Protective effects of an interaction between vagus nerve and melatonin on gastric ischemia/reperfusion: The role of oxidative stress

Objectives: Vagal pathways in gastrointestinal tract are the most important pathways that regulate
ischemia/reperfusion (I/R). Gastrointestinal tract is one of the important sources of melatonin
production. The aim of this study was to investigate probable protective effect of the interaction
between vagus nerve and melatonin after I/R.
Materials and methods: This study was performed in male rats that were divided into six groups.
Cervical vagus nerve was cut bilaterally after induction of I/R and the right one was stimulated by
stimulator. Melatonin or vehicle was injected intraperitoneally. The stomach was removed for
histopathological and biochemical investigations.
Results: A significant decrease in infiltration of gastric neutrophils and malondialdehyde (MDA) level
after I/R was induced by melatonin and was disappeared after vagotomy. The stimulation of vagus
nerve significantly enhanced these effects of melatonin. However, a stimulation of vagus nerve alone
increased neutrophils infiltration and MDA level. Melatonin significantly increased the activities of
catalase, glutathione peroxidase (GPx), superoxide dismutases (SOD). Unlike stimulation of vagus
nerve, vagotomy decreased these effects of melatonin.
Conclusion: According to these results, it is probable that protective effects of melatonin after I/R may
be mediated by vagus nerve. Therefore, there is an interaction between melatonin and vagus nerve in
their protective effects