The Effect of 1-(3-Chlorophenyl) Piperazine Serotonin Agonist and Apomorphine (Dopamine Agonist) on Fear Behavior in the Rats of Social Isolation Model

Social isolation in the early stages of life may lead to some types of neurological disorders. Dopamine is one of the most important brain neurotransmitters playing significant roles in reward pathway in the brain. The present study aimed at determining the impact of serotonin agonist and dopamine agonist on fear behavior in the rats of social isolation model. Forty rats (after the age of 23-day) were selected and kept in separate cages with black plastic buffers for six weeks. Eight rats were assigned to the control (social) group and the rest were placed in individual cages: one male rat per cage. In group 1 or control (social) group, they received saline carrier. Group 2 was only kept under social isolation conditions without any drug injections; and Group 3 received 1-(3-chloropheny) piperazine, serotonin agonist. Tolerating social isolation conditions, Group 4 received dopamine agonist apomorphine. Group 5 received both piperazine (m-cpp) serotonin agonist and dopamine agonist apomorphine. The results show that the time of entry in open arm in the group receiving apomorphine was significantly higher than in the control (social) group (P ≤ 0.001). The time of entry in open arm in the group receiving 1-(3-chlorophenyl) piperazine was significantly lower than in the control (social) group. The findings of the present study in social isolation conditions indicate that apomorphine can significantly decrease anxiety. 1-(3-chlorophenyl) piperazine (m-cpp) serotonin agonist has stimulating effects similar to serotonin, causing anxiety.