title: The critical period for thyroid hormone responsiveness through thyroid hormone receptor isoform alpha in the postnatal small intestine.
abstract: During second and third weeks after birth in rats, serum thyroid hormone level is elevated. In this study, we investigated the jejunal expression of thyroid hormone receptor (TR) alpha in developing rats. The TRalpha-1 mRNA level and TRalpha-1/TRalpha-2 mRNA ratio increased two-fold from 5 to 13 days after birth. This high level of TRalpha-1 mRNA was maintained until 20 days and then decreased to the basal level by the end of weaning period at 27 days; however, the level of TRalpha-2 mRNA remained unchanged throughout the developmental period. The increase in the TRalpha-1/TRalpha-2 mRNA ratio from 5 to 13 days was accompanied by an initial rise in the levels of mRNA for hexose transporters in the jejunum. Administration of T(3) during the suckling period (8-13 days) caused a 50% increase in the TRalpha-1/TRalpha-2 mRNA ratio, while administration of T(3) on days 12-17 and days 16-21, but not on days 22-27, caused a two to four-fold increase in the levels of mRNA for hexose transporters. These results suggest that a transient variation in the TRalpha-1/TRalpha-2 expression ratio is closely related to the critical period of thyroid hormone responsiveness for hexose transporters expression in the developing rat jejunum.
authors.affiliation: Graduate School of Nutritional and Environmental Sciences, COE Program in the 21st Century, The University of Shizuoka, Shizuoka 422-8526, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Eriko
authors.initials: E
authors.lastname: Yagi
authors.forename: Naomi
authors.initials: N
authors.lastname: Sakaguchi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Satsuki
authors.initials: S
authors.lastname: Takabe
authors.forename: Sachi
authors.initials: S
authors.lastname: Kuranuki
authors.forename: Takuji
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masaya
authors.initials: M
authors.lastname: Shimada
authors.forename: Toshinao
authors.initials: T
authors.lastname: Goda
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D015152:Blotting, Northern; D018938:Caco-2 Cells; D024202:Electrophoretic Mobility Shift Assay; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D051273:Glucose Transporter Type 2 / Q000378:metabolism; D051296:Glucose Transporter Type 5 / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000254:growth & development / Q000378:metabolism; D007583:Jejunum / Q000187:drug effects / Q000196:embryology / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051269:Sodium-Glucose Transporter 1 / Q000378:metabolism; D037021:Thyroid Hormone Receptors alpha / Q000235:genetics / Q000378:metabolism*; D013963:Thyroid Hormones / Q000378:metabolism* / Q000494:pharmacology; D013997:Time Factors; D015533:Transcriptional Activation; D014162:Transfection; D014284:Triiodothyronine / Q000378:metabolism; D014886:Weaning
chemical_list: D051273:Glucose Transporter Type 2; D051296:Glucose Transporter Type 5; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495683:Slc2a2 protein, rat; C495727:Slc2a5 protein, rat; C495676:Slc5a1 protein, rat; D051269:Sodium-Glucose Transporter 1; D037021:Thyroid Hormone Receptors alpha; D013963:Thyroid Hormones; D014284:Triiodothyronine