The role of nitric oxide in the relationship between different doses of sodium metabisulfite and depression

Objective: It has been known that sulfite toxicity has detrimental effects on the human brain. However, the relationship between sulfite toxicity and anxiety-depression-like behaviors has not been determined yet. This study was carried out to investigate the effects of sulfite toxicity on anxiety-depression-like behaviors and the role of nitric oxide (NO) in this interaction using behavioral, biochemical experiments, and recordings of Long-Term Potentiation (LTP) and Long-Term Depression (LTD). Method: One hundred male Wistar rats were divided into four groups. S25, S100, and S260 groups were given freshly prepared sulfite of 25 mg/kg, 100 mg/kg, and 260 mg/kg respectively for 35 days via gastric gavage while the control (C) group received equal volumes of distilled water via gavage for the same period. Fifteen rats from all groups were subjected to behavioral experiments. Five rats from each group were used for LTP, while the other five rats were used for LTD recordings. The levels of nitrite/nitrate, nNOS, and iNOS were analyzed on the hippocampi. Results: Behavioral experiments demonstrated that sulfite exposure caused anxiety-depression-like-behaviors, especially greater than or equal to 100 mg/kg dose. Moreover, it was detected that sulfite exposure caused impaired LTP and facilitated LTD in the hippocampus. When compared to the C group, nitrite/nitrate, nNOS and iNOS levels in S100 and S260 groups were significantly decreased. Conclusion: Consequently, sulfite toxicity in adults may induce anxiety-depression-like behaviors. These results suggest that the decrease in NO production may be involved in sulfite-induced anxiety-depression-like behaviors.