The effect of instability stress and exogenous oxytocin on the number of the natural killer cells in peripheral blood and spleen in male rats

Background and Aim : Natural killer cells are innate immune lymphocytes that they play a major role in defense against tumors and viral infections. Many factors such as social stress act on the immune system. This type of stress is an important factor in the etiology of psychopathological disorders, including depression and anxiety. Oxytocin is a 9-amino acid hormones synthesize in the central nervous system and some of the peripheral tissue and plays a main role in response to stress, and its injection reduces depression and stress-induced anxiety. The aim of this study was the evaluation of instability stress effect and oxytocin on the number of NK cells in rats exposed to this stress.Methods : WISTAR rats were subjected to instability stress for 21 days, hence their cage-mate were changed every three days. From the 11th day, a group of rats received 20 microliter and the other group received 40 microliter 1 mg/ml oxytocin and the control group received normal saline by intranasal rout. At the end of study, the animals were anesthesia and then were killed. Blood sample and spleen tissue were obtained and the number of NK cells was counted by flow cytometry by CD3-CD161 + markersResults : The number of NK cells in the peripheral blood in instability stress groups and treated with 20 and 40 microliter oxytocin was (3/6±1/8,4/4±0/9) compared to control group which was(4/5±2/1) there was no significant difference but in instability stress groups and treated with 20 and 40 microliter oxytocin in spleen was (4/4±1/6,4/7±1/1) compared to control group which was(2/2±0/6) there was significant .(Pvalue=0/025,Pvalue=0/008)Conclusion : Instability stress companed with treated with20 and 40 microliter oxytocin increases The number of NK cells in the rats spleen which indicates this synergic effect puts immune system in a ready state against infection and canser.