Cerebral blood flow at one year after controlled cortical impact in rats: assessment by magnetic resonance imaging.

Progressive tissue loss and delayed cognitive deficits are seen in rats during the initial year after experimental traumatic brain injury (TBI). As much as 10% of parenchymal volume is lost even in the contralateral hemisphere by 1 year after controlled cortical impact (CCI) in rats. Progressive declines in cerebral blood flow (CBF) are also associated with advanced age and neurodegenerative diseases.

Regulation of interstitial excitatory amino acid concentrations after cortical contusion injury.

Increases in brain interstitial excitatory amino acid (EAA(I)) concentrations after ischemia are ameliorated by use-dependent Na+ channel antagonists and by supplementing interstitial glucose, but the regulation of EAA(I) after traumatic brain injury (TBI) is unknown. We studied the regulation of EAA(I) after TBI using the controlled cortical impact model in rats. To monitor changes in EAA(I), microdialysis probes were placed in the cortex adjacent to the contusion and in the ipsilateral hippocampus.

Regulation of interstitial excitatory amino acid concentrations after cortical contusion injury.

Increases in brain interstitial excitatory amino acid (EAA(I)) concentrations after ischemia are ameliorated by use-dependent Na+ channel antagonists and by supplementing interstitial glucose, but the regulation of EAA(I) after traumatic brain injury (TBI) is unknown. We studied the regulation of EAA(I) after TBI using the controlled cortical impact model in rats. To monitor changes in EAA(I), microdialysis probes were placed in the cortex adjacent to the contusion and in the ipsilateral hippocampus.

Cerebral perfusion during anesthesia with fentanyl, isoflurane, or pentobarbital in normal rats studied by arterial spin-labeled MRI.

The influence of anesthetic agents on cerebral blood flow (CBF) was tested in normal rats. CBF is quantified with arterial spin-labeled MRI in rats anesthetized with either an opiate (fentanyl), a potent inhalation anesthetic agent (isoflurane), or a barbiturate (pentobarbital) using doses commonly employed in experimental paradigms. CBF values were found to be about 2.

Early perfusion after controlled cortical impact in rats: quantification by arterial spin-labeled MRI and the influence of spin-lattice relaxation time heterogeneity.

Early posttraumatic cerebral hypoperfusion is implicated in the evolution of secondary damage after experimental and clinical traumatic brain injury (TBI). This is the first report of cerebral blood flow (CBF) measurement by continuous arterial spin-labeled magnetic resonance imaging (MRI) early after TBI in rats using the controlled cortical impact (CCI) model. CCI reduced CBF globally at approximately 3 hr (versus normal), with 85% and 49% reductions in a contused cortical region and contralateral cortex, respectively.

Inducible nitric oxide synthase is an endogenous neuroprotectant after traumatic brain injury in rats and mice.

Nitric oxide (NO) derived from the inducible isoform of NO synthase (iNOS) is an inflammatory product implicated both in secondary damage and in recovery from brain injury. To address the role of iNOS in experimental traumatic brain injury (TBI), we used 2 paradigms in 2 species. In a model of controlled cortical impact (CCI) with secondary hypoxemia, rats were treated with vehicle or with 1 of 2 iNOS inhibitors (aminoguanidine and L-N-iminoethyl-lysine), administered by Alzet pump for 5 days and 1.

Neutrophils do not mediate blood-brain barrier permeability early after controlled cortical impact in rats.

Controlled cortical impact (CCI) produces blood-brain barrier (BBB) permeability and an acute inflammatory response in injured brain, associated with upregulation of cell adhesion molecules and accumulation of neutrophils. Nevertheless, the role of acute inflammation in the pathogenesis of BBB permeability after traumatic brain injury (TBI) is undefined. The purpose of this study was to examine the time course of acute inflammation and BBB permeability after CCI in rats and to determine the effect of neutrophil depletion on BBB permeability early after CCI.

Effect of traumatic brain injury in mice deficient in intercellular adhesion molecule-1: assessment of histopathologic and functional outcome.

