Elevated plasma norepinephrine levels in infants of substance-abusing mothers
S. L. Ward, S. Schuetz, L. Wachsman, X. D. Bean, D. Bautista, S. Buckley, S. Sehgal and D. Warburton
Division of Neonatology and Pediatric Pulmonology, Childrens Hospital of Los Angeles, CA 90027.
Infants of substance-abusing mothers (ISAM) have significant growth and
neurodevelopmental abnormalities. The origin of these abnormalities is
unknown. We postulated that ISAM have increased sympathetic nervous system
tone and altered catecholamine levels. Therefore, we measured plasma
norepinephrine, epinephrine, and dopamine levels and the number and
receptor affinity of beta-adrenoreceptor binding sites on lymphocytes and
alpha-adrenoreceptor binding sites on thrombocytes in 22 otherwise healthy
ISAM (age, 2.1 +/- 0.5 months; mean +/- SD) and 15 healthy controls (age,
2.5 +/- 0.8 months). Norepinephrine levels in venous blood were 1.8-fold
higher in ISAM than in control infants (6.30 +/- 3.85 nmol/L vs 3.55 +/-
2.45 nmol/L). There were no differences in plasma epinephrine or dopamine
levels. There were no differences in the number of binding sites or
receptor affinity for beta- and alpha-adrenoreceptors. We conclude that
ISAM have elevated circulating norepinephrine levels compared with
controls. We speculate that this is associated with increased sympathetic
nervous system tone in ISAM and that the absence of adrenoreceptor
down-regulation may create catecholamine suprasensitivity.
