1 Institute of Medical and Biological Cybernetics, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia
2 Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Earlier we found that male rats with genetic predisposition to catalepsy (G.C. rats) and Wistar rats had differences in an active avoidance learning. Experiments were performed on female G.C. and Wistar rats weighing 200-240 g. Animals were placed in a shuttle-box containing a 7 cm high partition. The rats were trained to avoid an electric shock (1 mA, 50 Hz). The tone with a frequency of 2000 Hz and a duration of 10 sec was a conditioned stimulus. The procedure included 50 stimuli presented at intervals of 60 sec. At the other experiment the shuttle-box was illuminated by an electric lamp (25 W) and the rat could turn off the light (during 60 sec) with the help of crossing over the partition. The procedure included 50 light cycles with a maximum duration of 60 sec (in sum 3000 sec).
It was found that the number of shock avoidance reactions in G.C. rats was non-significantly lower than in Wistar rats: 3.70 ± 1.09 (n=10) and 10.22 ± 4.49 (n=9) respectively, P > 0.05). However, the strains of rats differed significantly in the time spent in an illuminated box: 925 ± 145 sec (7 Wistar rats) and 1725 ± 195 sec (6 G.C. rats), P < 0.05. Thus G.C. rats had a lover tendency to escape the light than Wistar rats.
We believe that the presented method allows the study of avoidance behaviour without the use of pain stimuli.