Elucidating the Effect of Turmeric in Scopolamine-Induced Cognitive Impairment in Mouse

Abstract

The cholinergic theory claims that the decline in cognitive functions in dementia is predominantly related to a decrease in cholinergic neurotransmission. This hypothesis has led to great interest in the putative involvement of the cholinergic neurotransmission in learning and memory processes. Turmeric, a potent anti-inflammatory compound, like donepezil has shown to have sound effect on cholinergic system improving memory and learning. BALB/c mice were administrated Scopolamine (1mg/Kg/day) through subcutaneous injections for a period of 26 days. On 11 day, Donepezil (4mg/Kg/day) and Turmeric (20mg/Kg/day) was given mixed in feed. Novel recognition test, fear contextual and fear conditioning test a memory tests were performed to evaluate memory consolidation and acquisition. RT PCR was used to measure the mRNA expression of M1, M3, and M5 receptors in the cortex. Turmeric treatment significantly improved the expression of cholinergic muscarinic receptors M1 and M5 in the cortex as compared to Scopolamine-induced amnesia group. Moreover, turmeric significantly enhanced the expression of α7 in control and treated groups, the expression of α4 is reduced in turmeric treated and control group as compared to scopolamine-induced amnesia group and there is no-significant change in expression in β2 gene in groups. There were four proteins differentially expressed in turmeric treated group. The impairment in cortex dependent learning and memory was inverted in Scopolamine-induced amnesia group as evident from improvement in fear conditioning (p<0.001), contextual (p< 0.001), and fear extinction (p<0.001) in turmeric treated group as compared to Scopolamine induced amnesia group. Recognition memory was also improved (p<0.001) following turmeric administration as compared to scopolamine-induced amnesia, suggesting the positive effect of turmeric. Furthermore, turmeric show significant improvement in low scoring PAL and RT test in human aged subject as compared to placebo group of human subject. Therefore in the light of these findings turmeric Abstract x may serve as a potential candidate in improving cognitive functions. It can also act as a therapeutic option for neurodegenerative disorders.