Hormonal and photoperiodic modulation of testicular mRNAs coding for inhibin/activin subunits and follistatin in Clethrionomys glareolus, Schreber.
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.
Tähkä
K M
KM
Department of Biosciences, University of Helsinki, Finland.
Kaipia
A
A
Toppari
J
J
Tähkä
S
S
Tuuri
T
T
Tuohimaa
P
P
D028341:Activins; D000818:Animals; D003411:Arvicolinae / Q000502:physiology*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D038681:Follistatin; D006023:Glycoproteins / Q000096:biosynthesis*; D007265:Inhibins / Q000096:biosynthesis*; D046911:Macromolecular Substances; D008297:Male; D009929:Organ Size / Q000187:drug effects; D017440:Photoperiod; D012333:RNA, Messenger / Q000378:metabolism*; D012098:Reproduction; D012621:Seasons; D013737:Testis / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*
D006063:Chorionic Gonadotropin; D038681:Follistatin; D006023:Glycoproteins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D028341:Activins; D007265:Inhibins; D005640:Follicle Stimulating Hormone