Prostaglandin-endoperoxide synthase (PTGS1 and PTGS2) expression and prostaglandin production by normal monkey ovarian surface epithelium

Objective

To determine whether hCG regulates the expression of prostaglandin (PG) synthesis enzymes and the production of PGs by normal monkey ovarian surface epithelium (OSE).

Design

Experimental animal study.

Setting

Research laboratory.

Animal(s)

Adult cynomolgus macaques.

Intervention(s)

Monkeys received exogenous gonadotropins to stimulate multiple follicular development. Ovarian surface epithelium cells and whole ovaries were obtained before (0 hours) and 36 hours after an ovulatory dose of hCG.

Main Outcome Measure(s)

Ovarian surface epithelium expression of prostaglandin-endoperoxide synthase 1 (PTGS1) and PTGS2 proteins was determined by immunocytochemistry. Prostaglandin synthesis enzyme messenger RNA (mRNA) levels were determined by RT-PCR. Prostaglandin E₂ and PGF_2α production was assessed by enzyme immunoassays.

Result(s)

Ovarian surface epithelium maintained in long-term culture expressed mRNA and protein for PTGS1 and PTGS2 (n = 6); inhibition of PTGS1, but not PTGS2, reduced PGE₂ synthesis (n = 3). Prostaglandin-endoperoxide synthase 1 was present in OSE of ovarian tissue sections obtained 0 (n = 4) and 36 (n = 3) hours after hCG; PTGS2 was not detected. Ovarian surface epithelium collected 0 (n = 3) and 36 (n = 4) hours after hCG expressed mRNAs for PTGS1, PTGS2, and three PGE synthases; the ratio of PTGS2 to PTGS1 increased in response to hCG exposure.

Conclusion(s)

Monkey OSE expresses mRNA for PTGS1, PTGS2, and all PGE synthases and produces PGE₂ both before and 36 hours after hCG. Detection of PTGS1, but not PTGS2, protein in OSE in vivo supports the hypothesis that PTGS1 is the enzyme responsible for PGE₂ production by primate OSE in vivo.

Key Words:  Prostaglandin , primate , ovary , ovulation , cyclooxygenase , ovarian cancer