Acta Histochemica 117 (2015) 155–162 Contents lists available at ScienceDirect Acta Histochemica journal homepage: www.elsevier.de/acthis Effect of stab injury in the rat cerebral cortex on temporal pattern of expression of neuronal cytoskeletal proteins: An immunohistochemical study Irena Lavrnja a,∗ , Danijela Savic a , Ana Parabucki a , Sanja Dacic b , Danijela Laketa b , Sanja Pekovic a , Mirjana Stojiljkovic a a Department of Neurobiology, Institute for Biological Research “Sinisa Stankovic” University of Belgrade, Belgrade, Serbia b Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia article info Article history: Received 7 September 2014 Received in revised form 1 December 2014 Accepted 2 December 2014 Keywords: Neurofilaments MAP-2 Cortical stab injury Cytoskeleton Immunohistochemistry abstract Compelling evidence now points to the critical role of the cytoskeleton in neurodegeneration. In the present study, using an immunohistochemical approach, we have shown that cortical stab injury (CSI) in adult Wistar rats significantly affects temporal pattern of expression of neurofilament proteins (NFs), a major cytoskeleton components of neurons, and microtubule-associated proteins (MAP2). At 3 days post-injury (dpi) most of the NFs immunoreactivity was found in pyknotic neurons and in fragmentized axonal processes in the perilesioned cortex. These cytoskeletal alterations became more pronounced by 10 dpi. At the subcellular level CSI also showed significant impact on NFs and MAP-2 expression. Thus, at 3 dpi most of the dendrites disappeared, while large neuronal somata appeared like open circles pointing to membrane disintegration. Conversely, at 10 dpi neuronal perikarya and a few new apical dendrites were strongly labeled. Since aberrant NF phosphorylation is a pathological hallmark of many human neurodegenerative disorders, as well as is found after stressor stimuli, the present results shed light into the expression of neurofilaments after the stab brain injury. © 2014 Elsevier GmbH. All rights reserved. Introduction Traumatic brain injury (TBI) is associated with neuropatho- logical changes. These changes evolve over a period of minutes to months after TBI leading to degeneration of primarily unaf- fected neurons via secondary axotomy as the result of progressive structural damage in neurons (Gennarelli, 1996; Maxwell et al., 1997; Povlishock and Katz, 2005). Delayed axotomy is believed to occur subsequently to initial changes in permeability of the axonal membrane and disruption of certain elements of cytoskele- ton, particularly axonal neurofilaments (Pettus et al., 1994). Thus, the consequence of neuronal degeneration is an accumulation of various proteins including neurofilament proteins, as major cytoskeleton components of neuronal cells, and microtubule- associated proteins (MAPs) (Caner et al., 2004). MAP2 is a member of the MAPs family, with a particular role in stabilization of ∗ Corresponding author at: Department of Neurobiology, Institute for Biological Research “Sinisa Stankovic”, University of Belgrade, Blvd Despota Stefana 142, 11000 Belgrade, Serbia. E-mail address: irenam@ibiss.bg.ac.rs (I. Lavrnja). microtubules by crosslinking them with neurofilaments (NFs) and other microtubules, and in regulation of inter-microtubular spac- ing (Chapin and Bulinski, 1992). Integration of NFs and MAP-2 is essential for normal functioning of nerve cells, especially for the performance of axonal and dendritic transport (Caner et al., 2004). Neurofilaments (NFs) are intermediate filaments of the neu- ronal cytoskeleton that provide the mechanical stability of the cells and have a fundamental role in axonal transport (Liu et al., 2004; Barry et al., 2007). While NFs are present in dendrites and perikarya, they are abundantly present in axons, maintaining the structural integrity and caliber of axons through influencing the conduction velocity of nerve impulses (Shea and Lee, 2013). Accord- ing to their molecular size, neurofilament subunits are divided into three groups: light (NF-L, 68 kDa), medium (NF-M, 150 kDa) and heavy (NF-H, 200 kDa) (Nixon and Shea, 1992), along with - internexin (Int) (Yuan et al., 2012). NF-H plays an essential role in axonal outgrowth and stabilization (Lee and Shea, 2014), while NF-M is involved in stabilization of the filament network and helps in longitudinal extension (Elder et al., 1998; Barry et al., 2012), whereas NF-L is essential for the correct assembly of neu- rofilaments (Yuan et al., 2012). All NFs share a highly conserved central rod domain, which is responsible for the formation of http://dx.doi.org/10.1016/j.acthis.2014.12.004 0065-1281/© 2014 Elsevier GmbH. All rights reserved.