Follicle-stimulating hormone regulation of inhibin alpha-subunit mRNA in staged rat seminiferous tubules.
Steady-state levels of inhibin-alpha and -beta B mRNAs are higher in stages II-VI of the seminiferous epithelial cycle than in stages VII-VIII. We investigated follicle-stimulating hormone (FSH) regulation of inhibin alpha-subunit mRNA in stages II-VI and VII-VIII to study whether the stage specificity is due to differential hormonal regulation by FSH. Follicle-stimulating hormone caused a significant increase of inhibin-alpha mRNA levels in both stages during a 20-h incubation. The mechanism of the FSH effect was studied further in stages VII-VIII. Maximal stimulation of the inhibin-alpha mRNA level was achieved with 100 micrograms/l FSH, dibutyryl-3',5'-cyclic adenosine monophosphate (db-cAMP, 0.2 mmol/l) and Sp-adenosine-3',5'-monophosphothionate (Sp-cAMPS, 10 mumol/l) (a cAMP agonist). The presence of Rp-cAMPS (200 mumol/l) (a cAMP antagonist) abolished the stimulation, Rp-cAMPS alone had no effect. Inhibin-beta B mRNA levels in stages VII-VIII were not affected by FSH, db-cAMP, Sp-cAMPS or Rp-cAMPS. Phorbol 12-myristate 13-acetate (100 nmol/l) had no effect on inhibin-alpha or -beta B mRNA levels. Actinomycin D abolished the stimulatory effect of FSH on inhibin-alpha mRNA expression. In conclusion, FSH stimulated inhibin-alpha mRNA expression similarly both in stages II-VI and VII-VIII of the seminiferous epithelial cycle and the stimulation in stages VII-VIII was cAMP-mediated.
Kaipia
A
A
Department of Physiology, University of Turku, Finland.
Penttilä
T L
TL
Toppari
J
J
D000818:Animals; D000242:Cyclic AMP / Q000037:antagonists & inhibitors / Q000502:physiology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006207:Half-Life; D007265:Inhibins / Q000145:classification / Q000235:genetics*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012671:Seminiferous Tubules / Q000378:metabolism* / Q000502:physiology*
D012333:RNA, Messenger; D003609:Dactinomycin; D007265:Inhibins; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP