PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P531) Effects Of Multiple Estrogenic Contaminants on Organophosphate-induced Neurotoxicity in Juvenile Chinook Salmon.

Amweg, Erin^*,1, Weston, Donald¹, ¹ University of California, Berkeley., Berkeley, CA, US

ABSTRACT- Juvenile salmon move through urban streams and rivers as they migrate towards the ocean, with potential exposure to complex mixtures in sewage and from various industrial effluents. In this study, we exposed chinook salmon fry, Onchorhychus tshawytscha, to mixtures of common estrogenic contaminants as well as the organophosphate pesticide Chlorpyrifos. Organophosphate pesticides are activated by CYP1A to the neurotoxic oxon form, which inhibits acetylcholinesterase and impairs neural signaling. Since p450s are also hormonally regulated, we hypothesized that exposure to estrogenic compounds would reduce neurotoxicity. -estradiol. ethynylestradiol, -sitosterol, and 4-nonylphenol were used singly and in combination to determine their impact on brain acetylcholinesterase activity, CYP1A activity, and also to measure additivity of the compounds through quantification of liver vitellogenin levels. Previous work showed that at high doses, 4-nonylphenol significantly decreased acetylcholinesterase inhibition in the brain; however, the response seems to be independent of hormonal CYP1A modulation.

Key words: organophosphates, estrogen, salmon, acetylcholinesterase