Relating olfactory neurotoxicity to altered olfactory-mediated behaviors in rainbow trout exposed to three currently-used pesticides
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| Authors: | Tierney, KB; Singh, CR; Ross, PS; Kennedy, CJ |
| Year: | 2007 |
| Journal: | Aquatic Toxicology 81: 55-64 Article Link (DOI) |
| Title: | Relating olfactory neurotoxicity to altered olfactory-mediated behaviors in rainbow trout exposed to three currently-used pesticides |
| Abstract: | Odor-evoked neurophysiological responses can form the basis for behavioral responses. Here we first characterized olfactory-mediated behavioral and neurophysiological responses of juvenile rainbow trout to the amino acid L-histidine, then looked at whether there were similar responses to the carbamate antisapstain IPBC and the herbicides atrazine and Roundup((R)), and lastly explored how exposures to these pesticides modified the L-histidine responses. Trout were behaviorally attracted to 10(-7) M L-histidine (as assayed in a counter-current olfactometer), but this preference behavior switched to indifference with higher histidine concentrations. Neurophysiologically, the summed electrical responses of peripheral olfactory neurons, as measured using electro-olfactogram (EOG), was 0.843 +/- 0.252 mV to 10(-7) M L-histidine. Of the pesticides, only Roundup((R)) evoked EOGs, indicating the amino acid-based pesticide may have acted as an odorant, and generated a behavioral response: it was avoided at active ingredient [AI; glyphosate isopropyl amine] concentrations >= 10 mg/l. With 30 min pesticide exposures, 10(-7) M L-histidine preference behavior was eliminated following exposure to 1 mu p/l IPBC and atrazine, and 100 mu g/l AI Roundup((R)). Similarly, 10(-7) M L-histidine-evoked EOGs were significantly reduced by exposure to 1 mu g/l IPBC, 10 mu g/l atrazine, and 100 mu g/l AI Roundup((R)). When combined together, the results demonstrate that typical preference behavior can be abolished when neurophysiological responses are reduced by > 60% of control. This asymmetry in response thresholds suggests that behavioral responses may be more sensitive toxicological endpoints than netirophysiological responses. (c) 2006 Published by Elsevier B.V. |
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