Glasser F, Mikolajczyk T, Jalabert B, Baroiller J-F, Breton B
Inra-Scribe, Campus de Beaulieu, 35 042 Rennes Cedex, France.
Gen Comp Endocrinol. 2004 Apr;136(2):171-9. doi: 10.1016/j.ygcen.2003.12.009.
For grass carp (Ctenopharyngodon idella) raised in the Ivory Coast (with water temperatures of 26-31 degrees C), induced spawning is obligatory for fry production. However, ovulation rates following hormonal treatment are often low. We hypothesized that high temperatures are an inhibiting factor for the reproductive axis (brain-pituitary-gonad) in these conditions. By in vivo and in vitro experiments, we tried to determine the thermosensitive steps during spawning induction. We compared gonadotropin and maturation-inducing steroid (MIS) profiles during a spawning induction at controlled temperatures of 24 and 28 degrees C in relation to ovulation success. We performed pituitary cell cultures and ovarian fragment incubations at controlled temperatures. The ovulation rate was lower at 28 degrees C (10%) than at 24 degrees C (36%). At the pituitary level, we found only minor thermal impacts on GnRH-stimulated LH release, but our data suggest an increase of the dopaminergic inhibition by high temperatures. The main effects were found at the ovary level, where ovary responsiveness to gonadotropin by MIS synthesis was disturbed, as well as oocyte responsiveness to MIS triggering final maturation, and probably ovulation. These results show the importance of regulating temperature during spawning induction to ensure a high rate of ovulation.
对于在科特迪瓦养殖的草鱼（草鱼）（水温为26 - 31摄氏度），诱导产卵是鱼苗生产的必要条件。然而，激素处理后的排卵率往往较低。我们假设在这些条件下，高温是生殖轴（脑 - 垂体 - 性腺）的抑制因素。通过体内和体外实验，我们试图确定产卵诱导过程中的热敏步骤。我们比较了在24和28摄氏度的控制温度下产卵诱导期间促性腺激素和成熟诱导类固醇（MIS）的概况与排卵成功率的关系。我们在控制温度下进行了垂体细胞培养和卵巢片段孵育。28摄氏度时的排卵率（10%）低于24摄氏度时（36%）。在垂体水平，我们发现高温对GnRH刺激的LH释放只有轻微的热影响，但我们的数据表明高温会增加多巴胺能抑制作用。主要影响发生在卵巢水平，在那里，通过MIS合成，卵巢对促性腺激素的反应性受到干扰，以及卵母细胞对触发最终成熟和可能排卵的MIS的反应性也受到干扰。这些结果表明在产卵诱导过程中调节温度对于确保高排卵率的重要性。
