Biomedical subjects

T K McIntosh

Publications and source records attributed to T K McIntosh.

At least 37 records · Page 2Linked to original sources

PubMed2001

Magnetization transfer imaging and proton MR spectroscopy in the evaluation of axonal injury: correlation with clinical outcome after traumatic brain injury.

BACKGROUND AND PURPOSE: Current imaging does not permit quantification of neural injury after traumatic brain injury (TBI) and therefore limits both the development of new treatments and the appropriate counseling of patients concerning prognosis. We evaluated the utility of magnetization transfer ratio (MTR) and proton MR spectroscopy in identifying patients with neuronal injury after TBI. METHODS: Thirty patients with TBI (21-77 years old; mean age, 42 years; admission Glasgow Coma Scale (GOS) scores 3-15; mean score, 11) were studied on a 1.5-T system with magnetization transfer imaging and MR spectroscopy of the splenium. Magnetization transfer imaging was also performed in the brain stem in all patients, and other areas of the brain were sampled in one patient. The splenium of the corpus callosum and brain stem were studied because these are often affected by diffuse axonal injury. Scans were obtained 2 to 1129 days after injury (median, 41 days). MTR was considered abnormal if it was more than 2 SD below normal. Proton MR spectroscopy was used to calculate the N-acetylaspartate (NAA)/creatine (Cr) ratio. GOS was determined at least 3 months after injury. RESULTS: In 10 patients with a GOS of 1 to 4, the mean NAA/Cr was 1.24 +/- 0.28; two of these patients had abnormal MTR in normal-appearing white matter (NAWM). In 20 patients with a GOS of 5, the mean NAA/Cr was 1.53 +/- 0.37 (P < .05); four of these patients had abnormal MTR in NAWM. MTR abnormalities in NAWM were identified in six patients, but these changes did not correlate with GOS or MR spectroscopy changes. CONCLUSION: MTR and MR spectroscopy can quantify damage after TBI, and NAA levels may be a sensitive indicator of the neuronal damage that results in a worse clinical outcome.

Aspartic Acid↗

PubMed2001

Effects of chronic, post-injury Cyclosporin A administration on motor and sensorimotor function following severe, experimental traumatic brain injury.

PURPOSE: Cyclosporin A (CsA) is widely used in clinical situations to attenuate graft rejection following organ and central nervous system transplantation. Previous studies demonstrated that CsA administration is neuroprotective in models of traumatic brain injury (TBI). However, no studies, to date, have evaluated the influence of post-injury CsA administration on behavioral recovery after TBI. METHODS: Rats (n = 33) were anesthetized and subjected to severe, lateral fluid percussion brain injury. Fifteen minutes thereafter, animals were randomized to receive the first of 28 daily injections of either CsA (10 mg/kg, ip) or saline. Sham-operated animals (n = 14) were anesthetized and surgically prepared without injury and treated daily either with CsA or saline. Motor and sensorimotor functions were assessed at one day before and two days after injury, and weekly thereafter up to 4 wks post-injury. Cognition was assessed at 1 and 4 wks post-injury using a Morris Water Maze test. RESULTS: Injured animals showed significant impairments in motor, sensorimotor and cognitive function over the 4-week post-injury period. Injured animals treated with CsA showed a significant improvement in motor function assessed using a composite neuroscore (at day 28) and in sensorimotor function assessed using a sticky paper test (at days 2, 14, and 28) (p < 0.05, when compared to vehicle treated, injured animals). No beneficial effects on cognitive function were observed following CSA administration. CONCLUSION: These data suggest that daily post-injury treatment with CsA improves certain aspects of motor and sensorimotor function following experimental TBI.

Animals↗

PubMed2001

The assessment of genomic alterations using DNA arrays following traumatic brain injury: a review.

Recent advances in DNA microarray technology have enabled the simultaneous evaluation of thousands of genes and the subsequent generation of massive amounts of biological data relevant to injury or diseases of the central nervous system (CNS). This technology has the potential to bridge the gap between molecular and systems neuroscience by efficiently revealing the discrete molecular aspects underlying the perturbations of complex systemic insults such as those resulting from traumatic brain injury (TBI). One of the more intriguing and as of yet not understood aspects of TBI that can be efficiently explored with DNA microarrays, is the sequence of molecular events that results in pronounced cell death in specific areas of the brain. The elucidation of these changes in gene expression underlying the mechanism of cell death following brain injury is of central importance in the design of future therapeutic agents. This review focuses on the technical aspects of microarray manufacture (photolithography, microspotting, and ink jet technology) and their utility in elucidating the molecular sequelae of brain injury.

