Neurotrophin-mediated neuroprotection of hippocampal neurons following traumatic brain injury is not associated with acute recovery of hippocampal function.
Traumatic brain injury (TBI) causes selective hippocampal cell death which is believed to be associated with the cognitive impairment observed in both clinical and experimental settings. The endogenous neurotrophin-4/5 (NT-4/5), a TrkB ligand, has been shown to be neuroprotective for vulnerable CA3 pyramidal neurons after experimental brain injury. In this study, infusion of recombinant NT-4/5 increased survival of CA2/3 pyramidal neurons to 71% after lateral fluid percussion brain injury in rats, compared with 55% in vehicle-treated controls. The functional outcome of this NT-4/5-mediated neuroprotection was examined using three hippocampal-dependent behavioral tests. Injury-induced impairment was evident in all three tests, but interestingly, there was no treatment-related improvement in any of these measures. Similarly, injury-induced decreased excitability in the Schaffer collaterals was not affected by NT-4/5 treatment. We propose that a deeper understanding of the factors that link neuronal survival to recovery of function will be important for future studies of potentially therapeutic agents.
Department of Neurosurgery, 371A Stemmler Hall/6071, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. nicolas_royo@hotmail.com
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Royo
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LeBold
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Magge
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Chen
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Hauspurg
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Cohen
D J
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Watson
D000818:Animals; D001245:Association Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D001930:Brain Injuries / Q000188:drug therapy* / Q000473:pathology; D002452:Cell Count / Q000379:methods; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects / Q000528:radiation effects; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009414:Nerve Growth Factors / Q000627:therapeutic use*; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D009414:Nerve Growth Factors; D018696:Neuroprotective Agents; C071951:neurotrophin 5; C073922:neurotrophin 4