The effects of sex pheromones on locomotor activity in adult female sea lamprey (Petromyzon marinus L.) (#804)
Sea lamprey, Petromyzon marinus L., spermiated males release sex pheromones that attract ovulated females to the nest for spawning. Previous field studies have demonstrated that washings from spermiated males (SMW) reduce locomotor activity in pre-ovulated and ovulated females as well as elicit a switch from a nocturnal rhythm to arrhythmic behavior in ovulated females. Our goal was to elucidate the effects of individual compounds found within SMW on locomotor activity of adult females in controlled laboratory settings. Our results show that more than one compound is responsible for the changes in locomotor activity and pattern, and that the compounds that are effective depend on the maturity stage of the female. We hypothesize that behavioral changes are induced via the regulation of neural circuits between the olfactory bulb and the epithalamus, a region that includes the locomotor-dependent, photosensitive pineal complex and the habenula, which is an area associated with the limbic system and the integration of olfactory sensory information. Additionally, we investigated changes in γ-aminobutyric acid (GABA), which is known to play a role in the sea lamprey locomotor system, using liquid chromatography tandem mass spectrometry and RT-qPCR to measure GABA in the brain and the gene expression of multiple GABA receptors in the brain and pineal complex, respectively. Finally, as clock genes play a role in controlling the timing of locomotor activity, we examined gene expression changes in four major clock genes in the brain and pineal complex using RT-qPCR. Our results demonstrate that SMW compounds significantly increase GABA concentrations, decrease multiple GABA receptor gene transcript levels, and suppress the expression of several clock genes in the brain and pineal complex. We speculate that the interplay between these systems elicits the documented changes seen in adult female sea lamprey locomotor activity. This study was supported by the Great Lakes Fisheries Commission.