Abstract: Background: Stress is involved in memory impairment through multiple mechanisms, including
activation of hypothalamic-pituitary axis, which in turn activates release of corticosterone in
blood. Cholinergic system blockade by the muscarinic antagonist, scopolamine, also impairs memory.
Objective: This study aimed to investigate the effect of turmeric (20mg/kg) on learning and memory
and cholinergic system in a mouse model of stress along with cholinergic blockade.
Methods: Restrained stress was induced and cholinergic receptors were blocked using scopolamine in
mice. Animals were treated with turmeric (turmeric rhizome powder which was also subjected to
NMR analyses) and learning and social behavior was examined. Effect of turmeric on cholinergic
muscarinic receptors (mAChR; M1, M3 and M5) gene expression was assessed by RT-PCR in both
pre-frontal cortex and hippocampus.
Results: Ar-turmerone, curcuminoids and α-linolenic acid were the lead compounds present in turmeric
extract. Increased serum corticosterone levels were observed in stressed mice when compared
to the control group, while turmeric treatment significantly reduced serum corticosterone level. Turmeric
treatment caused an improved learning and memory in Morris water maze test in stressed animals.
Social novelty preference was also restored in turmeric treated animals. Following turmeric
treatment, M5 expression was improved in the cortex and M3 expression was improved in the hippocampus
of stress + scopolamine + turmeric treated group.
Conclusions: These findings highlight the therapeutic role of turmeric by increasing the expression of
M3, M5 and improving learning and memory. Turmeric can be an effective candidate for the treatment
of amnesia caused by the stress.