عنوان مقاله [English]
Social isolation in the weeks after lactation can change the behavior of mature animals including yawning, a phylogenetic and contagious behavior. This study was conducted with the aim of determining the effect of social isolation stress on yawning behaviors in adult male rats treated with morphine and naloxone. A sample of 32 rats (21-day after weaning) was selected and the rats were put in separate cages with black plastic buffers for 6 weeks. Eight rats were put in a group (control group) and the other rest were put in individual cages: one male rat in each cage; and we grouped them as follows: in group 1 or the control group (social), each cage had 8 rats receiving (saline) at a dose 1 mg/kg and their yawning behavior was recorded for 60 minutes after 6 weeks. Group 2 (social isolation) received no treatment with opioid agonist and antagonist kept in separate cages with one rat in each cage. Their yawning behavior was recorded for 60 minutes after 6 weeks. Group 3 (social isolation) received treatment with opioid agonists (morphine) at a dose 5 mg/kg for 6 weeks and their yawning behavior was recorded for a 60-minute period starting 30 minutes after injection. Group 4 (social isolation) received treatment with opioid antagonists morphine (naloxone)at a dose 1 mg/kg for 6 weeks and their yawning behavior was recorded for a 60-minute period starting 30 minutes after injection. The graph shows that the number of yawning in the group receiving morphine (n=8, p ≤0.05) was not significantly different from the control group in the social isolation condition (n=8, p ≤ 0.05). Moreover, there was an increase in the number of yawning in the groups receiving naloxone (n=8, p ≤0.001). In social isolation group, morphine injection did not change the number of yawning in male rats, while naloxone, a mu-opioid receptor antagonist, increased the number of yawning in social isolation conditions.