Effects of dietary sulfite on pge2 level and PGE2 receptors in the hippocampus

Objective: In our study, it has been planned to investigate the effects of sodium metabisulfite, which is used as a food additive, on learning and spatial memory, and the possible contribution of arachidonic acid, COX-2, PGE2 signal pathway and PGE2 receptor subtype to these effects. Method: 3-month-old male Wistar rats were divided into 3 groups as control (K), S100 and S260. Tap water was given to the control group, water containing 100 and 260mg/kg/day sodium metabisulphite dose were given to S100 and S260 group respectively via gavage for 35 days. Morris water maze (MWM) and open field (OF) test were performed to evaluate learning and spatial memory and locomotor activity respectively in rats. Afterwards, blood samples were taken to determine plasma S-sulfonate levels and brain tissues purified from blood were removed and hippocampus tissues were seperated. AA, PGE2 levels and COX-2 activity were determined in hippocampus and mRNA expressions of RT-PCR and PGE2 receptor subtypes were analyzed. Results: Total distance and average velocity performed on the 6th day in the sulfite groups were significantly higher, yet target quadrant entrance frequency in the sulphite groups was significantly lower compared to control group in the MWM test. Total distance and average velocity obtained using OF test, plasma S-sulfonate and AA levels in sulphite groups were significantly higher compared to control group. PGE2 level and COX-2 activity was found to be significantly higher only in S260 group. However, mRNA expressions of the four receptor subtypes of PGE2 in the hippocampus increased significantly in the S100 group. Conclusion: In our study, it was determined that spatial memory and learning were impaired due to sulfite intake, and AA, COX-2 and PGE2 signal pathways contributed to this process and the contribution of PGE2 receptors to the effects of sulfide depends on exposed sulfite dose.