Circadian clocks and the measurement of daylength in seasonal reproduction

MOLECULAR AND CELLULAR ENDOCRINOLOGY

卷:349

Review

Ikegami, Keisuke¹  Yoshimura, Takashi^1,2,3 

[1] Nagoya Univ, Grad Sch Bioagr Sci, Physiol Anim Lab, Chikusa Ku, Nagoya, Aichi 4648601, Japan

[2] Nagoya Univ, Grad Sch Bioagr Sci, Avian Biosci Res Ctr, Chikusa Ku, Nagoya, Aichi 4648601, Japan

[3] Nagoya Univ, Global COE Program Adv Syst Biol, Chikusa Ku, Nagoya, Aichi 4648601, Japan

关键词: Pars tuberalis;    Mediobasal hypothalamus;    Deep brain photoreceptor;    Melatonin;    Thyroid hormone;    Thyroid-stimulating hormone;   

DOI  :  10.1016/j.mce.2011.06.040

来源: Elsevier

【 摘 要 】

Temperate zone organisms measure changes in daylength to adapt to seasonal changes in their environment. Recent studies have revealed that the long day (LD)-induced thyrotropin (TSH) in the pars tuberalis (PT) of the pituitary gland act as a master factor regulating seasonal reproduction on the the ependymal cells (ECs) within the mediobasal hypothalamus (MBH) to induce expression of type 2 deiodinase (Dio2), a thyroid hormone (TH)-activating enzyme in both LD and short day (SD) breeders. Locally activated TH in the MBH is believed to trigger GnRH secretion from the hypothalamus in LD breeders, while it terminates reproductive activity in SD breeders. Circadian clock is involved in seasonal time measurement and clock genes are expressed in the PT and ECs. Although circadian and melatonin-dependent control of TSH appears to link the circadian clock and the photoperiodic response in mammals, how this circadian clock measure daylength remains to be clarified. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

【 授权许可】

Free