Neuroprotective effects of argon. Following trauma (OGD or TBI), slices were incubated for 72 hours in an atmosphere containing either x = 25, 50 or 74% argon in addition to 21% O2, 5% CO2 and 74-x% N2. After fluorescence imaging and image analysis all groups were normalized to their respective trauma control group at t = 72 hours. Panel A shows the results for OGD. For each group an average of 55 slices with a minimum of 42 slices was used (prepared from four to six mice). The trauma intensity in each argon group was significantly lower compared to the trauma control group (*P ≤ 0.001), while there was no significant difference amongst the different argon groups. Panel B shows the results for TBI. An average of 43 slices and a minimum of 35 slices was used for each group (prepared from four to eight mice). The detected trauma for each argon concentration was significantly lower compared to the control group (*P ≤ 0.001). Furthermore there was a significant difference between the three argon gas mixtures (P ≤ 0.004 between 25% and 74% Argon and P ≤ 0.001 between 50% and 74% argon).