title: Androgen-Induced Relaxation of Uterine Myocytes Is Mediated by Blockade of Both Ca(2+) Flux and MLC Phosphorylation.
abstract: BACKGROUND
  Uterine quiescence must be maintained until pregnancy reaches term. Premature activation of myometrial contractility leads to preterm labor and delivery.
  
  
  OBJECTIVE
  To scrutinize the potential of androgens to relax the myometrium and the mechanism of their action.
  
  
  METHODS
  A pregnancy-derived myometrial smooth muscle cell line (PHM1-41) and myometrial strips prepared from tissues obtained from pregnant women (lean, n = 9; obese, n = 6) undergoing elective cesarean section at term and from nonpregnant C57BL/6 mice (n=5) were each utilized.
  
  
  METHODS
  The contraction of collagen-embedded PHM1-41s and the stretch-induced contraction of human and murine myometrial strips were assessed after incubation with Testosterone (T), dihydrotestosterone (DHT), and T conjugated to BSA. Intracellular calcium ([Ca(2+)]) and phosphorylated myosin light chain concentrations were quantified in PHM1-41s using a Fluo-4 Ca(2+) assay and in-cell Westerns, respectively.
  
  
  METHODS
  University research institute.
  
  
  RESULTS
  DHT and T, but not T conjugated to BSA, impaired the contractile function of PHM1-41s and of human and murine myometrial strips. The response was rapid (observed within minutes), was sustainable for up to 48 hours, and was not abolished on knockdown of the androgen receptor. DHT (100 μm) reduced the amplitude of lean strip contraction to 2 ± 2% of the pretreatment value and T (100 μm) to 3.3 ± 1%. These values for obese strips were 15 ± 6.7% and 11 ± 6.7%, respectively. At the same doses, in murine strips, DHT reduced the amplitude to 4.8 ± 3% and T to 4.9 ± 3%. DHT (50 μm) pretreatment reduced the oxytocin-stimulated increase in [Ca(2+)] (P < .0001; n = 6) and phosphorylated myosin light chain (P < .05; n = 5) in PHM1-41s.
  
  
  CONCLUSIONS
  Lipid-soluble androgens could be developed as tocolytic agents for the treatment of preterm labor.
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Sofia
authors.initials: S
authors.lastname: Makieva
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Hutchinson
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Shalini P
authors.initials: SP
authors.lastname: Rajagopal
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Sara F
authors.initials: SF
authors.lastname: Rinaldi
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Pamela
authors.initials: P
authors.lastname: Brown
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Philippa T K
authors.initials: PT
authors.lastname: Saunders
authors.affiliation: Medical Research Council (MRC) Centre for Reproductive Health (S.M., L.J.H., S.P.R., S.F.R., P.B., J.E.N.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; Tommy's Centre for Maternal and Fetal Health at the University of Edinburgh (S.M., L.J.H., S.P.R., S.F.R., J.E.N.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; MRC Centre for Inflammation Research (P.T.K.S.), The University of Edinburgh, The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom; School of Physiology and Pharmacology (L.J.H.), University of Bristol, Bristol, BS8 1TD, United Kingdom; and Biomolecular Core Facility at The University of Edinburgh (P.B.), The Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
authors.forename: Jane E
authors.initials: JE
authors.lastname: Norman
mesh_terms: D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D013196:Dihydrotestosterone / Q000494:pharmacology; D005260:Female; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D032342:Muscle Cells / Q000187:drug effects / Q000502:physiology*; D009126:Muscle Relaxation / Q000187:drug effects*; D009215:Myometrium / Q000187:drug effects / Q000502:physiology*; D018994:Myosin Light Chains / Q000378:metabolism*; D009765:Obesity / Q000503:physiopathology; D010766:Phosphorylation / Q000187:drug effects; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control; D013739:Testosterone / Q000494:pharmacology; D014590:Uterine Contraction / Q000187:drug effects
chemical_list: D000728:Androgens; D018994:Myosin Light Chains; D013196:Dihydrotestosterone; D013739:Testosterone; D002118:Calcium