To explore the role of translocation protein (TSPO) in cerebral ischemia-reperfusion (IR) injury and its mechanism related to autophagy-lysosome pathway.

Forty-eight male rats were randomly divided into Sham group, IR group, IR+PK11195 group, and IR+chloroquine (CQ) group, with 12 rats in each group. The IR group used the middle cerebral artery occlusion method to establish a rat model of IR injury. The IR+PK11195 group was treated with PK11195 before IR, the IR+CQ group was treated with CQ before IR, and the Sham group was used as the surgical control group. Neurological function was assessed with Longa scoring 24 h after IR. Infarct areas were visualized through TTC staining, tissue deformation and necrosis observed via HE staining, apoptosis detected using TUNEL staining, CD86 and CD206 identified by immunohistochemistry, interleukin (IL)-6, IL-10, and tumor necrosis factor α (TNF-α) measured in ELISA assays, and protein expression levels of TSPO, Beclin 1, LC3B, p62, LAMP1, Cathepsin B, and Cathepsin D analyzed by Western blot.

The Longa score of the IR+PK11195 group was lower than that of the IR group, while the Longa score of the IR+CQ group was higher than that of the IR+PK11195 group, and the differences were statistically significant (P<0.05). TTC staining results showed that the infarct area of the IR+PK11195 group and the IR+CQ group were smaller than that of the IR group, and the differences were statistically significant (P<0.05). HE staining results showed that compared with the IR group, the IR+PK11195 group had slightly reduced swelling, degeneration, and necrosis of neuronal cells in brain tissue, while the IR+CQ group had disordered brain tissue arrangement, increased swelling, degeneration, and necrosis of neuronal cells, and increased infiltration of interstitial inflammatory cells. TUNEL staining results showed that the apoptosis rate of the IR+PK11195 group was significantly lower than that of the IR group, and the difference was statistically significant (P<0.05); The apoptosis rate of the IR+CQ group was slightly higher than that of the IR group, but the difference was not statistically significant (P>0.05). The immunohistochemical staining results showed that there was no statistically significant difference in the expression of CD86 and CD206 proteins in the brain tissues of the four groups of rats (P>0.05). ELISA results showed that IL-6 and TNF-α in the IR group were higher than those in the Sham group, while IL-10 was lower; The levels of IL-6 and TNF-α in the IR+PK11195 group were lower than those in the IR group, while they were higher in the IR+CQ group; The anti-inflammatory factor IL-10 increased in the IR+PK11195 group compared to the IR group, while it decreased in the IR+CQ group, and the differences were statistically significant (P<0.05). Western blot experiment results showed that the expression of autophagosome related proteins such as TSPO, LC3B, Beclin 1, etc. was reduced in the IR+PK11195 group compared to the IR group, while it was increased in the IR+CQ group compared to the IR group; The expression of lysosome related proteins such as p62, Cathepsin D, Cathepsin B, LAMP1 increased, while the IR+CQ group decreased compared to the IR group, and the differences were statistically significant (P<0.05).

In the rat cerebral IR model, TSPO expression increased and aggravated the injury, and the injury mechanism may be related to microglia-mediated inflammatory response and autophagy-lysosome pathway disorder.