If you are one of those who cannot easily take stress in your stride, it may be because of your genes, says a study.The findings could lead researchers to understand better the development of psychiatric disorders such as anxiety and depression and the consequent development of new treatments for these devastating disorders.The researchers found that the highly stress-susceptible mice had less of an important molecule known as mGlu2 in a region of the brain known as the hippocampus.The mGlu2 decrease, they determined, resulted from a genetic change, which affects the expression of genes, in this case the gene that codes for mGlu2."If you think of the genetic code as words in a book, the book must be opened in order for you to read it. These genetic changes effectively close the book, so the code for mGlu2 cannot be read," said first author Carla Nasca from the Rockefeller University in the US.A reduction in mGlu2 matters because this molecule regulates the neurotransmitter glutamate.While glutamate plays a crucial role relaying messages between neurons, too much can lead to harmful structural changes in the brain.In the experiments, the researchers induced stress in the mice by exposing them to daily, unpredictable conditions they dislike with the goal of reproducing the sort of stressful experiences which act as causal factors for the onset of depression in humans.