Mechanistic effects of a triazine pesticide on reproductive endocrine function in mature male Atlantic salmon (Salmo salar L.) parr

The s-triazine pesticide atrazine, a known contaminant of ground and surface water, had a significant sublethal impact upon the pheromonal mediated endocrine system in mature male Atlantic salmon (Salmo salar L.) parr. Previous studies have demonstrated that ovulated female salmon release a priming pheromone in their urine (considered to be an F-type prostaglandin) which is subsequently detected by the olfactory system of mature male salmon and results in increased levels of plasma sex steroids and expressible milt. Short-term exposure of the olfactory epithelium of male parr to concentrations of the pesticide ranging from 2.0-20 mu g L-1 significantly reduced the olfactory response to prostaglandin F-2 alpha. In addition, exposure of male parr to atrazine significantly reduced their ability to respond to the priming effect of ovulated female salmon urine. The priming effect on milt and plasma 17,20 beta-dihydroxy-4-pregnen-3-one levels were reduced at water atrazine concentrations at and above 0.04 mu g L-1. The priming effect of urine on plasma testosterone and 11-ketorestosterone concentrations was also affected at pesticide concentrations at and above 3.6 and 6.0 mu g L-1, respectively. Atrazine also affected the accumulation of steroids in bile rind directly impacted upon the testes, modifying 17,20 beta-dihydroxy-4-pregnen-3-one and androgen secretion. The results of the study are discussed in relation to the possible sublethal impacts of atrazine on the biology of Atlantic salmon with particular emphasis on olfaction and reproduction (C) 1998 Academic Press.