Not-so-Mellow Yellow: Pregnant Mice’s Urine Stresses Out Males

An odorant found in the pee of pregnant mice—and in bananas—induces stress but also relieves pain in male mice, a study shows.

Written bySophie Fessl, PhD
| 3 min read
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When male mice and pregnant or lactating female mice are placed closely together, chemical signals in the females’ urine stress the males out and make them less sensitive to pain, according to a study published on May 20 in Science Advances. The studies’ authors postulate that this newly discovered form of female-to-male signalling in mice helps females defend their pups from the males’ attacks. Coincidentally, the main odorant responsible also creates the characteristic smell of bananas, which stresses male mice as well.

The research reflects an increased focus on the biology of female lab animals and how they might differ from males in unpredictable ways, experts tell The Scientist.

“In the old times (maybe not so old), males were at the centre of biomedical research,” Ferran Martínez García, a cell biologist at Universitat Jaume I, in Spain, who was not involved in the study, tells The Scientist over email. Females ...

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  • Headshot of Sophie Fessl

    Sophie Fessl is a freelance science journalist. She has a PhD in developmental neurobiology from King’s College London and a degree in biology from the University of Oxford. After completing her PhD, she swapped her favorite neuroscience model, the fruit fly, for pen and paper.

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