Intercellular adhesion molecule-1 (ICAM-1) is an adhesion molecule of the immunoglobulin family expressed on endothelial cells that is upregulated in brain as part of the acute inflammatory response to traumatic brain injury (TBI). ICAM-1 mediates neurologic injury in experimental meningitis and stroke; however, its role in the pathogenesis of TBI is unknown. We hypothesized that mutant mice deficient in ICAM-1 (-/-) would have decreased neutrophil accumulation, diminished histologic injury, and improved functional neurologic outcome versus ICAM-1 +/+ wild type control mice after TBI.

One-year study of spatial memory performance, brain morphology, and cholinergic markers after moderate controlled cortical impact in rats.

Persistent cognitive deficits are one of the most important sequelae of head injury in humans. In an effort to model some of the structural and neuropharmacological changes that occur in chronic postinjury brains, we examined the longitudinal effects of moderate vertical controlled cortical impact (CCI) on place learning and memory using the Morris water maze (MWM) test, morphology, and vesicular acetylcholine (ACh) transporter (VAChT) and muscarinic receptor subtype 2 (M2) immunohistochemistry. Vertical CCI (left parietal cortex, 4 m/sec, 2.

72-kDa heat shock protein and mRNA expression after controlled cortical impact injury with hypoxemia in rats.

As part of the stress response, the 72 kDa heat shock protein (hsp72) is induced in neurons after ischemic and traumatic brain injury (TBI). To examine the stress response after TBI with secondary insult, we examined the regional and cellular expression of hsp72 mRNA and protein after controlled cortical impact (CCI) injury with secondary hypoxemia and mild hypotension in rats. Rats were killed at 6, 8, 24, 72, or 168 h after trauma.

Interstitial adenosine, inosine, and hypoxanthine are increased after experimental traumatic brain injury in the rat.

Adenosine is a putative neuroprotectant in ischemia, but its role after traumatic brain injury (TBI) is not clear. Metabolites of adenosine, particularly inosine and hypoxanthine, are markers of ischemia and energy failure. Adenosine triphosphate (ATP) breakdown early after injury and metabolism of cyclic adenosine monophosphate (cAMP) are potential sources of adenosine.

Augmented neuronal death in CA3 hippocampus following hyperventilation early after controlled cortical impact.

Unlabelled: Minimizing secondary injury after severe traumatic brain injury (TBI) is the primary goal of cerebral resuscitation. For more than two decades, hyperventilation has been one of the most often used strategies in the management of TBI. Laboratory and clinical studies, however, have verified a post-TBI state of reduced cerebral perfusion that may increase the brain's vulnerability to secondary injury.

The effect of brain temperature on acute inflammation after traumatic brain injury in rats.

The effect of varying brain temperature on neutrophil accumulation in brain and the expression of E-selectin and intercellular adhesion molecule-1 (ICAM-1) on cerebrovascular endothelium after controlled cortical impact (CCI) was studied in rats. Sprague Dawley rats were anesthetized and subjected to CCI to the left parietal cortex. Ten minutes after CCI, brain temperature was modulated and maintained at 32 degrees C, 37 degrees C, or 39 degrees C (n = 8 per group) for 4 h.

Assessment of cerebral blood flow and CO2 reactivity after controlled cortical impact by perfusion magnetic resonance imaging using arterial spin-labeling in rats.

We measured CBF and CO2 reactivity after traumatic brain injury (TBI) produced by controlled cortical impact (CCI) using magnetic resonance imaging (MRI) and spin-labeled carotid artery water protons as an endogenous tracer. Fourteen Sprague-Dawley rats divided into TBI (CCI; 4.02 +/- 0.

Expression of endothelial adhesion molecules and recruitment of neutrophils after traumatic brain injury in rats.

Traumatic brain injury (TBI) is often accompanied by an acute inflammatory reaction mediated initially by neutrophils. Adhesion molecules expressed on vascular endothelium are requisite elements during recruitment of leukocytes at sites of inflammation. In a rat model of TBI the induction and persistent expression of E-selectin (CD62E) on cerebrovascular endothelium ipsilateral, but not contralateral, to the site of contusion was demonstrated (P < 0.

The relationship between brain temperature and neutrophil accumulation after traumatic brain injury in rats.

