Our recent studies have shown that
curcumin protects
arsenic induced neurotoxicity by modulating oxidative stress,
neurotransmitter levels and dopaminergic system in rats. As chronic exposure to
arsenic has been associated with cognitive deficits in humans, the present study has been carried out to implore the neuroprotective potential of
curcumin in
arsenic induced
cholinergic dysfunctions in rats. Rats treated with
arsenic (
sodium arsenite, 20mg/kg
body weight, p.o., 28 days) exhibited a significant decrease in the learning activity, assessed by passive avoidance response associated with decreased binding of (3)H-QNB, known to label
muscarinic-
cholinergic receptors in hippocampus (54%) and frontal cortex (27%) as compared to controls. Decrease in the activity of
acetylcholinesterase in hippocampus (46%) and frontal cortex (33%), staining of Nissl body, immunoreactivity of
choline acetyltransferase (ChAT) and expression of ChAT
protein in hippocampal region was also observed in
arsenic treated rats as compared to controls. Simultaneous treatment with
arsenic and
curcumin (100mg/kg
body weight, p.o., 28 days) increased learning and memory performance associated with increased binding of (3)H-QNB in hippocampus (54%), frontal cortex (25%) and activity of
acetylcholinesterase in hippocampus (41%) and frontal cortex (29%) as compared to
arsenic treated rats. Increase in the expression of ChAT
protein, immunoreactivity of ChAT and staining of Nissl body in hippocampal region was also observed in rats simultaneously treated with
arsenic and
curcumin as compared to those treated with
arsenic alone. The results of the present study suggest that
curcumin significantly modulates
arsenic induced
cholinergic dysfunctions in brain and also exhibits neuroprotective efficacy of
curcumin.