Fatemeh Mohammadi - Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
Mohsen Abedini Esfahlani - Department of Anatomical Sciences, Afzalipour Medical Faculty, Kerman University of Medical Sciences, Kerman, Iran.
Mohammad Shabani - Intracellular Recording Lab, Kerman Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran

Background and Aim : Empathy for pain depends on the ability to feel, recognize, comprehend and share painful emotional conditions of others. In this study, for evaluation of a rat model of empathic pain and to investigate the role of NO, male Wistar rats were used.Methods : Pain was socially transferred from the sibling demonstrator (SD) in pain (received five times formalin injection) to the naïve sibling observer (SO) through observation of pain group. SO groups received L-NAME or L-Argninine prior to observing animals in pain. Then Nociception and concentrations of NO metabolites (NOx) in the serum, left and right hippocampus, prefrontal cortex, and cerebellum were evaluated.Results : It was seen that nociceptive response was significantly increased in the pain-observing groups. measuring NOx levels ۲۴h after last pain observation by Griess method, indicated that observing pain resulted in decreased and increased NOx concentrations in the left hippocampus and cerebellum, respectively. There was a uniform increase in tissue concentrations of NOx in cerebellum and prefrontal cortex in both pain and observer groups ۷ days after the fifth formalin injection.Conclusion : Our results suggest that NO may be involved in development of empathic hyperalgesia and observation of sibling’s pain also can change NO metabolites in different brain regions of the observer rats.

empathy, NOX, pain