Differential open field reactivity in HAS and LAS rats

To identify potential differences in emotional reactivity in high (HAS) and low (LAS) alcohol-sensitive rats in open field tests, 20 ethanol naive, 19th generation HAS and 20 LAS rats from the University of Colorado's Alcohol Research Center each received three consecutive daily 20-min exposures to a 1-sq m open field. The results of repeated-measures ANOVA and Keuls tests, performed on each of five concurrently recorded behaviors, indicated that, compared to HAS rats, LAS animals exhibited significantly greater latencies to begin ambulation, elevated ambulation, and rearing scores that failed to habituate over 3 days, and an increasing intersession bolus count. In addition, significant positive correlations occurred between days 2 + 3 (but not day 1) ambulation and bolus counts in LAS but not HAS rats, and between day 1 ambulation and (i) rearings and (ii) center square entries in HAS but not LAS rats. Together with other cited data, these results provide support for a hypothesis of relatively greater emotional reactivity in LAS rats and illustrate the need for multiple measures and sessions in evaluating open field behavior.