Abstract WP217: Key Role Of Translocator Protein (TSPO) In Stress-aggravated Ischemic Injury After Stroke

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Introduction: Ischemic stroke is the leading cause of death and disability worldwide. It was recently reported that mental stress could aggravate stroke damage. However, the causal relationship between mental stress and stroke outcomes remained unclear. In current study, we determined whether mitochondria dysfunction was induced by mental stress and thus enhanced brain damage after ischemic stroke. The translocator protein (TSPO) is a transmembrane protein located on the outer mitochondria membrane (OMM) and induced mitochondrial dysfunction. This study focused on the key role of TSPO in stress aggravated ischemia/reperfusion injury. Methods: Six-week-old male C57BL/6J mice were divided into four groups: control, chronic restraint stress (CRS), TSPO antagonist (PK11195, 3mg/kg, i.p.) and TSPO antagonist+CRS. Mice in CRS were placed in ventilated 50mL tubes 6 hours/day for 28 days. On the day 29 th , behavioral tests were conducted to measure the depressive-like levels. Mice then were subjected to middle cerebral artery occlusion (MCAO). At 6/24 hours after MCAO, TTC staining and modified scoring systems were applied to analyze infarct volume and neurological deficits, and the expression of TSPO was detected using immunofluorescence. Apoptotic cell death and apoptotic proteins (Bcl-2, Bax and caspase-3/9) were measured by TUNEL and Western blot. Effects of TSPO on mitochondrial membrane potential (MMP) and mito-ROS were measured by JC-1 staining and live cell imaging dyes (mitoSOX and DCFDA) in vitro . Results: As depressive model, CRS aggravated infarct volume and neurological deficits after MCAO, with increased levels of apoptosis (cell death and protein expressions), in association with increased TSPO levels. TSPO antagonist could decrease stress-aggravated stroke injury and apoptotic cell death, indicating TSPO was involved in stress related stroke outcomes. In vitro , MMP was increased and mito-ROS was decreased after TSPO siRNA transfection, suggesting TSPO may induce mitochondria deficits through producing more mito-ROS. Conclusions: Mental stress by CRS exacerbated ischemic injury after stroke. Importantly, the results showed that TSPO may play a key role in inducing mitochondrial dysfunction in stress-aggravated stroke damage.