The Effect of Epigallocatechin gallate on Morphine Induced Working Memory Defects in Rats: An Experimental Study

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 morphine-treated rats.

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, Y-maze spontaneous alternation was used. To measure the level of TNF-α protein expression in brain hippocampus tissue, the western blot test was used. One-way ANOVA with Tukey’s post hoc test was used for data analysis.

Intraperitoneal morphine injection resulted in working memory deficits and increased TNF-α 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-α protein expression level (p<0.05) compared to solely morphine treated group.

EGCG improved morphine induced working memory deficits in rats.