Journal of neurotrauma
-
Journal of neurotrauma · Jun 2010
Effect of acute poly(ADP-ribose) polymerase inhibition by 3-AB on blood-brain barrier permeability and edema formation after focal traumatic brain injury in rats.
Recent evidence supports a crucial role for matrix metalloproteinase-9 (MMP-9) in blood-brain barrier (BBB) disruption and vasogenic edema formation after traumatic brain injury (TBI). Although the exact causes of MMP-9 upregulation after TBI are not fully understood, several arguments suggest a contribution of the enzyme poly(ADP-ribose)polymerase (PARP) in the neuroinflammatory response leading to MMP-9 activation. The objectives of this study were to evaluate the effect of PARP inhibition by 3-aminobenzamide (3-AB) (1) on MMP-9 upregulation and BBB integrity, (2) on edema formation as assessed by magnetic resonance imaging (MRI), (3) on neuron survival as assessed by (1)H magnetic resonance spectroscopy ((1)H-MRS), and (4) on neurological deficits at the acute phase of TBI. ⋯ At both 6 and 24 h, neurological function was better in the 3-AB-treated than in the vehicle-treated rats. These data suggest that PARP inhibition by 3-AB protected the BBB against hyperpermeability induced by MMP-9 upregulation, thereby decreasing vasogenic edema formation 6 h after TBI. Furthermore, our data confirm the neuroprotective effect of 3-AB at the very acute phase of TBI.
-
Journal of neurotrauma · Jun 2010
Matrix metalloproteinase-9 expression and protein levels after fluid percussion injury in rats: the effect of injury severity and brain temperature.
The temporal and regional expression profiles of matrix metalloproteinase-9 (MMP-9), after moderate or severe traumatic brain injury (TBI) were measured to investigate the effects of post-traumatic hypothermia (33 degrees C) or hyperthermia (39 degrees C). In the first phase of this study, adult male Sprague-Dawley rats were randomly assigned to groups of moderate TBI (1.8-2.2 atm), severe TBI (2.4-2.7 atm), and sham-injured control. The rats were killed at 4, 6, 12, 24, 48, and 72 h, or 1 week after TBI, for mRNA and protein analysis. ⋯ In contrast, hyperthermia had no significant effect on mRNA (at 12 h) and protein levels (at 24 h) of MMP-9, compared with normothermic values (p > 0.05), but resulted in a significant increase in the levels of MMP-9 mRNA and protein at 24 and 72 h, respectively (p < 0.01). Increases in MMP-9 mRNA and protein after TBI were proportional to injury severity in this model. The effects of post-traumatic hypothermia on the expression of MMP-9 may partially explain the observed effects of post-traumatic temperature on secondary injury after TBI.
-
Journal of neurotrauma · May 2010
Multicenter StudyA method for reducing misclassification in the extended Glasgow Outcome Score.
The eight-point extended Glasgow Outcome Scale (GOSE) is commonly used as the primary outcome measure in traumatic brain injury (TBI) clinical trials. The outcome is conventionally collected through a structured interview with the patient alone or together with a caretaker. Despite the fact that using the structured interview questionnaires helps reach agreement in GOSE assessment between raters, significant variation remains among different raters. ⋯ The group using the alternative rating system coupled with central monitoring yielded the highest inter-rater agreement among the three groups in rating GOS (97%; weighted kappa = 0.95; 95% CI 0.89, 1.00), and GOSE (97%; weighted kappa = 0.97; 95% CI 0.91, 1.00). The alternate system is an improved GOSE rating method that reduces inter-rater variations and provides for the first time, source documentation and structured narratives that allow a thorough central review of information. The data suggest that a collective effort can be made to minimize inter-rater variation.
-
Journal of neurotrauma · May 2010
Diffuse brain injury elevates tonic glutamate levels and potassium-evoked glutamate release in discrete brain regions at two days post-injury: an enzyme-based microelectrode array study.
Traumatic brain injury (TBI) survivors often suffer from a wide range of post-traumatic deficits, including impairments in behavioral, cognitive, and motor function. Regulation of glutamate signaling is vital for proper neuronal excitation in the central nervous system. Without proper regulation, increases in extracellular glutamate can contribute to the pathophysiology and neurological dysfunction seen in TBI. ⋯ The amplitudes of KCl-evoked glutamate release were increased significantly only in the striatum after moderate injury, with a 249% increase seen in the dorsal striatum. Thus, with the MEAs, we measured discrete regional changes in both tonic and KCl-evoked glutamate signaling, which were dependent on injury severity. Future studies may reveal the specific mechanisms responsible for glutamate dysregulation in the post-traumatic period, and may provide novel therapeutic means to improve outcomes after TBI.
-
Journal of neurotrauma · May 2010
Blockade of acute microglial activation by minocycline promotes neuroprotection and reduces locomotor hyperactivity after closed head injury in mice: a twelve-week follow-up study.
Traumatic brain injury (TBI) causes a wide spectrum of consequences, such as microglial activation, cerebral inflammation, and focal and diffuse brain injury, as well as functional impairment. In this study we aimed to investigate the effects of acute treatment with minocycline as an inhibitor of microglial activation on cerebral focal and diffuse lesions, and on the spontaneous locomotor activity following TBI. The weight-drop model was used to induce TBI in mice. ⋯ More interestingly, minocycline significantly decreased TBI-induced locomotor hyperactivity at 48 h post-TBI, and its effect lasted for up to 8 weeks. Taken together, the results indicate that microglial activation appears to play an important role in the development of TBI-induced focal injury and the subsequent locomotor hyperactivity, and its short-term inhibition provides long-lasting functional recovery after TBI. These findings emphasize the fact that minocycline could be a promising new therapeutic strategy for head-injured patients.