Scientists in Germany are studying naked mole-rats to understand why they do not feel some types of pain. The researchers have been monitoring 120 naked mole-rats living in six colonies in their Berlin laboratory. Naked mole-rats have pain receptors that are weakly activated, and their internal body temperature matches their surroundings. The scientists hope to use their findings on naked mole-rats to develop new pain relief treatments for humans.

1. October 27, 2016
PAIN-FREE STUDY
Nakedmole-ratsarestrangeanimals.
Researchers are interested in them
for several reasons. They live for
over 30 years. This is far longer than
other animals of a similar size. Na-
ked mole-rats almost never get can-
cer. Also, they don’t feel some types
of pain. Oddly, the creatures run as
fast backwards as they do forwards.
Scientists working in Germany
have been studying naked mole-
rats. They want to better understand
why the animals are not affected by
pain. The scientists have been mon-
itoring 120 naked mole-rats. All are
living in the scientists’ laboratory
in Berlin, Germany’s capital city.
The animals live in groups known
as colonies. The laboratory mole-
rats are divided into six colonies.
In the wild, 300 naked mole-rats
might live in one colony.
Naked mole-rats are not moles or
rats. One of their closest relatives is
the guinea pig.As its name suggests,
the naked mole-rat is hairless. It has
no fur. The animals are found only
in the East African countries of So-
malia, Ethiopia and Kenya. There,
they are also called the sand puppy
or desert mole-rat. The animals live
under ground in hot dry, or desert,
areas. They spend most of their lives
in darkness.
Fully-grown naked mole-rats are
about four inches (ten centimeters)
long. Nearly all mammals control
their internal body temperature.
This stays the same whether the
weather is hot or cold. Naked mole-
rats are different.
Their body temperature matches the
surrounding temperature. If it is hot,
the mole-rats are hot. If it is colder,
their internal temperature
goes down. Naked mole-rats feed
on root tubers. These are the large
parts of some plants that grow
under the ground. Carrots are root
tubers.
Naked mole-rats have two long
lower teeth, or incisors. These do
not fit inside their mouths. The
animals use the teeth to dig their
underground tunnels. Unusually
for mammals, naked mole-rats are
what’s known as eusocial. Ants and
termites are eusocial. Like ants and
termites, a naked mole-rat colony
has a queen, soldiers and workers.
The queen will mate with one, two
or three males. Workers dig tunnels
and look after the young. Soldier
mole-rats defend the colony from
snakes and other mole-rats.
In humans, one type of pain is
caused when heat is applied to an
inflamed area of skin. For instance,
a warm bath will make sunburned
skin even more painful. Inside the
body, two things joining, or
binding, together, cause this pain.
These are molecules called nerve
growth fac-tor (NGF) and a pain
receptor. Most mammals feel this
type of pain. Naked molerats don’t.
In a naked mole-rat, the NGF
joins with the pain receptor. Yet it is
a very weak link. The scientists
discovered that if the NGF were
increased by a factor of ten, the
mole-rat would feel it. The scientists
took pain receptors from a mole-rat
and put them inside cells from a rat.
Then, the rat cells did not notice the
pain. The mole-rat’s pain receptors
seem to be “switched off”, or
“turned down”.
The scientists suspect that the
naked mole-rats have switched off
pain receptors for a reason. Pain
acts as a warning system for most
animals. It tells them to stop what is
happening, or what they are doing.
If they don’t, their injury will get
worse. In mole-rat colonies it can
be very crowded and hot. There is
not much oxygen in their tunnels. If
a person were in these conditions, it
would be difficult to breathe. Their
pain receptors would be “always
on”. This is how naked mole-rats
live. Therefore they have evolved in
a way that means their pain recep-
tors are “always off”.
The scientists plan to continue
their studies. Eventually, they hope
to use naked mole-rats to create pain-
relief treatments for humans.