Effect of turmeric on scopolamine-induced cholinergic hypo-function in mice

Abstract

Cholinergic system plays an important role in higher cognitive functions and its chief modulator is acetylcholine. These neurons form a widespread network in brain regions. With passage of time various factors deteriorates their functions, which results in cholinergic dysfunction and ultimately cause cognitive impairment. Cholinergic dysfunction is a major cause in several neurodegenerative diseases. Turmeric is a yellow spice, also used as herbal medicine. Due to its neuro protective action, it has profound pharmacological effect in various central nervous system disorders. Donepezil hydrochloride is an acetylcholinesterase inhibitor (AChEI), is currently used for Alzheimer's disease (AD). The conformation of turmeric and donepezil can potentially rescue cholinergic hypo function. Therefore, the aim of this study is to observe synergistic effect of Turmeric (20mg/Kg/day) and donepezil (0.5mg/Kg/day) treatment on cognitive function and gene expression in scopolamine (1mg/Kg) induced amnesic mouse model. Scopolamine was used to induce cholinergic hypo-function in BALB/c mice. The effect of turmeric and donepezil on memory was investigated by Morris water maze (MWM) and social interaction test. In 5th day of MWM, Scopolamine + Turmeric + Donepezil group (5.29 ± 0.73) showed significant (p < 0.001) decrease in escape latency relative to scopolamine (24.9 ± 2.82) and control (18.37 ± 2.71) groups. Similarly in social preference test, Scopolamine + Turmeric + Donepezil treatment group (210.75 ± 45.23) displayed significant (p < 0.001) increase in sociability and social novelty as compare to scopolamine group (63.25 ± 14.44). The study also includes evaluation of the effect of turmeric powder on the expression of Nicotinic Receptors (nAChRs) like (α-7, α-4, and β 2) and Muscarinic Receptors (mAChRs) (M1, M3, and M5) in hippocampus of mice brain. Turmeric significantly increases (p < 0.05) the expression of α-7, α-4, β-2, M1, M3, and M5. Whereas, in Scopolamine + Turmeric + Donepezil also increase the expression but the difference in expression values was not significant. In protein profiling, the Scopolamine + Turmeric + Donepezil group has shown significant (p < 0.01) increase in protein expression at 35KDa, 55KDa and 70KDa as compare to Scopolamine and control. In histological studies, Scopolamine + Donepezil showed significant (p < 0.05) increase in neuronal cell density in relative to scopolamine. Thus, in the light of these findings turmeric may serve as a potential candidate in improving brain functions and cognitive properties. Turmeric with donepezil’s synergistic capability can be a potential therapeutic and preventive strategy for cognitive deficits. It can also act as a therapeutic option for psychiatric disorders and neurodegeneration disease