Animals↗

PubMed2000

Bilateral growth-related protein expression suggests a transient increase in regenerative potential following brain trauma.

The potential of mature central nervous system (CNS) neurons to regenerate after injury represents a fundamental issue in neurobiology. The regional expression of proteins associated with axonal elongation, such as microtubule-associated protein 1B (MAP1B), its phosphorylated isoform (MAP1B-P), growth-associated protein 43 (GAP-43), and polysialylated neural cell-adhesion molecule (PSA-NCAM), was examined using immunohistochemistry from 24 hours to 2 months following lateral fluid percussion brain injury of moderate severity (2.4-2.6 atmospheres) in anesthetized rats. Uninjured (control) rats were subjected to anesthesia and surgery without injury or were subjected to anesthesia alone. Within the site of maximal injury, only increases in MAP1B and MAP1B-P were observed. Increased immunoreactivity was observed bilaterally for all growth-related proteins that were evaluated. By 24 hours postinjury, MAP1B and MAP1B-P increased within the cortex (P < 0.01) and the hippocampus (P < 0.001), whereas MAP1B-P also was elevated in the thalamus (P < 0.05). Within the dentate gyrus, increased immunoreactivity was observed for all proteins examined. By 48 hours postinjury, GAP-43 was elevated bilaterally within the inner molecular layers of the dentate gyrus (P < 0.005) and within the stratum lacunosum moleculare (P < 0.01), the stratum radiatum (P < 0. 005), and the stratum oriens (P < 0.05) of the hippocampus. Increased numbers of PSA-NCAM-labeled neurons were observed in the granule cell layers of the dentate gyrus from 48 hours through 2 weeks postinjury (P < 0.0005). The bilateral nature of increased expression of growth-related proteins differs from unilateral patterns of neuronal degeneration previously characterized for the lateral fluid-percussion model of brain injury. Taken together, these results suggest the existence of a temporary posttraumatic state in which the CNS may have increased regenerative potential. Enhancement of such a response may be one therapeutic strategy in treating CNS injury.

Animals↗

PubMed2000

Traumatic brain injury alters the molecular fingerprint of TUNEL-positive cortical neurons In vivo: A single-cell analysis.

The cerebral cortex is selectively vulnerable to cell death after traumatic brain injury (TBI). We hypothesized that the ratio of mRNAs encoding proteins important for cell survival and/or cell death is altered in individual damaged neurons after injury that may contribute to the cell's fate. To investigate this possibility, we used amplified antisense mRNA (aRNA) amplification to examine the relative abundance of 31 selected candidate mRNAs in individual cortical neurons with fragmented DNA at 12 or 24 hr after lateral fluid percussion brain injury in anesthetized rats. Only pyramidal neurons characterized by nuclear terminal deoxynucleotidyl transferase-mediated biotinylated dUTP nick end labeling (TUNEL) reactivity with little cytoplasmic staining were analyzed. For controls, non-TUNEL-positive neurons from the cortex of sham-injured animals were obtained and subjected to aRNA amplification. At 12 hr after injury, injured neurons exhibited a decrease in the relative abundance of specific mRNAs including those encoding for endogenous neuroprotective proteins. By 24 hr after injury, many of the mRNAs altered at 12 hr after injury had returned to baseline (sham-injured) levels except for increases in caspase-2 and bax mRNAs. These data suggest that TBI induces a temporal and selective alteration in the gene expression profiles or "molecular fingerprints" of TUNEL-positive neurons in the cerebral cortex. These patterns of gene expression may provide information about the molecular basis of cell death in this region after TBI and may suggest multiple avenues for therapeutic intervention.

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PubMed2000

The rotating pole test: evaluation of its effectiveness in assessing functional motor deficits following experimental head injury in the rat.

Neurological motor dysfunction is often an integral component of the neurological sequelae of traumatic brain injury (TBI). In experimental TBI, neurological motor testing is an outcome measure used to monitor severity of injury, and the response to treatment. This study evaluates the effectiveness and sensitivity of the rotating pole test (RP) to characterize and evaluate the temporal course of motor deficits after lateral fluid percussion (FP) injury to the rat brain. The results are compared with the previously characterized and widely used composite neuroscore of motor function (NS). The animals were required to walk across an elevated wooden pole that was either stationary or rotating to left or right directions at different speeds. Male Wistar rats underwent lateral FP injury of moderate severity (mean 2.4 atm, n = 9) or sham surgery (n = 9), and were tested at 48 h and 7 days post-injury using the NS and RP. The results of the NS directly correlated to the results of the RP, showing a significant injury effect at both 48 h and 7 days. This is the first study to show that the RP-test detects neurological motor deficits after lateral FP injury, and suggests that this technique is a reliable behavioral tool for evaluating neurological motor function in the acute period after experimental TBI.

