Olfactory exposure to late-pregnant and lactating mice causes stress-induced analgesia in male mice

In an attempt to improve reproducibility, more attention is being paid to potential sources of stress in the laboratory environment. Here, we report that the mere proximity of pregnant or lactating female mice causes olfactory-mediated stress-induced analgesia, to a variety of noxious stimuli, in gonadally intact male mice. We show that exposure to volatile compounds released in the urine of pregnant and lactating female mice can themselves produce stress and associated pain inhibition. This phenomenon, a novel form of female-to-male chemosignaling, is mediated by female scent marking of urinary volatiles, such as n-pentyl-acetate, and likely signals potential maternal aggression aimed at defending against infanticide by stranger males.

Automated summary

In an effort to enhance reproducibility, researchers are increasingly paying attention to potential stressors in the laboratory environment. A recent study demonstrates that the mere presence of pregnant or lactating female mice causes stress-induced analgesia in male mice, mediated by olfactory cues. The release of volatile compounds in the urine of pregnant and lactating females produces stress and pain inhibition, likely informing potential maternal aggression to protect against infanticide by stranger males.