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Deficiency in taste buds leaves mice craving sweets
By Christina A. Pan

Japanese researchers studying receptors and nerves on the tongue have found a sensitivity to leptin, a protein produced by fat cells. Discovered a few years ago, leptin is known to inhibit food intake and increase energy expenditure. The researchers show that a defect in the leptin receptor may lead to increased cravings for sweets.

In a study published in the current issue of the Proceedings of the National Academy of Sciences, a team of researchers led by Yuzo Ninomiya, of the Section of Oral Neuroscience, Kyushu University, studied the reactions of normal mice and mice that were genetically diabetic, extremely obese, and had defective leptin receptors. After administering leptin, the normal mice exhibited significantly smaller taste responses to sweets; however, the obese mice exhibited no decreased response to sweets. The absence of significant responses to salty, sour, or bitter substances suggests that leptin is selective to sweets.

"These observations suggest that the taste organ is a peripheral target for leptin," says Ninomiya, "leptin may be a sweet-sensing suppressor that may take part in the regulation of food intake."

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Kawai, K. et al. Leptin as a modulator of sweet taste sensitivities in mice. Proc Natl Acad Sci USA 97, 11044-11049 (September 26, 2000).

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