Statins: Are they also memory enhancers? A study in relation to their hypocholesterolemic and antioxidant effects in Swiss albino mice

Abstract

Background:The most common cause of dementia with progressive loss of memory is Alzheimer's disease (AD), a neurodegenerative disorder that occurs due to increased oxidative stress, deposition of amyloid protein, and loss of cholinergic neurons. Statins, by their hypocholesterolemic, antioxidant, and other activities may be helpful in this regard. Aims and Objectives: The aim of this study is to examine the relation between memory restoring effect, lipid lowering effect as well as the antioxidant properties of statins in experimental dementia models using Swiss albino mice. Materials and Methods: Cognitive ability was tested in randomly selected young Swiss albino mice with two exteroceptive behavioral models, passive avoidance paradigm, and Morris Water Maze (MWM) by assigning 30 animals divided equally into 5 groups for each model. Amnesia was induced by feeding high-fat-diet for 90 days in 4 groups of mice. The 5 th group served as control with young mice. Piracetam, atorvastatin, and simvastatin were given, respectively, to 3 of the amnesic groups of each model whereas the 4 th group treated with vehicle served as positive control. Results:Step-down latency was significantly higher in young mice as well as amnesic mice treated with piracetam, simvastatin, or atorvastatin in comparison to vehicle-treated amnesic mice. Similar result was also seen during retrieval test in MWM, although all the groups performed comparably during acquisition trial. Brain malondialdehyde (MDA) levels were significantly low in all the groups who performed well in either of the exteroceptive behavioral models. Cholesetrol levels in young control and statin-treated groups were significantly low in comparison to piracetam-or vehicle-treated mice. Conclusions: Atorvastatin and simvastatin improved the cognitive ability in terms of learning as well as retrieval of learned experience which may be attributed to their hypocholesterolemic and antioxidant properties.

Scopolamine-induced amnesia model: A possible anticholinergic mechanism with reversibility with statins and nootropic agents

“…In our earlier study on dementia using high-fat diet, the statins also protected against learning impairment and memory loss. [7] Some similar but reversible changes in altering the memory, cognition and learning were caused by the use of scopolamine, a known anticholinergic drug in our present experimental study model of AD. Further, Naringenin, a flavanone found in citrus fruits was found to have reversed the scopolamine-induced amnesia attributed to its antioxidant and anticholinesterase activity.…”

“…The experiment was conducted in a way similar to our earlier experiment on mice with ageinduced and high-fat-diet-induced amnesia. [6,7] Here, in this experiment, scopolamine-induced experimental dementia model was used. All 60 mice were divided into 10 groups (Group I to Group X) with 6 animals in each group.…”