Measuring Behavior 2005: Malatynska et al.

Reduction of dominant or submissive behavior as models for antimanic or antidepressant drug testing: Technical considerations

E. Malatynska, A. Pinhasov, J. Crooke and D.E. Brenneman

Johnson & Johnson Pharmaceutical Research & Development, L.L.C, Spring House, PA, USA

Using observer-based scoring we have previously shown that dominant behavior measured in a food competition test, can serve as a model of mania and submissive behavior as a model of depression. These two models are based on a selection of animal pairs where one animal shows the behavioral trait of dominance and another submissiveness. Three criteria have to be achieved to assign dominant or submissive status to the animal. First, there has to be a significant difference between the average daily drinking scores of both animals in a pair. Second, the dominant animal score has to be at least 25% greater than the submissive animal’s score. Third, there must not be any ‘reversals’ during the pair selection week, where the putative submissive rat out-scores its dominant partner on isolated occasions. Twenty-five to thirty-three percent of the initial animal pairs achieve these criteria. The importance of the application of these criteria to the selection process as a reflection of the experimental outcomes will be discussed in this presentation.

Recently we have used automatic scoring of the time spent by rats in the feeder zone done by a multiple subject video-tracking system. We have noticed a similar reduction of rat submissive behavior after treatment with antidepressants, imipramine or fluoxetine as we have done previously with observer-based scoring. It is possible to observe four pairs of rats during each five-minute experimental session (one set). A duplicate parallel set enables the immediate switch to the observation of the next four pairs. The multiple video-tracking system increases the capacity of antidepressant drug testing and reduces the variability between observations.

The onset time of the drugs in the two models was delayed. The mechanism of delayed therapeutic activity of antimanic and antidepressant drugs is not known and animal models reflecting this clinical feature will enable progress in this area. The application of the reduction of submissive behavior model to such studies will also be discussed.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.