If you are one of those people who’s taste palate is insensitive to anything that is not spicy, and you go by the motto “the spicier the better”, then you must be familiar with the burning sensations that chilli peppers leave on your tongue. Now consider this: every time you slather your food with a fat pile of hot sauce, like Sriracha, you’re putting your body in pain. It probably never occurred to you that the brain perceives that burning spicy sensation in your mouth as pain; but how does something that tastes so delicious to many of us become painful to our bodies?
There are receptors called TRPV1 that are scattered all over the surface of our skin and tongue. The structure and mechanisms of this receptor were discovered by David Julius. Below is a video that shows the molecular structure of this receptor.
Julius’ studies found that TRPV1 acts as a channel that has two gates between the outside and inside of a neuron. In order for the neuron to fire a signal to the brain, both gates on TRPV1 must be opened. Capsaicin, which is the molecule that gives chilli pepper’s their spicy property, binds to the receptor to open the channel. This triggers an electrical activity that sends a message of pain to the brain. Interestingly, heat can induce the same effect, as it too can open the gates. Perhaps this is why the body responds to spicy foods in the same way it does in high temperatures, like during summer time.
To protect the body from further injury, TRPV1 can make certain sensations more painful. The body releases inflammatory molecules in response to the trigger of TRPV1 and they bind to the receptor just like capsaicin. This either makes the channel easier to open or keeps the channel open, causing the threshold to send in impulse up the neuron to be lowered. The skin is then hypersensitive to additional dangers of heat and “spiciness” (think of drinking hot tea after eating spicy food). In addition, capsaicin can also have long-term effects on the TRPV1 receptor; it can silence the pain sensing nerves. In another word, long term exposure to capsaicin can cause numbing feelings (or the lack thereof).
The next time you smother your food with hot sauce, perhaps consider the consequences of extreme spiciness. Although one’s undying love for Sriracha sauce (or another hot sauce of one’s choice) is unlikely to be challenged, think of the possibility of not being able to taste anything at all with a desensitized tongue!
By: Kimberley Xiao
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