An ovulatory gonadotropin stimulus increases cytosolic phospholipase A2 expression and activity in granulosa cells of primate periovulatory follicles.

Context: Prostaglandins (PGs) produced within ovarian follicles in response to the ovulatory gonadotropin surge are essential for follicle rupture and oocyte release. Arachidonic acid, the common precursor for PG synthesis, is cleaved from membrane phospholipids via the activity of phospholipase A2 (PLA2).

Objective: The purpose of this study was to determine which PLA2 form(s) is involved in PG production by primate periovulatory follicles.

Microsomal prostaglandin E synthase-1 (mPGES-1) is the primary form of PGES expressed by the primate periovulatory follicle.

Background: Prostaglandin E2 (PGE2) has been identified as the key ovulatory PG in the primate follicle. Follicular PGE2 levels increase just before the expected time of ovulation, suggesting that the midcycle LH surge induces the expression of enzymes involved in PGE2 synthesis.

Methods: To identify the specific form(s) of prostaglandin E synthase (PGES) expressed by the primate periovulatory follicle, we examined granulosa and theca cell expression of the three microsomal (m) and cytosolic (c) forms of PGES (mPGES-1, mPGES-2 and cPGES) identified to date.

Adipose differentiation-related protein: a gonadotropin- and prostaglandin-regulated protein in primate periovulatory follicles.

The midcycle LH surge stimulates a rise in follicular fluid prostaglandin E2 (PGE2), which is necessary for normal ovulation. To examine PGE2-regulated processes in primate follicles, monkey granulosa cells were cultured with hCG alone or with hCG and PGE2, and the resulting total RNA was subjected to microarray analysis. Twenty PGE2-regulated mRNAs were identified, and we selected a lipid droplet protein, adipose differentiation-related protein (ADRP), for further study.

Prostaglandin dehydrogenase and prostaglandin levels in periovulatory follicles: implications for control of primate ovulation by prostaglandin E2.

Prostaglandin (PG) E2 produced by the periovulatory follicle in response to the midcycle LH surge is essential for successful ovulation in primates. Granulosa cells express the PG synthesis enzyme cyclooxygenase-2 in response to the LH surge, but elevated cyclooxygenase-2 mRNA levels precede rising follicular fluid PGE2 levels by 24 h. Therefore, PG metabolism may play a significant role in regulating follicular concentrations of PGE2 during the periovulatory interval.