Stressed-out men can pass on anxiety and depression to their children and grandchildren via their sperm, Australian researchers say.

Key points: Excessive stress hormones in a dads prior to conception can cause following two generations to be moody

Excessive stress hormones in a dads prior to conception can cause following two generations to be moody Researchers advise men hoping to be dads to stay calm

Researchers advise men hoping to be dads to stay calm Mother's experiences and lifestyles also has a big impact on their offspring

Studies on mice have revealed that the presence of excessive stress hormones in a male parent prior to conception can cause the following two generations to be moody and depressed.

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According to the team from the Florey Institute of Neuroscience and Mental Health, men hoping to father happy and well-adjusted offspring are advised to keep calm and carry on.

Professor Anthony Hannan, who led the research team, said they gave male mice increased stress hormones in their drinking water and then compared them with control male mice who had not received the stress hormones.

"And then we mated those mice with female mice and then we studied the offspring of those mice and what we found were behavioural changes relevant to depression anxiety disorders in the offspring of the male mice with increased stress hormone," he said.

Professor Hannan said by feeding the mice the stressed hormones, the mice have a single stress hormone molecule circulating in their blood system, giving the researchers a specific way of understanding the mechanism.

"That increased stress hormone changed the contents of the sperm," he said.

"So it changed what we call epigenetics, so epigenetics means above the genome.

"So if you imagine the genome being an orchestra and the instruments are the genes, and the musicians is the epigenetics and together they create a symphony.

"So the epigenetics dictates where the genes are turned on and off, that's what it is.

"And so we found changes within the sperm that changes behaviour in the offspring in ways that are relevant to depression and anxiety disorders and this has major public health implications."

Second generation also feel the effects

Professor Hannan said measuring anxiety levels in mice was carried out by putting them into a maze where the mice have to choose between being in the dark side or the light side.

"They're nocturnal so they actually prefer the dark side, and so a more anxious mouse will spend most of its time in the dark chamber.

"Or you can put them in another chamber where they can go out on an open ledge or they can stay in the more protected part of the maze, and again that's just another test of anxiety and in both these tests, the offspring showed a disposition to be more anxious in those tests."

Professor Hannan said that they focused on fathers because researchers have known for awhile that the mother's experiences and lifestyles have a big impact on their offspring.

"But on the other hand it's been assumed that males contribute half their genome, you have two copies of every gene but after that, the males role was much less," he said.

"So this new work suggests that the experience of the father before they become a father, can carry this information through the sperm to affect the offspring."

Professor Hannan said as part of the study they examined the second generation, which they called the F2 generation in mice.

"And we did find changes in that generation and really that has even greater public health implications if you're talking about effects that might carry across not just one generation but multiple generations," he said.

The research has been published in the journal "Translational Psychiatry".