Quantitative analyses of matrix metalloproteinase activity after traumatic brain injury in adult rats.

Recent laboratory evidence implicates matrix metalloproteinases (MMPs) as playing a pivotal role in ischemic and traumatic brain injuries (TBI). Here, quantitative real-time PCR analyses revealed that brains from TBI rats displayed significantly elevated MMP-9 expression at 24 h post-TBI, which remained upregulated at least until 48 h after injury. Immunohistochemical analyses similarly revealed significantly increased MMP-9 immunoreactivity at 24 and 48 h post-TBI. These results demonstrate that alterations in MMPs (i.e., MMP-9) commenced immediately after TBI, suggesting that treatment strategies designed to maintain MMP integrity should be initiated in the acute phase of injury.