Effects of castration and androgen-treatment on the expression of FSH-beta and LH-beta in the three-spine stickleback, gasterosteus aculeatus--feedback differences mediating the photoperiodic maturation response?
In many animals, including the three-spine stickleback (Gasterosteus aculeatus), photoperiod strongly influences reproduction. The aim of this study was to investigate if feedback mechanisms on the brain-pituitary-gonadal axis play a role in mediating the photoperiodic response in the stickleback. To that end, stickleback males, exposed to either non-stimulatory short photoperiod (light/dark 8:16) or under stimulatory long photoperiod (LD 16:8), were subjected to either sham-operation, castration, castration combined with treatment with the androgens 11-ketoandrostenedione (11KA) and testosterone (T), and the effects on levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH)-beta mRNA were analyzed. During breeding season the kidney of the stickleback male hypertrophies and produces a glue used for building nests. Kidney weight and expression of both LH-beta and FSH-beta were higher in sham-operated fish kept under long than under short photoperiod. Under both photoperiods, LH-beta mRNA levels were lower in castrated males compared to sham-operated males and treatment with 11KA and T increased expression, indicating a positive feedback. A positive feedback was also found on FSH-beta expression under long photoperiod, where castration decreased, and androgen replacement restored FSH-beta mRNA expression. On the contrary, castration under short photoperiod instead increased FSH-beta levels whereas treatment with 11KA and T decreased FSH-beta expression, indicating a negative feedback on FSH-beta under these conditions. The positive feedback on FSH-beta expression under stimulatory photoperiod may accelerate maturation, whereas the negative feedback under inhibitory photoperiod may suppress maturation. This could be part of the mechanisms by which photoperiod controls maturation.
Hellqvist
Anna
A
Department of Zoology, Stockholm University, S-106 91 Stockholm, Sweden. hellqvist.anna@gmail.com
Schmitz
Monika
M
Borg
Bertil
B
D000736:Androstenes / Q000494:pharmacology*; D000818:Animals; D005246:Feedback / Q000502:physiology; D037201:Follicle Stimulating Hormone, beta Subunit / Q000096:biosynthesis* / Q000235:genetics; D037101:Luteinizing Hormone, beta Subunit / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D009693:Nucleic Acid Hybridization; D009919:Orchiectomy / Q000662:veterinary; D017440:Photoperiod; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012741:Sexual Maturation / Q000187:drug effects / Q000502:physiology; D023701:Smegmamorpha / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013737:Testis / Q000502:physiology; D013739:Testosterone / Q000494:pharmacology*
D000736:Androstenes; D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger; D013739:Testosterone; C011657:adrenosterone