No abstract

Chronic opioid abuse can impair the hippocampal region of the brain. This study evaluates the neuroprotective effect of Achillea millefolium (Ach) on chronic morphine‑induced learning and memory impairment, oxidative stress, and neuronal apoptosis in the CA1 region of the rat hippocampus. Thirty‑two male Wistar rat rats were classified into four treatment groups (n=8). Morphine sulfate was administered chronically. The treatment groups were given Ach aqueous extract (100, 250, and 500 mg/kg), orally, each day. After 28 days, the Morris water maze test was performed on all subjects. Caspase‑3, Bax, and Bcl‑2 proteins expression in the CA1 region of hippocampal tissue was analyzed using the western blot method. Also, malondialdehyde concentration, glutathione peroxidase activity, and superoxide dismutase activity were evaluated. The results indicated that Ach extract can improve spatial learning and memory defects in morphine‑treated rats. Ach administration also ameliorated apoptosis and oxidative stress indicator levels in hippocampal CA1 of morphine‑treated animals. Based on the present study, Ach improved spatial learning and memory defects, and reduced oxidative stress and apoptosis in the hippocampus CA1 region, in chronic morphine‑treated animals.

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 morphine-treated 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, 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. Results: 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. Conclusion: EGCG improved morphine induced working memory deficits in rats.