Journal Article

Sex Differences in Brain Thyroid Hormone Levels during Early Post-Hatching Development in Zebra Finch (Taeniopygia guttata)

Aoki, Naoya, Homma, Koichi J., Yamaguchi, Shinji, Matsushima, Toshiya, Takehara, Akihiko, Ishigohoka, Jun, Wada, Kazuhiro, Hayase, Shin

2017

Overview

Thyroid hormones are closely linked to the hatching process in precocial birds. Previously, we showed that thyroid hormones in brain had a strong impact on filial imprinting, an early learning behavior in newly hatched chicks; brain 3,5,3'-triiodothyronine (T3) peaks around hatching and imprinting training induces additional T3 release, thus, extending the sensitive period for imprinting and enabling subsequent other learning. On the other hand, blood thyroid hormone levels have been reported to increase gradually after hatching in altricial species, but it remains unknown how the brain thyroid hormone levels change during post-hatching development of altricial birds. Here, we determined the changes in serum and brain thyroid hormone levels of a passerine songbird species, the zebra finch using radioimmunoassay. In the serum, we found a gradual increase in thyroid hormone levels during post-hatching development, as well as differences between male and female finches. In the brain, there was clear surge in the hormone levels during development in males and females coinciding with the time of fledging, but the onset of the surge of thyroxine (T4) in males preceded that of females, whereas the onset of the surge of T3 in males succeeded that of females. These findings provide a basis for understanding the functions of thyroid hormones during early development and learning in altricial birds.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adenosine / Animals / Biology / Biology and Life Sciences / Birds / Brain / Brain - growth & development / Brain - metabolism / Chicks / Computer and Information Sciences / Critical period / Development and progression / Endocrinology / Female / Females / Finches - physiology / Gender aspects / Gender differences / Gene Expression / Hatching / Health aspects / Health sciences / Hormones / Imprinting / Iodide Peroxidase - genetics / Iodide Peroxidase - metabolism / Juveniles / Learning / Learning behavior / Male / Males / Metabolism / Neurosciences / Oncorhynchus keta / Pharmaceutical sciences / Radioimmunoassay / Receptors, Thyroid Hormone - metabolism / Research and Analysis Methods / RNA, Messenger - genetics / RNA, Messenger - metabolism / Sex Characteristics / Sex differences / Social Sciences / Songbirds / Taeniopygia guttata / Thyroid / Thyroid gland / Thyroid hormones / Thyroid Hormones - blood / Thyroid Hormones - metabolism / Thyroxine / Triiodothyronine / Zebra finch