Background and Purpose-Hyperbaric oxygen (HBO) preconditioning (PC) allows brain protection against transient global ischemia. In the present study, we hypothesize that the mechanism of HBO-PC involves the induction of cyclooxygenase-2 (COX-2) in cerebral tissues before ischemia, which leads to a suppression of COX-2 and its downstream targets after global ischemic insult. Methods-One hundred twenty-nine male Sprague Dawley rats (body weight 280 -300 grams) were allocated to the naive control group and the sham operation group, and 3 groups of animals were subjected to 15-minute 4-vessel occlusion: untreated, preconditioned with HBO 2.5 atmospheres absolutes for 1 hour daily for 5 days, preconditioned as mentioned and administered with COX-2 inhibitor NS-398 (1 mg/kg body weight intraperitoneal) before each preconditioning session, and normal rats preconditioned with HBO without ischemia. The mortality, the incidence of seizures, and T-maze scores were recorded. The quantitative cell count in Nissl stain and TUNEL was conducted on day 7 after ischemia. The brain expression of COX-2 was analyzed with Western blotting and immunofluorescence staining. Results-HBO-PC increased the number of surviving neurons in the Cornu Ammonis area 1, which was associated with the reduced COX-2 expression in the hippocampus and in the cerebral cortex at 1 and 3 days after ischemia. HBO-PC improved functional performance and tended to decrease mortality and the frequency of seizures. These beneficial effects of HBO-PC were abolished by the COX-2 selective inhibitor NS-398. Conclusions-HBO-PC

Among many proinflammatory cytokines, interleukin-1β (IL-1β) is considered a key mediator of neuronal injury. However, in order to become activated, it must be processed and cleaved by a caspase-1 enzyme. In this study, we tested the neuroprotective effect of Ac-YVAD-CMK, a known selective caspase-1 inhibitor, in a mouse model of intracerebral hemorrhage (ICH). Sixty-six adult male CD-1 mice were subjected to collagenase-induced ICH. Ac-YVAD-CMK or vehicle was administered into the left lateral ventricle 20 min before ICH modeling. Brain edema and neurological functions were assessed at 24 and 72 h after the surgery. Expression of IL-1β, phosphorylated JNK, tight junction protein zona occludens 1 (ZO-1), and matrix metalloproteinase-9 (MMP-9) were measured by Western blot along with MMP-9 activity measured by zymography at 24 h after ICH. At 24 h after ICH, Ac-YVAD-CMK treatment significantly reduced brain edema and improved © Springer Science+Business Media, LLC 2009Correspondence to: Jiping Tang, jtang@llu.edu. NIH Public Access Author ManuscriptTransl Stroke Res. Author manuscript; available in PMC 2011 March 1. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript neurological functions. The neuroprotection was associated with downregulation of IL-1β, JNK, MMP-9, and an inhibition of ZO-1 degradation in brain. We conclude that Ac-YVAD-CMK protects the brain against ICH-induced injury, and the neuroprotective effect may result from antiinflammation-induced blood-brain barrier protection.

This study suggests that r-OPN may down-regulate iNOS expression by the inhibition of Stat1 phosphorylation, and therefore suppressing the MMP-9 activation, preventing ICH-induced brain injury in mice.