Cognitive enhancement in aged rats after chronic administration of Equisetum arvense L. with demonstrated antioxidant properties in vitro.

The aim of this work was to verify if chronic administration of the hydroalcoholic extract of stems from Equisetum arvense (HAE) reverses the cognitive impairment in aged rats, as well as, evaluates it in vitro antioxidant properties. Chronic administration of HAE at dose of 50 mg/kg, i.p., improved both short- and long-term retention of inhibitory avoidance task and ameliorated the cognitive performance in reference and working memory version of the Morris Water Maze. No differences were found between all three groups of young controls, aged controls and EHA-treated animals with regard to the open field and elevated plus maze tests. Indeed, no toxicity manifestations were observed during treatment. In vitro assays revealed that HAE diminished the thiobarbituric acid reactive substances as well as nitrite formation, but did not alter catalase activity. Thus, the cognitive enhancement effects of the HAE may be attributed, at least in part, to it antioxidant action.