Abstract:

The gut hormone peptide YY 3-36 [PYY (3-36)] has been suggested to posses anorexigenic actions in animals and human adults. However, its circulating concentrations and function have not been studied in neonates. Serum concentrations of PYY (3-36) were determined by RIA (RIA) in 62 healthy preterm infants [mean(SD) gestational age, 32.0(2.1) weeks; postnatal age, 40.9(14.8 d)] and 15 healthy fullterm infants of comparable postnatal age and gender. The correlations between PYY (3-36) levels and anthropometric characteristics, food intake, growth rates and circulating concentrations of total PYY, ghrelin, leptin, insulin and adiponectin were examined. Mean (SD) PYY (3-36) concentrations were higher in preterm [543.7(157.6) ng/L) than full term infants [350.9(114.1) ng/L; p < 0.001) and accounted for 48% and 42% of total PYY basal plasma immunoreactivity in preterm and full term infants, respectively. In multiple regression analysis, PYY (3-36) concentrations correlated negatively with the infants’ BMI and positively with serum ghrelin concentrations, but not with caloric intake, weight gain or concentrations of any other hormone studied. In conclusion, PYY (3-36) represents almost half of total PYY immunoreactivity in neonates. It’s correlations with ghrelin and BMI suggest a role of this peptide in the regulation of energy homeostasis; however, its specific functions and physiologic significance in neonates remain to be elucidated.