The vomeronasal organ is required for the expression of lordosis behaviour, but not sex discrimination in female mice

• Published in: The European journal of neuroscience Vol. 23; no. 2; pp. 521 - 530
• Main Authors: Keller, Matthieu, Pierman, Sylvie, Douhard, Quentin, Baum, Michael J., Bakker, Julie
• Format: Journal Article Web Resource
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.01.2006; Blackwell Publishing
• Subjects: accessory olfactory system; Analysis of Variance; Animals; Behavior, Animal; Discrimination, Psychological - physiology; Electrophoresis, Polyacrylamide Gel - methods; Female; Gene Expression - physiology; Gonadotropin-Releasing Hormone - pharmacology; Human health sciences; Immunohistochemistry - methods; Male; mate recognition; Maze Learning - physiology; Mice; Mice, Inbred C57BL; Molecular Weight; Neurologie; Neurology; Neurosciences & behavior; Neurosciences & comportement; Odorants; olfaction; Olfactory Pathways - metabolism; Posture; Proto-Oncogene Proteins c-fos - metabolism; Sciences de la santé humaine; Sciences sociales & comportementales, psychologie; Sexual Behavior, Animal - drug effects; Sexual Behavior, Animal - physiology; sexual behaviour; Smell - physiology; Social & behavioral sciences, psychology; Urine - chemistry; Vomeronasal Organ - physiology
• ISSN: 0953-816X; 1460-9568; 1460-9568
• DOI: 10.1111/j.1460-9568.2005.04589.x

The role of the vomeronasal organ (VNO) in mediating neuroendocrine responses in female mice is well known; however, whether the VNO is equally important for sex discrimination is more controversial as evidence exists for a role of the main olfactory system in mate recognition. Therefore, we studied the effect of VNO removal (VNOx) on the ability of female mice to discriminate between volatile and non‐volatile odours of conspecifics of the two sexes and in different endocrine states using Y‐maze tests. VNOx female mice were able to reliably distinguish between male and female or male and gonadectomized (gdx) male volatile odours. However, when subjects had to discriminate between male and female or gdx male non‐volatile odours, VNOx females were no longer able to discriminate between sex or different endocrine status. These results thus show that the VNO is primarily involved in the detection and processing of non‐volatile odours, and that female mice can use volatile odours detected and processed by the main olfactory system for mate recognition. However, VNO inputs are needed to promote contact with the male, including facilitation of lordosis responses to his mounts. A single subcutaneous injection with gonadotropin‐releasing hormone (GnRH) partially reversed the deficit in lordosis behaviour observed in VNOx females suggesting that VNO inputs may reach hypothalamic GnRH neurons to influence the display of sexual behaviour.