Experimental neurology
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Experimental neurology · Oct 2002
Postischemic administration of basic fibroblast growth factor improves sensorimotor function and reduces infarct size following permanent focal cerebral ischemia in the rat.
Basic fibroblast growth factor (bFGF) is a polypeptide with potent trophic and protective effects on the brain. bFGF has been reported to exert neuroprotection against a wide variety of insults, including ischemic neuronal injury. To date, animal models of focal ischemia have not been translated to efficacy in stroke clinically with respect to testing of neuroprotective agents. Because functional outcome is the measurement of efficacy for putative neuroprotective agents in the clinic, we sought to evaluate the functional consequences of bFGF administration in rats subjected to focal ischemia. ⋯ Treatment of rats with bFGF showed a significant 46% improvement in rotarod fall latency when compared with that from the animals treated with vehicle alone. The volume of cortical infarction was significantly reduced by 32% as a function of bFGF treatment. These results suggest that the delayed intravenous administration of bFGF improves sensorimotor function as well as reduces infarct size following permanent focal ischemia in rat.
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Experimental neurology · Sep 2002
L-4-chlorokynurenine attenuates kainate-induced seizures and lesions in the rat.
Blockade of the strychnine-insensitive glycine site of the NMDA receptor is considered an attractive strategy for the development of novel neuroprotective and anticonvulsive agents. 7-Cl-kynurenic acid (7-Cl-KYNA) is a potent, selective antagonist of the NMDA/glycine receptor but penetrates poorly through the blood-brain barrier. Its prodrug, L-4-Cl-kynurenine (4-Cl-KYN), readily enters the brain from the circulation and provides antiexcitotoxic neuroprotection after systemic application. We now examined the effect of 4-Cl-KYN on seizures and neuronal loss caused by the systemic administration of the chemoconvulsant kainate (KA). 4-Cl-KYN (50 mg/kg, ip) was given 10 min before and 30, 120, and 360 min after KA (10 mg/kg, sc). ⋯ In contrast, neurons in the hilus and in layer III of the entorhinal cortex were not protected. Consistent with the in vivo results, in vitro application of 7-Cl-KYNA to brain slices containing hippocampus and entorhinal cortex preferentially blocked low Mg(2+)-induced seizure activity in hippocampal pyramidal cells. Taken together, these data suggest that a prodrug approach using 4-Cl-KYN might offer advantages in the treatment of temporal lobe epilepsy.
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Experimental neurology · Aug 2002
The nitroxide antioxidant tempol is cerebroprotective against focal cerebral ischemia in spontaneously hypertensive rats.
Free radicals appear to participate in the final common pathway of neuronal death in ischemia and may therefore be an adequate target for therapy. Tempol is a nitroxide antioxidant with proven protective efficacy in several animal models, including myocardial ischemia, that has not been previously tested in models of permanent cerebral ischemia. Spontaneously hypertensive rats underwent permanent middle cerebral artery occlusion (PMCAO). ⋯ Significantly better performance in the water maze test for performance on days 26-30 was noted in the tempol group compared with the vehicle-treated group (P < 0.05). Injury volumes at days 1 and 30 were significantly reduced in the tempol group (9.83 +/- 1.05 vs 19.94 +/- 1.43% hemispheric volume, P = 0.0009, and 13.2 +/- 2.97 vs 24.4 +/- 2.38% hemispheric volume, P = 0.02, respectively). In conclusion, treatment with tempol led to significant motor and behavioral improvement and reduced injured tissue volumes both in the short and in the long term after stroke.
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Experimental neurology · Jul 2002
Traumatic brain injury in the immature mouse brain: characterization of regional vulnerability.
We characterized the regional and temporal patterns of neuronal injury and axonal degeneration after controlled cortical impact of moderate severity in mice at postnatal day 21. Animals were euthanized at 1, 3, or 7 days after injury or sham operation. The brains were removed and prepared for immunolocalization of neurons and microglia/macrophages or subjected to Fluoro-Jade and silver stains, indicators of irreversible neuronal cell injury and axonal degeneration. ⋯ Silver- and Fluoro-Jade-labeled degenerating axons were observed in the ipsilateral subcortical white matter by 1 day post injury, in the ipsilateral external capsule, caudate putamen, and contralateral subcortical white matter by 3 days post injury, and in the internal capsule, pyramidal tracts, and cerebellar peduncles by 7 days post injury. Our findings demonstrate that controlled cortical impact in the developing brain generates neuronal loss in both the ipsilateral and the contralateral cortex, a temporally distinct pattern of subcortical neuronal injury/death, and widespread white matter damage. These observations serve as an important baseline for studying human brain injury and optimizing therapies for the brain-injured child.
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Experimental neurology · Jul 2002
Regeneration of axons after nerve transection repair is enhanced by degradation of chondroitin sulfate proteoglycan.
Our past work indicates that growth-inhibiting chondroitin sulfate proteoglycan (CSPG) is abundant in the peripheral nerve sheaths and interstitium. In this study we tested if degradation of CSPG by chondroitinase enhances axonal regeneration through the site of injury after (a) nerve crush and (b) nerve transection and coaptation. Adult rats received the same injury bilaterally to the sciatic nerves and then chondroitinase ABC was injected near the injury site on one side, and the contralateral nerve was injected with vehicle alone. ⋯ On the basis of these results we concluded that growth inhibition by CSPG contributes critically to the poor regenerative growth of axons in nerve transection repair. In addition, degradation of CSPG by injection of chondroitinase ABC at the site of nerve repair increased the ingress of axonal sprouts into basal laminae of the distal nerve segment, presumably by enabling more latitude in growth at the interface of coapted nerve. This suggests that chondroitinase application may be used clinically to improve the outcome of primary peripheral nerve repair.