23 August, 2007

Painfull food

Red and yellow chili pepper

The chili pepper is faking our nerves while eating: normal temperature appears incredibly hot. And this is quite useful, as this protects us from inflammations, but also protects the pepper from being eaten.

On the 23rd of October 1997, David Julius and colleges wrote in Nature an article about their discovery, which got them the Unilever Science Prize. They found the protein in the pain nerves that reacted to heat and to capsaïcine, the hot substance in Capsicum annuum (chili pepper). Without that protein, mice tend to keep their tail four times longer in hot water as well as that can drink peppered water without any problems.

Drug targets in periphery
Drug targets in periphery

The protein (or receptor) of capsaïcine is located on the surface of the nerve cell. If capsaïcine binds to the receptor, a canal connected to that receptor opens and ions can float through it. This results in an electric pulse, signaling the spine: “I’ve eating something hot, I’m in pain!”.
This protects us from burning either our inside or our outside. Because the capsaïcine-receptor also effects our skin. When we come in contact with something hot (like hot water), we are able to pull our affected skin back, without even consciouses realizing that is hot, and thus dangerous.
Experiments show that when the back paws of normal mice are heated till 49° Celsius, they can take the heat 12 seconds. When mice receive an injection with the protein, they can only take the heat for 6 seconds.
Genetically manipulated mice, without the capsaïcine-receptor, still react slow after the injection; they don’t feel the pain, like normal animals feel with an inflammation. Striking, this only works with heat; at stings from a needle, the mouse without the receptor reacts irritated.

DNA, Neuroscience