Ontogenic expression profiles of thyroid-specific genes in embryonic and hatching chicks

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• 作者：S.V.H. Grommen ; A. Iwasawa ; V. Beck ; V.M. Darras ; B. De Groef
• 关键词：Chicken ; Thyroid gland ; Thyroid hormones ; Gene expression ; Development
• 刊名：Domestic Animal Endocrinology
• 出版年：2011
• 出版时间：January 2011
• 年：2011
• 卷：40
• 期：1
• 页码：10-18
• 全文大小：907 K

文摘

The last trimester of the embryonic life of chickens is marked by a steady increase in circulating thyroxine (T₄) levels, reaching a maximum around hatching. We have measured thyroidal mRNA expression levels of several genes involved in the biosynthesis of T₄, namely sodium/iodine symporter (NIS), thyroglobulin (Tg), thyroid peroxidase (TPO), thyrotropin receptor (TSHR), and thyroid transcription factor 1 (TTF-1), during this period. Subsequently, we measured the expression of these genes in more detail during the entire hatching process and compared the gene expression profiles with concomitant changes in intrathyroidal and circulating thyroid hormone levels. We found that NIS and TPO mRNA expression increased significantly in the perinatal period, whereas Tg mRNA expression rose gradually throughout the last week of embryogenesis but was stable during hatching. TSHR and TTF-1 mRNA levels did not change significantly during the last week of embryonic development and hatching. Our results suggest that the elevated plasma T₄ levels observed in the developmental period studied are caused by an increased synthesis and secretion of T₄ by the thyroid gland. Augmented expression of Tg may play an important role in the increasing T₄ production during the last week of embryonic development, whereas increased NIS and TPO expression around hatching allows the thyrocytes to boost T₄ synthesis even further.