The ontogenesis of human fetal hormones. III. Prolactin.

Abstract

A B S T R A C T The synthesis and release of human prolactin (hPRL) in the human fetus was assessed by radioimmunoassay analysis of the content and concentration of hPRL in 82 pituitary glands and the concentration of serum hPRL in 47 fetuses of gestational age 68 days to term. Fetal hPRL exhibited parallelism with the reference standard (Lewis 203-1). hPRL was detected by 68 days of gestation (10 wk), the earliest fetal pituitary gland studied; 8 out of 33 pituitaries had a prolactin (PRL) content above 2.0 ng between 10-15 wk gestation. The mean content of PRL in the pituitary gland increased sharply from 14.8±4.6 ng at 15-19 wk to 405±142 ng at 20-24 wk and 542±204 ng at 25-29 wk gestation. By term, the mean content was 2,039± 459 (range 493-3,689) and the mean concentration 15.9±2.4 ng/mg (range 7-20). There was a significant positive correlation (P < 0.001) between the hPRL and human growth hormone (hGH) content of fetal pituitary glands; at term the hPRL/hGH ratio was 1/290. The concentration of serum hPRL between 12 and 24 wk ranged from 2.9 to 67 ng/ml, mean 19.5±2.5 ng/ml (n = 41); by 26 wk fetal serum hPRL increased sharply and attained levels of 300-500 ng/ml in late gestation. At delivery, the mean plasma concentration of hPRL was 167±+14.2 ng/ml in 36 umbilical venous specimens and 111.8±12.3 ng/ml in the matched maternal venous specimens. No correlation between serum hPRL and the pituitary content or concentration of hPRL was demonstrable in 12 matched fetal specimens.In five anencephalic infants, umbilical venous hPRL levels were between 65 and 283 ng/ml. In two anencephalic infants, thyrotropin releasing factor (TRF) (200 Ag IV) evoked a rise in serum hPRL in one patient from 43 to 156 ng/ml at 30 min, and in the other from 65 to Dr. Aubert is recipient of a grant from the Swiss National Fund for Scientific Research.

The human fetal prolactin and estradiol levels, and their correlationship.

“…Moreover, prolactin was present in the fetal pituitary gland as early as 9 gestational weeks (Clements et al 1977), and after 20 gestational weeks a large amount of prolactin was produced from the fetal pituitary gland (Aubert et al 1975). In this study, we found that the level of cord arterial prolactin was significantly (p <0.05) higher than that of cord venous prolactin.…”

“…Even though, the control mechanism of fetal prolactin secretion is not clearly known. It has been reported that the serum levels of prolactin in anencephalic infants are not significantly different from those in normal infants (Aubert et al 1975;Hauth et al 1973) ; so the fetal hypothalamus does not seem to have an important role in the fetal pituitary prolactin control system. On the other hand, estrogen may have some effects on the fetal pituitary prolactin secretion (Shutt et al 1974).…”

“…Prolactin was reported to exist in the fetal pituitary as early as 9 gestational weeks (Clements et al 1977), and serum levels of fetal prolactin could be measured as early as 12 gestational weeks (Aubert et al 1975). Fetal serum prolactin reached a 10-fold higher level than that of normal adults at the end of late gestation.…”

Prolactin Levels in Umbilical Cord Serum and Its Relation to Fetal Adrenal Activity in Newborns of Women with Pregnancy-Induced Hypertension

“…It is known that fetal pituitary secretion of prolactin increases progressively during normal human gestation (22,23). This is thought to be due, in part, to the ever increasing production of estrogen that is characteristic of human pregnancy.…”

Croissance et maturation fœtales

“…Durant la première semaine de vie, la prolac tine est sécrétée de manière continue (non pulsatile). Sa concentration cir culante chute à 50-100 ng/ml, puis atteint, à trois mois de vie, le niveau normal trouvé chez l'enfant, qui est de l'ordre de 5 ng/ml (38]. L'aug mentation du taux circulant foe tal de prolactine en fin de grossesse est liée à l'augmentation de la concentration d'estradiol.…”