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Elevated plasma norepinephrine levels in infants of substance-abusing mothers
S L Ward1, S Schuetz, L Wachsman
1Division of Neonatology and Pediatric Pulmonology, Childrens Hospital of Los Angeles, CA 90027.
Insights
Infants of substance-abusing mothers (ISAM) show higher norepinephrine levels, indicating increased sympathetic nervous system activity. This may contribute to neurodevelopmental issues in these infants.
Area of Science:
- Neonatal research
- Neurodevelopmental abnormalities
- Sympathetic nervous system function
Background:
- Infants of substance-abusing mothers (ISAM) exhibit significant growth and neurodevelopmental deficits.
- The underlying causes of these abnormalities remain unclear.
Purpose of the Study:
- To investigate the hypothesis that ISAM possess heightened sympathetic nervous system tone and altered catecholamine levels.
- To compare plasma catecholamine concentrations and adrenoreceptor binding characteristics between ISAM and healthy controls.
Main Methods:
- Measurement of plasma norepinephrine, epinephrine, and dopamine levels in 22 ISAM and 15 healthy control infants.
- Assessment of beta-adrenoreceptor binding sites on lymphocytes and alpha-adrenoreceptor binding sites on thrombocytes.
- Analysis included receptor number and affinity.
Main Results:
- ISAM infants displayed significantly higher plasma norepinephrine levels (1.8-fold increase) compared to controls.
- No significant differences were observed in plasma epinephrine or dopamine levels between the groups.
- Adrenoreceptor binding site number and affinity were comparable in both ISAM and control infants.
Conclusions:
- ISAM exhibit elevated circulating norepinephrine levels, suggesting increased sympathetic nervous system tone.
- The lack of adrenoreceptor downregulation in ISAM may lead to catecholamine suprasensitivity.
- These findings provide insights into the physiological underpinnings of ISAM abnormalities.
Abstract:
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.