Hinds L A, Reader M, Wernberg-Moller S, Saunders N R
CSIRO Division of Wildlife and Ecology, Lyneham, Australia.
J Reprod Fertil. 1992 May;95(1):303-12. doi: 10.1530/jrf.0.0950303.
Breeding activity in the South American grey opossum, Monodelphis domestica, is stimulated by the presence of males. This study presents the first analysis of changes in concentrations of plasma progesterone during pregnant and nonpregnant cycles. In Expt 1, females were paired with either intact or vasectomized males to stimulate a reproductive cycle, or were isolated from males. Within 4-8 days of pairing, females showed marked changes in the size of the urogenital opening (vulva), which were paralleled by similar changes in body weight (11.4 +/- 2%; mean +/- SEM; n = 13). There was a second increase and decrease in body weight (21.7 +/- 3.3%; n = 13) in pregnant and nonpregnant cycles during the luteal phase of the cycle. Changes in concentrations of plasma progesterone, determined from samples collected three times a week, were similar in pregnant and nonpregnant cycles. Plasma progesterone concentration, which was increased for 15-18 days, showed two distinct peaks. The first peak, 3-4.5 ng ml-1, occurred immediately after the decrease in vulval swelling, and the second peak (1-2 ng ml-1) occurred 8-12 days later. Concentrations of plasma progesterone were low before parturition occurred. Females isolated from males for 35 days showed no changes in body weight or vulval swelling and concentrations of plasma progesterone remained undetectable. In Expt 2, concentrations of luteinizing hormone (LH) in plasma were determined twice a day for the first few days after pairing. In three of five females an LH peak was detected coincident with the maximal swelling of the vulva.
南美灰负鼠（Monodelphis domestica）的繁殖活动受到雄性存在的刺激。本研究首次分析了怀孕周期和非怀孕周期血浆孕酮浓度的变化。在实验1中，将雌性与完整或输精管切除的雄性配对以刺激生殖周期，或将其与雄性隔离。配对后的4 - 8天内，雌性泌尿生殖孔（外阴）大小出现明显变化，体重也有类似变化（11.4 +/- 2%；平均值 +/- 标准误；n = 13）。在周期的黄体期，怀孕和非怀孕周期的体重出现第二次增加和减少（21.7 +/- 3.3%；n = 13）。每周采集三次样本测定的血浆孕酮浓度变化在怀孕和非怀孕周期中相似。血浆孕酮浓度在15 - 18天内升高，出现两个明显的峰值。第一个峰值为3 - 4.5 ng/ml，在外阴肿胀消退后立即出现，第二个峰值（1 - 2 ng/ml）在8 - 12天后出现。分娩前血浆孕酮浓度较低。与雄性隔离35天的雌性体重和外阴肿胀无变化，血浆孕酮浓度仍检测不到。在实验2中，配对后的头几天每天测定两次血浆促黄体生成素（LH）浓度。在五只雌性中的三只中检测到LH峰值与外阴最大肿胀同时出现。
