title: Dietary soybean enhances Pit-1 dependent pituitary hormone production in iodine deficient rats.
abstract: Reports have shown that soybeans are goitrogenic. In the present study, we investigated the effects of a high soybean diet in rats that were fed normal or iodine-deficient chow on the regulation of anterior pituitary hormone production. Iodine deficiency alone resulted in thyroid hyperplasia, reduced serum thyroxine levels, and a tendency towards an increase in serum thyroid stimulating hormone (TSH). The combination of a high soybean and low iodine diet (ID + DS) acted synergistically to induce thyroid hypertrophy, reduce serum thyroxine and tri-iodothyronine, and markedly increase serum TSH. Immunohistochemical analysis revealed that rats fed the ID + DS diet exhibited a marked increase in their number of pituitary TSH, prolactin (PRL), and growth hormone (GH) producing cells. Pituitary transcription factor-1 (Pit-1) which is involved in the expression of the TSH, PRL, and GH genes was also increased in ID + DS fed rats. These results suggest that a diet high in soybean products modulates anterior pituitary hormone production by regulating Pit-1 induction, in iodine-deficient animals.
authors.affiliation: Graduate School of Human Life Science, Showa Women's University, 1-7, Taishido, 154-8533, Japan.
authors.forename: Hanako
authors.initials: H
authors.lastname: Kajiya
authors.forename: Susumu
authors.initials: S
authors.lastname: Takekoshi
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Miyai
authors.forename: Takako
authors.initials: T
authors.lastname: Ikeda
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kimura
authors.forename: R Yoshiyuki
authors.initials: RY
authors.lastname: Osamura
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004032:Diet; D005260:Female; D007031:Hypothalamus / Q000166:cytology / Q000187:drug effects; D015151:Immunoblotting; D007150:Immunohistochemistry; D007455:Iodine / Q000172:deficiency*; D009929:Organ Size / Q000187:drug effects; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D010907:Pituitary Hormones / Q000096:biosynthesis* / Q000097:blood; D051381:Rats; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000494:pharmacology*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects; D013963:Thyroid Hormones / Q000097:blood; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism; D050817:Transcription Factor Pit-1 / Q000378:metabolism*
chemical_list: D010907:Pituitary Hormones; D030262:Soybean Proteins; D013963:Thyroid Hormones; D050817:Transcription Factor Pit-1; D013973:Thyrotropin-Releasing Hormone; D007455:Iodine