Fruit flies age faster when they see dead flies: scientists uncover the brain mechanisms that do it

US researchers looking at fruit flies have figured out how seeing dead flies causes live flies to age.

The research team showed a few years ago that, if they see corpses of their peers, fruit flies aged faster and died sooner.

Now, they’ve narrowed in on the cause: a group of brain cells in the fly called R2 and R4 neurons.

When they see, and to a lesser extent smell, dead fruit flies, these neurons are activated in the brains of live fruit flies and this advances fly aging.

The research is published in PLOS Biology.

“We identified specific neurons and evolutionarily conserved molecules in the fly brain that help tune rates of aging in response to environmental conditions and experiences,” explains co-author Professor Scott Pletcher, a researcher at the University of Michigan, US.

The researchers genetically modified fruit flies so that certain neurons would be suppressed or encouraged. The neurons were tagged with a glowing green protein so that the researchers could see how active they were.

They could see which section of the brain lit up when the flies were exposed to dead flies.

Read more: Fruit flies enjoy ‘culture’ and ‘tradition’

They then narrowed this down to the R2 and R4 neurons, and a specific receptor on each of these neurons which received the chemical serotonin.

Then, the researchers activated these neurons in fruit flies which hadn’t been exposed to dead compatriots, and found that these fruits flies had shorter lifespans too.

In their paper, the researchers say that understanding this fruit fly ageing may eventually help to understand and prevent ageing in humans.

They point out that death perception “produces psychological changes in humans such as emotional dysregulation and depression, as well as important physiological changes that negatively impact overall health, including depression, headache, fatigue, and cardiovascular disease”.

“Could motivational therapy or pharmacologic intervention in reward systems, much like what is done for addiction, slow aging?” they continue.

“Such ideas are testable today, in humans, using approved drugs once we have a clearer mechanistic insight into the neural circuits and signalling systems that are involved.”

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