Investigation the effects of syringic acid on hippocampus and learning after chronic deltamethrin application

Objective: Although several studies have published on deltamethrin (DTM) toxicity, few studies have described protective agents against toxicity mechanisms. The aim of present study is to determine the protective role of syringic acid (SA) after chronic DTM toxicity on hippocampus and to assess possible effects by biochemical, histopathologic, immunohistochemical methods and learning & memory tests. Method: Adult male rats (250-270 gr) of Wistar albino, Rattus norvegicus were divided into 4 groups (n = 64) with 16 in each group. SA (25 mg / kg), DTM (1.28-1.35 mg / kg), Corn Oil (CO, 0.5 ml) were given by oral gavage every day for 2 months. Group I; Control (CO), Group II; (CO + DTM), Group III; (CO + DTM + SA), Group IV; (CO + SA). Open field and radial arm maze tests were performed all groups. After the research, the animals were sacrificed under anesthesia by transcardial perfusion and decapitation for immunohistochemistry, histopathology and biochemical analysis. Results: SA increased total antioxidant capacity, protein level and locomotor activity while decreasing reactive oxidative and nitrogen levels (ROS / RNS) of the hippocampus (p<0,05). Hippocampal CA1 and CA3 neuron apoptosis were significantly higher in DTM group and least in SA (p<0,05) and significantly different from SA + DTM group (p<0.001). While DTM disrubting the learning and memory, SA, as an antioxidant agent, has improved spatial and working memory especially after 6th day. Conclusion: Biochemical and histopathological results have shown that SA may increase total antioxidant levels by decreasing oxidative stress and apoptosis in hippocampus after chronic DTM exposure. Learning tests have shown positive effect on short and long term memory. So, analysis the effect of SA on memory by different pathways may lead to new and alternative therapy.