Thyrotrophin in the pars tuberalis triggers photoperiodic response

Nobuhiro Nakao, Hiroko Ono, Takashi Yamamura, Tsubasa Anraku, Tsuyoshi Takagi, Kumiko Higashi, Shinobu Yasuo, Yasuhiro Katou, Saburo Kageyama, Yumiko Uno, Takeya Kasukawa, Masayuki Iigo, Peter J. Sharp, Atsushi Iwasawa, Yutaka Suzuki, Sumio Sugano, Teruyuki Niimi, Makoto Mizutani, Takao Namikawa, Shizufumi EbiharaHiroki R. Ueda, Takashi Yoshimura

Research output: Contribution to journalArticlepeer-review

399 Citations (Scopus)


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) β-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.

Original languageEnglish
Pages (from-to)317-322
Number of pages6
Issue number7185
Publication statusPublished - Mar 20 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General


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