Combination of hyperbaric oxygenation and selective JNK-inhibition by D-JNK-I-1 as a potent neuroprotective strategy in a focal ischaemia/reperfusion injury model in rats
Background: In pervious studies, hyperbaric oxygenation (HBO) was proven as a potent neuroprotective treatment in animal models of acute stroke by reducing apoptotic cell death. Furthermore, c-Jun N-terminal kinase (JNK) is activated in ischaemic neurons downstream of the activated glutamate receptors and thus mediating neuronal cell death. The highly specific peptide JNK-inhibitor D-JNK-I-1 (XG-102) has been shown to be neuroprotective in acute stroke in mammals, acting by intracellular inhibition of JNK-kinase. We thus hypothesized that combination of both treatments might enhance the neuroprotective effect of each regimen. Infarct volumetry and clinical outcome were the primary endpoints.
Methods: Male SD-rats (200–220g) were randomized in 5 groups (n=6, respectively). The suture model induced transient MCAO for 90min. Any treatment started 3h following MCAO. HBO was performed in a pressure chamber with 100% O2, 3 ATA for 1h at 3h following MCAO. D-JNK-I-1 was administered intraperitoneally 3h following MCAO (2mg/kg). Controls: Sham (no MCAO), MCAO alone. Treatment groups: MCAO+HBO; MCAO+D-JNK-I-1; MCAO+HBO+D-JNK-I-1. Clinical outcome was used using Garcia and Bederson score. Infarct volume was assessed histologically 24h following MCAO.
Results: Data are mean±SD. Total infact volume in controls was: Sham (0±0); MCAO (308mm3±63,4). MCAO+XG-102 (169mm3±84,6); MCAO+HBO (106mm3±82,4); MCAO+XG-102+HBO (66mm3±38,8). Garcia- and Bederson-scores showed significant improvement in all treatment groups compared to control (MCAO), however, the best results were seen in MCAO+XG-102+HBO group (12,8 vs. 7 points).
Discussion: We conclude from the presented data that combination of HBO and D-JNK-I-1 (XG-102) treatment in acute transient stroke in rats augments the neuroprotective effect of each therapy alone and thus might be a promising way for further treatment studies in humans.