Investigation of Epidermal Growth Factor, Tumor Necrosis Factor-alpha and Thioredoxin System in Rats Exposed to Cerebral Ischemia

Background: Thioredoxin reductase (TrxR), epidermal growth factor (EGF) and tumor necrosis factor-α (TNF-α) have neuroprotective/neurotoxic effects in cerebral ischemia. We aimed to investigate the TrxR activity, EGF and TNF-α levels in cerebral ischemic, sham-operated and non-ischemic rat brains.

Methods: Sprague-Dawley rats divided into three groups. Rats in control group were not subjected to any of treatments and their brains were removed under anesthesia. Middle cerebral arters were exposed but not occluded for the sham-operated rats. Animals were subjected to permanent middle cerebral arter occlusion (MCAO) in MCAO-operated group. The rats were decapitated at 16 hours (h), 48 h and 96 h after sham operation and focal cerebral ischemia. TrxR activities, EGF and TNF-α levels were measured in ischemic and non-ischemic hemispheres for all groups.

Results: In group MCAO, TrxR activities were significantly low at 48 h in ischemic hemisphere in comparison to control. After the 48 h, a remarkable increase was observed at 96 h. EGF and TNF-α levels were substantially high at 96 h in group MCAO of ischemic brain.

Conclusion: TrxR activity was reduced by oxidative stress which was formed by ischemia. EGF levels increased to exhibit neurotrophic and neuroprotective effects. After ischemia, TNF-α levels increased as a response to the tissue damage. Further studies with a higher number of experimental subjects and shorter or longer periods such as from first 30 minutes up to 3 months may be more informative to show the time-dependent variations in TrxR, EGF and TNF-α in cerebral ischemic injury.