Neuroscience

One Singular Sensation

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Science  02 Sep 2005:
Vol. 309, Issue 5740, pp. 1459
DOI: 10.1126/science.309.5740.1459e

While not everyone enjoys the zing that garlic imparts to culinary fare, a variety of cultures—dating back to the ancient Egyptians—have firmly believed that the herb has extraordinary medicinal powers. Although its health benefits remain somewhat contentious, garlic is currently marketed as an alternative therapy for high blood pressure, high cholesterol levels, excessive blood clotting, and many other disorders. Garlic's pungent taste and odor are due to sulfur-containing components such as allicin, whose physiological mechanism of action has been unclear.

Bautista et al.and Macpherson et al.show that allicin activates an excitatory ion channel called TRPA1, which is expressed on sensory neurons involved in innervation of the skin, tongue, and other tissues, including vascular smooth muscle. Based on experiments with isolated rat arteries, Bautista et al.propose that allicin-induced excitation of these neurons causes release of peptides that mediate vasodilation, which could potentially explain garlic's effect on blood pressure. Interestingly, the TRP family of ion channels had previously been identified as the molecular target of ingredients in other spicy foods such as chili peppers, wasabi, and yellow mustard, suggesting that these compounds all activate a common pathway. — PAK

Proc. Natl. Acad. Sci. U.S.A. 102, 12248 (2005); Curr. Biol. 15, 929 (2005)

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