Neuroprotective and Antiamnesic Effects of Mitragyna inermis Willd (Rubiaceae) on Scopolamine-Induced Memory Impairment in Mice.

David Bougolla Pahaye,Jean Pierre Omam Omam,Josiane Lucie Ojong,Nadège Kouemou,Gwladys Temkou Ngoupaye,Elisabeth Ngo Bum,Neteydji Sidiki,Veronique Mairaira,Germain Sotoing Taïwé,Antoine Kandeda,Gisele Nkantchoua,Fleur Clarisse Okomolo Moto,Stephanie Jacqueline Kameni Njapdounke

doi:10.1155/2017/5952897

Abstract

Aim. To assess memory improvement and neuroprotective and antioxidant effects of Mitragyna inermis (M. inermis) leaf decoction on the central nervous system. Methodology. Leaf decoction of M. inermis was tested on learning and memory in normal and scopolamine-induced cognitive impairment in mice using memory behavioral tests such as the Morris water maze, object recognition task, and elevated plus maze. Oxidative stress enzymes—catalase, superoxide dismutase, and the thiobarbituric acid reactive substance, a product of lipid peroxidation—were quantified. In each test, mice 18 to 25 g were divided into groups of 5. Results. The extract reversed the effects of scopolamine in mice. The extract significantly increased discrimination index in the object recognition task test and inflexion ratio in the elevated plus maze test. The times spent in target quadrant in MWM increased while the transfer latency decreased in mice treated by M. inermis at the dose of 196.5 mg/kg. The activity levels of superoxide dismutase and catalase were significantly increased, whereas the thiobarbituric acid reactive substance was significantly decreased after 8 consecutive days of treatment with M. inermis at the dose of 393 mg/kg. Conclusion. These results suggest that M. inermis leaf extract possess potential antiamnesic effects.

Highlights

Dementia is a syndrome of gradual onset and continuing decline of higher cognitive functioning
Mice treated with the plant extract showed a significant decrease of transfer latency (TL) and a significant increase of inflexion ratio (IR) when compared to scopolaminetreated group
That result was obtained by other authors [37,38,39], since scopolamine is a muscarinic cholinergic receptor antagonist which causes memory impairments in rodents especially in the processes of learning acquisition and short-term memory [40,41,42]

Summary

Introduction

Dementia is a syndrome of gradual onset and continuing decline of higher cognitive functioning. It is a common disorder in older persons and becomes more prevalent in each decade of life [1]. The most common cause of dementia is Alzheimer’s disease, which is a progressive neurodegenerative disorder associated with loss of neurons in distinct brain areas [2]. Alzheimer’s disease is a progressive neurodegenerative disorder characterized by a gradual decline in memory [3]. Cholinergic system has been found to play a role in learning and memory [4]. It has been shown that cholinergic antagonists, scopolamine and atropine, disrupted memory process in various tasks in animals

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Conclusion