Publication Abstract

The three-spined stickleback as the Eurepoean sentinel and a model species for endocrine disruption research

I. Katsiadaki, I. Mayer and A. P. Scott

An increasing number of studies have linked the appearance of reproductive disorders in wildlife species to exposure to environmental contaminants that are capable of eliciting responses typically induced by sex steroids, termed endocrine-disrupting chemicals (EDCs). Endocrine Disruption in the Marine Environment (EDMAR) was a UK government-funded programme, has been very successful in developing and validating a novel in vivo biomarker test for the detection of androgens and anti-androgens. The test is based on measurement (by ELISA) of spiggin - the androgen-induced protein which is produced by the kidney of the male three-spined stickleback during breeding and used as a cementing or glue substance for the building of a nest. Although it has been well established that spiggin is under the control of androgens, the way of quantifying its production involved measuring the height of the epithelium cells lining the secondary segments of the renal tubules. The specific ELISA for spiggin shows a strong correlation (r²=0.93), can be carried out much faster and has a considerably higher response range than the histological method. Clear graded responses were obtained by exposing intact females to increasing doses of 17a -Methyltestosterone and 5a -Dihydrotestosterone administered via the water over 3-week periods, revealing that the lowest effective concentrations for these two steroids were 100ngl^-1 and 4µgl^-1, respectively. Female sticklebacks that were exposed to pulp mill effluent, which is of known androgenicity, also produced spiggin in their kidneys. It has been established that spiggin production is inhibited in males and androgen-stimulated females by flutamide (FL), a well-known anti-androgenic drug, used in the treatment of prostate cancer. Using a system where female sticklebacks are simultaneously treated with a model androgen and suspected antiandrogens we have shown the antiandrogenicity of selected pesticides. The development of an ELISA for stickleback vitellogenin and its application to whole body homogenates and tissue extracts is also described. These results indicate that the female stickleback is a unique bioassay organism for detecting xenobiotic contamination in the aquatic environment. The advantages of the stickleback as a model for endocrine disruption research in Europe (where the majority of endocrine disruption studies have been on non-indigenous species, with no androgen endpoint) are highlighted.