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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/45988

Title: Androgen feedback effects on LH and FSH and photoperiodic control of reproduction in male three-spined sticklebacks, Gasterosteus aculeatus.
Authors: Yi Ta Shao
Mia Arvidsson
Susanne Trombley
Rüdiger W.Schulz
Monika Schmitz
Bertil Borg
Contributors: 國立臺灣海洋大學:海洋生物研究所
Keywords: Photoperiod
Date: 2013
Issue Date: 2018-04-19T02:01:53Z
Publisher: General and Comparative Endocrinology
Abstract: Abstract: Sexual maturation in the stickleback is controlled by photoperiod. The aim of this study was to find out whether changes in feedback effects exerted by sex steroids could mediate the photoperiodic effect, which is regarded to be of an all-or-nothing character. To that end, males were castrated and treated with different doses of testosterone (T) and in one experiment also with the aromatase inhibitor fadrozole (AI) and kept under different photoperiods. In control fish, long day (LD 16:8) stimulated maturation, associated with more hypertrophied kidneys (a secondary sexual character) and higher levels of pituitary lhb and fshb mRNA than under short day conditions (LD 8:16). Under LD 8:16, low doses of T suppressed both lhb and fshb mRNA levels. However, with the use of high doses of T and/or longer photoperiods the inhibitory effects on lhb and fshb mRNA levels became less clear or instead positive effects were observed. Under intermediate photoperiod conditions, the negative feedback effect of a low dose of T on fshb was more prominent with shorter photoperiods, whereas no such shift was observed for lhb mRNA. The inhibitory effect of the low dose of T on lhb mRNA levels under LD 8:16 was abolished by AI, whereas the stimulatory effect of the high dose of T was not. The negative feedback effects were more marked under short days than under long days, whereas positive feedback effects were more marked under long days. The suppression of both fshb and lhb mRNA levels by low androgen levels, especially under short days, may inhibit maturation completely unless a rise of androgens above threshold levels would allow complete maturation.
Relation: 182(1) pp.16-23
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/45988
Appears in Collections:[海洋生物研究所] 期刊論文

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