Silymarin Antioxidant Effect on Ethanol-Induced Anxiety and Learning Impairments in Rats: An Experimental Study

Ethanol has shown strong neurodegenerative consequences in brain that are associated with oxidative stress. The aim of this study was to investigate the effects of silymarin on oxidative stress, anxiety, and learning disorder induced by ethanol in rats.

In this experimental study, 35 male Wistar rats with 200gr average weight were divided into five groups. The control group and four groups that received 4 gr/kg ethanol for 14 days. Three treatment groups were treated with doses of 50, 100, and 150 mg/kg silymarin for 14 days, respectively. Cognitive impairment and anxiety were assessed. The average activity of catalase and superoxide dismutase enzymes and glutathione (GSH) level in the hippocampus were also assessed. Data were analyzed using one-way analysis of variance (ANOVA) and Turkey’s post hoc test.

Ethanol consumption significantly decreased the discrimination index (p<0.001), the percentage of open arm time (%OAT) (p<0.001), and the percentage of open arm entry (%OAE) (p=0.007) compared to the control group. Also, it reduced the activity of antioxidants catalase (p<0.001), superoxide dismutase (p=0.002), and glutathione level (p<0.001) compared to the control group, while silymarin consumption with dose 150 mg/kg significantly increased the discrimination index, OAE (p=0.022), and OAT (p=0.023) compared to the ethanol group. Also, it increased antioxidant activity of catalase (p=0.008), superoxide dismutase (p=0.030), and glutathione (p<0.001) compared to the ethanol group.

Silymarin may protect the hippocampus against behavioral disorder induced by ethanol consumption by increasing the level of antioxidants.