Why Do Chillis Burn and Make Us Sweat?

– nobel medal –
(Photo by Niklas HALLE’N / POOL / AFP)

Re-posting this 2015 post after the winners of 2021’s Nobel Prize in Physiology and Medicine tell how they used the chili pepper’s capsaicin to narrow down the molecule that lets us sense heat and pain (or temperature and touch) – a ground-breaking discovery which is going to lead to advances in medicine). See link at the end. And step up your chili eating!

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nsmail

I love hot food so I looked into the whole effect-of-chilis thing a couple years ago and was really intrigued and pleased at what I discovered.

Good stuff.

Tongue
– human tongue up close –

If you could watch cells and nerves on your tongue through a powerful microscope as someone burnt them with a flame you would actually see them get physically damaged as they sent a mad “heat and pain!” signal to your brain. If you watched them as you ate a habanero chili the same urgent message would be sent, but NO HARM would be happening to the cells! No harm whatsoever.

Once you process this info you can really start to relax and enjoy hot food. It’s “capsaicin” that’s responsible for that burn and pain sensation. Marvellous stuff! Capsaicin selectively binds to a protein known as TRPV1 that resides on the membranes of pain and heat-sensing neurons. TRPV1 is a heat-activated calcium channel that usually opens between 37 and 45°C. When capsaicin binds to TRPV1, it causes the channel to open at or below normal human body temperature, which is why capsaicin is linked to the sensation of heat. Glorious heat! So what happens when you add chillis to your grub is your body thinks it is being exposed to heat. Your tolerance for heat in the exposed tissues goes so low that the temperature of your own body is mistaken for a serious burn. Your brain says ouch! and eina! at first, but once you know what’s happening, you learn to say to your brain, Relax! and then you can say Ooh! and Aah! and you get to LURV that sensation and the feeling of well-being that follows.

So: You can go on a long boring run for your endorphin pleasure, or you can sit and enjoy a delicious meal for the same effect!

That’s the brain’s response. Meantime, your body responds to this heat like it would normally by trying to cool you. Capillaries expand in the area of contact and redness and swelling begin so the blood can carry heat away and bring in healing factors to fix the injury (in this case: the “injury”). The chemical only works locally on the tissues it directly touches (on nerve endings). This is why your tongue and lips will burn, as they have lots of nerve endings close to the surface. But the pain may also cause general stress sweating as your body is chemically reacting to pain and trying to counteract it. Your body thinks it is in the presence of a dangerous level of heat and responds with the sensation of pain even though there is no danger.

Incidentally, your body’s ability to feel temperature is a separate sense. TPRV1 receptors are an “Ouch! that’s hot” sense not a “Hmm, this is hot or cold” sense. Normally heat only begins to generate pain if it goes over about 37°C and the pain climbs as the heat does!

You get used to (and learn to love) the effect of chillis. Repeated exposure to capsaicin causes the chemicals that communicate pain to be depleted from your nerve endings, making you tougher and less of a ninny. Did I mention: Marvellous stuff!?

Aside: Chillies originally come from South and Central America, and were taken to Europe first and then to India and Asia, where they became an integral part of Asian cuisine.

(Thanks to Ariel Williams on quora for a lot of this!)

Read how the chili pepper helped us find out more about how heat and pain works. Prize-winning work!

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Remember: 'Tis a boring man who can only spell a word one way. chili chilli chillie

C. elegans’ Colleague Dies

One of my heroes died! Sydney Brenner, Germiston boykie, Witsie and a real mensch. Always a heavy smoker, he only lived one thousand five hundred and ninety five C. elegans life cycles. Or 92 human years. He was amazing. Some colleagues called him “the funniest scientist who ever lived.”

So what was he famous for? For his research fellow Caenorhabditis elegans, who is pictured below. And also for RNA. Syd was short, but his colleague was only 1mm long – and transparent. Syd could see right through him . .

Syd Brenner realized he needed a simpler animal to study than the fruit fly, a standard organism used in laboratories. He settled on Caenorhabditis elegans, or C. elegans, a tiny, transparent roundworm that dwells in the soil, eats bacteria and completes its life cycle in three weeks. That worm has spun off many developments, starting with the decoding of the human genome.

The worm is, of course, an invertebrate, but Syd said as it was a hermaphrodite worm with occasional males he would call it a PERvert-ebrate. Using the worm, Dr. Brenner and his colleagues first worked out methods for breaking a genome into fragments, multiplying each fragment in a colony of bacteria, and then decoding each cloned fragment with DNA sequencing machines. His other colleagues John Sulston and Robert Waterston completed the worm’s genome in 1998, and they and others used the same methods to decode the human genome in 2003.

