The researchers studied the number and kind of microRNAs expressed by adult mice exposed to traumatic conditions in early life and compared them with non-traumatized mice. They discovered that traumatic stress alters the amount of several microRNAs in the blood, brain and sperm - while some microRNAs were produced in excess, others were lower than in the corresponding tissues or cells of control animals. These alterations resulted in mis-regulation of cellular processes normally controlled by these microRNAs.
After traumatic experiences, the mice behaved markedly differently: they partly lost their natural aversion to open spaces and bright light and had depressive-like behaviors. These behavioral symptoms were also transferred to the next generation via sperm, even though the offspring were not exposed to any traumatic stress themselves.