Normabaric Hyperoxia Treatment Improved Locomotor Activity of C57BL/6J Mice through Enhancing Dopamine Genes Following Fluid-Percussion Injury in Striatum

Abstract

Closed traumatic brain injury (CTBI) leads to increase mortality rates in developing countries. However, a sustainable therapeutic approach has not been established yet. Therefore, the present study was designed to evaluate the impact of normabaric hyperoxia treatment (NBOT) on striatum associated Locomotor Activity (LA) in IntelliCage after Fluid-Percussion Injury (FPI). Animals were divided in four groups: Group I control (n=24), Group II sham (n=24), Group III FPI (n=24) and Group IV FPI with NBOT (n=24). Animals were habituated in IntelliCage for 4 days following transponder implanted in mice neck region on day 5. Then the LA of all groups was assessed 6hr daily for 5 days before inducing FPI. On day 6, cannula was implanted on the striatum, on day 7 FPI was performed in Group III (kept in normal environment) and IV (immediately exposed to NBOT for 3 hr). LA (in terms of number of visits in all four corners) was assessed 6 hr at days 1, 7, 14, 21 and 28 following FPI. After the animals were sacrificed to study the neuronal damage, dopamine receptors and transporters expression in striatum. The results suggested that the LA of FPI impaired mice as compared to the control and sham showed less number of visits in all four corners in IntelliCage. Morphological results revealed that FPI induced neuronal damage as compared to sham and control. Dopamine receptors and transporters were down regulated in the FPI group as compared to the control. Immediate exposure to NBOT improved LA in terms of increased number of visits in all four corners, reduced number of cell death and improved receptor expression as compared to FPI. In conclusion, NBOT exposure could improve the LA of mice following FPI through prevention of neuronal damage, improved dopamine receptors and transporters.