Effects of dihydropyrimidinase-related protein 2-induced anxiety on decision making in rats

Abstract

Goal of the Study. The effect of intracerebral administration of dihydropyrimidinase-related protein 2 (DRP2) to the rats on anxiety and decision-making.

Methods. DRP2 was obtained by fractionation from bovine brain. Object of study: Wistar male rats. Via the audiogenic stress model stress-resistant rats were chosen for the following studies. The animals were divided into 2 groups: 1) control group – inactive, and 2) experimental group – DRP2. Preparations (1 mg/mL, 10 µL) were administered into the brain lateral ventricle of the etherized rats 24 h prior to behavioral studies. In the first experimental series, the level of rat anxiety was defined in the plus-maze. In the second experimental series, the animals were trained of getting food in the left (bigger reinforcement) and in the right (smaller reinforcement) arms of the plus-maze. The barrier was placed into the left arm on the way to the reinforcement. Then the arms preferences were evaluated again and the preparations were administered.

Results. The results of the studies carried out on the elevated plus-maze under the effect of DPB2 showed a sharp decline in the number of rearing (p < 0.001), of total duration of grooming acts (p < 0.001), of a number of crossed squares (p < 0.001), a three-fold increase of total duration of freezing time (p < 0.001) in the closed arm and prominent, more than four-time decrease of a number of hanging in the experimental animals (p < 0.001) relative to the control ones. In the T-shaped maze with a barrier impeding the animal’s access to a big-sized food reinforcement in the left arm, intra-cerebral administration of DRP2 brought to switching experimental animals’ choice towards low-sized food reinforcement in the right arm (90% of trials, p < 0.01), while administration of inactive DRP2 did not change preference of control animals towards big-sized food reinforcement.

Conclusion. A conclusion concerning the anxiogenic effects of intra-cerebral administration of DRP2 on animal behavior, bringing to switching the behavioral “cost/profit” tactics towards lower reinforcement choice, is made.