title: Thyrotrophin in the pars tuberalis triggers photoperiodic response.
abstract: Molecular mechanisms regulating animal seasonal breeding in response to changing photoperiod are not well understood. Rapid induction of gene expression of thyroid-hormone-activating enzyme (type 2 deiodinase, DIO2) in the mediobasal hypothalamus (MBH) of the Japanese quail (Coturnix japonica) is the earliest event yet recorded in the photoperiodic signal transduction pathway. Here we show cascades of gene expression in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone. We identified two waves of gene expression. The first was initiated about 14 h after dawn of the first long day and included increased thyrotrophin (TSH) beta-subunit expression in the pars tuberalis; the second occurred approximately 4 h later and included increased expression of DIO2. Intracerebroventricular (ICV) administration of TSH to short-day quail stimulated gonadal growth and expression of DIO2 which was shown to be mediated through a TSH receptor-cyclic AMP (cAMP) signalling pathway. Increased TSH in the pars tuberalis therefore seems to trigger long-day photoinduced seasonal breeding.
authors: Division of Biomodelling, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors: Nobuhiro
authors: N
authors: Nakao
authors: Hiroko
authors: H
authors: Ono
authors: Takashi
authors: T
authors: Yamamura
authors: Tsubasa
authors: T
authors: Anraku
authors: Tsuyoshi
authors: T
authors: Takagi
authors: Kumiko
authors: K
authors: Higashi
authors: Shinobu
authors: S
authors: Yasuo
authors: Yasuhiro
authors: Y
authors: Katou
authors: Saburo
authors: S
authors: Kageyama
authors: Yumiko
authors: Y
authors: Uno
authors: Takeya
authors: T
authors: Kasukawa
authors: Masayuki
authors: M
authors: Iigo
authors: Peter J
authors: PJ
authors: Sharp
authors: Atsushi
authors: A
authors: Iwasawa
authors: Yutaka
authors: Y
authors: Suzuki
authors: Sumio
authors: S
authors: Sugano
authors: Teruyuki
authors: T
authors: Niimi
authors: Makoto
authors: M
authors: Mizutani
authors: Takao
authors: T
authors: Namikawa
authors: Shizufumi
authors: S
authors: Ebihara
authors: Hiroki R
authors: HR
authors: Ueda
authors: Takashi
authors: T
authors: Yoshimura
mesh_terms: D000818:Animals; D002645:Chickens; D003370:Coturnix / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D003624:Darkness; D004790:Enzyme Induction; D005260:Female; D005786:Gene Expression Regulation / Q000528:radiation effects; D016678:Genome; D023281:Genomics; D007031:Hypothalamus / Q000378:metabolism / Q000528:radiation effects; D007453:Iodide Peroxidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D008027:Light; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D017440:Photoperiod; D010902:Pituitary Gland / Q000033:anatomy & histology / Q000378:metabolism* / Q000528:radiation effects*; D011989:Receptors, Thyrotropin / Q000378:metabolism; D012098:Reproduction / Q000502:physiology* / Q000528:radiation effects*; D012621:Seasons; D015398:Signal Transduction / Q000528:radiation effects; D013737:Testis / Q000254:growth & development; D013972:Thyrotropin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*
chemical_list: D011989:Receptors, Thyrotropin; D007986:Luteinizing Hormone; D013972:Thyrotropin; D000242:Cyclic AMP; D007453:Iodide Peroxidase