Szechuan peppers neuroscience

Nature Neuroscience 11, 772 – 779 (2008)
Published online: 22 June 2008 | doi:10.1038/nn.2143

Pungent agents from Szechuan peppers excite sensory neurons by inhibiting two-pore potassium channels

Diana M Bautista1,2,3,4, Yaron M Sigal1,2,4, Aaron D Milstein2, Jennifer L Garrison2,3, Julie A Zorn2, Pamela R Tsuruda1,2,3, Roger A Nicoll1,2 & David Julius1,2


In traditional folk medicine, Xanthoxylum plants are referred to as ‘toothache trees’ because their anesthetic or counter-irritant properties render them useful in the treatment of pain. Psychophysical studies have identified hydroxy-alpha-sanshool as the compound most responsible for the unique tingling and buzzing sensations produced by Szechuan peppercorns or other Xanthoxylum preparations. Although it is generally agreed that sanshool elicits its effects by activating somatosensory neurons, the underlying cellular and molecular mechanisms remain a matter of debate. Here we show that hydroxy-alpha-sanshool excites two types of sensory neurons, including small-diameter unmyelinated cells that respond to capsaicin (but not mustard oil) as well as large-diameter myelinated neurons that express the neurotrophin receptor TrkC. We found that hydroxy-alpha-sanshool excites neurons through a unique mechanism involving inhibition of pH- and anesthetic-sensitive two-pore potassium channels (KCNK3, KCNK9 and KCNK18), providing a framework for understanding the unique and complex psychophysical sensations associated with the Szechuan pepper experience.



If they do it well this is very encouraging.

明報 2007年12月17日







walnuts & blueberries good for the (rat’s) brain

Diets containing two percent, six percent, or nine percent walnuts, when given to old rats, were found to reverse several parameters of brain aging, as well as age-related motor and cognitive deficits, says James Joseph, PhD, of the U.S. Department of Agriculture Human Nutrition Research Center at Tufts University in Boston.

In previous research, Joseph and his colleagues showed that old rats maintained for two months on diets containing two percent high antioxidant strawberry or blueberry extracts exhibited reversals of age-related deficits in the way that neurons function and in motor and cognitive behavior. In the brain, antioxidant molecules wage war against molecules known as free radicals, which can harm brain cells and brain function. The present research extends these findings and shows that walnuts can have a similar effect.

ciguatera (雪卡毒) and temperature reversal

Ciguatera often appears in Hong Kong news, with people getting poisoned by eating coral fish such as grouper. What is not reported is the surprising fact that in some cases this makes hot things feel cold and cold things feel hot. A nice example of qualia inversion!



Fish Poison makes Hot Things Feel Icy and Cold Things Feel Burning Hot
By Aaron Rowe
October 11, 2007

Grouper Eating some bad fish might not seem like the most spectacular way to ruin a tropical vacation, but for a 45-year-old man from England, a bit of tainted seafood was the beginning of a wild ride.

Cold water felt burning hot. Hot things felt icy cold. His tongue felt strange. Drinking alcohol or coffee only increased his suffering.

The patient had ciguatera poisoning — an ailment caused by ciguatoxin, a neurotoxin that is produced by microorganisms and found in a wide variety of tropical fish.

More choices might not be better

From this blog

“When Choice is Demotivating: Can One Desire too Much of a Good Thing?” Iyengar, S. S., & Lepper, M. Journal of Personality and Social Psychology, 79, 995-1006. (2000).

This paper explored the phenomena of “choice overload.” Here is what they did.

They created two displays of gourmet jams. One display had 24 jars. The other had 6. Each display invited people to try the jams and offered them a discount coupon to buy the jam. They alternated these displays in a grocery store and tracked how many people passed the displays, how many people stopped and sampled the jams, and how many subsequently used the offered coupon to buy the jam.

The results were surprising.

* 24 jar display: 60% of the people passing the display sampled the jam, 3% purchased jam.
* 6 jar display: 40% of the people passing the display sampled the jam, 30% purchased jam.

Drink your way to a longer life

Good news – moderate drinking correlates with longevity. This is a very large meta-studies involving a million subjects. But to what extent is it related to lifestyle and income?

Link: Drink up for a longer life – Aging –

Moderate drinking may lengthen your life, while too much may shorten it, researchers from Italy report. Their conclusion is based on pooled data from 34 large studies involving more than 1 million people and 94,000 deaths.

According to the data, drinking a moderate amount of alcohol — up to four drinks per day in men and two drinks per day in women — reduces the risk of death from any cause by roughly 18 percent, the team reports in the Archives of Internal Medicine.

However, “things radically change” when consumption goes beyond these levels.

The original paper:

Alcohol Dosing and Total Mortality in Men and Women
An Updated Meta-analysis of 34 Prospective Studies
Arch Intern Med. 2006;166:2437-2445.

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The World’s 50 Best Restaurants 2006

The world’s best 50 restaurants ranking is out. El Bulli has re-captured first place, followed by The Fat Duck, Pierre Gagnaire, French Laundry, and Tetsuya.

I am glad to see that L’Atelier de Joel Rebuchon is on the list. There is also a branch in Tokyo which is just as good. They have the same deco – modelled after a bar/sushi counter. The food is consistently creative and wonderful, and better value for money than most over-priced HK resturants. This includes Felix at the Penisula in HK, which has dropped out of the list this year. But then again, you go there for the view and not the food. After all, where else can you pee while starring down the whole of Kowloon?

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Does drinking really improve health?

Researchers poured cold water on the idea that moderate drinking helps prevent heart disease, noting that many studies include teetotalers as a control group but don’t ask why they did not drink.

Several major studies have found that light to moderate drinking — up to two drinks a day on a regular basis — is associated with a lower risk of heart disease. Some have also found a lower risk of some cancers.

But a team at the University of Victoria in British Columbia and the University of California San Francisco analyzed 54 studies and found that only seven of them differentiated between people who abstain from choice and those who may have quit drinking for health reasons.

When such studies show a higher death rate for abstainers than for moderate drinkers, it may be because of the poor health of some abstainers who recently quit drinking and not because alcohol is good for health, they said.

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