Open field is more sensitive than automated activity monitor in documenting ouabain-induced hyperlocomotion in the development of an animal model forbipolar illness

1. Intracerebroventricular (ICV) administration of ouabain to rats induces motor hyper- and hypoactivity that have been hypothesized to model the mani a and depression of bipolar illness, respectively. 2. The extent of ouabain-induced change in activity may vary according to t he test environment. 3. To determine the degree of differential response to ICV ouabain in the o pen field and automated activity monitors, the authors examined a large num ber of animals (n=40) in both environments. 4. ICV ouabain produced a four-fold increase in open field activity versus ICV artificial cerebrospinal fluid (aCSF) (mean +/- SD: 258.7 +/- 316.61 vs . 84.8 +/- 86.16 squares traversed) (t = 2.648, P = 0.011), but did not alt er horizontal activity in automated activity monitors (8193.5 +/- 4902.52 v s. 7088.47 +/- 3046.85 beam interruptions) [t = 0.847, P = 0.4). This incre ase in activity persisted for at feast one week (161.0 +/- 186.35 for ICV o uabain vs. 46.1 +/- 47.46 for ICV aCSF, P = 0.065). 5. Open field is superior to automated activity monitors in capturing ouaba in-induced hyperlocomotion response.