title: Female Mice Avoid Male Odor from the Same Strain via the Vomeronasal System in an Estrogen-Dependent Manner.
abstract: Inbreeding avoidance is essential to providing offspring with genetic diversity. Females' mate choice is more crucial than males' for successful reproduction because of the high cost of producing gametes and limited chances to mate. However, the mechanism of female inbreeding avoidance is still unclear. To elucidate the mechanism underlying inbreeding avoidance by females, we conducted Y-maze behavioral assays using BALB/c and C57BL/6 female mice. In both strains, the avoidance of male urine from the same strain was lower in the low estrogen phase than in the high estrogen phase. The estrous cycle-dependent avoidance was completely prevented by vomeronasal organ (VNO) removal. To assess the regulation of the vomeronasal system by estrogen, the neural excitability was evaluated by immunohistochemistry of the immediate early gene products. Although estrogen did not affect neural excitability in the VNO, estrogen enhanced the neural excitability of the mitral cell layer in the AOB induced by urine from the cognate males. These results suggest that female mice avoid odor from genetically similar males in an estrogen-dependent manner via the vomeronasal system and the excitability of the mitral cells in the AOB is presumed to be regulated by estrogen.
authors.affiliation: Laboratory of Physiology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan yanos@vetmed.hokudai.ac.jp.
authors.forename: Saori
authors.initials: S
authors.lastname: Yano
authors.affiliation: Laboratory of Physiology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan.
authors.forename: Kentaro Q
authors.initials: KQ
authors.lastname: Sakamoto
authors.affiliation: Laboratory of Physiology, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, 060-0818, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Habara
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004958:Estradiol / Q000008:administration & dosage; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009812:Odorants; D009830:Olfactory Bulb / Q000378:metabolism; D010675:Pheromones / Q000652:urine; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D019147:Vomeronasal Organ / Q000378:metabolism*
chemical_list: D010675:Pheromones; D016760:Proto-Oncogene Proteins c-fos; D004958:Estradiol
keywords: accessory olfactory bulb; estradiol; inbreeding avoidance; mouse; pheromone