Compared to defects in vision or hearing, hypo/anosmia (loss of olfactory sense) has received less attention because of its less serious effect on daily life activities compared to blindness or deafness. However, the dysfunction in olfactory sense often accompanies inabilities to appreciate food and to notice rotten food or toxic gas. Thus, studies on olfactory sense may significantly improve the quality of our life. Our physiological conditions are also more affected by the odor of people around us than we recognize. Studies from 1970s have shown that women who live together and spend time together show synchronized menstrual cycles and recent studies have shown that hormone secretions are stimulated by exposure to the odors of opposite sex. In my recent studies, I have found in mice that sperm density is higher in male mice exposed to female-soiled bedding (Koyama and Kamimura 2000) and subordinate males show lower sperm motility (1999).
In collaboration with analytical chemists in the Chemistry Department of IUB, I have also identified the male murine pheromones that enhance cell proliferation in the subventricular zone in the brain of female mice and female murine pheromones that do so in male mice (Koyama et al. 2013, 2014).
We also found a new phenomenon for which exposure to a synthetic analogue of the male murine pheromone stimulates expansion of mammary glands in female mice and the offspring of these females showed higher cognitive function in spatial memory tests using a Morris water maze (Koyama et al. 2015) (Press release at IUB News Room: http://news.indiana.edu/releases/iu/2015/07/pheromone-intelligence-study.shtml).
We are currently investigating the milk of these dams and the brain development in their offspring to obtain molecular mechanistic insight into the pheromone induced trans-generational influences.
Another project we started is focusing on odorants (aromas) rather than pheromones and their influences on improving wound healing. We hope to determine the odorants that enhance wound healing and suppress neuropathic pain.
Patent application Chemical component attractant for mice: Patent application number: JA03046, Japan