PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P530) Does a chemical exposure change thyroid hormone levels in salmon embryos?
Honkanen, Jani*,1, Sorsa, Karoliina1, Penttinen, Olli-Pekka1, Kukkonen, Jussi1, 1 University of Joensuu, Joensuu, Finland
ABSTRACT- In fish eggs thyroid hormones are known to be maternal origin during the earliest phases of development. Earlier studies have shown that the concentrations of thyroid hormones decrease gradually during the embryonic phase. However, the role of maternal hormones is not fully understood in fish development. It seems that they have an essential role before embryonic production of thyroid hormones initiates. Currently it is believed that some chemicals may change the elimination rate of thyroid hormones. Possible changes in elimination rates may be a result of similar elimination mechanisms (such as glucuronidation) in both chemicals and hormones. Because thyroid hormones are essential for embryonic development, possible changes in their concentrations in fish eggs might cause developmental disorders. The effects of waterborne chemicals (bisphenol A, pyrene and ultrasitosterol) on thyroid hormone concentrations in tissue extracts were studied in landlocked salmon (Salmo salar m. sebago) eggs. The eyed eggs were exposed to chemicals at two temperatures (+5 oC and +10 oC). The exposure concentrations of chemicals were sublethal and therefore no high mortality of embryos was observed. The exposure time was 4 weeks for eggs at +5 oC and 2 weeks at +10 oC. Samples for tissue extraction and hormone analyses were taken three times during the exposure period. Preliminary results of our experiments indicate that chemical exposure may induce changes in T3 and T4 levels in salmon embryos.
Key words: thyroid hormones, bisphenol A, sitosterol, pyrene