title: Effect of dexamethasone on rat plasma platelet activating factor acetylhydrolase during the perinatal period.
abstract: It has been previously reported that the administration of dexamethasone (DEX) to adult rats increases the activity of plasma platelet-activating factor acetylhydrolase (PAF-AH) and prevents the development of intestinal necrosis caused by platelet activating factor (PAF) injection. In this report, we examined the effect of DEX administration on plasma PAF-AH activity during the perinatal period. Timed-pregnant rats received DEX (0.2-1.0 mg/kg/d) or normal saline (controls) on days 16-18 (early group) or days 18-20 (late group) of gestation. Maternal plasma PAF-AH activity was lower in late gestation than in postpartum period (P < 0.001). Fetal and neonatal plasma PAF-AH activity was higher than maternal values (P < 0.05). No changes of PAF-AH activity were seen in maternal, fetal or neonatal plasma after prenatal DEX administration at the aforementioned doses. A higher dose of DEX (1.3 mg/kg/d x 4d) or cortisone (200 mg/kg/d) produced an elevation of maternal plasma PAF-AH activity (DEX 79.2+/-3.0, cortisone 70.5+/-1.9 vs. controls 49.4+/-2.3 nmol/min/ml, P < 0.01), but resulted in a high fetal mortality. Treatment of newborn rats with DEX (0.5 mg/kg/d) on days 1-3 after birth, increased plasma PAF-AH activity on day 4 (DEX 292+/-5 versus controls 140+/-9 nmol/min/ml, P < 0.001) and day 6 (DEX 302+/-12 versus controls 136+/-6 nmol/min/ml, P < 0.001). Postnatal administration of DEX increases the plasma PAF-AH activity in the rat. Only high doses of prenatal corticosteroids that cause fetal death can elevate maternal plasma PAF-AH activity.
authors.affiliation: Department of Surgery, UT Southwestern Medical Center, Dallas, TX 75235, USA.
authors.forename: M
authors.initials: M
authors.lastname: Contador
authors.forename: F R
authors.initials: FR
authors.lastname: Moya
authors.forename: B
authors.initials: B
authors.lastname: Zhao
authors.forename: M
authors.initials: M
authors.lastname: Furukawa
authors.forename: R A
authors.initials: RA
authors.lastname: Frenkel
authors.forename: P
authors.initials: P
authors.lastname: Guzzetta
authors.forename: J M
authors.initials: JM
authors.lastname: Johnston
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007273:Injections, Intramuscular; D010741:Phospholipases A / Q000097:blood* / Q000187:drug effects*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D003907:Dexamethasone; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase