A1 Journal article – refereed
Hormonal and photoperiodic modulation of testicular mRNAs coding for inhibin/activin subunits and follistatin in Clethrionomys glareolus, Schreber

List of Authors: Tähkä KM, Kaipia A, Toppari J, Tähkä S, Tuuri T, Tuohimaa P
Publication year: 1998
Journal: Journal of Experimental Zoology
Journal name in source: The Journal of experimental zoology
Journal acronym: J Exp Zool
Volume number: 281
Issue number: 4
ISSN: 0022-104X

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.

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