Stimulation of Prostaglandin Synthesis in Bovine Ovarian Tissues by Arachidonic Acid and Luteinizing Hormone

Abstract

Bovine corpora lutea and follicles removed from heifers at the 16th or 17th day of the estrous cycle were sliced and incubated for 2 h at 37°C with Kreb’s-Ringer bicarbonate buffer containing glucose. The concentration of prostaglandins of the F series (PGF) in unincubated control luteal tissue was 25.3 ± 5.1 ng/g and increased to 54.8 ± 13 ng/g (P<0.01) during incubation. PGF concentration increased when either LH or arachidonic acid was added to the medium; net stimulation on addition of LH amounted to 33.1 ng/g tissue (P<0.01) and in response to arachidonic acid was 85.2 ng/g (P<0.001). A higher level of PGF was found in follicles (148 ± 36 ng/gm). This level increased to 287.3 ± 63 (P<0.01) in incubated control tissues; when LH or arachidonic acid (AA) were added to the medium the net stimulated synthesis amounted to 199.7 ng/gm (P<0.01) and 352.7 ng/gm (P<0.001), respectively. Addition of indomethacin to the incubation medium prevented stimulated synthesis in both folhicular and luteal tissues and resulted in PGF levels that were not significantly different from levels of unincubated control tissues. The data indicate that the bovine ovary synthesizes PGF in both follicular and luteal tissues. The stimulation of PGF synthesis by LH provides further evidence that the preovulatory release of LH causes increased PGF synthesis in the ovary leading to increased steroidogenesis and ovulation.