Mice inherit learned behaviour

US researchers have found that mice biologically inherit information learned by their grandfathers, with their ancestors’ experiences passed down through modified DNA. Their research has been published in the journal Nature Neuroscience.

It has already been established that genes can be turned on or off in a semi-permanent manner with molecular changes to the DNA, known as epigenetic marks, and some of these changes can be maintained across generations. Traumatic or stressful experiences in animals typically have been associated with effects on the emotional behaviour of later-generation offspring through epigenetic changes.

Brian Dias and Kerry Ressler, of Emory University, said in their paper that the inheritance of parental traumatic exposure “has been frequently observed, but not understood”. The researchers trained a group of mice to fear a cherry-blossom-like smell (acetophenone) before allowing these mice to conceive offspring.

The offspring were immediately found to exhibit more fearful responses to whiffs of cherry blossom than to other odours, as did the next generation of offspring. This response was transmitted even when offspring were conceived via artificial insemination using sperm from their cherry-blossom-fearing fathers.

The team found that, in both the trained mice and their offspring, the fear response was associated with structural changes to the brain, specifically to regions used to detect the feared odour, and with epigenetic marks in the sperm on the gene responsible for detecting the odour.

Noting that acetophenone activates the odourant receptor Olfr151, the researchers said, when this odour was used to condition the mice, the sensitivity of subsequent generations to acetophenone “was complemented by an enhanced neuroanatomical representation of the Olfr151 pathway”. They also found that the transgenerational effects are inherited via parental gametes.

Professor Marcus Pembrey, Emeritus Professor of Paediatric Genetics, University College London, says the research “provides compelling evidence of biological transmission” and should be of interest to public health researchers.

“I suspect we will not understand the rise in neuropsychiatric disorders or obesity, diabetes and metabolic disruptions generally without taking a multigenerational approach,” Professor Pembrey said.