The Effects of Dopamine and Serotonin on Yawning Behavior in the Rat Model of Social Isolation

Abstract

A sample of 80 Male rats (21-day post weaning) were chosen, and were put for 6 weeks in separate cages with black plastic buffers. Eight rats were put in one group of 8 rats in a single cage (the control group) and the rest were put in individual cages: one male rat in each cage. In group 1 or the control group (social conditions) 8 rats were put in one cage. They received saline carrier and their yawning behavior was recorded for 60 minutes. Group 2 (n=8; in separate cages) (social isolation conditions) received no treatment with serotonin and dopamine agonist and antagonist and were kept in separate cages with one rat in each cage. Their yawning behavior was also recorded for 60 minutes. Group 3 (n=8; in separate cages) included the rats that received Apomorphine (dopamine agonist) at a dose of 0.08 mg/kg via subcutaneous injection (SC), and their yawning behavior was recorded for 60 minutes. Rats in group 4 (n=8; in separate cages) received serotonin agonist (m-CPP) at a dose of 0.5 mg/kg via subcutaneous injection, and their yawning behavior was recorded for 60 minutes. Group 5 (n=8; in separate cages) included rats that received Serotonin Antagonist (Mianserin) at a dose of 0.2 mg/kg via subcutaneous injection, and their yawning behavior was recorded for 60 minutes. Group 6 (n=8; in separate cages) included rats receiving dopamine antagonist (haloperidol) at a dose of 0.1 mg/kg via Intraperitoneal (IP) injection, and their yawning behavior was recorded for 60 minutes. Group 7 (n=8; in separate cages) included rats receiving Serotonin antagonist (Mianserin) at a dose of 0.2 mg/kg via subcutaneous injection 15 minutes before injection of apomorphine (dopamine agonist) and their yawning behavior was recorded for 60 minutes. Rats in group 8 (n=8; in separate cages) received dopamine antagonist (haloperidol) at a dose of 0.1 mg/kg via intraperitoneal injection (IP) 15 minutes before the injection of serotonin agonist (m-ccp), and their yawning behavior was recorded for 60 minutes. Rats in group 9 (n=8; in separate cages) received Apomorphine (dopamine agonist) at a dose of 0.08 mg/kg and Serotonin agonist (m-CPP) injected subcutaneously (SC) at a dose of 0.5 mg/kg and their yawning behavior was recorded for 60 minutes. Group 10 (n=8; in separate cages) included rats that received dopamine antagonists (haloperidol) at 0.1 mg/kg via intraperitoneal injection (IP) and antagonist serotonin (Mianserin) at 0.2 mg/kg injected subcutaneously and their yawning belabor was recorded for 60 minutes. Dopamine agonist (apomorphine) and serotonin antagonist (Mianserin) induce yawning in the social conditions and injection of haloperidol (dopamine antagonist) before serotonin agonist (m-ccp) reduces yawning in social conditions. Yawning is different in social conditions and social isolation conditions. Using Meta-Chlorophenylpiperazineserotonin (serotonin agonist), Mianserin (serotonin antagonist), apomorphine (dopamine agonist), haloperidol (dopamine antagonist) the role of serotonin and dopamine in yawning, fear, erection etc. can be investigated as a model for human studies.