Changes of mRNA of Group I and II metabotropic glutamate receptors after diffuse brain injury and diffuse brain injury with secondary brain insults. Group I mGluRsThe bar graph shows that there were no statistical differences in the number of group I and II mGluRs positive neurons among sham-operated control and SBI alone groups (P > 0.05). Compared with that of the sham-operated control and SBI alone groups, the number of group ImGluRs positive neurons increased at 12 hours and peaked at 24 hours in the DBI alone group (P < 0.05). And when compared with that in the DBI alone group, the number of group I mGluRs positive neurons increased significantly in the DBI with SBI group. In addition, the number of mGluR5 positive neurons remained higher until 72 hours (P < 0.05). In contrast to the expressing pattern of group I mGluRs, the number of mGluR2 positive neurons began to decrease 12 hours after injury and the lowest point occurred 24 hours after injury in the DBI alone group. The expression of mGluR3 significantly decreased 6 hours post-injuries and the lowest pointwas at 24 hours after injury (P < 0.05). In the DBI with SBI group, the changes in the number of mGluRs positive neurons were similar to that in the DBI alone group, but the number was much lower (P < 0.05). aP < 0.05 sham-operated control and SBI alone groups. bP < 0.05 vs DBI alone group.