Cognition enhancing effect of the aqueous extract of Cinnamomum zeylanicum on non-transgenic Alzheimer's disease rat model: Biochemical, histological, and behavioural studies

Abstract

Objective: Several dietary supplements are actively being tested for their dual role of alleviating the metabolic perturbations and restricting the consequent cognitive dysfunctions seen in neurodegenerative disorders such as Alzheimer's disease (AD). The aim of the current study was to assess the influence of aqueous extract of cinnamon (CE) on the monosodium glutamate-induced non-transgenic rat model of AD (NTAD) established with insulin resistance, hyperglycaemia, neuronal loss, and cognitive impairment at a very early stage of life.

Methods: The experimental design included oral administration of CE (50 mg/kg body weight) for 20 weeks to 2-month and 10-month-old NTAD rats. Following the treatments, the animals attained 7 and 15 months of age, respectively. They were then subjected to behavioural testing, biochemical analysis, and stereology experiments.

Results: The results demonstrated that CE treatment improved the insulin sensitivity, increased phosphorylated glycogen synthase kinase-3β (pGSK3β), inhibited the cholinesterase activity, and improved the learning ability in NTAD rats. Histological evaluation has shown an increase in neuron count in the DG sub-field of hippocampus upon treatment with CE.

Discussion: These beneficial effects of CE are suggestive of considering cinnamon as a dietary supplement in modulating the metabolic changes and cognitive functions.

Keywords:

• Alzheimer's disease
• Cinnamomum zeylanicum
• Cholinesterase
• Glycogen synthase kinase-3β
• Hippocampus
• Cognition

Acknowledgements

The authors would like to thank Vijaya Kumar Kapgal for his help with the preparation of the histological material.

Disclaimer statement

Contributors S.M. and S.S. were involved in designing the experiments; S.M. conducted the research; S.M. and S.S. analysed the data and written the manuscript. Both the authors read and approved the final manuscript.

Conflict of interest None.

Ethics approval This study was approved by Institutional Animal Ethics Committee.

Additional information

Funding

Financial assistance received from Council of Scientific and Industrial Research, New Delhi and Department of Science and Technology, New Delhi, India.