Transient disruption of mouse home cage activities and assessment of orexin immunoreactivity following concussive- or blast-induced brain injury

Abstract

The employment of explosive weaponry in modern warfare exposes populations to shock wave-induced and impact-related brain injuries. Among the most common clinical complaints resulting from traumatic brain injury (TBI) are sleep-wake disturbances. The current study assessed the acute effects of mild concussive brain injury (CBI) and mild blast wave-induced brain injury (BTBI) on mouse behavior and orexin-A expression. Male C57BL/6J mice were exposed to CBI, BTBI, or sham procedures. Injured animals and their shams were further divided into the following subgroups: 24-h survival in standard group (SG) housing, 72-h survival in SG housing, and 72-h survival in Any-Maze cages (AMc). AMc enabled continuous monitoring of home cage activities. BTBI caused significant but transient decreases in wheel running and ingestive behaviors 24 h post-injury (PI), while CBI transiently decreased running and water intake. BTBI resulted in general hypoactivity in the open field (OF) at both PI time points for SG-housed animals. In contrast, CBI did not cause hypoactivity. Mice subjected to CBI traveled more in the center of the OF at both time points PI, suggesting that CBI caused reduced anxiety in mice. Increased activity in the center of the OF was also seen at 24 h PI after BTBI. CBI treatment caused increased CD11b immunostaining. However, neither injury was accompanied by an alteration in the number of orexin-A hypothalamic neurons. Taken together, shock wave exposure and concussive injury transiently reduced mouse activities, but some differences between the two injuries were seen.

Sex differences in cued fear responses and parvalbumin cell density in the hippocampus following repetitive concussive brain injuries in C57BL/6J mice

“…The auditory cortex in an additional set of parvalbumin-stained sections ranging from Bregma -2.5 mm to -3.4 mm was also processed for parvalbumin cell density. The particle analysis feature of ImageJ was employed to count cells on 8-bit, thresholded images (minimum size: 150 pixel units, circularity 0.0–1.0) similar to methods previously described [36]. Most brain regions were thresholded using the Yen method (Fig 2C); a fixed lower threshold of 0.5% was employed for the CA2 region due to tissue heterogeneity of this region.…”

Hippocampal-Dependent Cognitive Dysfunction following Repeated Diffuse Rotational Brain Injury in Male and Female Mice

“…38 These findings were coupled with increased inflammation in the optic tracts, a common finding following single or repeated mTBI in rodent models. [39][40][41][42] This behavioral, physiological and pathological evidence suggests that braininjured mice suffer visual dysfunction, which may interfere with behavioral testing.…”

Sex as a Biological Variable in Preclinical Modeling of Blast-Related Traumatic Brain Injury

“…For several years now outstanding-and edifying-publications outline details for proper design of shock wave studies (198, (198). (D) Photograph of the ABS at the Uniformed Services University of the Health Sciences [cf., (205)]. The illustration depicts several aspects of optimal design of a shock tube.…”

“…(A) An example of a Friedlander-type shock wave initiated in an ABS. The tube has been previously described ( 205 ), and in this setting, a Valmex (7270, Low & Bonar, Martinsville, VA) membrane was employed to generate a shock wave of ~22 psi “peak pressure” (green arrow). The time-pressure trace shows the almost instantaneous change (yellow arrow) in ambient pressure from the shock wavefront, as well as the positive phase (red horizontal bar) and negative phase (blue horizontal bar) that follows as “blast wind.” (B) An example of the complex end-jet waveform.…”

“…Larger test objects in a confined shock tube can alter the flow of the shock wave, distorting free-field conditions [From ( 198 ). (D) Photograph of the ABS at the Uniformed Services University of the Health Sciences [cf., ( 205 )]. The illustration depicts several aspects of optimal design of a shock tube.…”