Background: The impact of hyperprolactinaemia on endometrial function, along with embryo implantation, has been the subject of discussion. This article examines whether experimental hyperprolactinaemia can affect mouse ovarian function, endometrial pinopodes and embryo implantation.
Methods: For pinopode analysis, 60 female mice were randomly divided into two groups: control (vehicle) and experimental [metoclopramide (MCP) 200 microg per day]. Injections were given subcutaneously for 50 days, and then, normally cycling females were housed with male mice for copulation during proestrus. The animals were killed on the fifth day following coitus when the antimesometrium portions of the uterine horns were removed for endometrial analysis. Blood was collected for prolactin (PRL) determination. In the second experiment, 60 female mice were used to evaluate the ovarian function by measuring estrogen and progesterone levels and counting luteal bodies and oocytes in the oviduct and uterus during estrus.
Results: The highest pregnancy rates and the largest population of pinopodes were both found in the vehicle group (P<0.01). Estrogen and progesterone levels in MCP-treated mice were lower than those in control mice (P<0.05). Also, the number of implantations was significantly lower in the MCP-treated group compared with the vehicle group after embryo transfer (P<0.001).
Conclusion: PRL seems to have suppressive effects on ovarian function and the number of pinopodes; conceivably, hyperprolactinaemia has a negative effect on mouse embryo implantation.