Effect of triiodothyronine treatment on thyrotrophin beta- and alpha-messenger RNAs in the pituitary of the euthyroid rat.
We have examined the effect of triiodothyronine (T3) treatment of the euthyroid rat on serum thyrotrophin (TSH) concentration, pituitary content of TSH and on pituitary cytoplasmic levels of TSH beta- and alpha-subunit messenger (m)RNAs, measured using the technique of dot hybridization to radiolabelled complementary (c)DNA probes. Serum concentration of TSH fell rapidly after T3 treatment of euthyroid rats, but no effect of T3 treatment was evident on pituitary TSH content. In contrast, marked effects of T3 on cytoplasmic levels of both TSH beta- and alpha-subunit mRNAs were demonstrated, with reductions in beta- and alpha-mRNAs at both early (6 h) and late (72 h) time points after administration of T3. These observations, which have not been documented previously in the euthyroid state, contrast with earlier findings in hypothyroidism in which stimulatory influences of T3 on TSH mRNAs are evident at 6 h.
Franklyn
J A
JA
Department of Medicine, University of Birmingham, Queen Eliabeth Hospital, Edgbaston, U.K.
Wood
D F
DF
Balfour
N J
NJ
Sheppard
M C
MC
D000818:Animals; D003593:Cytoplasm / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit / Q000032:analysis / Q000097:blood / Q000235:genetics*; D007037:Hypothyroidism / Q000097:blood / Q000503:physiopathology; D010902:Pituitary Gland / Q000032:analysis / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000502:physiology; D013972:Thyrotropin / Q000032:analysis / Q000097:blood / Q000235:genetics*; D013997:Time Factors; D014284:Triiodothyronine / Q000494:pharmacology*
D015292:Glycoprotein Hormones, alpha Subunit; D012333:RNA, Messenger; D014284:Triiodothyronine; D013972:Thyrotropin