Osteopontin Mediates Hyperbaric Oxygen Preconditioning-Induced Neuroprotection Against Ischemic Stroke

Neurosurgical operations may result in surgical injury which would lead to postoperative neurological deficits. Hyperbaric oxygen preconditioning (HBO-PC) may be beneficial for such people. However, the exact mechanism underlying HBO-PC is not well known yet. The aim of this study is to explore the role of osteopontin (OPN) in HBO-PC-induced neuroprotection. The study consisted of two experiments. In experiment 1, Sprague Dawley (SD) rats were divided into four groups: sham group, HBO-PC sham group, stroke group, and HBO-PC group (HBO-PC + stroke). The animals in the second experiment were randomly assigned to one of two groups: OPN small interfering (siRNA) group (HBO-PC + stroke + OPN siRNA) and control siRNA group (HBO-PC + stroke + negative control siRNA). Neurological outcome in HBO-PC group was better than that of stroke group. After OPN siRNA was administered, neurological function aggravated compared with control siRNA group. Brain morphology and structure seen by light microscopy was diminished in stroke group and OPN siRNA group, while fewer pathological injuries occurred in HBO-PC and control siRNA group. The infarct volume in HBO-PC group was the lowest, followed by OPN siRNA group and stroke group, respectively. Preconditioning with HBO promoted expression of OPN, which reduced the expression of interleukin (IL)-1 beta/nuclear factor-kappa-gene binding (NF kappa B) and augmented protein kinase B (Akt). OPN siRNA reversed these changes. OPN plays an important role in the neuroprotection elicited by HBO-PC. Pretreatment with HBO may be beneficial for people going to undertake brain surgery.