| Summary: | National Natural Science Foundation of China [40776080]; Natural Science Foundation of Fujian Province [2007J0068] The role of PGE(2) as a putative sex pheromone in Chinese black sleeper Bostrichthys sinensis was investigated, using immunocytochemistry and how the immunoreactivities of the prostaglandin E-2 (PGE(2)) receptor subtypes EP1, EP2, EP3 and EP4 varied with reproductive status in the olfactory system was determined. The results showed that PGE(2) receptors were present in the whole of the olfactory system of B. sinensis, and that the number of receptors was linked to the reproductive status of the fish. The densities of EP1 immunoreactivity in the olfactory epithelium of mature fish were significantly (P < 0 center dot 01) higher than those in immature fish of both sexes, and the densities of EP2 and EP3 immunoreactivities in mature fish were higher (but not significantly) than those in immature fish of both sexes. In the olfactory nerve, the density of EP2 immunoreactivity in mature fish was higher (but not significantly) than that in immature fish in both sexes. In the olfactory bulb, the densities of EP1-4 immunoreactivities in mature females were significantly (P < 0 center dot 05 or < 0 center dot 01) higher than those in immature females, and the density of EP4 immunoreactivity in mature males was significantly (P < 0 center dot 01) higher than that in immature males. As far as is known, the present study is the first report of the immunoreactivities of PGE(2) receptor subtypes in the olfactory system of a teleost, and offers new findings regarding the role of PGE(2) as sex pheromone and hormone in the reproductive behaviour and pheromonal communication of B. sinensis.
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