Chemical control of reproduction in mice Female pheromones prompt the release of luteinising hormone (LH) leading to testosterone production in many animals. An EU funded project has investigated the complexities of this reflex action. Health © anyaivanova, Shutterstock The vomeronasal organ is an olfactory sense organ found in most animals. Mainly used to detect pheromones, the organ is part of the vomeronasal system that links via the accessory olfactory bulb (AOB) to central brain targets – hypothalamic gonadotropin releasing hormone (GnRH) neurons – that regulate reproductive behaviour. The GNRH & REPRODUCTION (Role of GnRH neurons in reproductive behavior and physiology) study has investigated how chemosensory stimuli modulate neuronal activity in male mice. In particular, they looked at responses to three female secretions: urine, saliva and vaginal fluid. All three chemical stimuli were able to communicate information about the female's strain and her reproductive cycle status. To test how variations in the stimuli, dilution, source and any interactions affected the response, the researchers devised an experiment where the male mice were subjected to a stimulus set from female mice. Results showed that information about socially relevant traits can be represented by a combinatorial code of AOB neurons. Insights into the complexity of these chemosensory stimulus effects and potential solutions under various scenarios have been published in Frontiers in Neuroscience and PLOS computational biology. GNRH & REPRODUCTION collaborations explored other aspects of the chemosensory stimuli including acidity of urine, bursting activity of AOB neurons and the slow temporal dynamics of accessory olfactory responses. Project research results have revealed how the action of GnRH neurons is modulated by chemosensory stimuli. Translated into reproductive behaviour in the GNRH & REPRODUCTION initiative, the methods can be used to study and model other systems involving neuronal activity and chemical cues. Keywords Reproduction, mice, vomeronasal organ, accessory olfactory bulb, hypothalamic gonadotropin releasing hormone, GNRH & REPRODUCTION
