Date of Award:
Master of Science (MS)
Animal, Dairy, and Veterinary Sciences
R. P. Sharma
Locoweed, a well-known teratogenic plant affecting livestock, is prevalent in mountain regions of the Western United States. Two common species (Astragalus lentiginosus and A. wootoni), administered to pregnant rats, induced behavioral deviations in their offspring. Treated mothers consumed less feed and gained less wieght during gestation than controls when gavaged locoweed at the rate of 1 gram whole plant per day on days 7 through 17 of gestation. A. lentiginosus reduced pup weight at birth (13% less than controls) and this weight reduction (as much as 29% less than controls) continued at least four weeks. A. lentiginosus also reduced number of offspring born alive (34.9% less than controls) and number which survived until weaning (86.4% less than controls). No gross malformations were observed in the offspring of loco-treated dams. however, when the pups were subjected to behavioral testing (beginning at 30 days of age), deviations were observed. there was considerable difference among the treatment groups when tested with the activity wheel (P=.0000). Water-intubated controls did not differ from non-fed controls, but the two loco-treated groups differed in opposite directions from controls. A. lentiginosus offspring were more active (26.5%) overall than other groups, and had an abnormal pattern of activity in the day to evening night activity totals. A. wootoni offpsring were less active (25%) than other groups in the activity wheel. Significant differences among groups were also observed in the open-field test. The trend was toward decreased activity (P=.027; 31 and 43% less than controls - A. lentiginosus and A. wootoni respectively) and increased number of fecal boluses (P=.06; 45.5 and 19.3% more than controls - A. lentiginosus and A. wootoni respectively) in the loco-treated offspring. There were no significant differences in avoidance conditioning in a two-way shuttle box among the groups, though the loco offspring made fewer avoidance responses than controls. Alizarin Red-S staining of fetuses revealed no skeletal defects in the pups. Microscopic examination of maternal tissues showed the kidney and liver degenerative changes which are typical of locoweed intoxication: primarily vacuolation of proximal tubular epithelium and of the hepatocytes. Tissues from pups on day of birth also showed mild kidney and liver changes. Older pups had no visible microscopic deviations from normal. The results indicate that the locoweed teratogen produces behavioral deviations in the offspring of rats in the absence of gross malformations.
Nelson, Benjamin K., "Subtle Teratogenic Effects of Locoweed in Rats" (1977). All Graduate Theses and Dissertations. 4570.
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