title: Increased squalene concentrations in the clitoral gland during the estrous cycle in rats: an estrus-indicating scent mark?
abstract: Squalene in the rat clitoral gland is reported to be semi-volatile and may serve as a chemo-signal. The objective was to determine squalene concentrations in the clitoral gland throughout the reproductive cycle. Clitoral glands were extracted with dichloromethane; 23 compounds were identified with Gas Chromatography linked Mass Spectrometry (GC-MS). Since squalene concentrations were significantly higher during proestrus and estrus, and remarkably reduced during metestrus and diestrus, we inferred that it could be an ovulation-indicating chemosignal in the female rat, acting as a scent mark for the male. This hypothesis was tested by investigating its efficacy to attract males, including studying the role of the olfactory-vomeronasal system of the male in perceiving squalene. For detection of squalene, males used their conventional olfactory system when at a distance from the female, whereas the vomeronasal organ was used when they were in close proximity to the female. We concluded that squalene was a female-specific chemosignal that attracted males, and furthermore, that the olfactory-vomeronasal system had an important role in the perception of squalene.
authors.affiliation: Department of Environmental Biotechnology, Bharathidasan University, Tiruchirappalli, Tamilnadu, India.
authors.forename: Shanmugam
authors.initials: S
authors.lastname: Achiraman
authors.forename: Govindaraju
authors.initials: G
authors.lastname: Archunan
authors.forename: Bethunaicken
authors.initials: B
authors.lastname: Abirami
authors.forename: Palanivel
authors.initials: P
authors.lastname: Kokilavani
authors.forename: Udhayaraj
authors.initials: U
authors.lastname: Suriyakalaa
authors.forename: Devaraj
authors.initials: D
authors.lastname: SankarGanesh
authors.forename: Soundararajan
authors.initials: S
authors.lastname: Kamalakkannan
authors.forename: Soundarapandian
authors.initials: S
authors.lastname: Kannan
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Habara
authors.forename: Ramaiyan
authors.initials: R
authors.lastname: Sankar
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002987:Clitoris / Q000378:metabolism; D004971:Estrus / Q000378:metabolism*; D004972:Estrus Detection; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006120:Grooming / Q000187:drug effects; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012724:Sex Attractants / Q000378:metabolism*; D013185:Squalene / Q000378:metabolism* / Q000494:pharmacology; D019147:Vomeronasal Organ / Q000502:physiology
chemical_list: D012724:Sex Attractants; D013185:Squalene