The Yomiuri Shimbun
TOKYO — Tears of sexually immature female mice inhibit the mating behavior of male mice, a Japanese research team has found.
The research group, which includes Kazushige Tohara, a professor at the University of Tokyo and an expert on applied biological chemistry, released the finding in an electronic version of the British journal Nature in its Thursday edition.
A pheromone called exocrine-gland secreting peptide 22 (ESP22), which is abundant in tears of 2- to 3-week-old female mice, inhibits the sexual arousal of male mice, the team found.
It is known that pheromones increase sexual arousal in animals, but this is the first time a pheromone has been found to decrease sexual excitement in a mammal.
The researchers studied two groups of mice: one that secreted ESP22 and another that lacked the pheromone. Then the researchers studied the sexual responses of the male mice toward the females from the two groups.
The sexual behavior of male mice toward the females that did not secrete ESP22 was three to five times greater than that toward females that produced the pheromone. However, application of ESP22 to the bodies of the females that lacked the pheromone inhibited sexual behavior of the males.
ESP22 is detected by the vomeronasal organ, which is located below the nasal cavity, stimulating an area of brain that controls instinctive behavior. Human beings lack the system that produces and detects the pheromone.