title: Identification and characterization of luteinizing hormone-releasing hormone (LH-RH) receptors in the endometrial tissue of pregnant rats.
abstract: The mechanisms by which LH-RH or its agonists inhibit decidua formation and terminate pregnancy in rats are not clear. Evidence so far accumulated indicates that the gonadotropic releasing hormone or its analogues may act directly on the uterus. If this is the case, then we would be able to identify LH-RH receptors in the endometrial tissue. The results presented here demonstrate that the homogenate preparation of rat endometrial tissue bound 125I-LH-RH with an affinity constant of Ka = 1.3 X 10(8) M-1. The binding capacity was measured as 236 fmole/mg protein. It was found that the binding is highly specific, because no binding was observed in a variety of non-target tissues, such as liver, kidney and muscle. Competitive binding with TRH, P substance and bradykinin did not occur under our experimental condition. It was of particular interest to note that Day 3 of pregnancy is a critical time showing a higher binding activity. The significance of work is discussed.
mesh_terms: D000818:Animals; D001414:Bacitracin / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D004717:Endometrium / Q000032:analysis*; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000032:analysis*; D011966:Receptors, LHRH; D013997:Time Factors
chemical_list: D011956:Receptors, Cell Surface; D011966:Receptors, LHRH; D001414:Bacitracin