Parental olfactory experience influences behavior and neural structure in subsequent generations

This study demonstrates an epigenetic inheritance of a learned behavior that is transmitted across generations via the gametes whereby learning about a specific olfactory stimulus changes brain structure and the behavior of future generations. Specifically, Dias and Ressler show that behavioral response to olfactory fear conditioning in male parents is transmitted to their offspring via DNA methylation changes in the corresponding odorant receptor gene in the sperm, which is accompanied by the changes to the corresponding neuroanatomical structure that mediates olfactory perception. Using olfactory molecular specificity, we examined the inheritance of parental traumatic exposure, a phenomenon that has been frequently observed, but not understood. We subjected F0 mice to odor fear conditioning before conception and found that subsequently conceived F1 and F2 generations had an increased behavioral sensitivity to the F0-conditioned odor, but not to other odors. When an odor (acetophenone) that activates a known odorant receptor (Olfr151) was used to condition F0 mice, the behavioral sensitivity of the F1 and F2 generations to acetophenone was complemented by an enhanced neuroanatomical representation of the Olfr151 pathway. Bisulfite sequencing of sperm DNA from conditioned F0 males and F1 naive offspring revealed CpG hypomethylation in the Olfr151 gene. In addition, in vitro fertilization, F2 inheritance and cross-fostering revealed that these transgenerational effects are inherited via parental gametes. Our findings provide a framework for addressing how environmental information may be inherited transgenerationally at behavioral, neuroanatomical and epigenetic levels.