How Dad's Stresses Get Passed Along To Offspring

An anonymous reader quotes a report from Scientific American: A stressed-out and traumatized father can leave scars in his children. New research suggests this happens because sperm 'learn' paternal experiences via a mysterious mode of intercellular communication in which small blebs break off one cell and fuse with another. Carrying proteins, lipids and nucleic acids, these particles ejected from a cell act like a postal system that extends to all parts of the body, releasing little packages known as extracellular vesicles. Their contents seem carefully chosen. 'The cargo inside the vesicle determines not just where it came from but where it's going and what it's doing when it gets there,' says Tracy Bale, a neurobiologist at the University of Maryland School of Medicine. To probe the inheritance of such changes at the cellular level, Bale and co-workers performed a series of mouse experiments.

In one set of experiments [Jennifer Chan, a former PhD student that was part of the study] stressed a group of male mice, let them mate and looked at stress responses in the pups. The clincher was a set of in vitro fertilization -- like experiments in which she collected sperm from a male mouse that had never experienced induced stress. Half his sperm went into a lab dish with vesicles previously exposed to stress hormones. The other half was cultured with vesicles that had no contact with stress hormones. Chan injected sperm cells from each batch into eggs from a non-stressed female, then implanted the fertilized eggs -- zygotes -- into the same foster mom. The pups from non-stressed zygotes developed normally. Pups from stress-exposed zygotes, however, showed the same abnormal stress response as those whose dads had experienced stress before mating. That showed extracellular vesicles act as the conduit for transmitting paternal stress signals to the offspring, Chan says.

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