The role of F-series prostaglandins as reproductive priming pheromones in the brown trout

Electrophysiological studies demonstrated that the olfactory epithelium of mature male brown troutSalmo trutta parr was acutely sensitive to F-series prostaglandins (PGFs) PGF sub(1 alpha ) and PGF sub(2 alpha ), with detection threshold concentrations of 10 super(-11) . The olfactory epithelium was also sensitive to the PGF metabolite 15-ketoPGF sub(2 alpha ) (threshold 10 super(-8) ), but did not detect a further metabolite, 13,14,-dihydro-15-ketoPGF sub(2 alpha ). Immature brown trout did not detect any of the prostaglandins tested. Exposure of mature male brown trout parr to waterborne PGF sub(1 alpha ) and PGF sub(2 alpha ) (concentration 10 super(-8) ), resulted in significant increases in levels of expressible milt and the plasma concentrations of 17,20 beta -dihydroxy-4-pregnen-3-one, testosterone and 11-ketotestosterone. The olfactory epithelium of both immature and mature male brown trout parr was sensitive to the urine and ovarian fluid from ovulated female brown trout. Exposure of mature male brown trout parr to ovarian fluid resulted in an increase in the levels of plasma 17,20 beta -dihydroxy-4-pregnen-3-one whilst exposure to urine increased the levels of expressible milt. In addition, PGF sub(2 alpha ) was found to be present within both the urine and ovarian fluid of mature female brown trout. It is suggested that the F-series prostaglandins have a role as priming pheromones in male brown trout. Copyright 2002 The Fisheries Society of the British Isles