Bromocriptine reduces rat thyrotropin beta-subunit mRNA stability.
We have examined the effect of orally administered bromocriptine on TSH beta-subunit messenger (m)RNA in the anterior pituitary glands of Sprague-Dawley rats using in situ and dot-blot hybridization histochemistry. Quantitative in situ hybridization of pituitary sections demonstrated a 60% reduction in TSH beta-subunit mRNA probe binding from rats fed a diet containing bromocriptine 10 mg/kg/day. This was confirmed by dot-blot analysis of nuclear and cytoplasmic pituitary extracts from the same tissue. Hybridization of cytoplasmic extracts of pituitary cells cultured under actinomycin D-induced transcription arrest showed that part of the effect of bromocriptine appeared to be mediated through a change in TSH beta-subunit mRNA stability and implies that the acute influence of dopamine on TSH metabolism may be transduced by control of TSH beta-subunit mRNA catabolism. This suggests a mechanism by which cells with relatively stable tissue specific mRNAs appear to respond rapidly to hormonal effects at the transcriptional level.
Levy
A
A
Medical Unit, Charing Cross and Westminster Medical School, London, England.
Lightman
S L
SL
D000284:Administration, Oral; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D001971:Bromocriptine / Q000008:administration & dosage / Q000494:pharmacology*; D002478:Cells, Cultured; D003609:Dactinomycin; D004298:Dopamine / Q000502:physiology; D005786:Gene Expression Regulation; D008297:Male; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000235:genetics; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013972:Thyrotropin / Q000235:genetics*; D014158:Transcription, Genetic
D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D003609:Dactinomycin; D001971:Bromocriptine; D013972:Thyrotropin; D004298:Dopamine