Chang C F, Lau E L, Lin B Y
Department of Aquaculture, National Taiwan Ocean University, Republic of China.
Gen Comp Endocrinol. 1995 Dec;100(3):355-67. doi: 10.1006/gcen.1995.1166.
The objective was to investigate the effects of various doses of estradiol-17 beta (E2) on gonadal development, gametogenesis, and plasma levels of sex steroids in 1-year-old protandrous male black porgy, Acanthopagrus schlegeli. Juvenile black porgy were divided into four groups, fed with control diet or diet mixed with E2 (0.25, 1.0, or 4.0 mg/kg feed) for 7 months, respectively. Significantly higher gonadosomatic index was observed in the 0.25- and 1.0-mg E2 groups compared to that in the control and 4.0-mg E2 groups during the spawning season. E2 at 4.0 mg completely suppressed spermiation, while lower doses of E2 (0.25 and 1.0 mg) delayed spermatogenesis but increased the number of spermiating fish and spermiation volume. Sperm concentrations were similar in spermiating black porgy. At 10 months and older, gonads in all the groups except E2 (4.0-mg)-treated fish underwent an intensive spermatogenesis while spermatids were not observed until 11 and 12 months in the 0.25- and 1.0-mg E2 groups, respectively. Primary oocytes appeared in the 10- and 11-month-old gonads in testicular tissue of the 1.0- and 4.0-mg E2 groups. After 5 months of 4-mg E2 treatment, testicular tissue regressed and ovarian tissue with primary oocytes developed. Elevated levels of plasma E2 were observed only in the 4.0-mg E2 group while low levels of E2 and testosterone (T) were observed in the control and other E2-treated groups. Significantly higher levels of plasma 11-ketotestosterone (11-KT) were observed in the 0.25- and 1.0-mg E2-treated groups during the spawning season. Plasma vitellogenin levels showed a dose-dependent effect of E2 treatment. The present data suggest that exogenous E2 could stimulate the development of either testicular or ovarian tissues, depending on the dosage of E2. Plasma 11-KT but not T concentrations closely correlate with testicular development and spermiation in black porgy.
目的是研究不同剂量的17β-雌二醇（E2）对1龄先雄后雌的黑鲷（黑棘鲷）性腺发育、配子发生以及性类固醇血浆水平的影响。将幼年黑鲷分为四组，分别投喂对照饲料或添加E2（0.25、1.0或4.0毫克/千克饲料）的饲料，持续7个月。在产卵季节，与对照组和4.0毫克E2组相比，0.25毫克和1.0毫克E2组的性腺指数显著更高。4.0毫克的E2完全抑制了排精，而较低剂量的E2（0.25和1.0毫克）延迟了精子发生，但增加了排精鱼的数量和排精量。排精的黑鲷精子浓度相似。在10个月及以上时，除4.0毫克E2处理组的鱼外，所有组的性腺都经历了强烈的精子发生，而在0.25毫克和1.0毫克E2组中，分别直到11个月和12个月才观察到精子细胞。在1.0毫克和4.0毫克E2组的睾丸组织中，10个月和11个月大的性腺中出现了初级卵母细胞。4毫克E2处理5个月后，睾丸组织退化，出现了带有初级卵母细胞的卵巢组织。仅在4.0毫克E2组中观察到血浆E2水平升高，而在对照组和其他E2处理组中观察到低水平的E2和睾酮（T）。在产卵季节，0.25毫克和1.0毫克E2处理组的血浆11-酮睾酮（11-KT）水平显著更高。血浆卵黄蛋白原水平显示出E2处理的剂量依赖性效应。目前的数据表明，外源性E2可根据其剂量刺激睾丸或卵巢组织的发育。血浆11-KT而非T浓度与黑鲷的睾丸发育和排精密切相关。
