Modified device for fluid percussion injury in rodents

Abstract

Fluid percussion (FP) injury model is a popular animal model of traumatic brain injury (TBI), but still there are some issues need to be addressed. To increase the validity and reliability of this technique, we adapted the FP device using electromagnetic protractor, stainless-steel cylinder, changing pressure transducer position, and foam pads to adjust the parameters of FP pulse. Besides, the adjusted FP device is more automatic. The FP pulse is promptly measured and displayed in a graphic user interface software. The modified device resulted in reliable FP pulse. The accuracy of the pendulum leveling was improved with using the electromagnetic protractor with slots. We then collected behavioral, cognition, electrophysiological, and immunohistochemical data to verify the percussion effects in TBI mice. Lateral fluid percussion injury (FPI) or sham treatment was administered at the right frontal motorsensory region of male C57BL/6J mice. TBI mice showed evident motor, cognitive, and functional impairments, characterized by evaluation of neurological, righting, geotaxis and cliff aversion reflexes, limb asymmetrical use, rotarod running, and Morris water maze testing. The neurobehavioral damages were scaled with histopathological findings. Further, the overall firing rates and theta powers in hippocampal CA1 were significantly reduced in TBI mice compared to sham mice at Days 2 and 3 after electrode implanting. The adapted device induced effects on behavior and biology in mice that agree with existing models. These findings confirmed the validity of adjustments, and the modified device may boost the interest in TBI studies.

Modified mouse model of repeated mild traumatic brain injury through a thinned‐skull window and fluid percussion

“…In this study, we adapted the fluid percussion procedure using a thinned‐skull window (Figure 1a,b) to eliminate brain injury caused by craniotomy preparation in conventional percussion modeling of TBI; and made it easy for TPLSM imaging. The repeat fluid percussion was applied by using our modified device (Ouyang et al, 2018). The microvasculature, part of the frontal lateral branch of mouse middle cerebral artery and caudal rhinal vein (Xiong et al, 2017), beneath the thinned skull were clearly seen under the camera, and two percussions at 2.0 atm cause minor subdural hematomas (Figure 1c) at 0 DPI in all rmTBI mice though repeated percussion did not break the integrity of the thinned‐skull.…”

“…CHI rmTBI was introduced in 13 mice (including mice for GCaMP6s expression and Ca 2+ imaging) using the lateral fluid percussion method with a modified percussion device (Ouyang et al, 2018). Briefly, mice were anesthetized with sodium pentobarbital (45 mg/kg i.p.).…”

“…The depth of the anesthesia was monitored by checking the palpebral and paw withdrawal reflexes. Since animal righting reflex time and injury severity post‐percussion seem to be influenced by anesthesia protocol (Bolton‐Hall et al, 2019; Fehily & Fitzgerald, 2017); therefore, after the return of a withdrawal reflex to a paw pinch, TBI was introduced with a closed form pad (with hardness values of 50) attached to the strike face of the piston pole (Ouyang et al, 2018). While a single mTBI may not result in behavioral impairments (Fehily & Fitzgerald, 2017), thus in this study, two rmTBI (48‐h interval) were induced and animals receive same anesthesia procedure.…”

“…Electrode implantation and verification were similar as described in our previous papers (Ouyang et al, 2017(Ouyang et al, , 2018. Six control and six rmTBI mice (without AAV injection) were used to investigate the spontaneous neural firing and local field potentials/electroencephalographic data (LFPs/EEG) changes at the percussion region.…”

“…In this study, we adapted the fluid percussion procedure using a thinned-skull window (Figure 1a,b) to eliminate brain injury caused by craniotomy preparation in conventional percussion modeling of TBI; and made it easy for TPLSM imaging. The repeat fluid percussion was applied by using our modified device (Ouyang et al, 2018).…”