ABSTRACT
<p><b>BACKGROUND</b>Traumatic brain injury (TBI) is a major cause of death and disability in children and young adults worldwide. Therefore, we investigated the role of AG490 in regulating brain oedema, expression of CD40 and neurological function after TBI.</p><p><b>METHODS</b>Sprague Dawley rats (n = 240) were randomly divided into a sham operation group, TBI+saline group and TBI+AG490 (JAK/STAT inhibitor) group. Members of each group were euthanized at 6, 12, 24 or 72 hours after injury. Neurological severity score (NSS) was used to evaluate the severity of neurological damage. Brain water was quantitated by wet/dry weight method. The expression of CD40 was assessed by flow cytometry.</p><p><b>RESULTS</b>In both the TBI+saline group and the TBI+AG490 group, the brain water content was elevated after TBI, reached a peak at 24-hour and remained high for the rest of the period investigated; the expression of CD40 reached a peak 24 hours after TBI; the NSS was elevated after TBI and then decreased after 6 hours. Elevations in the level of CD40, degree of brain edema and NSS after TBI were significantly reduced in TBI+AG490 group.</p><p><b>CONCLUSION</b>Inhibition of the JAK/STAT signalling pathway reduces brain oedema, decreases the expression of CD40 and exerts neuroprotective effects after TBI.</p>