Influence of dietary soy isoflavones on immature hamster uterotrophic and Hershberger assays

Abstract

To select appropriate diet for hamsters used in the uterotrophic and Hershberger assays two rodent diets were compared: Murigran (Agropol, Poland) and Altromin 7010 (Altromin Spezialfutter GmbH&Co., Germany). The contents of bioactive compounds in feeds were evaluated by liquid chromatography, and their oestrogenic activity by yeast enhanced green fluorescent protein assay. In opposition to Altromin, Murigran contained high amounts (µg/kg) of genistein (765 600) and daidzein (132 000), and the oestrogenic activity of these compounds, expressed as 17β-oestradiol equivalent concentration (EEQ), was found to be 9.54 µg EEQ/kg. In in vivo study, Murigran induced a high degree of oestrogenisation in immature hamsters, and females failed to exhibit a normal uterine response to recommended dose of a model oestrogen agonist 17α-ethinyloestradiol. There was no influence of the diet on the weight of five accessory sex organs (ASO): ventral prostate, seminal vesicles with coagulating glands, levator ani bulbocavernosus muscles, Cowper`s glands, and glans penis of control males. However, the impact on ASO response to model androgen agonist, testosterone propionate was observed. The obtained results provide the evidence that phytooestrogen-rich feed modulates the oestrogenic and androgenic response to chemicals.

Usefulness of immature golden hamster (Mesocricetus auratus) as a model for uterotrophic assay

“…It was found that soy isoflavones present in feed at high amounts interfere with the value of animal models and with experimental results (10). An example of this was a decreased sensitivity of immature rats (5) and hamsters (20) in the uterotrophic bioassay.…”

In vivo study of the oestrogenic activity of milk

“…To assess the risk to consumer health and ensure the safety of infants and children as the most vulnerable groups it is important to study the effects of xenohormones on the endocrine system using the available in vivo models. Therefore, biotests are particularly useful for assessing the total hormonal load of different diet types ( 13 , 19 ). The rodent uterotrophic bioassay is the preferred in vivo oestrogenicity screen and is the “gold standard” for oestrogenicity study ( 23 ).…”