Exo70 intracellular redistribution after repeated mild traumatic brain injury

BACKGROUND: Exo70 is a subunit of the greater exocyst complex, a collection of proteins that oversees cellular membrane addition and polarized exocytosis by acting as a tethering intermediate between the plasma membrane and newly synthesized secretory vesicles. Although Exo70 function has been implicated in several developmental events including cytokinesis and the establishment of cell polarity, its role in neuropathologies is poorly understood. On the other hand, traumatic brain injury is the result of mechanical external force including contusion, fast acceleration, and expansive waves that produce temporal or permanent cognitive damage and triggers physical and psychosocial alterations including headache, memory problems, attention deficits, difficulty thinking, mood swings, and frustration. Traumatic brain injury is a critical health problem on a global scale, constituting a major cause of deaths and disability among young adults. Trauma-related cellular damage includes redistribution of N-methyl-D-aspartate receptors outside of the synaptic compartment triggering detrimental effects to neurons. The exocyst has been related to glutamate receptor constitutive trafficking/delivery towards synapse as well. This work examines whether the exocyst complex subunit Exo70 participates in traumatic brain injury and if it is redistributed among subcellular compartments RESULTS: Our analysis shows that Exo70 expression is not altered upon injury induction. By using subcellular fractionation, we determined that Exo70 is redistributed from microsomes fraction into the synaptic compartment after brain trauma. In the synaptic compartment, we also show that the exocyst complex assembly and its interaction with GluN2B are increased. Finally, we show that the Exo70 pool that is redistributed comes from the plasma membrane. CONCLUSIONS: The present findings position Exo70 in the group of proteins that could modulate GluN2B synaptic availability in acute neuropathology like a traumatic brain injury. By acting as a nucleator factor, Exo70 is capable of redirecting the ensembled complex into the synapse. We suggest that this redistribution is part of a compensatory mechanism by which Exo70 is able to maintain GluN2B partially on synapses. Hence, reducing the detrimental effects associated with TBI pathophysiology.

Changes of MDA, SOD, TNF-alpha, and IL-1beta in rat brain tissue after concussion / 法医学杂志

OBJECTIVE@#To observe the changes of malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) in rat brain tissue and to explore the mechanism of secondary cerebral injury after brain concussion.@*METHODS@#The brain concussion model was established with the pathological changes of rat brain tissue by Weil stain. The expressions of MDA and SOD in brain tissue were examined by photochemical method. The expressions of TNF-alpha and IL-1beta in cerebral cortex and hippocampus were examined by immunochemistry.@*RESULTS@#Nerve myelin sheath showed disorder, disruption, gryposis and swelling by Weil stain. Above changes were more severe at 12h. The quantity of MDA in rat brain tissue after concussion was significantly higher than that in the control group. The activity of SOD was significantly lower than that in the control group. The expressions of TNF-alpha and IL-1beta increased more significantly in cerebral cortex and hippocampus in rat brain tissue after concussion than that in the control group.@*CONCLUSION@#Oxidative stress and inflammatory injury in the rat brain tissue, which may play an important role in secondary cerebral injury after concussion.

Bcl-2 expression following the brain concussion in rats / 法医学杂志

OBJECTIVE@#To evaluate the expression of Bcl-2 protein after brain concussion.@*METHODS@#Expression levels of Bel-2 protein in cortex, pontine and cerebellum of rats were investigated using immunohistochemistry.@*RESULTS@#There was no expression of Bcl-2 protein in control group seen. The expression of Bcl-2 protein in brain concussion groups was detected at l hour, and the expression level reached its peak 4 days after the concussion and then declined gradually.@*CONCLUSION@#Our findings suggest that the detection of Bel-2 protein could be an indicator for diagnosis of brain concussion and for estimation of the post injury time interval.

A study on the expression of C-FOS protein after experimental rat brain concussion / 法医学杂志

OBJECTIVE@#To study the relationship between expression of C-FOS protein and brain concussion and find a sensitive marker of diagnosis of the brain concussion.@*METHODS@#Fifty-five rats were randomly divided into brain concussion groups and control group. The expression of C-FOS protein was microscopically observed by immunohistochemical method.@*RESULTS@#There were negative expression of C-FOS protein in control group. In brain concussion group, however, positive expression of C-FOS protein in some neurons was seen at 15 min after brain concussion, and reach to the peak at 6 h after brain concussion, then decreased gradually.@*CONCLUSION@#These findings suggest that detection of C-FOS protein could be an index of diagnosis of brain concussion and a sensitive marker of timing of injury after brain concussion.