title: The effect of altered thyroid status on pituitary hormone messenger ribonucleic acid concentrations in the rat.
abstract: To study the effects of altered thyroid status on pretranslational control of pituitary hormones, adult male rats were given propylthiouracil for 6 weeks and underwent the following studies. 1) Rats were injected with T3 at 10 micrograms/100 g BW daily for 10 days. 2) Rats were given T3 injections at 0, 0.01, 0.1, 1.0, or 10 micrograms/100 g BW for 10 days. 3) Rats were killed 0, 1, 6, or 24 h after a single injection of T3 at 10 micrograms/100 g BW or after 5 or 10 days of daily T3 injections. Pituitary mRNA concentrations of TSH beta, alpha-subunit, PRL, GH, POMC, FSH beta, and LH beta were determined for individual animals. Marked increases in TSH beta and alpha-subunit mRNAs occurred after PTU treatment, and these changes were reversed by 1.0 microgram/100 g BW T3 and within 24 h of a single T3 injection of 10 micrograms/100 g BW. Further increases in the dose or time course of T3 administration led to a relatively greater suppression of TSH beta mRNA levels than alpha-subunit mRNA levels. In contrast, GH and PRL mRNA levels were low in hypothyroid animals, and both rose toward control levels with 0.1 microgram/100 g BW T3 and by 24 h after a single T3 dose. Induction of hyperthyroidism did not further increase GH mRNA levels above control, but increased PRL mRNA levels 2-fold over control. No changes were seen in FSH beta, LH beta, or POMC mRNA levels with any treatment. Thus, studies of altered thyroid status in the rat reveal dose-response and time-course variability in the pretranslational control of TSH beta, alpha-subunit, GH, and PRL by thyroid hormone.
authors.affiliation: Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
authors.forename: M H
authors.initials: MH
authors.lastname: Samuels
authors.forename: M E
authors.initials: ME
authors.lastname: Wierman
authors.forename: C
authors.initials: C
authors.lastname: Wang
authors.forename: E C
authors.initials: EC
authors.lastname: Ridgway
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D013006:Growth Hormone / Q000378:metabolism; D008297:Male; D009994:Osmolar Concentration; D010907:Pituitary Hormones / Q000235:genetics / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism; D011441:Propylthiouracil / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013963:Thyroid Hormones / Q000502:physiology*; D013972:Thyrotropin / Q000378:metabolism; D014284:Triiodothyronine / Q000097:blood / Q000494:pharmacology
chemical_list: D010907:Pituitary Hormones; D012333:RNA, Messenger; D013963:Thyroid Hormones; D014284:Triiodothyronine; D011441:Propylthiouracil; D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone