TY - JOUR
T1 - Isolated spinal cord contusion in rats induces chronic brain neuroinflammation, neurodegeneration,and cognitive impairment
T2 - Involvement of cell cycle activation
AU - Wu, Junfang
AU - Stoica, Bogdan A.
AU - Luo, Tao
AU - Sabirzhanov, Boris
AU - Zhao, Zaorui
AU - Guanciale, Kelsey
AU - Nayar, Suresh K.
AU - Foss, Catherine A.
AU - Pomper, Martin G.
AU - Faden, Alan I.
N1 - Funding Information:
We thank Katherine Cardiff and Angela Pan for expert technical support, Dr Soren M Bentzen and Ms Shari Kronsberg for expert statistical consultation and analysis. This study was supported by the National Institutes of Health Grants R01 NS054221 (AIF), R01 NR013601 (AIF), R21 NR014053 (JW).
PY - 2014/8/1
Y1 - 2014/8/1
N2 - Cognitive dysfunction has been reported in patients with spinal cord injury (SCI), but it has been questioned whether such changes may reflect concurrent head injury, and the issue has not been addressed mechanistically or in a well-controlled experimental model. Our recent rodent studies examining SCI-induced hyperesthesia revealed neuroinflammatory changes not only in supratentorial pain-regulatory sites, but also in other brain regions, suggesting that additional brain functions may be impacted following SCI. Here we examined effects of isolated thoracic SCI in rats on cognition, brain inflammation, and neurodegeneration. We show for the first time that SCI causes widespread microglial activation in the brain, with increased expression of markers for activated microglia/macrophages, including translocator protein and chemokine ligand 21 (C-C motif). Stereological analysis demonstrated significant neuronal loss in the cortex, thalamus, and hippocampus. SCI caused chronic impairment in spatial, retention, contextual, and fear-related emotional memory - evidenced by poor performance in the Morris water maze, novel objective recognition, and passive avoidance tests. Based on our prior work implicating cell cycle activation (CCA) in chronic neuroinflammation after SCI or traumatic brain injury, we evaluated whether CCA contributed to the observed changes. Increased expression of cell cycle-related genes and proteins was found in hippocampus and cortex after SCI. Posttraumatic brain inflammation, neuronal loss, and cognitive changes were attenuated by systemic post-injury administration of a selective cyclin-dependent kinase inhibitor. These studies demonstrate that chronic brain neurodegeneration occurs after isolated SCI, likely related to sustained microglial activation mediated by cell cycle activation.
AB - Cognitive dysfunction has been reported in patients with spinal cord injury (SCI), but it has been questioned whether such changes may reflect concurrent head injury, and the issue has not been addressed mechanistically or in a well-controlled experimental model. Our recent rodent studies examining SCI-induced hyperesthesia revealed neuroinflammatory changes not only in supratentorial pain-regulatory sites, but also in other brain regions, suggesting that additional brain functions may be impacted following SCI. Here we examined effects of isolated thoracic SCI in rats on cognition, brain inflammation, and neurodegeneration. We show for the first time that SCI causes widespread microglial activation in the brain, with increased expression of markers for activated microglia/macrophages, including translocator protein and chemokine ligand 21 (C-C motif). Stereological analysis demonstrated significant neuronal loss in the cortex, thalamus, and hippocampus. SCI caused chronic impairment in spatial, retention, contextual, and fear-related emotional memory - evidenced by poor performance in the Morris water maze, novel objective recognition, and passive avoidance tests. Based on our prior work implicating cell cycle activation (CCA) in chronic neuroinflammation after SCI or traumatic brain injury, we evaluated whether CCA contributed to the observed changes. Increased expression of cell cycle-related genes and proteins was found in hippocampus and cortex after SCI. Posttraumatic brain inflammation, neuronal loss, and cognitive changes were attenuated by systemic post-injury administration of a selective cyclin-dependent kinase inhibitor. These studies demonstrate that chronic brain neurodegeneration occurs after isolated SCI, likely related to sustained microglial activation mediated by cell cycle activation.
KW - Brain
KW - Cell cycle activation
KW - Cognitive impairment
KW - Inflammation
KW - Neurodegeneration
KW - Spinal cord injury
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U2 - 10.4161/cc.29420
DO - 10.4161/cc.29420
M3 - Article
C2 - 25483194
AN - SCOPUS:84905913374
SN - 1538-4101
VL - 13
SP - 2446
EP - 2458
JO - Cell Cycle
JF - Cell Cycle
IS - 15
ER -