Thyrotrophin in the pars tuberalis triggers photoperiodic response.
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.
Nakao
Nobuhiro
N
Division of Biomodelling, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Ono
Hiroko
H
Yamamura
Takashi
T
Anraku
Tsubasa
T
Takagi
Tsuyoshi
T
Higashi
Kumiko
K
Yasuo
Shinobu
S
Katou
Yasuhiro
Y
Kageyama
Saburo
S
Uno
Yumiko
Y
Kasukawa
Takeya
T
Iigo
Masayuki
M
Sharp
Peter J
PJ
Iwasawa
Atsushi
A
Suzuki
Yutaka
Y
Sugano
Sumio
S
Niimi
Teruyuki
T
Mizutani
Makoto
M
Namikawa
Takao
T
Ebihara
Shizufumi
S
Ueda
Hiroki R
HR
Yoshimura
Takashi
T
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*
D011989:Receptors, Thyrotropin; D007986:Luteinizing Hormone; D013972:Thyrotropin; D000242:Cyclic AMP; D007453:Iodide Peroxidase