title: Photoperiodic changes in hypothalamic insulin receptor gene expression are regulated by gonadal testosterone.
abstract: In order to adapt to seasonal changes, animals exhibit robust changes in their reproductive status, body weight, and molt. However, the molecular mechanisms regulating such seasonal changes in physiology and behavior are not fully understood. Here, we report the photoperiodic regulation of the insulin receptor (IR) gene in the infundibular nucleus (anatomically homologous to the mammalian arcuate nucleus) of the Japanese quail. When the birds were transferred from short-day to long-day conditions, a significant increase in the level of IR mRNA was observed on the 10th long day, whereas that in testicular length was observed on the 5th long day. Castration abolished IR mRNA expression induced by long-day conditions, whereas the testosterone administration mimicked induction of IR mRNA expression induced by long-day conditions. These results suggested that the photoperiodic regulation of the IR mRNA in the infundibular nucleus is mediated by testosterone from the testes. It has been known that the central administration of insulin increases luteinizing hormone (LH) secretion, and neuron-specific disruption of IR gene causes impaired gonadal function due to the dysregulation of LH and increased food intake and body weight. Together with these results, the photoperiodic regulation of the IR mRNA in the hypothalamus may enhance the effect of long days in the seasonal response of reproduction and body weight changes.
authors.affiliation: Division of Biomodeling, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Anraku
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takagi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakao
authors.forename: Miwa
authors.initials: M
authors.lastname: Watanabe
authors.forename: Shinobu
authors.initials: S
authors.lastname: Yasuo
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Katou
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Ueda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Murai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iigo
authors.forename: Shizufumi
authors.initials: S
authors.lastname: Ebihara
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000704:Analysis of Variance; D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D001835:Body Weight / Q000187:drug effects / Q000528:radiation effects; D003370:Coturnix; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D017403:In Situ Hybridization; D008297:Male; D017440:Photoperiod; D011784:Quail; D012333:RNA, Messenger / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics* / Q000378:metabolism; D013737:Testis / Q000187:drug effects / Q000528:radiation effects; D013739:Testosterone / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000728:Androgens; D012333:RNA, Messenger; D013739:Testosterone; D011972:Receptor, Insulin