TSUKUBA HIGH-EMOTIONAL AND LOW-EMOTIONAL STRAINS OF RATS (RATTUS-NORVEGICUS) - AN OVERVIEW

This report compiles the results of a series of studies on the Tsukuba High- and Low-emotional strains (THE and TLE) of rats (Rattus norvegi cus) established at the University of Tsukuba, Japan. The THE and TLE strains have been selected, respectively, for low and high activity in a runway test. During the course of selection, defecation has increas ed in the THE strain and decreased in the TLE strain. These strain dif ferences were not affected by maternal influences, early experience, o r psychotropic drugs. THE rats were consistently inactive in all novel situations examined, while TLEs were very active. The level of sponta neous activity, however, was similar between the two strains. It was r emarkable that THE rats showed more burrowing activity than TLE animal s, whereas the latter displayed more aggression than the former. Diffe rences in learning ability, concentration of neural transmitters, and social behavior were examined.