Sex-specific differences in olfactory receptor expression following gender separation

Sex-specific differences in olfactory receptors following gender separation

A team researchers and discovered that separating male and female mice, over time, changes the way they smell. The study published in Nature Communications investigates how the olfactory sensory receptors in mice change as a function of exposure to odors emitted from members of the opposite sex, says the senior author.

"The idea is that our experiences change our sensory system in a way that is semipermanent. This is probably true in humans as much as mice," the senior author says.

Housing mice either sex-separated or sex-combined until six months of age, authors find that sex-separated mice exhibit significantly more numerous differentially expressed genes within their olfactory epithelia. A subset of these chemoreceptors exhibit altered expression frequencies following both sex-separation and olfactory deprivation. The authors show that several of these receptors detect either male- or female-specific odors. 

"We found that mice that are housed with the opposite sex all of the time have olfactory sensory receptors that are similar in composition because they are smelling similar smells. On the other hand, mice that were housed separately by sex have sex-specific differences in their olfactory receptors. As a result, they may perceive odors differently."

"The olfactory system of mice and humans is very similar," the senior author says. "Mice are a very good model to understand how neural systems work, in general. They are a much better model for humans than flies and other common-model organisms."

Sensory activity plays pivotal roles in the development of the nervous system. Mouse odors are a complex mixture of volatile and non-volatile chemicals derived from skin secretions, urine, tears, saliva and feces, which are known to differ substantially in their chemical compositions between males and females.

"Human males and females smell different, too. Men give off odors from testosterone metabolites, for example," the senior author explains. "There are genetic differences in being able to detect this. Some people would say the smell is good, while others find it unpleasant or cannot detect it at all. These differences in perception are related to genetic differences in people's receptors. Some researchers speculate that these kinds of molecules might function as pheromones in humans."

Unlike most neurons in the mammalian nervous system, olfactory sensory neurons (OSNs) are continually born and replaced throughout life, a process that normally replaces damaged neurons in humans when we have a cold or use a zinc nasal spray, the senior author says. Changes in the abundance of specific OSN subtypes occur, in part, through a use-it-or-lose-it mechanism in which active OSNs are retained and silent OSNs are eliminated from the population, the paper concludes.