EMBRYONIC MORTALITY IN SPRAGUE-DAWLEY RATS INDUCED BY SNAKEWEED (GUTIERREZIA-MICROCEPHALA)

Three experiments were conducted to determine the effects of ingested snakeweed foliage (SW) on gestating rat embryos. Mature female Sprague -Dawley rats were paired with male rats and after breeding were random ly allotted to diets containing up to 15% SW. Feeding SW caused a decr ease (P < .01) in the percentage of live embryos and markedly increase d (P < .01) the percentage of dead or resorbed embryos. Snakeweed decr eased (P < .01) feed intake in a dose-dependent manner and caused BW l oss (P < .01) compared with control animals. However, decreased feed i ntake had no effect on gestating embryos. Rats fed the control diet, w ith intakes restricted to equal the average intake of rats fed SW, and those with ad libitum access to the control diet had similar percenta ges of live and dead embryos (P > .10). Serum clinical profiles reflec ted undernutrition (decreased triglycerides and cholesterol; P < .01) and mild toxicosis (elevated blood urea nitrogen, creatinine, and bili rubin; P < .01). Because fluid accumulation was noted in the uterus of several rats fed SW, a uterine weight bioassay was conducted. Snakewe ed, fed as 10% of the total diet, decreased (P < .01) uterine weight o f immature Sprague-Dawley rats. Ingestion of SW during early gestation caused embryonic mortality that could not be attributed to undernutri tion or estrogenicity.