Open field test in male C57BL/6J mice three months following low-intensity blast exposure using EthoVision software

STUDY PURPOSE: Assessment of the long-term behavioral changes in anxiety-like behavior, locomotion, and exploratory activity three months after low-intensity open-field blast exposure to the brain. DATA COLLECTED: A total of 40 male C57BL/6J mice, 2 months old, were used in the study of single Low Intensity Blast (LIB) exposure, described by Heather R. Siedhoff et al. 2024 [PMID: 39744609]. Mice were randomly assigned to two groups: LIB-exposed (n = 20) and sham controls(n = 20). Mice were anesthetized with an intraperitoneal injection of 10 microL/g body weight of ketamine/xylazine mixture (12.5 mg/mL ketamine and 0.625 mg/mL xylazine). Mice in the sham control group underwent the identical anesthesia procedures but without LIB exposure. Mice were placed in the prone position in metal-mesh holders on a platform 1-meter above ground and 3-meters away from the detonation of a 350-g spherical C-4, generating a magnitude of 46.6 kPa peak overpressure and a maximum impulse of 60.0 kPa*ms. Mice had free access to food and water before and after blast exposure. The open-field behavior test was performed 3 months after LIB exposure.

There were no significant changes in body weight (g ± SEM) before or after blast exposure. Pre-blast body weights were 23.53 ± 0.44 g for the Sham group and 24.48 ± 0.43 g for the Blast group. The final recorded body weights at the time of sacrifice were 29.96 ± 0.52 g for the Sham group and 31.07 ± 0.66 g for the Blast group.

To minimize external stress, the mice were socialized with the investigators daily for 7 days before the behavioral testing. Before the open-field test, the mice were transferred to the testing room and allowed to acclimate for at least 60 minutes.

The test arena (gray) measured 40 x 40 cm, with 30 cm walls and a central zone of 10 x 10 cm (RRID: SCR_004074; Noldus Information Technology, Leesburg, VA, USA). The duration of the test was 10 min, and the activity of mice was tracked using EthoVision software (EthoVision HTP 2.1.2.0, based on EthoVision XT 4.1, Noldus Information Technology, Wageningen, The Netherlands). Each mouse was placed at the center of a square open field arena, which featured a virtual 10 x 10 cm center zone. After each trial, the arena was cleaned with a 20% ethanol solution and air-dried.

Different parameters, such as total distance traveled, total duration of moving, duration in the center zone, and frequency of entry into the center zone, were measured to assess the anxiety, locomotor, and exploratory behavior. Statistical analysis showed a trend for reduced movement and center zone engagement in LIB-exposed mice compared to sham controls. DATA USAGE NOTES: