RESUMO
Anterior pituitary responsiveness to parturition was studied in 28 normal newborn infants. Cord blood sera samples were obtained for measurement of TSH, HGH, PRL, and FSH at birth and at intervals during four hours. The neonate infant's pituitary response to parturition consists of both PRL and TSH increments, which is probably mediated by an increase in TRH release.
Assuntos
Recém-Nascido , Adeno-Hipófise/fisiologia , Sangue Fetal/análise , Hormônio Foliculoestimulante/sangue , Hormônio Foliculoestimulante/metabolismo , Hormônio do Crescimento/sangue , Hormônio do Crescimento/metabolismo , Humanos , Prolactina/sangue , Prolactina/metabolismo , Tireotropina/sangue , Tireotropina/metabolismoRESUMO
Serum prolactin (PRL) was measured by radioimmunoassay in pregnant women at term and in newborns. In 38 newborns of gestational age 39--40 weeks, concentration of PRL in umbilical venous blood was 280.8 +/- 11.2 ng/ml; in maternal venous blood, concentration of PRL was 347.0 +/- 20.1 ng/ml. In the newborn it was found a significant difference in PRL values between both sexes (p less than 0.05), being higher in males than in females (290.0 +/- 14.6 vs. 260.0 +/- 17.1 ng/ml). In three anencephalic infants, PRL ranged from 92.6 to 369.0 ng/ml; 400 mug of thyrotropin-releasing hormone (TRH) administered as bolus injection evoked a rise in PRL in two out of the three, while synthetic luteinizing hormone releasing hormone (LH-RH) elicited no response of FSH secretion. These observations in the fetus and anencephalic infants confirm that the fetus produces high levels of PRL and that this function is independent of any hypothalamic control. The high levels of gestational estrogens seem to be the direct stimulus on the lactotropes to induce synthesis and secretion of PRL. The role of PRL during gestation has not been elucidated.