Fetal androgen exposure inhibits fetal rat lung fibroblast lipid uptake and release.

Abstract

Fetal lung fibroblasts provide lipid substrate for type II cell surfactant phospholipid synthesis. This process is developmental and glucocorticoid dependent. Previous studies in our laboratory demonstrating sex differences in several aspects of lung maturation suggest that these differences may be due to effects of fetal androgens. Based on these studies, we hypothesized that fetal lung fibroblast triglyceride metabolism is determined by opposing effects of fetal androgens and glucocorticoids. To model the effects of androgens on fetal lung fibroblast triglyceride metabolism, pregnant rats were treated with dihydrotestosterone (DHT) 1 mg/kg/day from the days 15 to 20 of gestation, and changes in triglyceride content of freshly isolated fetal rat lung fibroblasts (FRLF) and rates of uptake and prostaglandin E2 (PGE2)-mediated release by cultured FRLF in response to glucocorticoids in the presence or absence of DHT in vitro were measured. During lung development, the triglyceride content and rate of uptake of female-derived FRLF increased 3.5- and 4.8-fold, respectively, between days 18 and 20 of gestation. From days 19 to 22, male FRLF trigyclyceride content and rate of uptake were lower than the content and uptake by female FRLF. Maternal DHT treatment inhibited the normal developmental increase in fibroblast triglyceride content and rate of uptake between days 19 and 22 by both male and female FRLF. In the absence of maternal DHT, in vitro dexamethasone stimulated triglyceride uptake 3-fold by day 21 in FRLF. This effect was blocked by maternal pretreatment with DHT. Maternal DHT exposure prevented stimulation of triglyceride release by PGE2. Although in vitro dexamethasone stimulated triglyceride release by maternal DHT-exposed fibroblasts, it did not enhance the response to PGE2. These data suggest that in utero exposure to androgens (1) delay the developmental increase in triglyceride content and (2) oppose the effects of glucocorticoid on cultured FRLF triglyceride uptake and PGE2-mediated release.