The Biological Significance of Prostaglandins and Related Eicosanoids in Invertebrates

Abstract

SYNOPSIS. Prostaglandins and related eicosanoids are oxygenated metabolites of C20 polyunsaturated fatty acids. These compounds have been detected in many vertebrate and invertebrate species that represent all major phyla. The significance of eicosanoids relates to two broad areas of animal biology, one as mediators of crucial cellular events and another in mediation of certain ecological interactions. Eicosanoids exert physiological actions in reproduction, including release of egg-laying behavior in some insects, hatching in barnacles, egg-production in snails, spawning in bivalves, oocyte maturation in sea stars, and prevention of polyspermic fertilizations in sea urchin eggs. Eicosanoids are also involved in salt and water transport physiology (insects and bivalves), neurophysiology (mollusks) and cellular immune defenses (insects). I propose that some eicosanoid actions are fundamental to animal physiology. Eicosanoids also mediate certain host-parasite and predator-prey interactions. These include skin penetration by blood fluke larvae, blood feeding by ticks and predator avoidance by certain octocoral and nudibranchs. Research in eicosanoids yields insights that help explain details of physiological and ecological phenomena in vertebrates and invertebrates. Although we have seen considerable progress in our appreciation of eicosanoids in invertebrates, we are sorely lacking in our understanding of the biochemical mechanisms of eicosanoid actions in invertebrates. I suggest that research in this area will yield meaningful insights into the physiology and ecology of invertebrates.