Localization of Luteinizing Hormone (LH) Subunits Like Substances in the Mouse Placenta

Luteinizing hormone (LH) is a vital reproductive hormone produced by the anterior pituitary gland, essential for both fertility and sexual development. Interestingly, there is evidence indicates that rodent placenta is extrapituitary site of LH synthesis. On this basis, we performed immunohistochemistry (IHC) using specific antisera for LH subunits to investigate the tissue distribution of the LH subunits like molecules in mice placentae. Pregnant mice on gestation day 17 were sacrificed and the placentae were obtained Glycogen rich trophoblast cells (GlyT) in the junctional zone (JZ) were positive for CGα immunohistochemical staining, and the LH-β positive staining was found in all cell layers in both JZ and labyrinth zone (LZ). Immunoreactive LH-receptor (LH-R) staining was observed on the membrane of GlyT in JZ and partial syncytiotrophoblast cells layer in LZ. The present study demonstrated that immunoreactive LH subunits like substances were localized differentially in the microstructures of mice placentae. This finding that the substances exhibiting immune responses to these and their receptors exist in the same type of cells and/or adjacent cells, suggesting the possibility of local regulation through these substances. Further studies will be helpful for understanding the biochemical nature and the role(s) of local LH-like substances in sophisticated placental physiology.