Effect of midazolam on in vitro cerebral endothelial ICAM-1 expression induced by astrocyte-conditioned medium.

Background And Objective: Astrocytes exposed to hypoxia produce pro-inflammatory cytokines and upregulate intercellular adhesion molecule-1 on cerebral endothelium. This study investigated the effects of midazolam on this response.

Methods: Mouse astrocytes were exposed to 4 h of hypoxia and 24 h of reoxygenation. Astrocyte-conditioned medium were applied to mouse cerebral endothelial cell cultures for 4 h and 24 h in normoxia. Endothelial cells were pre-incubated for 1 h with midazolam (0, 5, 50 microg L-1). Flow cytometry was used to estimate endothelial ICAM-1 expression. IL-1beta concentrations were measured with ELISA. Repeated comparisons were made using ANOVA and post hoc Tukey Test as appropriate. Data are mean (SD).

Results: Mouse cerebral endothelial cell ICAM-1 expression was greater after 24 h exposure to hypoxia-reoxygenation astrocyte-conditioned medium compared to normoxic astrocyte-conditioned medium (mean channel flouresence 112.5 (9.5) vs. 81.5 (7.5), P = 0.01). ICAM-1 expression was decreased by midazolam (5 microg L(-1)) compared to control (mean channel flouresence 81.35 (7.5) vs. 112.5 (9.5), P = 0.01). Supernatant IL-1beta concentrations (pg mL(1)) in astrocytes exposed to hypoxia-reoxygenation were greater than those exposed to normoxia (16.41 (2.35) vs. 10.5 (2.13), P = 0.01).

Conclusion: We conclude that decreased cerebral endothelial ICAM-1 expression in response to activated glial cell compartment by midazolam may decrease post ischaemic brain inflammation and secondary brain injury.