急性温度胁迫对妊娠期许氏平鲉生殖内分泌机能的影响

Effects of Acute Temperature Stress on the Reproductive Endocrine Function of Gestational Ovoviviparous Black Rockfish(Sebastes schlegelii)

为探究温度对妊娠期许氏平鲉(Sebastes schlegelii)生殖内分泌机能的影响,采用内分泌学和分子生物学方法,对急性温度胁迫后许氏平鲉的血清性类固醇激素的变化及脑和卵巢生殖相关基因表达的变化进行了系统的探究和分析。研究表明:妊娠期许氏平鲉的性腺型芳香化酶(P450aromA)具有温度敏感性。血清中17β-雌二醇(E2)和卵巢雌激素受体α(ERα)表达水平在急性高温胁迫后发生了显著下降,在急性低温胁迫后明显升高。在温度胁迫下,卵巢中雌激素受体β1(ERβ1)和雌激素受体β2(ERβ2)呈现出显著不同的表达方式;急性高温胁迫后,与性腺型芳香化酶基因(CYP19a1a)相比,脑型芳香化酶基因(CYP19a1b)的转录水平上升显著,表明二者在不同组织中承担着不同的生理功能;在妊娠期许氏平鲉脑中,CYP19a1b、E2、ERα间形成了自动反馈调节,促进CYP19a1b的转录;此外,Foxl2能够促进脑中芳香化酶的表达。研究结果表明,妊娠期许氏平鲉对高温胁迫更敏感,所需恢复期更长。在实际生产中,对于进入生殖期的雌鱼,应密切关注养殖水温的变化,减少温度应激。维持水温的相对恒定,以保证亲鱼胚胎发育和产仔进程的顺利进行。

This study mainly examinedthe effects of temperature on the reproductive endocrine function of gestational ovoviviparous black rockfish,Sebastes schlegelii.Serum sexual steroids hormones and gene expression related to the reproduction in ovary and brain were detected using endocrinological and molecular biological methods after acute temperature stress（thermal stress,25℃;chilling stress,7℃;control,16℃）.Results showed that P450 aromatase A（P450aromA）is sensitive to temperature in gestational black rockfish.The results indicated that the concentration of serum 17β-estradiol（E2）and the expression level of estrogen receptorsα（ERα）gene decreased significantlyafteracute heat shock,which were found to be up-regulated after acute chilling stress.On the other hand,expression levels of estrogen receptorsβ1（ERβ1）and estrogen receptorsβ2（ERβ2）genes varied with different factors.As a precursor of 17α-hydroxy-20β-dihydroprogesterone（DHP）,serum progesterone（P4）was thought to have some unknown functions during gestation of black rockfish.No significant change was found in expression level of transcription factor Foxl2 gene in acute heat or cold shock,which might indicate the participation of some other regulators.The expression level of cytochrome P450 19a1b（CYP19a1b）gene in brain elevated significantly in acute thermal stress,which was different from cytochrome P450 19a1a（CYP19a1a）gene in ovary,indicating distinct physiological functions of CYP19 samong tissues.It was tentatively suggested that there was an auto-feedback loop involved in regulating expression levels of CYP19a1 b,E2and ERαgene in order to promote transcription of CYP19a1 bgene.In addition,the results indicated that the expression of aromatase can be up-regulated by Foxl2 in brain.The results indicated the heat-sensitivity of gestational black rockfish require longer recovery time after thermal challenge.When female fish enter the reproductive phase,itwas of great importance to monitor water temperature closely,toavoid damage induced by temperature stress during pregnancy.It was suggested that maintaining the water temperature constant or less changed could benefit the embryonic development and delivery process of gestataional black rockfish.