Bluhm C K, Phillips R E, Burke W H
Biol Reprod. 1983 Mar;28(2):295-305. doi: 10.1095/biolreprod28.2.295.
Temporal changes of circulating serum hormones were measured to compare the reproductive endocrinology of laying and nonlaying mallards. In this study all sixteen control mallards left with their mates laid eggs, while only one of sixteen mallards stressed by daily movement into new pens, laid eggs. Serum levels of luteinizing hormone (LH), prolactin, estradiol, and progesterone were significantly lower (P less than 0.05) in stressed nonlaying mallards than in laying mallards over the 7-week period. Within 1 week of the rotation treatment, LH concentrations in stressed mallards averaged (means +/- SEM) 2.72 +/- 0.19 ng/ml and were significantly lower (P less than 0.05) than LH levels in the controls (3.62 +/- 0.18 ng/ml). After 7 weeks, injections of luteinizing hormone releasing hormone (LHRH) induced a greater change in circulating LH levels in stressed mallards (2.1 +/- 0.3 ng/ml) than in breeding control mallards (0.9 +/- 0.2 ng/ml). These data demonstrate that the lack of reproduction in stressed mallards was associated with LHRH-sensitive pituitary pools of LH, despite their low concentrations of serum LH. These data suggest that the block in reproduction is a failure of the hypothalamus to produce or release releasing hormones. The serum hormone levels of the control mallards varied temporally with stages in the nesting cycle. LH levels increased with the onset of nesting activity, and showed marked fluctuations during the laying period. LH levels fell at the onset of incubation but increased after loss of clutch. Estradiol levels were highest prior to the laying of the first egg and their peak coincided with the initial nest building behavior of the females. Progesterone levels increased sharply with the laying of the 2nd-4th eggs, decreased sharply with the laying of the 6th egg, and then increased slightly at the end of the nesting cycle. Prolactin levels were initially low but gradually increased with laying and incubation activity, declined with loss of clutch, and increased again with renesting activity. Prolactin levels in the stressed mallards also increased (P less than 0.01) over the 7-week period, but significantly less (P less than 0.05) than in layers.
为比较产蛋和不产蛋绿头鸭的生殖内分泌情况，对循环血清激素的时间变化进行了测量。在本研究中，与配偶一起留下的16只对照绿头鸭都产了蛋，而在每天被转移到新围栏中受到应激的16只绿头鸭中，只有1只产了蛋。在7周的时间里，受到应激的不产蛋绿头鸭的血清促黄体生成素（LH）、催乳素、雌二醇和孕酮水平显著低于产蛋绿头鸭（P<0.05）。在轮换处理的1周内，受到应激的绿头鸭的LH浓度平均为（均值±标准误）2.72±0.19 ng/ml，显著低于对照组的LH水平（3.62±0.18 ng/ml）（P<0.05）。7周后，注射促黄体生成素释放激素（LHRH）后，受到应激的绿头鸭循环LH水平的变化（2.1±0.3 ng/ml）大于繁殖对照绿头鸭（0.9±0.2 ng/ml）。这些数据表明，尽管受到应激的绿头鸭血清LH浓度较低，但其繁殖能力的缺乏与LHRH敏感的垂体LH储备有关。这些数据表明，繁殖受阻是下丘脑无法产生或释放释放激素的结果。对照绿头鸭的血清激素水平随筑巢周期的阶段而发生时间变化。LH水平随着筑巢活动的开始而升高，在产蛋期出现明显波动。LH水平在孵化开始时下降，但在失去一窝蛋后升高。雌二醇水平在产下第一枚蛋之前最高，其峰值与雌性最初的筑巢行为一致。孕酮水平在产下第2 - 4枚蛋时急剧上升，在产下第6枚蛋时急剧下降，然后在筑巢周期结束时略有上升。催乳素水平最初较低，但随着产蛋和孵化活动逐渐升高，随着失去一窝蛋而下降，随着重新筑巢活动再次升高。在7周的时间里，受到应激的绿头鸭的催乳素水平也有所升高（P<0.01），但显著低于产蛋绿头鸭（P<0.05）。
