Interactions of prostaglandins with subpopulations of ovine luteal cells. I. Stimulatory effects of prostaglandins E 1, E 2 and I 21

• Published in: Prostaglandins Vol. 28; no. 1; pp. 119 - 126
• Main Authors: Fitz, T.A., Hoyer, P.B., Niswender, G.D.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 1984
• ISSN: 0090-6980
• DOI: 10.1016/0090-6980(84)90119-9

Preparations of small and large steroidogenic cells from enzymatically dispersed ovine corpora lutea were utilized to study the in vitro effects of luteinizing hormone (LH) and prostaglandins (PG) E 1, E 2 and I 2. Cells were allowed to attach to culture dishes overnight and were incubated with either LH (100 ng/ml), PGE 2, PGE 2, or PGI 2 (250 ng/ml each). The secretion of progesterone by large cells was stimulated by all prostaglandins tested (P < 0.05) while the moderate stimulation observed after LH treatment was attributable to contamination of the large cell population with small cells. Prostaglandins E 1 and E 2 had no effect on progesterone secretion by small cells, while LH was stimulatory at all times (0.5 to 4 hr) and PGI 2 was stimulatory by 4 hr. Additional studies were conducted to determine if the effects of PGE 2 upon steroidogenesis in large cells were correlated with stimulated activity of adenylate cyclase. In both plated and suspended cells PGE 2 caused an increase (P < 0.05) in the rate of progesterone secretion but had no effect upon the activity of adenylate cyclase or cAMP concentrations within cells or in the incubation media. Exposure of luteal cells to forskolin, a nonhormonal stimulator of adenylate cyclase, resulted in marked increases in all parameters of cyclase activity but had no effect on progesterone secretion. These data suggest that the actions of prostaglandins E 1, E 2 and I 2 are directed primarily toward the large cells of the ovine corpus luteum and cast doubt upon the role of adenylate cyclase as the sole intermediary in regulation of progesterone secretion in this cell type.