A calpain inhibitor attenuates cortical cytoskeletal protein loss after experimental traumatic brain injury in the rat

• Published in: Neuroscience Vol. 77; no. 3; pp. 875 - 888
• Main Authors: Posmantur, R, Kampfl, A, Siman, R, Liu, S.J, Zhao, X, Clifton, G.L, Hayes, R.L
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-04-1997; Elsevier
• Subjects: Animals; axons; Biological and medical sciences; Brain Injuries - metabolism; Brain Injuries - pathology; Calpain - antagonists & inhibitors; Calpain - metabolism; calpain inhibitor 2; Cerebral Cortex - metabolism; Cerebral Cortex - pathology; Cysteine Proteinase Inhibitors - pharmacology; dendrites; Functional Laterality; Injuries of the nervous system and the skull. Diseases due to physical agents; Male; Medical sciences; neurofilament proteins; Neurofilament Proteins - metabolism; Oligopeptides - pharmacology; Rats; Rats, Sprague-Dawley; spectrin; Spectrin - metabolism; TBI; Traumas. Diseases due to physical agents; MAP-2, microtubule-associated protein-2; EDTA, ethylenediaminetetra-acetate; NF200, neurofilament 200; dendrites; IV, injured group of animals treated with vehicle; NF68, neurofilament 68; calpain inhibitor 2; SD, sham group of animals treated with drug; N, naive group of animals; axons; H&E, hematoxylin and eosin; PBS, phosphate-buffered saline; ID, injured group of animals treated with drug; BDP, breakdown product; TBI, traumatic brain injury; TBI; spectrin; neurofilament proteins; SV, sham group of animals treated with vehicle; EGTA, ethyleneglycolbis(aminoethyl ether)tetra-acetate; Nervous system diseases; Rat; Enzyme; Cysteine endopeptidases; Rodentia; Central nervous system; Enzyme inhibitor; Calpain; Trauma; Proteins; Peptidases; Vertebrata; Neurofilament; Experimental disease; Mammalia; Animal; Hydrolases; Cytoskeleton; Brain (vertebrata)
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/S0306-4522(96)00483-6

The capacity of a calpain inhibitor to reduce losses of neurofilament 200-, neurofilament 68- and calpain 1-mediated spectrin breakdown products was examined following traumatic brain injury in the rat. Twenty-four hours after unilateral cortical impact injury, western blot analyses detected neurofilament 200 losses of 65% (ipsilateral) and 36% (contralateral) of levels observed in naive, uninjured rat cortices. Neurofilament 68 protein levels decreased only in the ipsilateral cortex by 35% relative to naive protein levels. Calpain inhibitor 2, administered 10
min after injury via continuous arterial infusion into the right external carotid artery for 24
h, significantly reduced neurofilament 200 losses to 17% and 3% relative to naive neurofilament 200 protein levels in the ipsilateral and contralateral cortices, respectively. Calpain inhibitor administration abolished neurofilament 68 loss in the ipsilateral cortex and was accompanied by a reduction of putative calpain-mediated neurofilament 68 breakdown products. Spectrin breakdown products mediated by calpain 1 activation were detectable in both hemispheres 24
h after traumatic brain injury and were substantially reduced in animals treated with calpain inhibitor 2 both ipsilaterally and contralaterally to the site of injury. Qualitative immunofluorescence studies of neurofilament 200 and neurofilament 68 confirmed western blot data, demonstrating morphological protection of neuronal structure throughout cortical regions of the traumatically injured brain. Morphological protection included preservation of dendritic structure and reduction of axonal retraction balls. In addition, histopathological studies employing hematoxylin and eosin staining indicated reduced extent of contusion at the injury site.
These data indicate that calpain inhibitors could represent a viable strategy for preserving the cytoskeletal structure of injured neurons after experimental traumatic brain injury
in vivo.