title: Repeated blast exposure alters open field behavior recorded under low illumination.
abstract: Blast-induced traumatic brain injury (bTBI) can have devastating behavioral consequences. This study was designed to evaluate the behavioral consequences of single or repeated bTBI, as evaluated by an open field (OF) test conducted in near-darkness to avoid confounding effects of illumination and photophobia. Sprague-Dawley rats under isoflurane anesthesia were exposed to a series of 3 sub-lethal blasts into a compressed air-driven blast chamber separated by 2 week intervals (n=11). Sham controls received anesthesia but without blast exposure (n=11). OF tests were performed 1 or 7 days after each blast using a computerized video tracking system in near-darkness to monitor spontaneous activity. Spatial and temporal variables calculated for both blast and sham groups were: Distance moved (cm) and time (s) spent in the center or periphery zones of the field, total distance traveled, speed in center and periphery zones, rearing events and non-linear regressions of distance moved and rearing events on time. Results showed that the sham group expressed the expected decrease (habituation) in total distance walked, and distance walked as well as speed in center and periphery in successive exposures to the OF while the blast group did not, a sign of impaired learning. The blast group also walked more and faster and demonstrated more rearing behavior, both considered OF signs of anxiety. These results indicate that OF outcomes of bTBI in animals have resemblance to alterations observed in human subjects with this condition and might be useful in evaluating the response of behavioral outcomes of bTBI to experimental treatments.
authors.affiliation: UCLA/VA Multi-campus Residency Program, Los Angeles, CA, USA.
authors.forename: Emerald
authors.initials: E
authors.lastname: Huang
authors.forename: Mai
authors.initials: M
authors.lastname: Ngo
authors.forename: Stuart
authors.initials: S
authors.lastname: Yee
authors.forename: Laura
authors.initials: L
authors.lastname: Held
authors.forename: Keith
authors.initials: K
authors.lastname: Norman
authors.forename: A M Erika
authors.initials: AM
authors.lastname: Scremin
authors.forename: Oscar
authors.initials: O
authors.lastname: Scremin
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001930:Brain Injuries / Q000150:complications*; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000502:physiology*; D008029:Lighting; D008124:Locomotion; D001523:Mental Disorders / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
keywords: Blast injury; Brain injury; Rat