Oestrus odours from rats and mares: Behavioural responses of sexually naive and experienced rats to natural odours and odorants

• DOI: 10.1016/j.applanim.2016.01.014
• Publication Date: 2016-01-19T21:22:57Z
• Authors: Birte L. Nielsen; Nathalie Jerôme; Audrey Saint-Albin; Christian Ouali; Sophie Rochut; Emilie-Laure Zins; Christine Briant; Elodie Guettier; Fabrice Reigner; Isabelle Couty; Michèle Magistrini; Olivier Rampin
• Keywords: 0301 basic medicine; [SDV.OT]Life Sciences [q-bio]/Other [q-bio.OT]; brown Norway rat; ketones; [SDV.OT] Life Sciences [q-bio]/Other [q-bio.OT]; reproduction animale; estrus; comportement animal; jument; horse; réponse comportementale; 03 medical and health sciences; allelochemics; penile erection; mares; rat; oestrus; cheval; odeur; olfaction; équin

Abstract Three experiments were conducted to investigate if sexual experience affects the behavioural response of male rats to natural oestrus odours and constituent odorants. In the first experiment, 16 male Brown Norway rats were exposed before and after sexual training to four odours (1-hexanol (herb odour), a ketone mixture, and faeces from mares and rats in oestrus) presented one at a time to individual rats during a 30-min test. More penile erections were observed during tests when rats were exposed to the two types of faeces as well as the ketone mixture compared to 1-hexanol, both when sexually naive ( P = 0.032) and experienced ( P = 0.002). In the second experiment, 30 male rats were tested using a habituation/dishabituation protocol. The rats were able to distinguish the ketone mixture used in Experiment 1 from another single-molecule ketone ( P N = 30) were analysed using gas chromatography–mass spectrometry (GC–MS) for the presence of three ketones and 1-hexanol using menthol as an added calibrating compound. Although significant intra-species differences in ketone composition were found between faeces from males and females in oestrus and di-oestrus, these differences were dissimilar across species. Also, 1-hexanol was present in all six faeces types. The results indicate that the ketones used may not be specific oestrus odorants, but may share volatile characteristics with natural oestrus odours. These findings are discussed in relation to oestrus odours and their potential commonality across mammalian species.