Abstract
To determine whether a diurnal rhythm exists in neonates admitted to neonatal intensive care units (NICU) where there is continuous artificial lighting and periodic nursing and medical care exists, Plasma cortisol, ACTH and β-endorphin (BED) concentrations were measured in two groups of infants and another group of adult human volunteers. As expected, a diurnal rhythm is seen in adults. Plasma concentrations found during morning and (afternoon) hours were: cortisol - 475.0 ± 204.2 (255.0 ± 75.2) nmoles /L; ACTH - 10.9 ± 3.4 (13.0 ± 4.6) pg/mL; β-ED -22.l ± 9.5 (16.8 ± 7.2) pg/mL. A diurnal rhythm was also observed for ACTH and cortisol in neonates (3-4 days postnatally) :cortisol - 340 ± 194.5 (228.8 ± 101.0) nmoles/L; ACTH - 6.3 ± 4.2 (8.8 ± 5.5)pg/mL. Although there was not a statistically significant difference between morning and afternoon β -ED levels in this group, the afternoon levels like the adults were lower: 24.2 ± 13.0 (19 ± 9.8) pg/mL. There was no significant difference between the concentrations of any of the three substances in infants who were severely stressed clinically: cortisol - 320 ± 230.6 (406.4 ± 227.4) nmoles/L; ACTH - 7.0 ± 3.1 (8.0 ± 4.7) pg/mL; β- ED -37.1 ± 19.4 (45.6 ± 35.7) pg/mL. It would appear that a diurnal rhythm exists in neonates within the first few days of postnatal life and that the continuous lighting, medical and nursing interventions do not seem to interfere with this rhythm. Severe stress seems to override this rhythm.
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Hindmarsh, K., Sankaran, K., Laxdal, V. et al. CONTROLS, ACTH β -ENDORPHIN: DIURNAL RHYTHEMS OF INFANTS IN A NEONATAL INTENSIVE CARE UNIT. Pediatr Res 21 (Suppl 4), 215 (1987). https://doi.org/10.1203/00006450-198704010-00292
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DOI: https://doi.org/10.1203/00006450-198704010-00292