Baby Mouse Tears Turn Off Female Mice

A research group in Japan has discovered a pheromone in young mouse tears that reduces female interest in sex, a finding which could be used as natural pest control.

AsianScientist (Oct. 30, 2018) – A pheromone found in the tears of young mice makes female mice more likely to reject male sexual advances, according to research by scientists in Japan. They published their work in the journal Nature Communications.

Animals communicate using a wide variety of methods. Pheromones—chemicals produced by specific glands in the body—are an efficient way to motivate or inhibit certain behaviors within a community.

In the present study, scientists at the University of Tokyo, Japan, have found that a pheromone in the tears of mouse pups can influence sexual behavior in female mice. Only juvenile mice aged one to three weeks produce the pheromone, called exocrine gland-secreting peptide 22 (ESP22). ESP22 is not airborne and lacks a noticeable odor, but spreads between individuals as mothers and young mice wipe their tears while grooming.

Notably, pheromone signals from young mice overrode signals from adult males: mothers and virgin female mice rejected male advances when they were exposed to ESP22, even after being exposed to male pheromones that typically increase libido, the researchers found. A lowered female interest in sex would theoretically benefit juvenile mice by reducing the number of younger siblings competing for resources.

The researchers also found that pheromone signals are routed to the medial amygdala, a small group of neurons in the brain. The pheromones alter the neurocircuitry of the brain to effect a change in behavior.

“The medial amygdala is like a hub to receive and reroute pheromone signals,” said Mr. Kentaro Ishii of the University of Tokyo, who is a co-first author on the research paper.

Ongoing research in the laboratory will explore pheromone-related neurocircuitry beyond the medial amygdala hub. The scientists hope to use the tear pheromone as a natural mouse birth control to reduce mouse populations in the future.

“ESP22 is difficult to artificially synthesize, so we want to find a smaller portion of the pheromone molecule that could be added to mouse drinking water. This could prevent mice breeding in areas where they are pests,” said Touhara.

“It is unlikely that other animals would be affected because pheromones are so species-specific. The sex-rejecting behavior is an innate instinct, so it’s also unlikely that the mice will learn to change their behavior or ignore the artificial pheromone,” he added.

The article can be found at: Osakada et al. (2018) Sexual Rejection via a Vomeronasal Receptor-triggered Limbic Circuit.


Source: University of Tokyo; Photo: Shutterstock.
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