Delayed application of dexmedetomidine. Here, we applied dexmedetomidine 2 and 3 h after TBI in a concentration of 1 μM. The two-hour delay group contained n = 24 slices and the three-hour delay group contained n = 31 slices. We found that both groups showed a level of trauma intensity significantly lower than the positive control group's (p ≤ 0.001). An application delayed by 2 h appeared to protect slices even better than immediate application of dexmedetomidine (p ≤ 0.05). After a delay of 3 h no statistical difference from an immediate application was observed (p = 0.335).