Prostaglandin Secretion by the Neocortex and Fetal Zones of the Human Fetal Adrenal Gland*

Abstract

Previously, we reported that the human fetal adrenal (HFA) gland secretes various prostaglandins (PGs) in vitro and that PG secretion is inhibited by endogenously synthesized glucocorticosteroids. In this investigation, the neocortex (NC) and fetal zone (FZ) of the HFA gland were separated by microdissection and maintained as tissue fragments in organ culture. The rate of PG secretion into the culture medium was determined by measuring various PGs using specific RIAs in media collected at 24-h intervals. During the first 24 h in culture, the secretion rates of PGF2 alpha and PGE2 were 6- and 7-fold greater by NC [14 +/- 5 and 9.9 +/- 3 ng mg protein-1 24 h-1 (mean +/- SE)], respectively, than by FZ tissue (2.5 and 1.4 ng mg protein-1 24 h-1). The secretion rates of PGFM and PGD2 were 2-fold greater in NC tissue than in FZ tissue, but the secretion rates of thromboxane B2 were similar in both zones of HFA tissue. In another study, the patterns of secretion of PGF2 alpha and PGE2 were determined as a function of days in culture. The secretion rates of PGF2 alpha and PGE2 fell rapidly in NC from 19.0 +/- 11 and 38.3 +/- 9.7 ng mg protein-1 24 h-1, respectively, to 1.3 +/- 7.2 and 4.8 +/- 3.3 by day 4. In contrast, the secretion rates of PGF2 alpha and PGE2 rose 8- and 3-fold in FZ tissue (from 0.7 +/- 0.2 and 0.9 +/- 0.6 ng mg protein-1 24 h-1, respectively, to 5.9 +/- 0.5 and 3.1 +/- 1.2 by day 4). The addition of ACTH or dexamethasone inhibited PG secretion in both zones, but to a greater degree in FZ tissue than in NC tissue. In summary, the NC secretes larger quantities of PG than the FZ, and the patterns of secretion are different in the two zones. The secretion of PGs is inhibited more in FZ than in NC tissue by ACTH and glucocorticosteroids.