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Tarantula Venom and Chili Peppers Share Receptor
FiReaNGeL writes "Scientists have discovered that venom from a West Indian tarantula has been shown to cause pain by exciting the same nerve cells in mice that sense high temperatures and the hot, spicy ingredient in chili peppers. The findings demonstrate that some plants and animals have evolved the same molecular strategy to deter predators — triggering pain by activating a specific receptor on sensory nerves. The research provides new tools to understand how these pain- and heat-sensing neurons work, and to help develop drugs that ease persistent pain."
A biochemist friend of mine was telling me about some of his prospective research projects some time ago. It turns out that the receptor for capsacsin and for high temperature are one and the same, and what's unusual about these receptors is that they are not on the cell surface where most receptors are, but within the cell. This explains why it takes a little while for hot peppers to give you that tingle, and why it takes a while for it to go away, btw.
It may seem odd that capsaicin, a pain-causing compund, can relieve pain. Based on research, it appears that the receptors targetted by capsaicin can eventually become "fatigued", and stop responding, thus easing pain in the case of arthritis or shingles. A doctor friend of mine told me he was once involved in capsaicin pain-relief research. According to him, they injected several rabbits with a relatively pure capsaicin extract. The rabbits writhed in agony for an entire night, but the next day seemed calm and normal. They were put through a battery of tests, and to the incredulity of the researchers, they didn't respond to any pain stimulus whatsoever. It was (he said) as though they'd been completely and permanently anesthetised. In effect, they had "burned out" the capsaicin receptors of the rabbits.