Validation of Runway- An operant model developed to detect reinforcing effects in rats

SUMMARY Drugs of abuse becomes increasingly present in today’s affluent society. Immoderate drug abuse has risen to a deadly serious problem in today’s youth. Animal research with operant conditioning approach is one way of fathoming this problem and can contribute to gaining a clearer understanding of drug addiction. In order to establish an operandum for detecting reinforcing effects in rats we constructed an alley based on the idea of A. Ettenbergs Runway. The validation of the Runway was done step dy step. The first aim was to find the best food reinforcer [1.1] and to check if olfactory stimuli would provoke lokomotion in rats [1.2]. The construction of different-sized runways and modifications of Ettenbergs ideas[1.3] was the next step. Demonstration of reinforcing effects of food reinforcer[1.4] and morphine [1.5] was the last step. The analysis of effectiveness of food reinforcers showed that rats traverse an alley significantly faster when they have received roasted and salted peanuts or sweetened condensed milk. Based on these new findings sweetened condensed milk should be used as a reinforcer in following food reinforcment training sessions. Discriminatory influences of either an almond or an orange odor let rats locomote two times higher within the first minute, but not for a time of five minutes. There was no difference between the stimulation of locomotion and the two odors. The place of odor presentation had no influence on the stimulation of locomotion. The different dimensions of the runway did influence the rats’ running behaviour. The animals started to run through an alley earlier, when it was straight than when it had corners. A replacement of sliding doors by infrared beams was a definite improvement and reduced strongly disturbing influences. Accelerated food training worked in a straight runway (Fig 10). The same results were recorded in two- sessions per day training, but here some rats did not distinguish between the two sessions and ran two times faster (Fig. 9). The effects of subcutaneous morphine application was not as expected. The rats did not run significantly faster for morphine (Fig. 11, 12, 13, 14, 15). Milk as a reinforcer was always a stronger reinforcer than opioids