Abstract
Behavioral effects of doxepin, imipramine and amitriptyline, were investigated in rats trained on fixed ratio (FR 30) and fixed interval (FI 1) schedules of food reinforcement, continuous (Sidman-type) and discriminated avoidance as well as escape schedules. Effect of these drugs on conditioned emotional responses (CER) under FR and FI schedules developed by stimulus presentation associated with electric shock was simultaneously observed.
When 10mg/kg of doxepin was given orally, no change was observed in FR- and FI-respondings. At higher doses (20-60mg/kg P. O.), response decreased in proportion to the dosage. CER was not attenuated in all the cases.
The three drugs all showed suppressive effects on response and were arranged according to potency as, imipramine, doxepin and amitriptyline.
When 50mg/kg of doxepin was administered orally, no marked change was detected in either avoidance behavior. At the dose of 100mg/kg, doxepin and amitriptyline showed a decrease in response with a corresponding increase in the number of shocks delivered, while imipramine showed no change.
It is suggested that doxepin mainly revealed suppressive chlorpromazine like effects in all the schedules, but no attenuating effect of CER, when single large doses were administered orally. Thus diazepam-like effect was not confirmed.
