For most people, catching a whiff of someone’s pizza breath doesn’t inspire cravings for a slice. But for rodents, any food smell combined with breath odor sends an irresistible “eat this” message to the brain. Now scientists have uncovered exactly how the signal gets transmitted.
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Carbon disulfide, a byproduct of metabolism found in the breath of many mammals, stimulates a subset of cells in the mouse nose, scientists report online July 15 in Current Biology. When one mouse smells another’s breath, these nose cells trigger a signal that ultimately is transmitted to specialized structures within the mouse brain that associate an incoming odor with food that’s safe to eat.
“One mouse is saying, ‘My friend here just ate some food that smells like this — and he’s still breathing, he’s alive — so it must be safe,” says study coauthor Steven Munger of the University of Maryland School of Medicine in Baltimore.