A Missing Link Between Smell and Reproduction is Provided by a Novel Neuroendocrine Subsystem in the Olfactory Bulb

The sense of smell has long been known to exert a profound influence on the reproductive axis in both male and female rodents, yet despite intensive research over the past decades, the neural circuits and individual neurons linking olfaction with reproduction are still incompletely understood. A recent study by Decoster and colleagues uncovered a direct link between cells producing GnRH, the master molecule of reproduction, and the 2 major chemosensory epithelia in the murine nose. This hitherto undescribed GnRH subsystem, which is located in the olfactory bulb of mice as well as humans, may represent an evolutionarily ancient part of the neural circuits linking the olfactory system with the reproductive axis through the previously described classical GnRH system in the mediobasal hypothalamus. Here, we put these seminal new findings into perspective, highlighting their potential implications and their contribution to our current understanding of the neuroendocrine control of reproductive/sexual behavior by olfaction.