Changes in Plasma Levels of Thyroid and Sex Steroid Hormones in Rockfish (Sebastes schlegeli) during Maturation and Parturition Periods

조피볼락(Sebastes schlegeli)의 성숙$\cdot$출산기에 있어서 갑상선 및 성 스테로이드 호르몬의 혈중 변화

Changes in plasma levels of thyroid and sex steroid Hormones were examined during maturation and parturition periods in rockfish (Sebastes schlegeli) cultured in net pens. Plasma L-thyroxine levels were $35.2{\pm}5.7\;ng/m{\ell}\;(n=\;5;\;mean\;{\pm}\;sem)$ at vitellogenesis stage and then significantly decreased to $20.5\;{\pm}\;4.2\;ng/m{\ell}$ at parturition stage (P<0.05), and rapidly returned to high level, $44.9{\pm}\;7.2\;ng/m{\ell}$ at resting stage. Plasma 3,5,3'-triiodo-L-thyronine levels were 12.9 $\pm$ 1.6 ng/ml at vitellogenesis stage, but significantly decreased to $3.7{\pm}0.7\;ng/m{\ell}$ at ovulation stage (P<0.05) and increased to $52.9{\pm}7.0\;ng/m{\ell}$ at jesting stage. Plasma estradiol-17 $\beta$ level showed the highest value ($4.3{\pm}0.9\;ng/m{\ell}$) at vitellogenesis stage, but the level significantly decreased to $0.3{\pm}0.1\;ng/m{\ell}$, during parturition stage (P<0.05). In vitellogenesis and ovulation stages, plasma testosterone levels were $1.8{\pm}0.3\;ng/m{\ell}$ and $2.1{\pm}0.7\;ng/m{\ell}$, respectively, thereafter the level significantly decreased to $0.1{\pm}0.1\;ng/m{\ell}$ at parturition stage (P<0.05). These findings suggest that thyroid hormones may have relation to maturation and parturition of mother rockfish.

가두리에서 사육된 조피볼락의 성숙 및 출산기 동안 혈장내 갑상선 및 성 스테로이드 호르몬의 농도 변화를 조사하였다. 혈장 L-thyroxine 농도는 난황형성기에 $35.2{\pm}5.7\;ng/m{\ell}$이었고. 이후 출산기에 $20.5{\pm}4.2\;ng/m{\ell}$ 까지 유의하게 감소하였다. 그리고. 휴지기에 $44.9{\pm}7.2\;ng/m{\ell}$의 높은 농도로 상승하였다. 혈장 3,5,3'-triiodo-L-thyronine 농도는 난황형성 기에 $12.9{\pm}1.6\;ng/m{\ell}$이었지만, 배란기에 $3.7{\pm}0.7\;ng/m{\ell}$으로 유의하게 감소했고, 이후 $52.9{\pm}7.0\;ng/m{\ell}$까지 증가했다. 혈장 estradiol-17 $\beta$의 농도는 난황형성기에 최고치를 나타내었지만. 출산기에 $0.3{\pm}0.1\;ng/m{\ell}$까지 크게 감소하였다. 혈장 testosterone의 농도는 난황형성기와 배란기에 각각 $1.8{\pm}0.3\;ng/m{\ell}$ 및 $2.1{\pm}0.7\;ng/m{\ell}$이었고, 이후 출산기에 $0.1{\pm}0.1\;ng/m{\ell}$까지 감소했다. 이상의 연구 결과를 종합하여 볼 때. 갑상선호르몬은 조피볼락의 성숙 및 출산에 관련될 가능성이 높다.