Estrogen selectively up-regulates eNOS and nNOS in reproductive arteries by transcriptional mechanisms.
OBJECTIVE
To determine the mechanism(s) whereby daily and acute estradiol-17beta (E(2)beta) exposure modifies endothelium-derived nitric oxide synthase (eNOS) and vascular smooth muscle (VSM) neuronal nitric oxide synthase (nNOS) in reproductive and nonreproductive arteries and to localize NOS isoform expression within the vessel wall.


METHODS
Oophorectomized nonpregnant ewes received E(2)beta (1 microg/kg per day) or no E(2)beta for 5-6 days or acute E(2)beta (1 microg/kg) on day 6-7 with or without daily E(2)beta. Uterine, mammary, mesenteric, and femoral arteries were collected at completion of each study, adventitia were removed, and samples were frozen and stored at -80C. After separating endothelium and VSM, NOS isoform mRNA was measured using reverse transcription-polymerase chain reaction. VSM nNOS protein was determined by Western analysis.


RESULTS
Basal eNOS and nNOS mRNA was greatest (P <.02) in reproductive artery endothelium and VSM, respectively. Daily E(2)beta was required for maximum uterine vascular responses to acute E(2)beta and was associated with increased reproductive artery endothelial eNOS mRNA (>1.5-fold, P <.02) and uterine VSM nNOS mRNA (>2.5-fold, P <.003) and protein (21%, P <.05). Acute E(2)beta in the presence and absence of daily E(2)beta also increased uterine eNOS 68% and 28% (P =.01), respectively, within 90 minutes but did not affect VSM nNOS. Mammary eNOS increased 71% only after E(2)beta withdrawal; VSM nNOS was unchanged. Neither NOS isoform was altered in nonreproductive arteries by daily or acute E(2)beta.


CONCLUSIONS
Basal eNOS and nNOS isoform expression is greatest in arteries from reproductive tissues, and isoform responses to E(2)beta are cell specific and transcriptionally regulated. Furthermore, optimal uterine vascular responses to acute E(2)beta exposure require daily E(2)beta exposure that enhances basal NOS expression and abundance.
Rosenfeld
Charles R
CR
Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA. charles.rosenfeld@utsouthwestern.edu
Chen
Cui
C
Roy
Tim
T
Liu
Xiao tie
Xt
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015153:Blotting, Western; D004730:Endothelium, Vascular / Q000201:enzymology / Q000502:physiology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007150:Immunohistochemistry; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012756:Sheep / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects; D014599:Uterus / Q000098:blood supply* / Q000201:enzymology / Q000502:physiology
D012333:RNA, Messenger; D004958:Estradiol; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III