VOL. 1, No. 1, January 2005

W. X. Wu, et al. [2005] Med Hypotheses Res 2: 283-294.

Stimulation of Placental and Endometrial, but not
Myometrial Prostaglandin H Synthase-2 by Repeated
Maternal Dexamethasone Administration

Wen Xuan Wu*, David Howe, Kaushik Chakrabarty, Valta Collins,
James Rose and Peter W. Nathanielsz

Department of Obstetrics and Gynecology, Wake Forest University Baptist Medical
Center, Winston Salem, NC 27157 (W.X.W., K.C., V.C.); Wake Forest University School
of Medicine, Department of Obstetrics and Gynecology, Winston-Salem, NC 27157 (J.R.);
University of Texas Health Sciences Center at San Antonio, San Antonio, TX 78229
(P.W.R.), USA; and Department of Obstetrics and Gynecology, The Queen Mother's
Hospital, Yorkhill, Glasgow G3 8SJ, UK (D.H.D.)

Abstract. Objective: To determine whether maternal dexamethasone administration
in amounts inadequate to produce labor after 48 hours has a differential effect on
stimulation of prostaglandin H synthase (PGHS)-2 mRNA and protein expression in
different fetal and maternal intrauterine tissues. Methods: Saline or three courses (one
course per week) of dexamethasone were administered to pregnant sheep commencing at
103, 110 and 117 dGA for two days per course (4 x 2 mg doses at 12 hour intervals).
Maternal and fetal placenta, myometrium and endometrium were collected from saline
and dexamethasone treated ewes (N = 6 in each group) 48 hours after the last injection of
the third course of dexamethasone. Maternal and fetal placental, myometrial and
endometrial total RNA and proteins were extracted and analyzed by Northern and
Western blot and in situ hybridization for PGHS-2 mRNA and protein. Data were
analyzed by Anova. Results: After three courses of maternal dexamethasone, PGHS-2
mRNA and protein were significantly increased in maternal and fetal placenta and
endometrium, but remained low in myometrium. Conclusions: Induction of fetal and
maternal placental and endometrial but not myometrial PGHS-2 provides further evidence
for a tissue specific action of glucocorticoids on intrauterine PGHS-2 in pregnant sheep.

*Address all correspondence to: Dr. Wen Xuan Wu, Department of Obstetrics and
Gynecology, Wake Forest University Baptist Medical Center, 1st Medical Center Blvd,
Winston Salem, NC 27106, USA.
Phone: 336-716-1651. Fax: 336-716-6937. E-Mail:

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