Whittier J M, Mason R T, Crews D
Gen Comp Endocrinol. 1987 Jul;67(1):33-43. doi: 10.1016/0016-6480(87)90202-4.
Plasma levels of progesterone (P), testosterone (T), estradiol (E2), and corticosterone (B) of female red-sided garter snakes were measured during the period of ovarian development. Differences in hormone levels were analyzed with respect to three factors: whether the female mated in the spring, ovarian condition, and time after emergence from hibernation. The influence of these three factors on steroid hormone levels of two groups of females were then compared. In experiment I, females were obtained in the fall, subjected to an artificial dormancy period, and placed on warm, summer-like conditions in the laboratory. In experiment II, females were collected in the spring and sampled in the field. They were held in the field on fluctuating conditions for several weeks and then returned to the laboratory for sampling during early vitellogenesis. Females in experiment I had a shortened but otherwise normal ovarian and gestational cycle, whereas females in experiment II had an ovarian and gestational cycle typical of females in the field. In spite of these differences, the steroid hormone levels in relation to the ovarian cycle were remarkably similar for the two groups of females. We confirmed that mating in the spring induces a surge in E2; E2 also was elevated in a single sample obtained from animals collected in the fall. This elevation in plasma levels of E2 in the fall occurs at a time when the majority of females have recently deposited sperm in their oviducts. Plasma levels of T, P, and B were not significantly influenced by mating. Unlike previous reports of other viviparous snakes, plasma levels of P were low and mostly nondetectable, even during late gestation. Plasma T was significantly elevated around the time of late vitellogenesis and ovulation, and there was a tendency for E2 levels to be elevated at this time. In the field, plasma B levels were initially high immediately after capture and declined with time. Plasma B was significantly elevated in all females several weeks after emergence, suggesting that levels of B may vary with other annual cycles.
在卵巢发育期间，对雌性红边袜带蛇的血浆孕酮（P）、睾酮（T）、雌二醇（E2）和皮质酮（B）水平进行了测量。针对三个因素分析了激素水平的差异：雌性是否在春季交配、卵巢状况以及从冬眠中苏醒后的时间。然后比较了这三个因素对两组雌性类固醇激素水平的影响。在实验I中，秋季获取雌性蛇，使其经历人工休眠期，然后置于实验室温暖、类似夏季的环境中。在实验II中，春季收集雌性蛇并在野外采样。它们在野外处于波动环境中数周，然后在早期卵黄发生期间返回实验室进行采样。实验I中的雌性蛇卵巢和妊娠周期缩短但其他方面正常，而实验II中的雌性蛇具有野外雌性蛇典型的卵巢和妊娠周期。尽管存在这些差异，但两组雌性蛇与卵巢周期相关的类固醇激素水平非常相似。我们证实春季交配会诱导E2激增；从秋季收集的动物身上获取的单个样本中E2也有所升高。秋季血浆E2水平的这种升高发生在大多数雌性蛇最近在输卵管中储存精子的时候。交配对T、P和B的血浆水平没有显著影响。与之前关于其他胎生蛇的报道不同，即使在妊娠后期，P的血浆水平也很低，大多无法检测到。血浆T在晚期卵黄发生和排卵前后显著升高，此时E2水平也有升高的趋势。在野外，捕获后血浆B水平最初很高，并随时间下降。所有雌性蛇在苏醒几周后血浆B水平显著升高，这表明B的水平可能随其他年度周期而变化。
