Antenatal dexamethasone treatment decreases plasma catecholamine levels in preterm infants.
Antenatal corticosteroid therapy (ACT) has many beneficial effects on preterm infants. The cellular mechanisms of action of ACT include beta-adrenergic receptor-mediated cAMP generation. This study investigated the effects of ACT on sympathoadrenal mechanisms during immediate postnatal adaptation of preterm infants. Plasma epinephrine, norepinephrine, 3,4-dihydroxyphenylglycol, and cAMP were measured within 12 h after birth in 103 preterm infants (gestational age 24-36 wk), who were divided into two groups (non-ACT and ACT group) according to whether the mother had received dexamethasone treatment. Infants in the ACT group had significantly lower concentrations of plasma catecholamines than infants in the non-ACT group; plasma epinephrine was 38% lower, and plasma norepinephrine was 20-40% lower in the ACT group, depending on gestational age (r = -0.37 in the non-ACT group and r = -0.28 in the ACT group, p < 0.05). Plasma cAMP concentrations were similar in the two groups. Antihypertensive treatment of the mother was associated with low plasma cAMP (p < 0.001), whereas tocolytic treatment was associated with high plasma cAMP (p = 0.001) of the infant. The results indicate that ACT attenuates the birth-related increase in plasma catecholamines. Still, plasma cAMP levels remain high, which suggests enhanced beta-adrenoceptor signaling after ACT.
Kallio
J
J
Department of Pharmacology and Clinical Pharmacology, University of Turku, Finland.
Karlsson
R
R
Toppari
J
J
Helminen
T
T
Scheinin
M
M
Kero
P
P
D000959:Antihypertensive Agents / Q000627:therapeutic use; D001724:Birth Weight; D000242:Cyclic AMP / Q000097:blood; D036861:Delivery, Obstetric; D003907:Dexamethasone / Q000008:administration & dosage / Q000627:therapeutic use*; D004837:Epinephrine / Q000097:blood*; D005260:Female; D005865:Gestational Age; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood*; D008297:Male; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000097:blood; D009638:Norepinephrine / Q000097:blood*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000188:drug therapy; D011295:Prenatal Care; D012044:Regression Analysis; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*; D015149:Tocolytic Agents / Q000627:therapeutic use
D000959:Antihypertensive Agents; D015149:Tocolytic Agents; D008734:Methoxyhydroxyphenylglycol; D003907:Dexamethasone; D000242:Cyclic AMP; C010117:3,4-dihydroxyphenylglycol; D009638:Norepinephrine; D004837:Epinephrine