Characterization of the postconditioning effect of dexmedetomidine in mouse organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation.

BACKGROUND There is an increasing interest in the use of dexmedetomidine for anesthesia and sedation. Here, we used the mouse organotypic hippocampal slice culture to investigate whether dexmedetomidine exhibits postconditioning properties against oxygen and glucose deprivation (OGD). The role of the focal adhesion and extracellular-regulated kinases pathways in these effects were examined in both postconditioning and preconditioning. MATERIALS AND METHODS Slices were obtained from P5 mouse. In postconditioning experiments, Dexmedetomidine (1 microm) was incubated 60 min after the end of OGD. In preconditioning experiments, dexmedetomidine was applied 3 h before OGD. Pharmacologic modulation of the studied pathways was achieved by using selective inhibitors of these cascades. Cell death was assessed 72 h after OGD using propidium iodide labeling and protein expression of activated caspase 3. RESULTS Maximum cell death increased with the duration of OGD. Dexmedetomidine induced a postconditioning effect in the CA1 (but not dentate gyrus) subfield area, which was significantly reduced by modulators of the focal adhesion and the extracellular-regulated kinases pathways. The combination of the inhibitors of the two pathways completely abolished the postconditioning effect of dexmedetomidine. The preconditioning effect of dexmedetomidine against ischemia-induced injury was observed in all hippocampal subfield areas. Results obtained with the pharmacologic modulation used for postconditioning also applied to dexmedetomidine-induced preconditioning. DISCUSSION Dexmedetomidine exhibits significant, but moderate, postconditioning properties against oxygen and glucose deprivation-induced injury. Activation of focal adhesion and the imidazoline 1 receptors-extracellular-regulated kinases pathways is involved in dexmedetomidine-induced postconditioning and preconditioning as well.