LI, Weiming; CHUNG-DAVIDSON, Yuwen; SIEFKES, Michael J.; WU, Hong; REES, Chris B.; Michigan State University; Michigan State University; Michigan State University; Michigan State University; Michigan State University: Pheromone Regulation of Reproductive Neuroendocrine in the Sea Lamprey

The sea lamprey (Petromyzon marinus) is a jawless fish that relies on chemical communication to mediate many functions throughout its life history. Our objective is to elucidate the mechanisms whereby a male pheromone mediates reproductive function through regulation of the hypothalamus-pituitary-gonad axis. In previous studies, we have shown that male sea lampreys release through their gills two bile acids, 3 keto-petromyzonol sulfate (3kPZS) and 3 keto-allocholic acid (3kACA), upon spermiation. In this study, we used immunocytochemistry, real time quantitative PCR, in situ hybridization and radioimmunoassay analyses to demonstrate that 3kACA induces neuronal activation in the forebrain, elevation in transcripts of lamprey GnRH I prehormone mRNA (P<0.05), and increases in circulatory sex steroids (P<0.05) in less mature sea lampreys of both sexes. We conclude that 3kACA is an essential component of a male pheromone that promotes synchrony in reproductive physiology and behavior. Interference of this pheromone system may offer a target for environmentally benign control of the sea lamprey, a highly destructive exotic species in the Laurentian Great Lakes of North America. This research is supported by the Great Lakes Fishery Commission, Great Lakes Protection Fund and National Institute of Health.