Putative steroidal pheromones in the round goby, Neogobius melanostomus: Olfactory and behavioral responses

To identify potential hormonal pheromones of the round goby (Neogobius mela nostomus), a species recently introduced to the Great Lakes, we used electr o-olfactogram (EOG) recording to examine olfactory responsiveness to more t han 100 steroids and prostaglandins. Neogobius detected free and conjugated 18-, 19- and 21-carbon steroids, but did not detect prostaglandins. EOG cr oss-adaptation, used to determine if Neogobius can discriminate the detecte d compounds at the sensory level, suggested that the detected steroids act on four classes of olfactory receptor mechanisms named (according to the mo st potent Ligand for each): estrone, 1 betaP-estradiol-3 beta -glucuronide, etiocholanolone, and dehydroepiandrosterone-3-sulfate. Although none of th e detected steroids induced reproductive behaviors, exposure to steroids fr om three of the four receptor classes (estrone, 17 beta -estradiol-3 beta - glucuronide, or etiocholanolone) increased ventilation rate in males, where as only etiocholanolone increased ventilation rate in females. Using the ve ntilation increase as a behavioral bioassay of steroid detection, behaviora l cross-adaptation studies in males demonstrated that steroids discriminate d at the sensory level are also discriminated behaviorally. These findings suggest the round goby may use steroids as putative pheromones.