title: Prolactin-induced expression of intercellular adhesion molecule-1 and the accumulation of monocytes/macrophages during regression of the rat corpus luteum.
abstract: Intercellular adhesion molecule-1 (ICAM-1) is thought to facilitate the recruitment and migration of monocytes/macrophages to sites of inflammation. Here we investigated whether the luteolytic effect of prolactin in the hypophysectomized rat is associated with the expression of ICAM-1. In addition, we examined the effect of exogenous testosterone (or its potential conversion to estradiol endogenously) on the corpus luteum to address recent speculation that ovarian steroids might augment luteal regression. Immature, 30-day-old rats were ovulated with eCG and hCG and then hypophysectomized; this resulted in a single cohort of persistent corpora lutea. The rats were assigned randomly into four treatment groups: vehicle treatment without or with testosterone (VEH-T4, VEH+T4) and prolactin treatment without or with testosterone (PRL-T4, PRL+T4). Corpora lutea of control rats exhibited minimal ICAM-1 staining and contained relatively few monocytes/macrophages. In contrast, corpora lutea of prolactin-treated rats exhibited prominent ICAM-1 staining and contained numerous monocytes/macrophages. Testosterone did not overtly affect ICAM-1 staining, numbers of monocytes/macrophages, or concentrations of plasma progestins (progesterone and 20alpha-dihydroprogesterone) in either VEH or prolactin treatment groups; notwithstanding, luteal weights increased significantly in response to testosterone in VEH+T4 rats compared to VEH-T4 rats and prolactin-treated rats. We conclude that ICAM-1 expression and monocyte/macrophage accumulation are associated with prolactin-induced luteal regression in the rat and that these aspects are not influenced by testosterone.
authors.affiliation: Department of Animal and Nutritional Sciences, University of New Hampshire, Durham, New Hampshire 03824-3590, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Olson
authors.forename: D H
authors.initials: DH
authors.lastname: Townson
mesh_terms: D000818:Animals; D003338:Corpus Luteum / Q000033:anatomy & histology / Q000737:chemistry / Q000502:physiology; D005260:Female; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis / Q000378:metabolism*; D003341:Luteolysis / Q000187:drug effects* / Q000502:physiology; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D009929:Organ Size; D011372:Progestins / Q000097:blood; D011388:Prolactin / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000494:pharmacology
chemical_list: D011372:Progestins; D018799:Intercellular Adhesion Molecule-1; D013739:Testosterone; D011388:Prolactin