Effect of maternal administration of the antiestrogen ethamoxytriphetol throughout the last third of baboon gestation upon neonatal corticoid production

Fetal lung maturation in estrogen-deprived baboons

We have previously shown that estrogen plays a central integrative role in regulating key aspects of fetal-placental development and that inhibition of estrogen production during the second half of baboon pregnancy suppressed fetal adrenal function. Because maturation of the fetal lung is dependent on cortisol of fetal adrenal origin, the current study determined whether lung development and expression of surfactant proteins (SPs) A and B were altered at term in estrogen-deprived baboons. Fetal lungs were obtained on d 100, 165, and 175 of gestation (term = d 184) from untreated baboons and on d 165 from animals treated daily during the second half of pregnancy either with the aromatase inhibitor CGS 20267 alone or with CGS 20267 and estradiol benzoate. Umbilical venous estradiol levels were suppressed by more than 95% by CGS 20267 and elevated by CGS 20267 and estrogen. Although umbilical serum cortisol levels were also suppressed by 35% by CGS 20267, cortisol levels in the fetal lung of estrogen-suppressed baboons were similar to values in untreated animals. Immunocytochemistry demonstrated that CGS 20267 treatment did not alter fetal lung expression of the 11 beta-hydroxysteroid dehydrogenase enzyme-1 enzyme catalyzing reduction of cortisone to cortisol. However, immunocytochemical expression of the 11 beta-hydroxysteroid dehydrogenase enzyme-2 catalyzing oxidation of cortisol to cortisone appeared lower in lungs of estrogen-deprived fetuses and restored to normal by CGS 20267 and estrogen. SP-A levels in fetal lungs of untreated baboons were increased 16- to 20-fold between d 100 and d 165-175 of gestation in untreated baboons and baboons treated with CGS 20267 or CGS 20267 and estrogen. Similarly, SP-B levels in fetal lungs of untreated baboons were increased 10-fold between d 100 and d 165-175 of gestation in untreated baboons and baboons treated with CGS 20267 or CGS 20267 and estrogen. Moreover, in estrogen-suppressed baboons, as in untreated animals, the fetal lung continued to grow and exhibited normal alveolarization on histology. We conclude that development of the primate fetal lung can occur in utero in baboons in which fetal serum cortisol levels have been suppressed by the relative absence of estrogen perhaps because of the ability of the lung to coordinate local production of cortisol.

Effect of estrogen on dehydroepiandrosterone formation by baboon fetal adrenal cells in vitro

The present study determined if estrogen modulates the responsivity of the adrenal gland of the baboon fetus to tropic hormones such as adrenocorticotropic hormone and prolactin. Adrenal glands were obtained from seven baboon fetuses at midgestation (days 100 to 105). Adrenal cells were dispersed in medium 199 with 0.2% collagenase for 10 minutes at 37 degrees C. Approximately 10(5) cells/4.0 ml of medium 199 were incubated for 24 hours at 37 degrees C with 10 nmol of adrenocorticotropic hormone or 10 nmol of ovine prolactin in the presence or absence of 10(-5) or 10(-6) mol/L of estradiol. The major steroid formed and secreted into the medium was dehydroepiandrosterone. Mean +/- standard error basal formation of dehydroepiandrosterone was 176 +/- 64 ng/10(5) cells/24 hours. Dehydroepiandrosterone formation was increased (p less than 0.05) 3.5-fold and five-fold by adrenocorticotropic hormone and prolactin, respectively. Estradiol at 10(-5) mol/L prevented the response in dehydroepiandrosterone obtained with adrenocorticotropic hormone alone. Estradiol alone had no effect on dehydroepiandrosterone. The results suggest that estrogen modulates the regulatory effects of adrenocorticotropic hormone on dehydroepiandrosterone formation by the adrenal gland of the baboon fetus.

The effects of cortisone on the interconversion of cortisol and cortisone in the baboon

In the baboon fetus, the conversion of cortisol (F) to cortisone (E) [80%] exceeds the reverse reaction [15%]. Since the fetus is exposed to high quantities of E throughout most of pregnancy, we determined whether F to E interconversion is altered following acute changes in serum E. Adult female baboons (N = 3) were sedated with ketamine, constantly infused for 180 min via an antecubital vein with 15 microCi[14C]E and 15 microCi[3H]F, and saphenous vein blood samples obtained at 70, 80 and 90 min. At 90 min, an infusion of E (166 micrograms/min) was initiated and blood samples obtained at 160-180 min. This protocol was repeated in the same animals treated 24 and 3 h prior to infusion with 3 mg betamethasone. Metabolic clearance (MCR), transfer constants (%) and serum levels (microgram/dl) of F and E were determined. E increased (P less than 0.05; paired t) MCR-E, and serum F and E levels in control and betamethasone-treated baboons. E also decreased %F to E in betamethasone-treated but not control animals. These findings suggest that acute changes in serum E alter MCR-E, do not influence the conversion of E to F and may decrease the conversion of F to E. Therefore, we suggest that the high conversion of F to E in the baboon fetus is probably not the result of elevated concentrations of E.