Researchers at Rockefeller University have found differences in stress tolerance among mice that may correspond to the mGlu2 molecule. They divided the mice into two groups, those with a healthy amount of the molecule, and those without, and then deliberately stressed them in their cages. The mice that had less of this molecule exhibited the rodent equivalent of depression and anxiety and searched for ways to cope, whereas those with healthy amounts of the molecule did not show signs of anxiety or depression. Interestingly, the researchers noted that even before they induced stress, the mice with less of the mGlu2 molecule still sometimes searched out coping methods, whereas the healthy group did not. This study is of course only preliminary as it involves mice, but as much of research begins this way, it may only be a matter of time before further brain-based correlates are discovered that can explain how people respond to stress.