Behavioral comparisons of the Tsukuba emotional strains of rats (Rattus norvegicus) in three types of novel situations.

Tsukuba High- and Low-Emotional rats (THE and TLE), Wistar-Imamichi/Iar rats (control group for the Tsukuba Emotional rats), and F344/DuCrj rats were tested in three types of novel situations: the open field, a runway devised as a type of open field with a shelter, and an I-maze devised as a narrow runway with shelters and covers to remove rats' freezing behavior against predatory attack. The TLE was the most active, and the THE the least active in the three tests. While the F344 was inactive in the runway and the I-maze, this strain was as active as the Wistar-Imamichi in the open field. While the THE and F344 defecated frequently, the TLE never defecated.