Strain differences to the effects of central acting drugs on Sidman avoidance response in Wistar and Fischer 344 rats

Effects of methamphetamine (MAMP), chlorpromazine (CPZ), pilocarpine (PILO) and scopolamine (SCOP) on Sidman avoidance response (response-shock interval=30 sec, and shock-shock interval=5 sec) were investigated in male rats of Wistar and Fischer 344 strains. The results were compared between the two strains. Both the Wistar and Fischer 344 rats acquired the Sidman avoidance response well and exhibited almost the same baseline response rate (lever-presses/min) of about 6/min and shock rate (number of shocks delivered/min) of about 0.27/min. MAMP and SCOP facilitated the avoidance response with an increase in the response rate and a decrease in the shock rate. CPZ and PILO suppressed the avoidance response with a decrease in the response rate and an increase in the shock rate. The Wistar rats were less sensitive to the avoidance facilitating effect of MAMP, and more sensitive to the avoidance suppressing effect of CPZ than the Fischer 344 rats. In contrast, the Wistar rats were less sensitive to the avoidance suppressing effect of PILO, and more sensitive to the avoidance facilitating effect of SCOP than the Fischer 344 rats. These results suggest that the neural activities of both catecholaminergic and muscarinic-cholinergic systems are different between the Wistar and Fischer 344 rats, and that the two strains rats respond differently to central acting drugs.