Volatile female odors activate the accessory olfactory system of male mice without physical contact.
We previously reported that male mice are more attracted to volatile odors from intact female mice than from ovariectomized female mice. In the present study, we investigated male attraction to volatile odors from soiled bedding collected from the cages of estrous or ovariectomized female mice. There was no difference in the total time spent sniffing volatile odors from estrous and ovariectomized female mice, suggesting that female mice emit volatile odors which are not excreted into bedding. To test this possibility, we investigated c-Fos expression in the mitral cell layer and granule cell layer of the accessory olfactory bulb 60 min after exposure of male mice to volatile odors without physical contact. Volatile odors from an estrous female mouse significantly increased the total number of c-Fos positive cells in each of the rostral and caudal granule cell layer, but not in the mitral cell layer. After exposure to volatile odors from estrous bedding, the total number of c-Fos positive cells did not increase. Volatile odors from a male mouse did not increase the total number of c-Fos positive cells. Volatile odors from an ovariectomized female mouse increased c-Fos expression only in the caudal granule cell layer. These results suggest that female mice emit specific volatile odors which are not excreted into bedding, and that the volatile odors activate the accessory olfactory system of male mice without physical contact. To characterize the female-specific volatile odors, we conducted habituation-dishabituation tests. Whereas sham-operated male mice discriminated between volatile odors of estrous and ovariectomized female mice, vomeronasal organ-removed male mice did not. These results suggest that male mice discriminated whether or not female mice were ovariectomized, by volatile odors via the accessory olfactory system, and that the female-specific volatile odors are involved in reproduction.
Muroi
Y
Y
Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan. Electronic address: S09038@ST.OBIHIRO.AC.JP.
Ishii
T
T
Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; The Laboratory of Pharmacology, Department of Pathobiological Science, School of Veterinary Science, Faculty of Animal Husbandry, Obihiro University of Agriculture and Veterinary Medicine, Obihiro Hokkaido 080-8555, Japan.
Komori
S
S
Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
Kitamura
N
N
Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; The Laboratory of Anatomy, Department of Basic Veterinary Science, School of Veterinary Science, Faculty of Animal Husbandry, Obihiro University of Agriculture and Veterinary Medicine, Obihiro Hokkaido 080-8555, Japan.
Nishimura
M
M
Department of Pathogenetic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; The Laboratory of Pharmacology, Department of Pathobiological Science, School of Veterinary Science, Faculty of Animal Husbandry, Obihiro University of Agriculture and Veterinary Medicine, Obihiro Hokkaido 080-8555, Japan.
D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count / Q000379:methods; D004971:Estrus; D005260:Female; D006185:Habituation, Psychophysiologic; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism; D009812:Odorants; D009833:Olfactory Pathways / Q000166:cytology / Q000502:physiology*; D010052:Ovariectomy / Q000379:methods; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012737:Sex Factors; D012903:Smell / Q000502:physiology*; D019147:Vomeronasal Organ / Q000502:physiology*
D016760:Proto-Oncogene Proteins c-fos