Animals↗

PubMed2000

Magnetization transfer imaging of traumatic brain injury.

Magnetization transfer imaging (MTI) has been shown to be sensitive for the detection of white matter abnormalities in entities such as multiple sclerosis, progressive multifocal leukoencephalopathy, and wallerian degeneration. Our hypothesis was that MTI would detect traumatic white matter abnormalities (TWMA) and provide information additional to that obtainable with routine spin- and gradient-echo imaging. We hypothesized that the presence of TWMA defined by MTI would correlate with outcome following TBI. Twenty-eight victims of head trauma and 15 normal controls underwent magnetic resonance imaging including MTI. Magnetization transfer ratios (MTR) were calculated for areas of shearing injury and for normal-appearing white matter (NAWM) in locations frequently subject to diffuse axonal injury. Abnormal MTRs were detected in NAWM in eight patients. All eight had persistent neurologic deficits, including cognitive deficits, aphasia, and extremity weakness. Seven of the 28 patients had no abnormal findings on neurologic exam at discharge, transfer, or follow-up. None of these patients had an abnormal MTR in NAWM. In the remaining 13 patients, who had persistent neurologic deficits, no regions of abnormal MTR were detected in NAWM. MTI is a sensitive method for the detection of TWMA. Detection of abnormal MTR in NAWM that is prone to axonal injury may predict a poor patient outcome. The presence of normal MTR in NAWM in these areas does not necessarily confer a good outcome, however.

Adult↗

PubMed2000

Brain trauma in aged transgenic mice induces regression of established abeta deposits.

Traumatic brain injury (TBI) increases susceptibility to Alzheimer's disease (AD), but it is not known if TBI affects the progression of AD. To address this question, we studied the neuropathological consequences of TBI in transgenic (TG) mice with a mutant human Abeta precursor protein (APP) mini-gene driven by a platelet-derived (PD) growth factor promoter resulting in overexpression of mutant APP (V717F), elevated brain Abeta levels, and AD-like amyloidosis. Since brain Abeta deposits first appear in 6-month-old TG (PDAPP) mice and accumulate with age, 2-year-old PDAPP and wild-type (WT) mice were subjected to controlled cortical impact (CCI) TBI or sham treatment. At 1, 9, and 16 weeks after TBI, neuron loss, gliosis, and atrophy were most prominent near the CCI site in PDAPP and WT mice. However, there also was a remarkable regression in the Abeta amyloid plaque burden in the hippocampus ipsilateral to TBI compared to the contralateral hippocampus of the PDAPP mice by 16 weeks postinjury. Thus, these data suggest that previously accumulated Abeta plaques resulting from progressive amyloidosis in the AD brain also may be reversible.

Aging↗

PubMed2000

Neurofilament-rich intraneuronal inclusions exacerbate neurodegenerative sequelae of brain trauma in NFH/LacZ transgenic mice.

Several neurodegenerative disorders are characterized by filamentous inclusions in neurons that selectively degenerate. The role these inclusions play in neuron degeneration is unclear, but this issue can be investigated experimentally in relevant animal models. The NFH/LacZ transgenic (TG) mice overexpress the high-molecular-weight neurofilament (NF) subunit (NFH) fused to beta-galactosidase, and these hybrid proteins aggregate into NF-rich, filamentous neuronal cytoplasmic inclusions (NCIs) that have been implicated in the progressive, age-dependent degeneration in subsets of affected neurons. Thus, these TG mice recapitulate some of the key pathology of neurodegenerative disorders with intraneuronal inclusions. To determine if the NCIs compromise neuron survival following traumatic brain injury (TBI), 3- to 6-month old TG and wild-type (WT) mice were subjected to TBI or sham injury. At 2 weeks post-TBI, the TG group showed increased TUNEL staining and activated caspase-3 immunoreactivity in cells of cerebral cortex, adjacent white matter, and hippocampus underlying the injury site, relative to control mice, but this labeling decreased at 4 weeks and was minimal thereafter. Compared to control mice, by 8 weeks postinjury, the TG mice showed a marked decrease in neuron density and increased gliosis in the hippocampal dentate gyrus and CA3 region as well as in the lateral thalamus, while the few remaining CA3 neurons exhibited cytoskeletal alterations, decreased synaptic protein immunoreactivity, and dissolution of NCIs. The more profound long-term neurodegenerative sequelae of TBI in the NFH/LacZ mice compared to WT mice suggest that the presence of intraneuronal inclusions may impair the recovery and long-term viability of injured neurons.

