1. Hormonal and photoperiodic modulation of testicular mRNAs coding for inhibin/activin subunits and follistatin in Clethrionomys glareolus, Schreber.
- Author
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Tähkä KM, Kaipia A, Toppari J, Tähkä S, Tuuri T, and Tuohimaa P
- Subjects
- Activins, Animals, Chorionic Gonadotropin pharmacology, Follicle Stimulating Hormone pharmacology, Follistatin, Macromolecular Substances, Male, Organ Size drug effects, Reproduction, Testis anatomy & histology, Testis drug effects, Arvicolinae physiology, Glycoproteins biosynthesis, Inhibins biosynthesis, Photoperiod, RNA, Messenger metabolism, Seasons, Testis physiology
- Abstract
Photoperiodic and hormonal modulation of mRNAs for testicular inhibin/activin subunits and follistatin were studied in a seasonally breeding rodent, the bank vole (Clethrionomys glareolus). Photoperiod-induced testicular regression had no effect on the relatively low steady-state levels of follistatin mRNA. Inhibin alpha (I alpha) and beta B (I beta B) mRNA levels were significantly higher in regressed than in active gonads, but inhibin beta A was undetectable. The effect of gonadotropin administration on testicular weight and mRNA concentrations differed between the sexually active and quiescent voles. Neither FSH (1.2 U/kg; s.c. for 5 days) nor hCG (600 IU/kg; s.c. for 5 days) affected testicular weight in sexually active voles, whereas both gonadotropins significantly increased testicular weight in photo-regressed individuals. FSH had no effect on I alpha or I beta B mRNA concentrations in the active testes, whereas excessive hCG challenge induced a decrease in the steady-state levels of these mRNAs. FSH induced an increase in I alpha mRNA concentrations in the regressed gonad, whereas both gonadotropins concomitantly down-regulated I beta B mRNA levels. In conclusion, the high expression of I alpha and I beta B mRNA in the regressed testis imply autocrine and paracrine roles for inhibin/activin in the quiescent gonad of seasonal breeders. Inhibin alpha-subunit expression is at least partly under the control of FSH in the bank vole testis.
- Published
- 1998
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