title: Immunohistochemical localization of phospholipase A2 isoforms in human myometrium during pregnancy and parturition.
abstract: OBJECTIVE
  The purpose of this study was to localize secretory phospholipase A2 and cytosolic phospholipase A2 isoforms in pregnant human myometrium and to determine changes in expression with gestational age or parturition.
  
  
  METHODS
  Myometrium was collected at cesarean section at term (>37 weeks) or preterm (<37 weeks) from patients who were or were not in labor (n = 5 each group). Frozen sections were incubated with specific monoclonal antibodies against secretory phospholipase A2 or cytosolic phospholipase A2 and immunostaining visualized with the Vectastain ABC method. The intensity of immunostaining in different cellular localizations was scored by an investigator blinded to tissue identity and compared among tissues with use of the Mantel-Haenszel chi2 test.
  
  
  RESULTS
  Secretory phospholipase A2 immunostaining was dispersed in the perinuclear region throughout the myometrial smooth muscle fibers and in vascular smooth muscle. Cytosolic phospholipase A2 immunostaining was predominantly localized to endothelial cells of myometrial blood vessels and weakly throughout myometrial fibers. There was no apparent change in intensity of immunostaining for either isoform with gestational age or with the absence or presence of labor.
  
  
  CONCLUSIONS
  The differential localization of the two phospholipase A2 isoforms suggests different functions. The apparent lack of change in expression during late gestation or with labor possibly suggests changes in myometrial phospholipase A2 activity and hence local myometrial arachidonic acid mobilization and presumably prostaglandin synthesis may not be associated with the onset of or maintenance of parturition.
authors.affiliation: Department of Obstetrics and Gynecology, University of Cincinnati College of Medicine, OH 45267-0526, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: Skannal
authors.forename: A L
authors.initials: AL
authors.lastname: Eis
authors.forename: D
authors.initials: D
authors.lastname: Brockman
authors.forename: T A
authors.initials: TA
authors.lastname: Siddiqi
authors.forename: L
authors.initials: L
authors.lastname: Myatt
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D007743:Labor, Obstetric / Q000378:metabolism; D009215:Myometrium / Q000737:chemistry* / Q000378:metabolism; D007752:Obstetric Labor, Premature / Q000378:metabolism; D010741:Phospholipases A / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D054467:Phospholipases A2; D011247:Pregnancy
chemical_list: D010741:Phospholipases A; D054467:Phospholipases A2