Animals↗

PubMed2000

NPS 1506 attenuates cognitive dysfunction and hippocampal neuron death following brain trauma in the rat.

Although several noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists have been shown to be substantially efficacious in experimental models of brain trauma, side effects associated with this class of compounds have impeded clinical application. Therefore, new noncompetitive NMDA receptor antagonists have been developed, including NPS 1506, that appear to be nontoxic but retain efficacy. In the present study, we evaluated the efficacy of NPS 1506 in a model of parasagittal fluid percussion brain trauma in the anesthetized rat. Administration of 1 mg/kg NPS 1506 at both 10 min and 4 h posttrauma induced no changes in brain temperature, mean arterial pressure, pulse, or arterial blood gasses. At 1 week postinjury, animals treated with the same dosing regimen of NPS 1506 demonstrated a dramatic attenuation of memory dysfunction evaluated by a water maze task (P < 0.02) and had greatly reduced neuron death in the CA3 subfield of the hippocampus (P < 0.01). However, NPS 1506 treatment did not significantly affect the extent of cortical tissue loss following injury. Since memory dysfunction and hippocampal damage are common and potentially related consequences of brain trauma in humans, our results suggest that NPS 1506 treatment may have clinical utility.

Animals↗

PubMed2000

Tissue tears in the white matter after lateral fluid percussion brain injury in the rat: relevance to human brain injury.

A characteristic feature of severe diffuse axonal injury in man is radiological evidence of the "shearing injury triad" represented by lesions, sometimes haemorrhagic, in the corpus callosum, deep white matter and the rostral brain stem. With the exception of studies carried out on the non-human primate, such lesions have not been replicated to date in the multiple and diverse rodent laboratory models of traumatic brain injury. The present report describes tissue tears in the white matter, particularly in the fimbria of Sprague-Dawley rats killed 12, 24, and 48 h and 7 days after lateral fluid percussion brain injury of moderate severity (2.1-2.4 atm). The lesions were most easily seen at 24 h when they appeared as foci of tissue rarefaction in which there were a few polymorphonuclear leucocytes. At the margins of these lesions, large amounts of accumulated amyloid precursor protein (APP) were found in axonal swellings and bulbs. By 1 week post-injury, there was macrophage infiltration with marked astrocytosis and early scar formation. This lesion is considered to be due to severe deformation of white matter and this is the first time that it has been identified reproducibly in a rodent model of head injury under controlled conditions.

Amyloid beta-Protein Precursor↗

PubMed2000

TUNEL-positive staining of surface contusions after fatal head injury in man.

In frontal lobe contusions obtained post mortem from 18 patients who survived between 6 h and 10 days after head injury, DNA fragmentation associated with either apoptotic and/or necrotic cell death was identified by the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick end labelling (TUNEL) histochemical technique. Additional histological techniques were also used to identify regional and temporal patterns of tissue damage. TUNEL-positive cells were present in both the grey and white matter of the contusion, where they peaked in number between 25 and 48 h, and were still identifiable at 10 days post injury. Fewer TUNEL-positive cells were observed in grey than in white matter; and most TUNEL-positive neurons in the grey matter demonstrated the morphological features of necrosis. However, the morphology of some TUNEL-stained neurons, and of TUNEL-stained oligodendroglia and macrophages in white matter was suggestive of apoptosis. Apoptosis was not seen in age- and sex-matched controls, none of whom had died from intracranial pathology or had pre-existing neurological disease. These findings suggest that multiple cell types in frontal lobe contusions exhibit DNA fragmentation and that both necrosis and apoptosis are likely to contribute to post-traumatic pathology. These findings provide further evidence that the observations made in animal models of traumatic brain injury have fidelity with clinical head injury.

Adult↗

PubMed2000

Brain-derived neurotrophic factor administration after traumatic brain injury in the rat does not protect against behavioral or histological deficits.

