Effects of multiple courses of antenatal corticosteroids on regional brain and somatic tissue water content in ovine fetuses.
OBJECTIVE
To study the effects of single and multiple courses of antenatal corticosteroids on tissue water content in ovine fetuses.


METHODS
After chronic catheterization of the ewes and fetuses, the ewes were randomly assigned to receive single or multiple courses of dexamethasone or placebo beginning at 104-106 or 76-78 days' gestation, respectively. In the single course groups, the ewes received dexamethasone (6 mg, n = 6) or placebo (n = 6) as four intramuscular injections every 12 hours over 48 hours. The fetal tissues were harvested for water content determination 66 hours after the first injection of dexamethasone or placebo was given. In the multiple-course groups, the ewes received the same treatment (dexamethasone, n = 10, or placebo, n = 8), once a week for 5 weeks starting at 76-78 days' gestation. In these groups, the tissues were harvested 66 hours after the first the injection of the fifth and last treatment course. In both groups, tissues were harvested at 106-107 days' gestation. Tissue water content was determined by wet-to-dry weight ratio in brain (cerebral cortex, caudate nucleus, cerebellum, midbrain, and medulla) and somatic tissues (kidney, liver, muscle, and skin).


RESULTS
Water content in the brain regions (cerebellum and medulla) was lower (P <.05) in fetuses of dexamethasone-treated ewes than placebo-treated ewes after the multiple course but not the single course. Water content of somatic tissue was lower (P <.05) in fetuses of dexamethasone-treated ewes than placebo-treated ewes after the multiple courses, and in the liver after a single course.


CONCLUSIONS
Dexamethasone treatment of ewes at 70% of gestation results in decreased regional brain water content in the fetuses after multiple but not single treatment courses, in somatic tissues (kidney, liver, muscle, and skin) after multiple courses, and in the liver after a single course.
Stonestreet
Barbara S
BS
Department of Pediatrics, Brown University Medical School, Women and Infants' Hospital of Rhode Island, Providence 02905-2499, USA. BStonest@wihri.org
Watkins
Shannon
S
Petersson
Katherine H
KH
Sadowska
Grazyna B
GB
D000305:Adrenal Cortex Hormones / Q000008:administration & dosage*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D001834:Body Water / Q000187:drug effects*; D001921:Brain / Q000033:anatomy & histology / Q000196:embryology*; D002245:Carbon Dioxide / Q000032:analysis; D003907:Dexamethasone / Q000008:administration & dosage; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005333:Fetus / Q000187:drug effects*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006400:Hematocrit; D006854:Hydrocortisone / Q000097:blood; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000097:blood; D009994:Osmolar Concentration; D010100:Oxygen / Q000032:analysis; D010919:Placebos; D011188:Potassium / Q000097:blood; D011247:Pregnancy; D012756:Sheep; D012964:Sodium / Q000097:blood
D000305:Adrenal Cortex Hormones; D001786:Blood Glucose; D007328:Insulin; D010919:Placebos; D002245:Carbon Dioxide; D003907:Dexamethasone; D012964:Sodium; D011188:Potassium; D010100:Oxygen; D006854:Hydrocortisone