Mild hypothermia reduces secondary damage after traumatic brain injury (TBI) in rodent models; however, the mechanisms involved in this beneficial effect remain unclear. We previously reported that TBI induces the upregulation of adhesion molecules and infiltration of neutrophils (PMN) in brain. Since PMN accumulation may be associated with the development of hyperemia and blood-brain barrier injury, we hypothesized that hypothermia would reduce acute inflammation after TBI in rats.

Antibodies against Mac-1 attenuate neutrophil accumulation after traumatic brain injury in rats.

Neutrophils (PMN) accumulate and are associated with cerebrovascular disturbances after experimental traumatic or ischemic brain injury, and meningitis. We hypothesized that posttraumatic PMN accumulation in brain is mediated by the PMN adhesion receptor Mac-1 (CD11b/CD18). Anesthetized rats were randomized to receive 2 mg/kg intravenously of murine monoclonal antibody to rat Mac-1 (1-B6) or anti-Mac-1 F(ab)2' [1-B6F(ab)2'] fragment (Repligen Corp.

Inducible nitric oxide synthase expression in cerebrovascular smooth muscle and neutrophils after traumatic brain injury in immature rats.

The inflammatory response after traumatic brain injury (TBI) includes cytokine production, leukocyte infiltration, and microglial activation. Production of nitric oxide by inducible nitric oxide synthase (iNOS) occurs during acute inflammation outside of the CNS and in models of cerebral ischemia, and therefore may contribute to the inflammatory response after TBI. The purpose of this study was to localize and define the time course of iNOS expression after TBI in the immature rat.

Posttraumatic hyperemia in immature, mature, and aged rats: autoradiographic determination of cerebral blood flow.

Clinical studies suggest that increased cerebral blood flow (CBF), or hyperemia, after traumatic brain injury (TBI) is commonly found in children and young adults, but is less often found in adults older than 40 years. However, whether posttraumatic cerebral hyperemia is truly an age-related phenomenon has not been proven. Using a model of focal percussive TBI, we hypothesized that (1) local CBF (ICBF) is increased by 24 after injury, and (2) the magnitude of the ICBF increase is age-related and is greatest in immature rats.

Mild posttraumatic hypothermia reduces mortality after severe controlled cortical impact in rats.

The effect of posttraumatic hypothermia (brain temperature controlled at 32 degrees C for 4 h) on mortality after severe controlled cortical impact (CCI) was studied in rats. Four posttraumatic brain temperatures were compared: 37 degrees C (n = 10), 36 degrees C (n = 4), 32 degrees C (n = 10), and uncontrolled (UC; n = 6). Rats were anesthetized and subjected to severe CCI (4.

Effects of hypothermia on traumatic brain injury in immature rats.

Hypothermia is beneficial in adult models of traumatic brain injury (TBI), but it has not been evaluated in an immature animal model. We hypothesized that brief hypothermia applied after TBI would reduce cerebral edema and lesion volume in immature rats. Male Wistar rats (3-4 weeks of age, 90-140 g) were anesthetized, intubated, mechanically ventilated, and subjected to TBI by weight drop onto the exposed right parietal cortex.

Severe controlled cortical impact in rats: assessment of cerebral edema, blood flow, and contusion volume.

Controlled cortical impact (CCI) is a contemporary model of experimental cerebral contusion. We examined the cerebrovascular and neuropathologic effects of a severe CCI in rats. The utility of magnetic resonance imaging (MRI) for the assessment of contusion volume after severe CCI was also established.

Effect of soluble complement receptor-1 on neutrophil accumulation after traumatic brain injury in rats.

As part of the acute inflammatory response, neutrophils accumulate in the central nervous system after injury. Recently, a soluble human recombinant complement receptor (sCR1; BRL 55730; T Cell Sciences, Inc., Cambridge, MA, U.

Optimization of epoxyeicosatrienoic acid syntheses to test their effects on cerebral blood flow in vivo.

Epoxyeicosatrienoic acids (EETs), normally present in brain and blood, appear to be released from atherosclerotic vessels in large amounts. Once intravascular, EETs can constrict renal arteries in vivo and dilate cerebral and coronary arteries in vitro. Whether EETs in blood will alter cerebral blood flow (CBF) in vivo is unknown.