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    Einfluß von verminderter Zunahme bzw. Abnahme des Körpergewichtes der Muttertiere (maternale Toxizität) auf Embryonen bei Kontroll- und behandelten Ratten (1998)

    Art
    Hochschulschrift
    Autor
    Ligensa, Anja
    Quelle
    Berlin, 1998 — 155 Seiten
    Kontakt
    Institut für Tierschutz und Tierverhalten

    Königsweg 67
    Gebäude 21, 1. OG
    14163 Berlin
    +49 30 838 62901
    tierschutz@vetmed.fu-berlin.de

    Abstract / Zusammenfassung

    Developmental toxicity studies are performed to investigate the effects of noxae on parent animals and their offspring. For embryo/fetotoxicity studies, pregnant animals are exposed to the drugs/chemicals together with their fetuses during gestation. The knowledge of the effects is a decisive prerequisite for risk assessments and classification of the substance examined. Exact differentiation of the effects on the mother and the fetus can only be made when the curves of the dose-response relationship of the effects differ. Differentiation is impeded when dosages induce embryofetal as well as maternal toxic effects. In these cases, it has to be decided whether the embryo/fetotoxicity is a primary, i.e. specific effect of the given substance, or a secondary, i.e. non specific effect mediated by the maternal toxicity.Effects on parameters, such as (fetal weight, esorption rate, anomalies) are regarded as embryo/fetotoxicity. On the other hand, maternal body weight changes are generally considered to be an indication of a toxic effect on the dams (maternal toxicity).The following hypothesis can be suggested based on the assumption that maternal toxicity always induces embryo/fetotoxicity, regardless of the specific effect of the substance: Litters from dams with maternal toxicity exhibit high rates of embryotoxicity than litters whose mother animals do not exhibit toxic effects. The main objective of this doctoral thesis was to investigate this hypothesis.Analysis of the data from the control groups as well as from the treated groups revealed that there is no correlation between maternal toxicity (decrease in maternal body weight during gestation) and embryo/fetotoxicity (decreased fetal weight, increased resorption rate and anomalies).It is evident that there is not necessarily an association between the maternal toxicity and embryotoxicity. However, it must not be concluded that maternal toxicity never leads to embryo/fetotoxicity, rather, all toxic effects should be taken into account to find out their interaction in every developmental toxicity study.