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Differential effects of FK506 on structural and functional axonal deficits after diffuse brain injury in the immature rat
Journal article   Open access   Peer reviewed

Differential effects of FK506 on structural and functional axonal deficits after diffuse brain injury in the immature rat

Ann Mae Dileonardi, Jimmy W Huh and Ramesh Raghupathi
Journal of neuropathology and experimental neurology, v 71(11), pp 959-972
Nov 2012
PMID: 23095847
url
https://doi.org/10.1097/NEN.0b013e31826f5876View
Published, Version of Record (VoR) Open

Abstract

Brain Injuries - drug therapy Aging - drug effects Axons - drug effects Rats Male Axons - physiology Brain Injuries - physiopathology Rats, Sprague-Dawley Animals Aging - physiology Axons - pathology Tacrolimus - pharmacology Female Brain Injuries - pathology Immunosuppressive Agents - pharmacology
Diffuse axonal injury is a major component of traumatic brain injury in children and correlates with long-term cognitive impairment. Traumatic brain injury in adult rodents has been linked to a decrease in compound action potential (CAP) in the corpus callosum, but information on trauma-associated diffuse axonal injury in immature rodents is limited. We investigated the effects of closed head injury on CAP in the corpus callosum of 17-day-old rats. The injury resulted in CAP deficits of both myelinated and unmyelinated fibers in the corpus callosum between 1 and 14 days postinjury (dpi). These deficits were accompanied by intra-axonal dephosphorylation of the 200-kDa neurofilament subunit (NF200) at 1 and 3 dpi, a decrease in total NF200 at 3 dpi and axonal degeneration at 3 and 7 dpi. Although total phosphatase activity decreased at 1 dpi, calcineurin activity was unchanged. The calcineurin inhibitor, FK506, significantly attenuated the injury-induced NF200 dephosphorylation of NF200 at 3 dpi and axonal degeneration at 3 and 7 dpi but did not affect the decrease in NF200 protein levels or impaired axonal transport. FK506 had no effect on CAP deficits at 3 dpi but exacerbated the deficit in only the myelinated fibers at 7 dpi. Thus, in contrast to adult animals, FK506 treatment did not improve axonal function in brain-injured immature animals, suggesting that calcineurin may not contribute to impaired axonal function.

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Collaboration types
Domestic collaboration
Web of Science research areas
Clinical Neurology
Neurosciences
Pathology
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