Pregnant mice block out unwelcome admirers to protect their pups

Mouse mothers-to-be have a remarkable way to protect their unborn pups. Because the smell of a strange male's urine can cause miscarriage and reactivate the ovulatory cycle, pregnant mice prevent the action of such olfactory stimuli by blocking their smell. Researchers from the European Molecular Biology Laboratory (EMBL) in Monterotondo, Italy, have now revealed the nature of this ability. A surge of the chemical signal dopamine in the main olfactory bulb - one of the key brain areas for olfactory perception – creates a barrier for male odours, they report in the current issue of Nature Neuroscience.