Brain-derived neurotrophic factor has been shown to be neuroprotective in models of excitotoxicity, axotomy and cerebral ischemia. The present study evaluated the therapeutic potential of brain-derived neurotrophic factor following traumatic brain injury in the rat. Male Sprague-Dawley rats (N=99) were anesthetized and subjected to lateral fluid percussion brain injury of moderate severity (2.4-2.8 atm) or sham injury. Four hours after injury, the animals were reanesthetized, an indwelling, intraparenchymal cannula was implanted, and infusion of brain-derived neurotrophic factor or phosphate-buffered saline vehicle was initiated from a mini-osmotic pump and continued for two weeks. In Study 1 (N=48), vehicle or 12 microg/day of brain-derived neurotrophic factor was infused into the dorsal hippocampus. In Study 2 (N=51), vehicle or brain-derived neurotrophic factor at a high (12 microg/day) or low dose (1.2 microg/day) was infused into the injured parietal cortex. All animals were evaluated for neurological motor function at two days, one week and two weeks post-injury. Cognitive function (learning and memory) was assessed at two weeks post-injury using a Morris Water Maze. At two weeks post-injury, neuronal loss in the hippocampal CA3 and dentate hilus and in the injured cortex was evaluated. In Study 2, neuronal loss was also quantified in the thalamic medial geniculate nucleus. All of the above outcome measures demonstrated significant deleterious effects of brain injury (P<0.05 compared to sham). However, post-traumatic brain-derived neurotrophic factor infusion did not significantly affect neuromotor function, learning, memory or neuronal loss in the hippocampus, cortex or thalamus when compared to vehicle infusion in brain-injured animals, regardless of the infusion site or infusion dose (P>0.05 for each). In contrast to previous studies of axotomy, ischemia and excitotoxicity, our data indicate that brain-derived neurotrophic factor is not protective against behavioral or histological deficits caused by experimental traumatic brain injury using the delayed, post-traumatic infusion protocol examined in these studies.

Animals↗

PubMed2000

Traumatic injury induces differential expression of cell death genes in organotypic brain slice cultures determined by complementary DNA array hybridization.

The expression of a large panel of selected genes hypothesized to play a central role in post-traumatic cell death was shown to be differentially altered in response to a precisely controlled, mechanical injury applied to an organotypic slice culture of the rat brain. Within 48 h of injury, the expression of nerve growth factor messenger RNA was significantly increased whereas the levels of bcl-2, alpha-subunit of calcium/calmodulin-dependent protein kinase II, cAMP response element binding protein, 65,000 mol. wt isoform of glutamate decarboxylase, 1beta isoform of protein kinase C, and ubiquitin messenger RNA were significantly decreased. Because the expression levels of a number of other messenger RNAs such as the neuron-specific amyloid precursor protein, beta(2) microglobulin, bax, bcl(xl), brain-derived neurotrophic factor, cyclooxygenase-2, interleukin-1beta, interleukin-6, tumor necrosis factor-alpha, receptor tyrosine kinase A, and receptor tyrosine kinase B were unaffected, these selective changes may represent components of an active and directed response of the brain initiated by mechanical trauma. Interpretation of these co-ordinated alterations suggests that mechanical injury to the central nervous system may lead to disruption of calcium homeostasis resulting in altered gene expression, an impairment of intracellular cascades responsible for trophic factor signaling, and initiation of apoptosis via multiple pathways. An understanding of these transcriptional changes may contribute to the development of novel therapeutic strategies to enhance beneficial and blunt detrimental, endogenous, post-injury response mechanisms.

Animals↗

PubMed2000

Postinjury treatment with magnesium chloride attenuates cortical damage after traumatic brain injury in rats.

The neuroprotective effect of magnesium chloride (MgCl2), a compound previously demonstrated to improve behavioral and neurochemical outcome in several models of experimental brain injury, was evaluated in the present study. Male Sprague-Dawley rats were anesthetized and subjected to lateral fluid-percussion brain injury of moderate severity (2.5-2.8 atm). A cannula was implanted in the left femoral vein and at 1 h following injury, animals randomly received a 15 min i.v. infusion of either MgCl2 (125 micromol/rat) or saline. A second group of animals received anesthesia, surgery, and either MgCl2 or vehicle to serve as uninjured (sham) controls. Two weeks following brain injury, animals were sacrificed, brains removed, and coronal sections were taken for quantitative analysis of cortical lesion volume and hippocampal CA3 cell counts. Traumatic brain injury resulted in a lesion in the ipsilateral cortex and loss of pyramidal neurons in the CA3 region of the hippocampus in vehicle-treated animals (p < 0.01 vs. uninjured animals). Administration of MgCl2 significantly reduced the injury-induced damage in the cortex (p < 0.01) but did not alter posttraumatic cell loss in the CA3 region of the ipsilateral hippocampus. The present study demonstrates that, in addition to its beneficial effects on behavioral outcome, MgCl2 treatment attenuates cortical histological damage when administered following traumatic brain injury.

