Lack of relationship between prolactin and adrenal steroidogenesis in the ovine fetus.

The role of fetal prolactin (PRL) as a fetal adrenotropic hormone was investigated in eight chronically catheterized fetal lambs. Catheters were placed for measurement of plasma prolactin (PRL), cortisol (F), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione (A). Daily (9 AM) samples were obtained until the onset of labor. In four animals 2-Br-alpha-ergocryptine (BC) was administered subcutaneously (1 mg/12 hours) for 11 to 21 days prior to delivery. Four animals served as controls. No difference between groups was noted in the duration of gestation. PRL increased in the control animals from 8.4 +/- 2.4 to 43.0 +/- 5.6 ng/ml (mean +/- SEM) at the time of delivery whereas in animals that received BC it decreased within 24 hour of administration and remained below 3 ng/ml throughout the study period. No differences were noted in the concentration of F, DHEA, DHEA-S, and A between groups. These results suggest that PRL does not play a role in adrenal steroidogenesis or in the initiation of parturition.