Pain-free mouse? (Image: Getty)
researchers suspect a link between pain and lifespan. We know, for instance,
experiencing chronic pain often die young. We also know that worms
and flies lacking certain sensory neurons live longer than expected.
Dillin at the University of California, Berkeley, and his colleagues have
shown that similar findings apply in mammals too.
found that male mice genetically engineered to lack TRPV1 pain receptors – which
in response to high temperatures and hot chilli peppers in food – live
almost 12 per cent longer than those with the receptor. Female mice lacking
TRPV1 do even better: they live 16 per cent longer than other females.
What's more, mice lacking the TRPV1 receptors retain some youthful features into
old age. For instance, older mice without TRPV1 could metabolise oxygen far more
efficiently than typical mice of the same age. They also had more pancreatic
beta cells – these release insulin, which makes cells absorb glucose from the
Further investigation revealed what was going on. Without the TRPV1 pain
receptor, two proteins involved in the production of a neuropeptide called CGRP
cannot be activated, says Dillin, so the mice produce less CGRP. As this
neuropeptide inhibits insulin release, mice lacking TRPV1 are able to produce
more insulin – which has beneficial knock-on effects for their metabolism.
well as these advantages to lacking TRPV1 there are disadvantages too, says
Dillin. For example, being able to sense pain helps animals avoid harmful
objects and life-threatening situations. This probably explains why natural
selection has retained the pain receptors in mammals.
is very important for animals living in the wild and probably outweighs the
benefits of a youthful metabolism," he says.
the results do suggest that reducing levels of TRPV1 or CGRP might be a way to
improve our metabolism in old age, and perhaps even boost lifespan.
lifespan-boosting properties of TRPV1 come as a surprise, says Gerard
Ahern at Georgetown University in Washington DC, who has also explored
the link between TRPV1 and metabolism in mice.
he thinks finding ways to apply the discoveries to human health won't be easy.
"Pharmacological antagonists [that block] TRPV1 have failed safety [testing],"
Ahern says – people who took the therapy experienced short-lived hyperthermia
and were prone to burning themselves because of their impaired heat sensation.
"CGRP antagonists, currently being developed for migraine treatment, might be
useful," he says.
Journal reference: Cell, DOI: 10.1016/j.cell.2014.03.051
Source: New Scientist URL: