LABYRINTH EXPLORATION, EMOTIONAL REACTIVITY, AND CONDITIONED FEAR IN YOUNG ROMAN VERH INBRED RATS/

An inbreeding program has been carried out with the Swiss sublines of Roman high- and low-avoidance rats since 1993. The present study repor ts the first experiments conducted with young animals of those inbred strains (RHA-I/Verh and RLA-I/Verh, respectively) from the sixth and s eventh inbreeding generations. The results confirmed expected behavior al profiles. Compared to the RHA-I/Verh strain, RLA-I/Verh rats showed decreased entries into the illuminated central arena of an hexagonal tunnel maze, as well as decreased spontaneous locomotor activity and i ncreased defecations, in two independent experiments. Young RLA-I/Verh females explored less than did their RHA-I/Verh counterparts during s ession 1 of a conditioned-fear experiment preceding shock administrati on, and in session 2 (conducted 24 h after the application of three fo otshocks), they showed greater conditioned behavioral inhibition (i.e. , reduced amount of rearing), as well as higher defecation scores, tha n did RHA-I/Verh females.