MP9 Developing Reliable Endpoints in Avian Endocrine Testing at the Population Level
Room 12A/B, Level 4
2:10 PM - 5:30 PM, Monday, 10 November 2003
Chair: Brugger, Kristin ,
(158) Suitability of additional parameters in reproduction studies in Japanese quail: preliminary experience.
Niemann, L.1, Selzsam, B.1, Gericke, Chr.2, Chahoud, I.2, 1 Federal Institute for Risk Assessment, Berlin, Germany2 Free University, Institute for Clinical Pharmacology and Toxicology, Berlin, Germany
ABSTRACT- In an ongoing research project funded by the German Ministry of Environment, additional toxicological endpoints are investigated for their suitability to be included in reproduction studies in birds. The main objective of our efforts is the selection of methods and parameters which might contribute to a better identification and characterization of hormone-mediated effects on male and female fertility and reproductive success. Apart from a rather large database on untreated Japanese quail (Coturnix coturnix japonica), our current experience is mainly based on a small number of recently performed experiments in this bird species using the anti-androgenic fungicide vinclozolin, the synthetic hormone methyltestosterone and the organic tin compound fentin which is known to inhibit aromatase at least in mammals and may also affect thyroidal activity. The outcome of these one-generation studies will be briefly reviewed and compared to previous results in the Bobwhite quail (Colinus virginianus). Preliminary results suggest that plasma concentrations of certain hormones like estradiol or testosterone, spermatide count in the testis and eggshell strength are the most promising candidate endpoints to become routinely examined in the future. It has been confirmed once more that testis weight, as in mammals, may be a very sensitive parameter, too. Histopathology, flow cytometric differentiation of testicular cell populations or determination of aromatase expression and activity could also provide valuable information but have not been sufficiently evaluated yet. The additional information must be compared with the results and conclusions obtained by assessing the "classical" reproductive endpoints. More studies including, e.g., substances with (anti)estrogenic properties are needed to decide whether the inclusion of new endpoints would actually enhance the reliability and sensitivity of testing chemicals for adverse effects on reproduction in birds.
Key words: Japanese quail, Endocrine disrupture, Reproduction, Additional test parameters