title: Vomeronasal signal deficiency enhances parental behavior in socially isolated male mice.
abstract: We previously reported that social isolation promotes parental care in sexually naïve male mice. This effect was blocked by exposure to chemosensory and auditory social signals derived from males in an adjacent compartment. In the present study, we examined whether the chemosensory signals detected in the vomeronasal organ (VNO) are involved in parental behavior by using mice deficient for a VNO-specific ion channel (Trpc2-/-) and thus impaired in VNO-input signaling. We housed virgin homozygous Trpc2-/-and heterozygous Trpc2±males for 3weeks during puberty (5-8weeks old) alone or in groups of 3-5 males. At 8weeks of age, the mice were placed with three pups in an observation cage and tested for parental behavior. The Trpc2-/-males housed under isolated conditions spent significantly longer in the vicinity of pups than did the Trpc2-/-males than had been group housed, whereas no isolation effect was observed in heterozygous Trpc2±males. Both Trpc2 knockout and isolation housing significantly increased the time males spent licking pups and crouching (arched back posture over pups to enable nursing), whereas only isolation housing increased the incidence of retrieval behavior. These results demonstrated that social signals transmitted not only through the VNO but also from other modalities, independent of each other, suppress the expression of parental behavior during puberty in sexually naïve males.
authors.affiliation: Institute for Advanced Medical Sciences, Nippon Medical School, Kanagawa 211-8533, Japan. Electronic address: orikasa@nms.ac.jp.
authors.forename: Chitose
authors.initials: C
authors.lastname: Orikasa
authors.affiliation: Department of Animal Sciences, Teikyo University of Science, Tokyo 120-0045, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kondo
authors.affiliation: Institute for Advanced Medical Sciences, Nippon Medical School, Kanagawa 211-8533, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Katsumata
authors.affiliation: Laboratory Animal Research Center, Dokkyo Medical University, Tochigi 321-0293, Japan.
authors.forename: Misao
authors.initials: M
authors.lastname: Terada
authors.affiliation: Division of Laboratory Animal Science, Nippon Medical School, Tokyo 113-8602, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Akimoto
authors.affiliation: University of Tokyo Health Science, Tokyo 206-0033, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sakuma
authors.affiliation: Institute for Advanced Medical Sciences, Nippon Medical School, Kanagawa 211-8533, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Minami
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010332:Paternal Behavior / Q000502:physiology*; D012934:Social Isolation / Q000523:psychology*; D018709:Statistics, Nonparametric; D050052:TRPC Cation Channels / Q000172:deficiency / Q000235:genetics; D019147:Vomeronasal Organ / Q000503:physiopathology*
chemical_list: D050052:TRPC Cation Channels; C491858:Trpc2 protein, mouse
keywords: Parental behavior; Social isolation; TRPC2; Trpc2(−/−) males; VNO-specific ion channel genetic ablation