Abstract
The homozygote mutant mouse tottering (chromosomal designation tg) is distinguished from the heterozygote by an ataxic gait and the occurrence of spontaneous stereotypic seizures. We determined the effects of this mutation on other neurally controlled behaviors. Three behaviors were studied: swimming ability, balance on the rotorod, and activity in the open field. Swimming ability was greatly reduced ( P < 0.001) in ( tg tg ) mice compared with wild type C57BL 6J (+/+) mice when rated on a scale designed to measure “swimming success,” whereas scores for “vigor” were normal. Heterozygotes ( tg/+) had normal swimming “vigor” but showed a bimodal distribution on the “success” scale. Open field activity of ( tg tg ) mice was significantly less ( P < 0.002) compared with heterozygote littermates. Homogyzous tottering mice were unable to maintain balance on a rotating wooden rod (rotorod test), whereas heterozygotes readily learned this task. Brain weights of 8-week-old mice were examined and found to be equal except for the cerebellum, which weighed less in ( tg tg ) mice. No significant differences in the degree of impairment between sexes or the age of testing were found. These results suggest a widespread involvement of the tg gene mutation in normal mouse behavior; however, other interpretations have not been ruled out.
Published Version
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