Dopamine is frequently used in neonatal intensive care for its vasopre
ssor, renal vasodilating, and cardiac inotropic properties, The effect
of i.v, dopamine infusion on neonatal pituitary hormone secretion is
currently unknown, We observed strikingly low serum concentrations of
growth hormone (GH) and prolactin (PRL) during a therapeutic, standard
ized, isovolumetric, partial exchange transfusion (blood sampling ever
y 20 min for 6 h) in two polycythemic neonates requiring intensive the
rapy, including continuous dopamine infusion, In addition, the secreti
on of GH and PRL was studied in three neonates with symptomatic polycy
themia (gestational age 34-38 wk; birth weight 2110-2530 p; postnatal
age 10-30 h) during a partial exchange transfusion, including an inter
vening dopamine infusion (8 mu g/kg/min i.v, for 2 h), The GH and PRL
profiles were evaluated by deconvolution analysis, Initially, the thre
e newborns exhibited high-amplitude, pulsatile GH secretion and contin
uously elevated PRL release, During the dopamine infusion, GH secretio
n was virtually abolished and PRL release was reduced by at least 50%,
Dopamine withdrawal was associated with a rebound release of GH and P
RL. Finally, serum GH and PRL concentrations were studied in nine nonp
olycythemic newborns (gestational age 31-40 wk; birth weight 1680-4000
g; postnatal age 2-28 d) at the end of a prolonged dopamine infusion
(3-5 mu g/kg/min i.v, for 2-27 d), Within 2 h after dopamine withdrawa
l, GH and PRL levels increased a median 3-fold and 10-fold respectivel
y. These data concord to indicate that dopamine is a potent inhibitor
of GH and PRL secretion in the human newborn.