QUANTITATIVE-ANALYSIS OF ABNORMAL SPONTANEOUS BEHAVIOR AND CLINICAL-ASSESSMENT OF THE STARGAZER RAT

A new mutant derived from the Zucker rat strain called stargazer (homo zygous stg/stg) displays abnormal behavior that is characterized by pr onounced arching of the neck (''stargazing''), rapid circling, and con spicuous hyperactivity. Results of serologic assays performed by two i ndependent diagnostic laboratories have indicated that the abnormal be havior in the stargazer is not the result of a viral or bacterial infe ction, In this report, different groups of stargazer rats and their no rmal-behaving littermates (heterozygous stg/+) were assessed with rega rd to spontaneous behaviors, heart rate, blood pressure, and plasma bi ochemical profiles. Besides frequent stargazing, the predominant behav ioral feature of the stargazers was extreme hyperactivity; they had se venfold greater activity than the normal littermates (P < 0.05), expre ssed in the form of rapid ambulation and tail-chasing, The stargazers had significantly greater daily calorie and water consumption, despite being significantly smaller in body weight than the littermates (P < 0.05 for all). However, urine output was not different between the two groups. Heart rate and blood pressure also were not different, Starga zers had significantly lower total triglycerides concentration and low er aminotransferase activity than littermates (P < 0.05 for both), a f inding probably related to their smaller body size, It is concluded th at stargazer rats are extremely hyperactive but normotensive; heterozy gous littermates are behaviorally normal, despite being carriers of th e stg gene; and routine diagnostic blood testing revealed no important differences between the stargazers and their unaffected littermates.