Acceleration of Puberty Onset in Female Mice by Male Urinary Odours: Chemosensory, Physiological and Neuroendocrine Mechanisms

Among many environmental factors, social factors, especially olfactory cues, can profoundly influence the timing of puberty onset. This is particularly well established in the house mouse (Mus musculus) where male urinary odours have been shown to accelerate puberty onset in prepubertal females. The urinary chemosignal(s) accelerate vaginal opening, the first oestrus and uterine growth, three parameters indicative of puberty onset. Several puberty-accelerating chemosignals, the majority of which are small volatile ligands bound to the major urinary proteins (MUPs), have been isolated from male urine; however when they are efficient, it is usually to a lower extent than male urine. These puberty-accelerating chemosignals are detected by the accessory olfactory system and the olfactory information is then transmitted to the hypothalamus. Among various potential neurological targets of the olfactory information, we focus on the hypothalamic neurons expressing neuropeptide kisspeptin, identified as a major regulator of the hypothalamic-pituitary-gonadal axis governing puberty onset. Preliminary results indicate that male odours seems to accelerate the structural changes usually observed in this neuronal population at puberty onset, thus suggesting that it could be a central hypothalamic relay of pheromonal information.