Induced luteolysis in the primate: rapid loss of luteinizing hormone receptors

The molecular mechanisms involved in luteolysis are still unclear in the primate. This study aimed to investigate the effect of induced luteolysis on the ovarian luteinizing hormone (LH) receptor and the steroidogenic enzyme, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in the marmoset monkey. Luteolysis was induced in the mid-luteal phase either directly by systemic prostaglandin F-2 alpha (PGF(2 alpha)), or indirectly by LH withdrawal using systemic gonadotrophin releasing hormone antagonist (GnRH(ant)) treatment. The LH receptor was studied by isotopic mRNA in-situ hybridization and in-situ ligand binding and 3 beta-HSD expression was studied using isotopic mRNA in-situ hybridization and immunohistochemistry. Induced luteolysis was associated with a reduction in the expression of LH receptor (P < 0.0001) and 3 beta-HSD mRNA, closely followed by a reduction in the LB receptor (P < 0.05) and 3 beta-HSD protein concentrations within 24 h. There were no differences in the findings whether luteolysis was induced with PGF(2 alpha) or GnRH(ant). This study shows that disparate mechanisms to induce luteolysis in the primate result in an identical rapid loss of the LH receptor and 3 beta-HSD. In conclusion, induced luteolysis leads to rapid loss of the steroidogenic pathway in luteal cells.