Animals↗

PubMed2000

Apoptosis after traumatic brain injury.

Apoptosis of neurons and glia contribute to the overall pathology of traumatic brain injury (TBI) in both humans and animals. In both head-injured humans and following experimental brain injury, apoptotic cells have been observed alongside degenerating cells exhibiting classic necrotic morphology. Neurons undergoing apoptosis have been identified within contusions in the acute port-traumatic period, and in regions remote from the site of impact in the days and weeks after trauma. Apoptotic oligodendrocytes and astrocytes have been observed within injured white matter tracts. We review the regional and temporal patterns of apoptosis following TBI and the possible mechanisms underlying trauma-induced apoptosis. While excitatory amino acids, increases in intracellular calcium, and free radicals can all cause cells to undergo apoptosis, in vitro studies have determined that neural cells can undergo apoptosis via many other pathways. It is generally accepted that a shift in the balance between pro- and anti-apoptotic protein factors towards the expression of proteins that promote death may be one mechanism underlying apoptotic cell death. The effect of TBI on regional cellular patterns of expression of survival promoting-proteins such as Bcl-2, Bcl-xL, and extracellular signal regulated kinases, and death-inducing proteins such as Bax, c-Jun N-terminal kinase, tumor-suppressor gene, p53, and the caspase family of proteases are reviewed. Finally, in light of pharmacologic strategies that have been devised to reduce the extent of apoptotic cell death in animal models of TBI, our review also considers whether apoptosis may serve a protective role in the injured brain.

Animals↗

PubMed2000

Recent advances in neurotrauma.

The frequency of and outcome from acute traumatic brain injury (TBI) in humans are detailed together with a classification of the principal focal and diffuse pathologies, and their mechanisms in extract laboratory models are outlined. Particular emphasis is given to diffuse axonal injury, which is a major determinant of outcome. Cellular and molecular cascades triggered by injury are described with reference to the induction of axolemmal and cytoskeletal abnormalities, necrotic and apoptotic cell death, the role of Ca2+, cytokines and free radicals, and damage to DNA. It is concluded that TBI in humans is heterogeneous, reflecting various pathologies in differing proportions in patients whose genetic background (APOE gene polymorphisms) contributes to the outcome at 6 months. Although considerable progress has been made in the understanding of TBI, much remains to be determined. However, a deeper understanding of the pathophysiological events may lead to the possibility of improving outcome from rational targeted therapy.

Animals↗

PubMed2000

Behavioral efficacy of posttraumatic calpain inhibition is not accompanied by reduced spectrin proteolysis, cortical lesion, or apoptosis.

Administration of the selective calpain inhibitor AK295 has been shown to attenuate motor and cognitive dysfunction after brain trauma in rats. To explore mechanisms underlying the behavioral efficacy of posttraumatic calpain inhibition, we investigated histologic consequences of AK295 administration. Anesthetized Sprague-Dawley rats received lateral fluid percussion brain injury of moderate severity (2.2 to 2.4 atm) or served as uninjured controls. At 15 minutes after injury, animals were randomly assigned to receive a 48-hour infusion of either 2 mmol/L AK295 (120 to 140 mg/kg) or saline via the carotid artery. At 48 hours and 1 week after injury, spectrin fragments generated specifically by calpain were detected by Western blotting and immunohistochemistry, respectively, in saline-treated, brain-injured animals. Interestingly, equivalent spectrin breakdown was observed in AK295-treated animals when cortical and hippocampal regions were evaluated. Similarly, administration of the calpain inhibitor did not attenuate cortical lesion size or the numbers of apoptotic cells in the cortex, subcortical white matter, or hippocampus, as verified by terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphate nick-end labeling and morphology, at 48 hours after injury. These data suggest that an overt reduction in spectrin proteolysis, cortical lesion, or apoptotic cell death at 48 hours or 1 week is not required for behavioral improvements associated with calpain inhibition by AK295 after experimental brain injury in rats.

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