Olfactory sensitivity and specificity of Arctic char, Salvelinus alpinus, to a putative male pheromone, prostaglandin F2α

Actively spawning male Arctic char, Salvelinus alpinus, release immunoreactive F-prostaglandins into the water that attract ovulated females and elicit spawning behaviour. To investigate a possible role played by the olfactory system, we determined the sensitivity and specificity of the char to prostaglandins by the electro-olfactogram (EOG) using a newly devised stimulatory apparatus. Of 18 prostaglandins tested, PGF(2 alpha) and two synthetic analogues, 16,16-dimethyl-PGF(2 alpha) and U-46619, were detected at threshold concentrations of 0.5-1.0 x 10(-11) M, and at a concentration of 10(-8) M evoked an EOG response equivalent to that of 10(-5) M L-serine. Olfactory nerve twig recordings further demonstrated that the EOG responses were transduced into nerve impulses and transmitted to the brain. No difference was found in the responses between sexes and maturational stages. We conclude that PGF(2 alpha) is a candidate of the male pheromone of Arctic char, supporting our previous behavioural studies. (C) 2000 Elsevier Science Inc. All rights reserved.