title: Progesterone receptor immunoreactivity differs in the uterus of pseudopregnant and medroxyprogesterone acetate-treated rabbits.
abstract: Progesterone receptor (PR) plays an important role in mammals pregnancy which is characterized by greater progesterone plasma concentrations. We assessed PR protein distribution in the rabbit uterus by immunohistochemistry in two progestational conditions: pseudopregnancy (intact adult animals treated with hCG) and after application of a synthetic progestin, medroxyprogesterone acetate (MPA), to ovariectomized animals (OVX). PR immunoreactivity in uterine epithelium of pseudopregnant rabbits was increased in relation to non-pseudopregnant (NP) rabbits. Amounts were similar on Days 1, 3, and 5 of treatment, and was greater on Day 7 (P<0.001). In contrast, a significant diminution in PR immunoreactivity was observed in stroma cells from Days 1 to 7 (P<0.001). In OVX rabbits treated with MPA, an increase in PR immunoreactivity was observed in the uterine epithelium on Days 1 to 5 of treatment, reaching a maximum on Day 3 (P<0.001). In contrast, in stromal cells a diminution in PR immunoreactivity was observed when compared to the OVX group on Days 1, 3 and 7 of MPA treatment (P<0.001), and there was a slight increase on Day 5. Results suggest a differential time course and tissue specific immunoreactivity for PR in the uterus of the rabbit in two progestational conditions. The present study indicated synthetic progestins have different mechanisms of receptor regulation than those of natural hormones and it should be taken into account in reproductive applications.
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Departamento de Morfología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacan 04510, Mexico, D.F., Mexico.
authors.forename: Santiago R
authors.initials: SR
authors.lastname: Anzaldúa Arce
authors.forename: C Adriana
authors.initials: CA
authors.lastname: Mendoza-Rodríguez
authors.forename: Ignacio
authors.initials: I
authors.lastname: Camacho-Arroyo
authors.forename: Marco
authors.initials: M
authors.lastname: Cerbón
authors.forename: Mario
authors.initials: M
authors.lastname: Pérez-Martínez
mesh_terms: D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D003270:Contraceptive Agents / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D005260:Female; D007150:Immunohistochemistry; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology*; D010052:Ovariectomy; D011374:Progesterone / Q000097:blood; D011555:Pseudopregnancy / Q000097:blood / Q000378:metabolism* / Q000473:pathology; D011817:Rabbits; D011980:Receptors, Progesterone / Q000378:metabolism*; D013997:Time Factors; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology
chemical_list: D006063:Chorionic Gonadotropin; D003270:Contraceptive Agents; D011980:Receptors, Progesterone; D011374:Progesterone; D017258:Medroxyprogesterone Acetate