Another major project, made possible because of the worm’s transparency, was to track the lineage of all 959 cells in the adult worm’s body, starting from the single egg cell. This feat, still not accomplished so far for any other animal, made clear that many cells are programmatically killed during development, leading to the discovery by H. Robert Horvitz of the phenomenon of programmed cell death.

The topic assumed an importance that transcended worm biology when it emerged that programmed cell death is supposed to occur in damaged human cells, and when that process is thwarted, we call it cancer! The humble worm’s DNA has turned out to be surprisingly similar to our own, helping us understand how our cells grow uncontrollably to cause cancer and why they sometimes die in excess.

For their work on programmed cell death, Dr. Brenner, Dr. Sulston (who died last year) and Dr. Horvitz were awarded the Nobel Prize in Physiology or Medicine in 2002. So the worm was good for him and colleagues would teasingly call him “the father of the worm.” In his Nobel lecture, Syd remarked, “Without doubt, the fourth winner of the Nobel Prize this year is Caenorhabditis elegans; it deserves all of the honor but, of course, it will not be able to share the monetary award.”

Long before he got the Nobel Prize, Dr. Brenner had been the first to conclude that there must be some means for copying the information in DNA and conveying it to the cellular organelles that manufacture proteins. That intermediary, now known as messenger RNA, was discovered in 1960 in an experiment devised by Dr. Brenner and others. Many people, including Dr. Brenner himself, believed he should have been awarded a Nobel Prize for his and Dr. Crick’s work on the genetic code. About his Nobel Prize he said, “In fact, to me this is my second Nobel prize. I just failed to get the first one.”

For years he wrote a tongue-in-cheek column called Loose Ends and later False Starts in which he’d offer advice and comment on matters scientific. To busy scientists seeking a polite way to turn down time-consuming invitations to meetings, he suggested the following reply: “Dear X, I regret I am unable to accept your invitation as I find I cannot attend your meeting. Yours sincerely.”

He held positions at Cambridge and at the Salk Institute in San Diego, where he was appointed, as he termed it, “extinguished professor.”

Insights into the nature of the cell would alternate with his playful scientific inventions, like Occam’s Broom — “to sweep under the carpet what you must to leave your hypotheses consistent” — or Avocado’s Number, “the number of atoms in a guacamole.” **

For a short time he had been director of the Cambridge Laboratory of Molecular Biology, but he did not much enjoy working as an administrator: “You become a mediator between two impossible groups,” he said, “the monsters above and the idiots below.”

In his last column he decided he’d need another job, writing: When one stops doing a job, one should immediately go and look for another one, if only to provide an excuse for not doing all the mundane things one has promised to attend to after retirement, so he wrote a personal service ad: Elderly, white, male, column writer, seven years experience, self-employed scientist, explorer, adventurer, inventor and entrepreneur seeks young, naive, preferably female editor of newly formed scientific journal with a view to obtaining un-refereed access to as wide an audience as possible. Has good title for a column: ‘The Well-deserved Rest.’ Please write, quoting circulation and impact factor.

As well as a good writer he was a great talker, it was hard for any listener not to fall under his spell. He spoke slowly and precisely in a lingering South African accent, his sentences long and perfectly constructed and often ending with a joke.

He tells of abandoning religion when very young on his way to Hebrew school when he had to walk through a rough part of town in Germiston. He got beaten up by a gang. “As I stood there, I said Shema Yisrael, Adonai Elohenu, Adonai Ehad, but nothing came. I got beaten up, nobody helped me and I said forget it. That sort of thing stuck in my mind. To me it was just a lot of nonsense, basically.

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https://www.cell.com/current-biology/fulltext/S0960-9822(00)00853-8

https://en.wikipedia.org/wiki/Sydney_Brenner#cite_note-66

https://www.theguardian.com/science/2019/apr/05/sydney-brenner-obituary

**see Occam’s Razor and Avogadro’s Number for the real things.

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Before he died Wits Review gave him a lovely write-up – and gave the worm nice coverage, too.

Brenner Wits Review
Brenner Wits Review 2

Obituary

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Whatta boykie!

‘the funniest scientist who ever lived’ – What a wonderful epitaph. The lady who helped my Mom bring me into the world had a lovely one too. Both very special.