1. An investigation into the role of prostaglandins in zebrafish oocyte maturation and ovulation.
- Author
-
Lister AL and Van Der Kraak G
- Subjects
- Animals, Arachidonic Acid pharmacology, Cyclooxygenase 1 genetics, Cyclooxygenase 1 metabolism, Cyclooxygenase 2 genetics, Cyclooxygenase 2 metabolism, Dose-Response Relationship, Drug, Female, Gene Expression Regulation, Developmental drug effects, Group IV Phospholipases A2 genetics, Group IV Phospholipases A2 metabolism, Indomethacin pharmacology, Oogenesis genetics, Ovarian Follicle drug effects, Ovarian Follicle metabolism, Ovulation genetics, Prostaglandin-Endoperoxide Synthases genetics, Prostaglandin-Endoperoxide Synthases metabolism, Prostaglandins metabolism, Prostaglandins E metabolism, Prostaglandins E physiology, Prostaglandins F metabolism, Prostaglandins F physiology, Radioimmunoassay, Reverse Transcriptase Polymerase Chain Reaction, Tissue Culture Techniques, Zebrafish genetics, Oogenesis physiology, Ovulation physiology, Prostaglandins physiology, Zebrafish physiology
- Abstract
This study explored the potential for ovarian-derived prostaglandins (PGs) to be involved in the regulation of oocyte maturation and ovulation in zebrafish. It was demonstrated that cultured vitellogenic follicles have the capacity to produce prostaglandin E(2) (PGE(2)) and PGF(2alpha) in response to arachidonic acid (AA) in a concentration-dependent manner, and that AA stimulates the in vitro production of 17beta-estradiol (E(2)). The production of AA-stimulated PGF(2alpha) was significantly reduced by treatment with the non-selective cyclooxygenase (COX) inhibitor, indomethacin (INDO). Treatment of full-grown follicles with AA did not induce oocyte maturation as assessed by germinal vesicle breakdown, but INDO significantly decreased the rate of spontaneous maturation. Using Real-Time PCR, it was shown that follicles of different developmental size classes (primary growth and pre-vitellogenic, early-vitellogenic, and mid- to full-grown vitellogenic) express enzymes that release (cytosolic phospholipase A(2) (cPLA(2)); phospholipase Cgamma1) or metabolize (COX-1, COX-2, and prostaglandin synthase-2) AA to PG metabolites. The expression of cPLA(2) was found to be significantly greater in full-grown follicles compared to follicles of the pre- and early-vitellogenic stages. In vivo studies demonstrated that breeding groups of zebrafish exposed to 100 microg/L INDO exhibited reduced spawning rates and clutch sizes compared with control and 1 microg/L INDO exposed fish. In other studies, it was shown that naturally spawning groups of females exhibit increased ovarian levels of PGF(2alpha), E(2), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (a maturation-inducing hormone in zebrafish) near the time of ovulation compared with non-breeding females. Collectively, these experiments indicate that the AA pathway in zebrafish ovaries is involved in the regulation of oocyte maturation and ovulation and a non-selective inhibitor of COX disrupts these processes.
- Published
- 2008
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