HUMAN CORPUS-LUTEUM - HUMAN CHORIONIC-GONADOTROPIN RECEPTORS DURING ECTOPIC PREGNANCY

Objective: To examine hCG receptor levels and binding kinetics in corpora lutea (CL) from tubal pregnancies. Design: Corpus luteum from tubal pregnancies, term normal pregnancies, and midluteal phase were obtained and compared for hCG binding. Setting: Department of Obstetrics and Gynecology, University Hospital. Interventions: Corpus luteum were obtained at elective cesarean section at term, tubal ligation, or surgery for ectopic pregnancy (EP). Main Outcome Measures: Human chorionic gonadotropin receptor levels, dissociation and association constants using saturation binding assay, and Scatchard analysis. Results: Corpus luteum from late tubal pregnancies (>7 weeks) and term intrauterine pregnancies had undetectable hCG binding. Corpus luteum from early tubal pregnancies (<6 weeks) had significantly reduced hCG receptors with higher dissociation constants than from midluteal phase CL. Conclusions: Significant reduction of hCG receptors with accelerated binding dissociation may be the basis of CL dysfunction in some EPs.