The Oleuropein Effect on Neurotrophic Factor Expression Level in Hippocampal Tissue and Memory Defect Induced by Morphine in Male Rats: An Experimental Study

Background and Objectives: Taking morphine can cause damage to the hippocampus. Oleuropein has a protective effect on brain neurons. The aim of this study was to determine the effect of oleuropein on brain-derived neurotrophic factor (BDNF) protein expression level in hippocampal tissue and memory defect induced by morphine in rats. Materials and Methods: In this experimental study, 40 male Wistar rats were used. The animals were divided into five groups (n=8) including control/saline group (receiving saline intraperitoneally for four weeks), morphine group (receiving 40 mg/kg morphine daily subcutaneously for four weeks) and morphine + Oleuropein groups (receiving doses of 5, 15, and 30 mg/kg oleuropein + morphine by intraperitoneal injection for 4 weeks). At the end, the animals’ working memory was evaluated using the Y-maze behavior measurement test. The hippocampal BDNF protein expression level was measured using the ELISA method. One-way ANOVA test with Tukey’s post-test was used to analyze the data. Results: Intraperitoneal injection of oleuropein at a dose of 30 mg/kg in the rats receiving morphine significantly improved the memory function (p<0.01) and increased the BDNF protein expression level (p<0.05) compared to the morphine treated groups. Conclusion: Oleuropein may increase the BDNF protein expression level in the hippocampal tissue and improves the memory defect induced by morphine in rats .