Preliminary urinary profiles of prolactin during gestation and the synergistic effects of embryonic diapause hormones in the giant panda (<i>Ailuropoda melanoleuca</i>)

The embryonic diapause of the giant panda (Ailuropoda melanoleuca) has caused great difficulties in monitoring pregnancy in this vulnerable species. The secretion of prolactin (PRL) from anterior pituitary glandular lactotropic cells is an important signal for the termination of embryonic dormancy. Currently, the mechanism by which PRL affects embryonic diapause in giant pandas and methods for detecting PRL in this species is poorly understood. In this study, the first sandwich enzyme immunoassay for detecting PRL in giant panda urine was established by using two antigiant panda PRL antibodies prepared as coating and labeling antibodies, and PRL recombinant proteins prepared via the prokaryotic system as standards. The established method was used to detect the levels of PRL in the urine of giant pandas during pregnancy. At the same time, the changes in PRL levels in giant pandas and the relationship between PRL and progestagen levels were analyzed during the luteal phase. The results showed that in female giant pandas, PRL levels significantly increased before the progestagen peak, and during the luteal phase, the PRL level was significantly greater in giant pandas that gave birth than in those that did not give birth and those in the nonestrus group. To the best of our knowledge, this is the first study to preliminarily explore the mode of action of PRL in the gestation period of giant pandas and lays a foundation for further study of the regulatory mechanisms of endocrine hormones in the giant panda.