A GnRH neuronal population in the olfactory bulb translates socially relevant odors into reproductive behavior in male mice.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons regulate fertility and integrate hormonal status with environmental cues to ensure reproductive success. Here we show that GnRH neurons in the olfactory bulb (GnRH OB ) of adult mice can mediate social recognition. Specifically, we show that GnRH OB neurons extend neurites into the vomeronasal organ and olfactory epithelium and project to the median eminence. GnRH OB neurons in males express vomeronasal and olfactory receptors, are activated by female odors and mediate gonadotropin release in response to female urine. Male preference for female odors required the presence and activation of GnRH OB neurons, was impaired after genetic inhibition or ablation of these cells and relied on GnRH signaling in the posterodorsal medial amygdala. GnRH receptor expression in amygdala kisspeptin neurons appear to be required for GnRH OB neurons' actions on male mounting behavior. Taken together, these results establish GnRH OB neurons as regulating fertility, sex recognition and mating in male mice.