Neonatal adaptive phenomenon: secretion of beta-lipotropin, and beta-endorphin in the first week of life [Fenomeni di adattamento neonatale: secrezione di βlipotropina (βLPH) e βendorfina (βEP) nella prima settimana di vita]

βLipotrophin and βendorphin plasma levels were measured in 35 newborns subdivided in 5 groups at 12, 24, 48, 72 and 168 hours of life, 10 umbilical mixed blood samples were also evaluated. After plasma extraction (3 ml) and G-75 Sephadex column chromatography, the peptides were measured by two specific RIAs. βLPH and βEP levels were high in umbilical cord plasma (241.0 ± 43.3 and 70.0 ± 8.5 pg/ml respectively. A progressive decrease was then observed until the 72th hour of life (28.1 ± 13.2 and 8.7 ± 4.8 pg/ml respectively) but the elevated levels found at the 24th hour demonstrate an active synthesis and release from fetal and neonatal pituitary. After a slight and transient decreased activity during the first week of life, the statistically significant increase of both βLPH and βEP observed at the seventh day indicate that at this moment pituitary function is restored.