title: Inhibition of oxytocin receptor and estrogen receptor-alpha expression, but not relaxin receptors (LGR7), in the myometrium of late pregnant relaxin gene knockout mice.
abstract: This study used relaxin (RLX) gene knockout mice (Rlx-/-) to investigate the effects of RLX on myometrial oxytocin receptor (OTR) and estrogen receptor (ER)-alpha gene expression in late gestation. We also characterized the temporal expression of the RLX receptor (LGR7) and demonstrated gene transcripts in the myometrium of Rlx+/+ and Rlx-/- mice. There was a significant (P < 0.05) decrease in myometrial LGR7 gene expression on d 17.5 and 18.5 post coitum (pc) compared with earlier stages of gestation, but no differences between Rlx+/+ and Rlx-/- mice. Myometrial OTR mRNA levels increased at the end of gestation in Rlx+/+ but not Rlx-/- mice. ERalpha gene expression was up-regulated on d 14.5 pc in Rlx+/+ mice, with mRNA levels remaining high throughout late gestation. In contrast, ERalpha mRNA levels were significantly lower in Rlx-/- mice on d 14.5 and 18.5 pc. These data show that the increases in myometrial OTR and ERalpha expression in late pregnant Rlx+/+ mice were attenuated in Rlx-/- mice. The effects of RLX on OTRs are probably mediated via activation of ERalpha. Finally, RLX receptor expression in the myometrium of Rlx-/- mice did not differ from wild-type mice, implying that RLX does not influence expression of its receptor.
authors.affiliation: Department of Zoology, University of Melbourne, Parkville, Victoria 3010, Australia. a.siebel@hfi.unimelb.edu.au.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Siebel
authors.forename: Helen M
authors.initials: HM
authors.lastname: Gehring
authors.forename: Irna Grace T
authors.initials: IG
authors.lastname: Reytomas
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Parry
mesh_terms: D000818:Animals; D047628:Estrogen Receptor alpha; D005260:Female; D005865:Gestational Age; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics; D009215:Myometrium / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors* / Q000235:genetics; D043562:Receptors, G-Protein-Coupled; D018045:Receptors, Oxytocin / Q000037:antagonists & inhibitors* / Q000235:genetics; D012065:Relaxin / Q000172:deficiency* / Q000235:genetics
chemical_list: D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; C478103:RXFP1 protein, mouse; D011956:Receptors, Cell Surface; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D018045:Receptors, Oxytocin; D012065:Relaxin