKGROUND
Only a certain proportion of individuals develop posttraumatic stress disorder (PTSD) in the aftermath of a trauma. Biomarkers of individual susceptibility are not yet known but would enable selected primary and secondary prevention of PTSD.


METHODS
Hippocampal N-acetylaspartate (NAA) levels were assessed by proton magnetic resonance spectroscopy ((1)H-MRS) in C57BL/6N mice prior to the perception of a 1.5 mA electric footshock. Associative (freezing to trauma context) and nonassociative (freezing to a neutral tone; i.e., hyperarousal) symptoms of PTSD-like fear were assessed 4, 5, 18, and 32 weeks after trauma.


RESULTS
Low NAA levels in the left dorsal hippocampus predicted persistent PTSD-like symptoms (both contextual freezing and hyperarousal), while animals with pretraumatic high levels of NAA decreased their fear reactions to control levels in consequence of re-exposure to associative and nonassociative cues. N-AA levels in the right dorsal hippocampus, in contrast, were only partially predictive of the individual susceptibility to develop PTSD-like symptoms.


CONCLUSIONS
Left hippocampal NAA levels might be a predictor of an increased susceptibility to develop PTSD after trauma.
Max Planck Institute of Psychiatry, Munich, Germany.
Anja
A
Siegmund
Sebastian F
SF
Kaltwasser
Florian
F
Holsboer
Michael
M
Czisch
Carsten T
CT
Wotjak
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001522:Behavior, Animal / Q000502:physiology; D003401:Creatine / Q000378:metabolism; D003627:Data Interpretation, Statistical; D004597:Electroshock; D006624:Hippocampus / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011237:Predictive Value of Tests; D013313:Stress Disorders, Post-Traumatic / Q000378:metabolism* / Q000523:psychology*; D014947:Wounds and Injuries / Q000378:metabolism* / Q000523:psychology*
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine