Press Release: How We Feel What We Feel
Scientists in Tübingen and Trieste (Italy) have made a major
contribution to understanding the sense of touch and pain. A team around Dr
Jing Hu (Werner Reichardt Centre for Integrative Neuroscience – CIN, Tübingen)
discovered that two substances contained within nerve cell membranes have a
crucial impact on our perception of touch. They were able to show how the
interaction of these two substances can be interrupted in such a way that touch
stimuli are not transmitted and constant pain is alleviated.
How we feel what we feel: this question has kept
neuroscience busy for a long time. The problem is fundamentally interesting, in
that we know less about the sense of touch than any other of our five senses –
even though the corresponding sensory organ, the skin, covers our entire
bodies. But more importantly, millions of pain patients all over the world
could expect more efficacious help if we knew more about the origins of our
Pushing, pulling, piercing, chafing – these
words can describe perceptions of touch, but in exaggerated form, they can also
become sources of pain. A mechanical contact produces an electrical impulse in
the cellular membranes of neurons that conduct touch stimuli to the brain, the
so-called mechanoreceptors. How this happens, and which biochemical and biophysical
mechanisms are at work, though, nobody was able to answer until relatively
recently. Since the 1980s we have at least known that ion channels play a major
role: when the nerve cell is deformed, this stimulates certain proteins that
run right through the cell membrane like a channel. The deformation opens this
protein channel for a specific kind of ion, which enters the cell and produces
an electrical impulse.
Dr. Hu and her team were now able to show that
this is not all: the cell membrane surrounding the ion channels is just as
important. If it is soft, it easily yields to pressure, which does not create
an impulse. But if it is more rigid, the ion channels in the area respond
strongly to the deformation.
The behaviour of these cell membranes is controlled
by two substances. That molecule of ill repute, cholesterol, has been
well-known for a long time. But Hu and her colleagues now showed that – at
least in mice – „stomatin-like protein‑3“, or STOML3, plays a decisive role
too. Only the interaction of cholesterol and STOML3 effects a stiffening of the
cell membrane under soft pressure. This makes the activation of surrounding ion
channels possible. If one of the pieces of this puzzle is not present, or if
their reaction is disrupted, there is no stimulus.
Through behavioural studies in mice, the
scientists showed that this mechanism could apply similarly in human pain
patients. If new drugs are developed following this line of inquiry, even
patients suffering from allodynia might stand to benefit in the future: this
condition turns even the slightest of touches into intense pain.
Yanmei Qi, Laura Andolfi, Flavia Frattini, Florian Mayer,
Marco Lazzarino & Jing Hu: Membrane Stiffening by STOML3 Facilitates
Mechanosensation in Sensory Neurons. Nature Communications 6: 8512, October 7th, 2015.
- Werner Reichardt Centre for Integrative Neuroscience