Sublethal effects of a carbamate pesticide on pheromonal mediated endocrine function in mature male Atlantic salmon (Salmo salar L.) parr |
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| Authors: | CP Waring A Moore |
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| Institution: | (1) School of Biological Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK;(2) Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk, NR33 0HT, UK |
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| Abstract: | The sublethal effect of the carbamate pesticide carbofuran on the priming pheromonal system of Atlantic salmon (Salmo salar L.) was investigated. 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 mature male salmon and results in increased levels of plasma sex steroids and expressible milt. In the present study, electrophysiological recordings from the olfactory epithelium of mature male salmon parr indicated that the responses to prostaglandin F2 (PGF2) were significantly reduced at nominal concentrations of carbofuran as low as 1.0 µg l-1, and the threshold of detection was reduced 10-fold. A 5 day exposure to carbofuran significantly reduced the ability of male parr to respond to PGF2 stimulation. The priming effect of PGF2 on milt and plasma 17,20 -dihydroxy-4-pregnen-3-one levels were abolished at water concentrations at and above 2.7 µg l-1. In addition, the priming effect of PGF2 on plasma testosterone and 11-ketotestosterone concentrations was abolished at water carbofuran concentrations above 6.5 µg l-1. Exposure to similar concentrations of carbofuran also resulted in a reduction in the levels of free and glucuronidated steroids in the bile of PGF2 primed male parr. The effect of carbofuran on the priming response did not appear to be due to a direct effect on the testes, since the ability of testes to respond to pituitary extract stimulation in vitro was not impaired in carbofuran-exposed males. Carbofuran appeared to reduce significantly or abolish the priming pheromonal system in mature male parr by directly affecting the ability of the olfactory system to detect PGF2, although the toxicological mechanism involved is as yet unknown. The results are therefore discussed in relation to the possible sublethal effects of carbofuran on reproduction in the Atlantic salmon. |
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| Keywords: | Atlantic salmon Salmo salar pheromone prostaglandin olfaction carbofuran pesticides toxicology |
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