Plasma Beta-Endorphin Concentration in Infants with Apneic Spells

ABSTRACT In an attempt to determine whether plasma beta-endorphin (β-ED) concentrations correlate with occurrence of apnea in preterm infants, measurements were made in three groups of infants. The control group consisted of 11 infants with a mean (±SEM) gestational age of 30.5 ± 0.8 weeks, a mean (±SEM) birthweight of 1650 ± 180 g, and a mean (±SEM) postnatal age of 1.3 ± 0.5 days. Eight infants with apnea, bradycardia, and associated hypotension had a mean (±SEM) gestational age, birthweight and postnatal age of 30 ± 0.9 weeks, 1165 ± 90 g, and 7.8 ± 1.9 days, respectively. The third group consisted of eight infants experiencing apnea alone without bradycardia and had a mean (±SEM) gestational age, birthweight, and postnatal age of 31 ± 0.8 weeks, 1380 ± 125 g, and 2.6 ± 0.9 days, respectively. The last two groups of infants suffered varying degrees of apnea, but differed in their severity. The plasma endorphin concentrations (±SEM) were 26.9 ± 2, 68.0 ± 9.0, and 39.6 ± 2.0 pg/ml, respectively, for the previously described three groups. Significant elevation in β-ED concentration was observed in the severely apneic infants with bradycardia when compared to the other two groups. The association of increased plasma β-ED release with severe apneic spells may suggest that these endogenous opiates play a role in the pathophysiology of apnea of prematurity.