An Introduction to Natural Experiment Studies

Background and Objectives: Chronic morphine use leads to structural changes in the brain. Some studies have shown the antioxidant and neuroprotective effects of Epigallocatechin gallate (EGCG) as a main polyphenol of green tea. Therefore, the aim of this study was to investigate the effect of EGCG on working memory in morphinetreated rats.Materials and Methods: In this experimental study, 32 male Wistar rats were divided into 4 experimental groups (8 rats in each group): 1 control; 2 Morphine group (the animals received 40 mg/kg morphine for 4 weeks, once a day, s.c.); 3 and 4 Morphine + EGCG, the animals received morphine (40 mg/kg, 4 weeks, once a day, s.c.) and EGCG (5 and 50 mg/kg, once a day, i.p.). To evaluate the working memory, Ymaze spontaneous alternation was used. To measure the level of TNF alpha; protein expression in brain hippocampus tissue, the western blot test was used. Oneway ANOVA with Tukey rsquo;s post hoc test was used for data analysis.Results: Intraperitoneal morphine injection resulted in working memory deficits and increased TNF alpha; protein expression levels compared to the control group (p<0.001). Moreover, intraperitoneal injection of 50 mg/kg EGCG in morphine treated rats significantly improved working memory (p<0.01) and decreased TNF alpha; protein expression level (p<0.05) compared to solely morphine treated group.Conclusion: EGCG improved morphine induced working memory deficits in rats.Key words: Morphine, EGCG, Working memory, Rat Funding: This research was funded by Rafsanjan University of Medical Sciences.Conflict of interest: None declared.Ethical approval: The Ethics Committee of Rafsanjan University of Medical Sciences approved the study (IR.RUMS.REC.1396.210). How to cite this article: Saffar S, Fatemi I, Rahmani M R, Hassanshahi J, PakHashemi M, Kaeidi A. The Effect of Epigallocatechin gallate on Morphine Induced Working Memory Defects in Rats: An Experimental Study. J Rafsanjan Univ Med Sci 2020; 19 (2): 11524. [Farsi]