Curcumin attenuates diabetic encephalopathy in rats: behavioral and biochemical evidences

Emerging epidemiological data indicates that diabetes is a potential predisposing factor for neuropsychiatric deficits as stroke, cerebrovascular diseases, diabetic encephalopathy, depression and anxiety. Diabetic encephalopathy, characterized by impaired cognitive functions and neurochemical and structural abnormalities, involves direct neuronal damage caused by intracellular glucose. Curcumin, a well-established phenolic antioxidant and anti-inflammatory molecule, is capable of playing an important role against amyloid and dendritic pathology and thus has neuroprotective properties. The aim of the present study was to explore the effect of curcumin (60 mg/kg; p.o.) on cognitive functions, oxidative stress and inflammation in diabetic rats. Learning and memory behaviors were investigated using a spatial version of the Morris water maze test. Acetylcholinesterase activity, a marker of cholinergic dysfunction, was increased by 80% in the cerebral cortex of diabetic rats. There was 107% and 121% rise in thiobarbituric acid reactive substance levels in cerebral cortex and hippocampus of diabetic rats, respectively. Reduced glutathione level and enzymatic activities of superoxide dismutase and catalase were decreased in both cerebral cortex and hippocampal regions of diabetic rat brain. Nitrite levels in cerebral cortex and hippocampus were increased by 112% and 94% respectively. Serum TNF-alpha, a marker for inflammation, was found to increase by 1100% in diabetic rats. Chronic treatment with curcumin (60 mg/kg; p.o.) significantly attenuated cognitive deficit, cholinergic dysfunction, oxidative stress and inflammation in diabetic rats. The results emphasize the involvement of cholinergic dysfunction, oxidative stress and inflammation in the development of cognitive impairment in diabetic animals and point towards the potential of curcumin as an adjuvant therapy to conventional anti-hyperglycemic regimens for the prevention and treatment of diabetic encephalopathy.