Fig. 5.

Blocking PK2 actions reduced infarct volume after stroke. (A) Chemical structure of PKR-A. (B) The PKR-A IC₅₀ for PKR2 is 48.1 ± 4.6 nM, measured by an aequorin-based Ca²⁺ luminescent assay in CHO cells stably expressing the photoprotein aequorin and PKR2. RLU, relative luminescence unit. (C) I.p. delivery of PKR-A (75 mg/kg) significantly reduced infarct volume when given 30 min poststroke. Error bars represent SEM. n = 6–7 per group. *P < 0.05, Student's t test. (D) Central delivery of lentiviral-mediated RNAi against PK2 reduced ischemic injury. Diagram displays sequence of shRNAs against PK2 and Scrambled negative control (Scr). (E) Screening of shRNA candidates in HEK cells indicated that shRNA candidates OB1 and OB2 are the most effective in knockdown of PK2 expression. (F) Glutamate (250 uM) induced PK2 expression in primary striatal cultures. n = 5. **P < 0.01, Student's t test. (G) Lentiviral-mediated OB2 shRNA inhibited glutamate-induced PK2 expression as compared with Scrambled negative control. n = 4–5. *P < 0.05, Student's t test. (H) Confocal images of GFP, OB2, and Scrambled expression in the striatum. Lentivirus was delivered into striatum stereotaxically 1 wk before dMCAO. (I) Lentiviral-mediated OB2 shRNA reduced infarct volume. Error bars represent SEM. n = 11–13 per group. *P < 0.05, Student's t test. (Scale bar, 0.1 mm.)