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[Intro Title] Why chillies are hot with Professor Peter McIntyre
[Professor Peter McIntyre, sitting in a laboratory]
Spicy foods can cause pleasure and pain. So, for instance, chilli peppers can liven up
a really bland meal and make it much more interesting. But they can also cause some
reactions in your body.
They can make you perspire, even when the temperature's not really hot outside. And
they can make your mouth feel like it's on fire, it hurts so much that you feel like
you're burning.
Chillies hurt because they contain a substance called capsaicin, which binds to a receptor
that's found on some pain sensing nerve cells. That receptor is called TRPV1 and it's an
ion channel. When capsaicin binds to it, it opens and allows a small current to pass across
the nerve cell membrane and causes the nerve to fire.
That impulse will travel all the way along the nerve, up to the spinal cord and then
on up to the brain where we'll perceive it as pain. And normally when we sense pain like
that, we'll try and remove ourselves from whatever is causing the painful stimulus.
We keep eating chilli probably because it activates a reward pathway in the brain that
rewards us for that sensation that we're having. But it may also be that it makes us feel cooler
and changes the way our bodies respond to temperature a little bit.
Understanding how these ion channels work is an important process in trying to find
new painkilling drugs because they seem to be in pain pathways and we don't really understand
how they work. They're not just there to respond to spicy foods. If we could understand how
they're normally opened, then we might be able to block that process when it occurs
in an inappropriate way and, thereby, make new painkilling drugs.
[Closing Title] Professor Peter McIntyre is the Deputy Director
of the Health Innovations Research Institute at RMIT University.