TY - JOUR
T1 - Long-day suppressed expression of type 2 deiodinase gene in the mediobasal hypothalamus of the Saanen goat, a short-day breeder
T2 - Implication for seasonal window of thyroid hormone action on reproductive neuroendocrine axis
AU - Yasuo, Shinobu
AU - Nakao, Nobuhiro
AU - Ohkura, Satoshi
AU - Iigo, Masayuki
AU - Hagiwara, Satoko
AU - Goto, Akemitsu
AU - Ando, Hiroshi
AU - Yamamura, Takashi
AU - Watanabe, Miwa
AU - Watanabe, Tsuyoshi
AU - Oda, Sen Ichi
AU - Maeda, Kei Ichiro
AU - Lincoln, Gerald A.
AU - Okamura, Hiroaki
AU - Ebihara, Shizufumi
AU - Yoshimura, Takashi
PY - 2006/1
Y1 - 2006/1
N2 - In most animals that live in temperate regions, reproduction is under photoperiodic control. In long-day breeders such as Japanese quail and Djungarian hamsters, type 2 deiodinase (Dio2) plays an important role in the mediobasal hypothalamus, catalyzing the conversion of prohormone T4 to bioactive T3 to regulate the photoperiodic response of the gonads. However, the molecular basis for seasonal reproduction in shortday breeders remains unclear. Because thyroid hormones are also known to be involved in short-day breeders, we examined the effect of an artificial long-day stimulus on Dio2 expression in the male Saanen goat (Capra hircus), a short-day breeder. Dio2 expression was observed in the caudal continuation of the arcuate nucleus, known as the target site for both melatonin and T4 action. In addition, expression of Dio2 and T3 content in the mediobasal hypothalamus was suppressed by artificial long-day conditions, which is the opposite of the results of long-day breeders. Thyroid hormone action on the development of neuroendocrine anestrus is known to be limited to a specific seasonal window. This long-day suppression of Dio2 may provide a mechanism that accounts for the lack of responsiveness to thyroxine during the mid to late anestrus.
AB - In most animals that live in temperate regions, reproduction is under photoperiodic control. In long-day breeders such as Japanese quail and Djungarian hamsters, type 2 deiodinase (Dio2) plays an important role in the mediobasal hypothalamus, catalyzing the conversion of prohormone T4 to bioactive T3 to regulate the photoperiodic response of the gonads. However, the molecular basis for seasonal reproduction in shortday breeders remains unclear. Because thyroid hormones are also known to be involved in short-day breeders, we examined the effect of an artificial long-day stimulus on Dio2 expression in the male Saanen goat (Capra hircus), a short-day breeder. Dio2 expression was observed in the caudal continuation of the arcuate nucleus, known as the target site for both melatonin and T4 action. In addition, expression of Dio2 and T3 content in the mediobasal hypothalamus was suppressed by artificial long-day conditions, which is the opposite of the results of long-day breeders. Thyroid hormone action on the development of neuroendocrine anestrus is known to be limited to a specific seasonal window. This long-day suppression of Dio2 may provide a mechanism that accounts for the lack of responsiveness to thyroxine during the mid to late anestrus.
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U2 - 10.1210/en.2005-0507
DO - 10.1210/en.2005-0507
M3 - Article
C2 - 16195409
AN - SCOPUS:29344459579
VL - 147
SP - 432
EP - 440
JO - Endocrinology
JF - Endocrinology
SN - 0013-7227
IS - 1
ER -