CAG-GFP AAV (Serotype Retrograde)

The mitochondrial permeability transition pore is a nonspecific transmembrane channel, and inhibition of mitochondrial permeability transition pore opening has been shown to reduce mitochondrial swelling, calcium overload, and axonal degeneration. In this study, an in vivo ICH mouse model was established by injecting autologous blood and oxygenated hemoglobin into the striatum of Thy1-YFP mice, in which pyramidal neurons and axons expressed yellow fluorescent protein. The researchers found that early axonal degeneration in ICH was dependent on mitochondrial swelling and mitochondrial permeability transition pore opening caused by cyclophilin D (CypD) activation. Both cyclosporin A inhibition and short hairpin RNA interference of cyclosporin D reduced mitochondrial permeability transition pore opening and mitochondrial damage. In addition, inhibition of cycloserine proteinase D and mitochondrial permeability transition pore opening protected the integrity of the corticospinal tract and alleviated motor dysfunction caused by ICH. These findings suggest that cycloserine proteinase D is a key mediator of axonal degeneration after ICH; inhibition of cycloserine proteinase D expression protects mitochondrial structure and function, further alleviating corticospinal tract damage and motor dysfunction after intracerebral hemorrhage.

Motor outcome after stroke depends on the integrity of the corticospinal tract (CST). To assess the integrity of the CST and CST-associated fine motor function after Intracerebral hemorrhage (ICH), viral retrograde tracking (AAV2/Retro-CAG-GFP) from the lumbar spinal cord and fine motor behavioral tests were performed. The number of retrogradely labeled GFP-positive corticospinal neurons in the ICH^CypD–/– and ICH^WT + CsA (Figure 1A and B) groups was greater than that in the ICH^WT group. The slip rates in the beam walking and irregular ladder walking tests were decreased in the ICH^CypD–/– and ICH^WT + CsA groups at 3 days after ICH compared with those in the ICH^WT group (Figure 1C and D). These results suggest that inhibition of CypD promotes the integrity of the CST and facilitates functional recovery after ICH.

Figure 1. CypD deficiency and CsA treatment protect the CST and alleviate motor dysfunction after ICH. (Yang Y, et al., 2023)