Abstract
To investigate the production of $C_{21}$-steroids during the spawning period of spotted sea bass, Lateolabrax maculatus, we have incubated maturing and ovulating follicles with radiolabeled pregnenolone and $17\alpha$-hydroxyprogesterone for 24 hours. The resulting metabolites were analyzed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), When maturing follicles ($700\sim800{\mu}m$ in diameters) were incubated with radiolabeled precursors, $C_{21}$-metabolites were corticosteroids and $17\alpha$-hydroxy, $20\beta$-dihydroprogesterone ($17\alpha20\beta OHP$). When ovulation follicles ($1,000\sim1,150{\mu}m$ in diameters) were incubated with radiolabeled precursors, the major $C_{21}$-metabolites were $17\alpha20\beta OHP$, $17\alpha$,$20\beta$, 21-trihydroxy-4-pregnen-3-one ($17\alpha20\beta21P$), and corticosterone. Additional chromatography by TLC and HPLC confirmed the presence of radioactive $17\alpha20\beta OHP$ in the maturing follicles, and $17\alpha20\beta OHP$,$17\alpha20\beta21P$ and corticosterone in ovulating follicles. Although $17\alpha20\beta OHP$ was found in a small peak, the synthesis of this steroid suggests that it may play a role in regulating the oocyte maturation process. Whereas ovulation is regulated by both $17\alpha20\beta OHP$ and $17\alpha20\beta21P$ in the spotted sea bass. In addition, an unusual finding was the biosynthesis of corticosterone. Whether this production is responsible for the ovulation, and is an area requiring continued research.
점농어의 난소성숙과 배란과정에서 생성되는 성 스테로이드 호르몬 특히, $C_{21}$-스테로이드를 분석하고자 전구물질 $^3H$-pregneolone와 $^3H$-$17\alpha$hydroxyprogesterone를 난소조직 배양초기에 첨가하여 24시간 배양 뒤 생성된 물질은 성숙기 난소 (난경 $700\sim800 \mu m$ )의 경우corticosteroids계의 호르몬과 $17\alpha20\beta OHP$가 관찰되었으나 $17\alpha20\beta OHP$만이 HPLC상에서 확인되었다 특히 배란중인 점농어에서는 $17\alpha20\beta OHP$, $17\alpha20\beta21P$그리고 corticosterone의 존재가 뚜렷하였다. 따라서 점농어에서는 난소의 성숙과 배란과정에 $17\alpha20\beta OHP$이 모두 관여하며, 배란에 이르면서 $17\alpha20\beta21P$의 출현이 뚜렷한 것으로 생각된다. corticosterone의 존재에 대해서는 이 물질이 점농 어의 배란과 관련이 있는지 또는 스트레스 조건에서 나타나는 순간적인 생성물인지 앞으로 더욱 상세한 분석방법으로 접근해야 할 부분이다.
(Aquaculture Division, National Fisheries Research & Development Institute)
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