Amelioration of cognitive deficits and neurodegeneration by curcumin in rat model of sporadic dementia of Alzheimer's type (SDAT).
ABSTRACT Recent evidence indicates that curcumin (CUR), the principal curcuminoid of turmeric, exhibits antioxidant potential and protects the brain against various oxidative stressors. The aim of the present study was to examine the modulating impacts of CUR against cognitive deficits and oxidative damage in intracerebroventricular-streptozotocin (ICV-STZ) infused rats. Rats were injected bilaterally with ICV-STZ (3 mg/kg), while sham rats received the same volume of vehicle and then supplemented with CUR (80 mg/kg) for three weeks. After two weeks of ICV-STZ infusion, rats were tested for cognitive performance using passive avoidance and water maze tasks and then sacrificed for biochemical and histopathological assays. ICV-STZ rats showed significant cognitive deficits, which were significantly improved by CUR supplementation. CUR supplementation significantly augmented increased 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA), thiobarbituric reactive substances (TBARS), hydrogen peroxide (H2O2), protein carbonyl (PC) and oxidized glutathione (GSSG); decreased levels of reduced glutathione (GSH) and its dependent enzymes (Glutathione peroxidase [GPx] and glutathione reductase [GR]) in the hippocampus and cerebral cortex; and increased choline acetyltransferase (ChAT) activity in the hippocampus of ICV-STZ rats. The study suggests that CUR is effective in preventing cognitive deficits, and might be beneficial for the treatment of sporadic dementia of Alzheimer's type (SDAT).
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ABSTRACT: Free radicals and other so-called 'reactive species' are constantly produced in the brain in vivo. Some arise by 'accidents of chemistry', an example of which may be the leakage of electrons from the mitochondrial electron transport chain to generate superoxide radical (O2*-). Others are generated for useful purposes, such as the role of nitric oxide in neurotransmission and the production of O2*- by activated microglia. Because of its high ATP demand, the brain consumes O2 rapidly, and is thus susceptible to interference with mitochondrial function, which can in turn lead to increased O2*- formation. The brain contains multiple antioxidant defences, of which the mitochondrial manganese-containing superoxide dismutase and reduced glutathione seem especially important. Iron is a powerful promoter of free radical damage, able to catalyse generation of highly reactive hydroxyl, alkoxyl and peroxyl radicals from hydrogen peroxide and lipid peroxides, respectively. Although most iron in the brain is stored in ferritin, 'catalytic' iron is readily mobilised from injured brain tissue. Increased levels of oxidative damage to DNA, lipids and proteins have been detected by a range of assays in post-mortem tissues from patients with Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis, and at least some of these changes may occur early in disease progression. The accumulation and precipitation of proteins that occur in these diseases may be aggravated by oxidative damage, and may in turn cause more oxidative damage by interfering with the function of the proteasome. Indeed, it has been shown that proteasomal inhibition increases levels of oxidative damage not only to proteins but also to other biomolecules. Hence, there are many attempts to develop antioxidants that can cross the blood-brain barrier and decrease oxidative damage. Natural antioxidants such as vitamin E (tocopherol), carotenoids and flavonoids do not readily enter the brain in the adult, and the lazaroid antioxidant tirilazad (U-74006F) appears to localise in the blood-brain barrier. Other antioxidants under development include modified spin traps and low molecular mass scavengers of O2*-. One possible source of lead compounds is the use of traditional remedies claimed to improve brain function. Little is known about the impact of dietary antioxidants upon the development and progression of neurodegenerative diseases, especially Alzheimer's disease. Several agents already in therapeutic use might exert some of their effects by antioxidant action, including selegiline (deprenyl), apomorphine and nitecapone.Drugs & Aging 02/2001; 18(9):685-716. · 2.65 Impact Factor
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ABSTRACT: Intracerebroventricular (ICV) injection of streptozotocin (STZ) causes cognitive impairment in rats. The beneficial effect of naringenin (NAR) was investigated on ICV STZ-induced learning, memory, and cognitive impairment in male rats. For this purpose, rats were injected with ICV STZ bilaterally, on days 1 and 3 (3 mg/kg). The STZ-injected rats received NAR (50 mg/kg/day p.o.) starting 1 day pre-surgery for 3 weeks. The learning and memory performance was assessed using passive avoidance paradigm, and for spatial cognition evaluation, radial eight-arm maze (RAM) task was used. It was found out that NAR-treated STZ-injected rats show higher correct choices and lower errors in RAM than vehicle-treated STZ-injected rats. In addition, NAR administration significantly attenuated learning and memory impairment in treated STZ-injected group in passive avoidance test. Therefore, these results demonstrate the effectiveness of NAR in preventing the cognitive deficits caused by ICV STZ in rats and its potential in the treatment of neurodegenerative diseases such as Alzheimer's disease.Pharmacology 02/2006; 78(4):193-7. · 1.60 Impact Factor
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ABSTRACT: Curcumin (diferuloylmethane), an active ingredient of turmeric, obtained from the powdered rhizomes of Curcuma longa Linn., has been traditionally recognized for treatment of several diseases. To evaluate the potential clinical use of curcumin, we determined the dose dependence of its effects in the therapeutic window and of the neuroprotective efficacy in a cerebral thromboembolic model of the rat. Rats were subjected to occlusion of the middle cerebral artery (MCAo) by a thrombus and treated with different doses of curcumin or the vehicle at 4h after ischemia. The animals were assessed after 24h for motor performance and neurological deficit. The rats were sacrificed immediately afterwards for evaluation of infarct, edema volume, estimation of nitrate and nitrite levels, neutrophil infiltration and levels of GSH and glutathione peroxidase (GSH-Px) in brain tissue. Curcumin reduced in a dose-dependent manner the ischemia-induced cerebral infarct and edema volume and attenuated neurological deficits observed after 24h. Curcumin reduced post-ischemic brain neutrophil infiltration, nitrate and nitrite levels and ameliorated the loss of GSH-Px and tends to increase the GSH levels but not significantly in the brain tissue. Neuronal levels of reactive oxygen species, peroxynitrite, and nitric oxide were lowered and in brain cryosections inducible nitric oxide synthase expression were significantly inhibited after treatment with curcumin. The present study is the first evidence of effectiveness of curcumin when given 4h post-ischemia in the rat thromboembolic stroke models, as it reduces infarct volume, ameliorates the sensory motor function and significantly attenuated the nitrosative stress.Behavioural Brain Research 07/2008; 193(2):289-97. · 3.33 Impact Factor