Plasma Somatostatin and Cholecystokinin Levels in Preterm Infants during Their First Two Years of Life

Plasma somatostatin and cholecystokinin are two gut peptides with opposite functions which are regulated by two different parts of the autonomic nervous system. Previously we have shown that plasma somatostatin and cholecystokinin levels are higher in preterm infants during the 1st d of life than in adults or in their mothers, and that plasma somatostatin is negatively correlated to gestational age. We have longitudinally studied these two peptides in 28 preterm infants, 17 boys and 11 girls, up until the age of 2 y. The mean (SD) gestational age was 32.3 (2.8) wk, the mean birth weight was 1877 (515) g, and the mean birth length was 42.8 (3.8) cm. Blood samples were taken on the 1st d of life, at 6 wk, and at 3, 6, 12, and 24 mo of age. Plasma was analyzed by specific somatostatin and cholecystokinin RIAs. The median plasma somatostatin and cholecystokinin levels were lowest at 3 mo (somatostatin = 17.4/cholecystokinin = 10.5 pmol/L) and highest at 6 mo (somatostatin = 37.3/cholecystokinin = 27.1 pmol/L). At 24 mo plasma somatostatin remained at the same level, and cholecystokinin had decreased to half that level. After the 1st d of life plasma somatostatin and cholecystokinin levels were not correlated to gestational age or attained weight or length. The plasma somatostatin level at 3 mo of age was negatively correlated to the increment in knee-heel distance between 3 and 6 mo of age.