Angiotensin II receptors on human fetal adrenal cells William E. Rainey, PhD, Ian M. Bird, PhD, J. Ian Mason, PhD, and Bruce R. Carr, MD Dallas, Texas OBJECTIVE: Our objective was to determine if angiotensin II receptors are present on adrenal cells isolated from the human fetal zone and neocortex and to investigate if angiotensin II affects steroid production by these cells. STUDY DESIGN: Primary cultures of both fetal zone and neocortex cells were prepared from fetal adrenal glands. Experiments were conducted to examine the binding of radiolabeled angiotensin II, angiotensin II activation of phospholipase C, and angiotensin II effects on steroidogenesis. RESULTS: The majority of angiotensin II binding sites were of the type 1 subtype, as determined by displacement of radiolabeled angiotensin with specific receptor antagonists. Angiotensin II caused an increase in tritiated inositol phosphate accumulation in both neocortex and fetal zone cells. This increase could be blocked by type 1 angiotensin II receptor antagonists. Angiotensin II stimulated the production of cortisol, dehydroepiandrosterone, and dehydroepiandrosterone sulfate production during treatment for 2 days. The stimulation by angiotensin II, however, was substantially less than that seen in response to corticotropin treatment. CONCLUSIONS: The human fetal adrenal gland contains type 1 angiotensin II receptors early in gestation. The number of these receptors, albeit low, is sufficient to activate inositol phosphate production and steroidogenesis. (AM J OBSTET GVNECOL 1992;167:1679-85.) Key words: Human fetal adrenal, angiotensin II, AT l , receptor, steroid production Throughout pregnancy the human fetal adrenal gland is an extremely active steroid-secreting organ. The human fetal adrenal cortex is composed of two principal zones, namely the fetal zone and the neocor- tex. The fetal zone constitutes about 85% of the volume of the human fetal adrenal and is the principal source for the large amount of steroid hormones secreted by this gland. I - 4 A peculiar feature of the fetal zone com- pared with the adult adrenal is the very low expres- sion of 3f3-hydroxysteroid dehydrogenase/isomerase (3f3-HSD). This low 3f3-HSD in the face of high expres- sion of steroid 17a-hydroxylase cytochrome P450 is reflected in the steroid secretory pattern of human fetal adrenals. The principal steroid hormones secreted by the fetal zone are dehydroepiandrosterone (DHEA) sulfate and pregnenolone sulfate; only low levels of 3-ketosteroids (e.g., cortisol) are produced. Cortisol From the Cecil H. and Ida Green Center for Reproductive Biology Sciences and the Division of Reproductive Endocrinology, Depart- ments of Obstetrics and Gynecology and Biochemistry, The University of Texas Southwestern Medical Center at Dallas. Supported in part by National Institutes of Health grant No. HD-11149 and the American Heart Association, Texas Affiliate grant No. 91G-082. Presented at the Thirty-ninth Annual Meeting of the Society for Gynecologic Investigation, San Antonio, Texas, March 18-21, 1992. Reprint requests: William E. Rainey, PhD, Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, 5323 Harry Hines Blvd., Dallas, TX 75235-9032. 6/6/41914 production by the neocortex increases, however, near the end of gestation and appears to be essential for various aspects of fetal maturation. 9 - 11 A central prob- lem in this area is to understand the possible mecha- nisms responsible for increasing expression of 3f3-HSD and the associated cortisol production late in gestation. We and others I2 - 15 have shown that angiotensin II can inhibit the corticotropin-stimulated production of cor- tisol in adult bovine, adult ovine, and fetal ovine adre- nal cells. The effects of angiotensin II on primary cultures of human fetal zone and neocortex cells, how- ever, has not been well defined. The purpose of the current study was to determine if human fetal adrenal cells exhibit angiotensin II receptors. Material and methods Tissue preparation and cell culture. Fetal adrenal glands (two to five per culture) were obtained from midtrimester (12 to 19 weeks' gestational age) human abortuses delivered electively by dilation and extrac- tion. The tissues were obtained under the auspices of the Donors Anatomical Gift Act of the State of Texas, after consent in writing was obtained from women undergoing abortion. The consent form and the exper- imental protocol were approved by the Institutional Review Board of The University of Texas Southwest- ern Medical Center at Dallas. The neocortex was re- moved from the fetal zone by microdissection as de- scribed. 16 Both zones were minced finely and dis- 1679