Progesterone Increases Mitochondria Membrane Potential in Non-human Primate Oocytes and Embryos.

Mitochondrial activity is critical and correlates with embryo development. The identification of a novel human mitochondrial progesterone receptor (PR-M) that increases cellular respiration brings into question a role for progesterone in oocyte and preimplantation embryo development. Oocytes and embryos were generated from three Rhesus non-human primates (Macaca mulatta) undergoing in vitro fertilization. Immunohistochemical (IHC) staining for the progesterone receptor and mitochondria, RT-PCR with product sequencing for a mitochondrial progesterone receptor, and mitochondrial membrane determination with JC-1 staining were performed. IHC staining with selective antibodies to the progesterone receptor showed non-nuclear staining. Staining was absent in mouse control embryos. RT-PCR with product sequencing demonstrated PR-M transcript in Rhesus oocytes and embryos, which was absent in mouse embryos. Treatment of Rhesus oocytes and embryos with progesterone showed increased mitochondrial membrane potential, which was absent in mouse embryos. Our results support that progesterone increases mitochondrial membrane potential in oocytes and developing embryos. This is likely an in vivo mechanism to support preimplantation embryo development, and brings up the possibility of in vitro manipulation of culture media for optimization of growth.