The gut could be key to understanding longevity, according to a study that found a gut hormone in fruit flies could control lifespan, a result important to humans as both species have many similar genes and hormones.
Researchers at Brown University in the US have found that suppressing the insulin-regulating 'neuropeptide F' hormone in the gut of fruit flies extended longevity.
The findings are important for humans too, especially as new diabetes and obesity drugs developed from gut hormones in the same insect family are becoming widespread, the researchers said.
Understanding ageing mechanisms in flies may thus help explain what's happening in humans as well, they said.
The findings are published in the journal Proceedings of the National Academy of Sciences.
Reducing insulin and targeting related processes have been found to slow ageing and extend lifespan in animals in previous studies.
In this study, the researchers manipulated gene activity in the intestines of fruit flies such that they produced lower levels of the neuropeptide F hormone, and thereby lower levels of insulin.
The team then compared the hormone production in the gut to what was happening in the fruit flies' brains and connected all the results with the diet that the insects were consuming.
The researchers found that suppressing the gut activity of the neuropeptide F hormone extended longevity in the flies, as did blocking the activity of related proteins in their brains. These proteins control the production of 'juvenile' hormones, which are known to regulate physiology.
The researchers said that neuropeptide F hormone in the gut impacted ageing in flies by integrating these factors — nutrient sensing, insulin processes and juvenile hormone production.
"Gut neuropeptide F modulates (fruit fly) ageing through the integration of nutrient sensing, insulin signalling, and juvenile hormone," the authors wrote.
"Based on (our) research, we suspect that over-production of gut neuropeptide F in flies will have a negative effect on ageing and decrease lifespan," study author Marc Tatar, a professor of biology at Brown University.
The researchers explained that humans do not produce either of the neuropeptide F or juvenile hormones. Instead, gut hormones are involved in regulating insulin in humans.
Given how diabetes and obesity drugs, which are known to target hormones involved in controlling insulin, and the findings on the relationship between insulin and ageing in flies, it may be time to consider how the drugs could impact human ageing, the authors said.
