Neuroprotective Effect Of Curcumin To Parkinson's And Alzheimer's Disease

PrefaceParkinson's Disease (PD) is a common age-related neurodegenerative disorder characterized by a progressive dopaminergic neuronal cell loss in the substantia nigra (SN), resulting in extrapyramidal motor dysfunction, including tremor, rigidity, and bradykinesia. Although the underlying mechanism of PD neurodegeneration is currently unclear, many studies have suggested that nigral dopaminergic cell apoptosis may play a critical role in the neurodegenerative processes in PD. Alzheimer's disease (AD) is a disease clinically characterized by progressive intellectual deterioration. AD is pathologically characterized by senile plaques (SP) formed by pathological deposition of (3-amyloid (Aβ), neurofibrillary tangles (NFT). With the gradual ageing of the population, the morbidity of PD and AD increased year by year. It had brought heavy burden to the society and family and become one of the fatal disease that hazard to human health. Now, how to find the causes of brain diseases, and to explore ways to treat these diseases have become the focus of attention worldwide.The natural phenolic compound curcumin, isolated from the roots of Curcuma longa (Zingiberaceae) and commonly used as a spice, is well documented for its medicinal properties in the traditional Indian and Chinese systems of medicine. Since 1937 the first paper published on The Lancet, there were 2600 papers which about curcumin cure human diseases have published on English Journals. Several epidemiological, clinical, and animal studies have shown that curcumin has a variety of pharmacological activities, including anti-inflammatory, antioxidant, anticarcinogenic, and wound-healing effects. In recent years, the potential therapeutic value of curcumin for neurodegenerative diseases, such as AD and PD, has been increasingly recognized. For example, curcumin has been found to inhibit the formation of amyloid b oligomers and fibrils and reduce oxidative damage and amyloid burden in AD transgenic mouse brain. Curcumin treatment protects against neuronal death in middle cerebral artery occlusion-induced focal cerebral ischemia in rats. An in vitro study has shown that curcumin protects PC 12 cells against MPP+-induced apoptosis. Furthermore, curcumin has been demonstrated to protect against nigral dopaminergic cell death from 6-OHDA neurotoxicity.Therefore, our study systematic and comprehensive reveals curcumin's protective effect on the PD mice cell models, and AD double-transgenic mouse model from a new perspective, which is an experimental basis in the treatment of neurodegenerative diseases.MethodsC57BL/6 mice IP MPTP, MPP+induced SH-SY5Y cells prepare model of PD, APP/PSl transgenic mice as the model of AD were used for the present study. Applicated open-field test and traction test in mice models of PD to detect and identify of behavior change of mice model. Immunohistochemical techniques, Stereology and Western blot were used for detected protection mechanisms of curcumin on the model of PD in vivo and in vitro. PCR technique was used for assaying AD transgenic mice, Morris water maze and Step Down Test, immunohistochemistry, Western blot were used for detected protective effect of curcumin on the APP/PS1 transgenic model of AD.Results1,The protective effect of curcumin to dopaminergic neuron of the mice model and SH-SY5Y model(1) Curcumin alleviates MPTP-induced mouse behavioral symptomsOpen-field test is shown 1. The MPTP+vehicle group exhibited a significant decrease in locomotion frequencies and rearing frequencies, compared with the vehicle control group on day 5 and 12. On day 12, the MPTP+curcumin group mice showed a significant increase in locomotion frequencies and rearing frequencies compared with the MPTP+vehicle group.In the traction test, the vehicle control mice gripped the wire with all four paws, while on day 12, in the MPTP+vehicle treated group, mice gripped the wire only by their forepaws. MPTP+curcumin group mice gripped the wire by one or two hindpaws, and the traction scores were increased significantly compared with the MPTP+vehicle group.(2) Curcumin protects against dopaminergic neuronal degenerationAs shown, compared with the vehicle control mice, a significant loss of the dopaminergic neurons and nerve fibers were seen in the SN and striatum after MPTP+ vehicle treatment. In contrast, those losses in the MPTP+curcumin group were clearly reduced.Unbiased stereological and optical density (O.D.) quantification showed that MPTP+vehicle produced a 43% loss of TH positive neurons in the SN and a 91% reduction of DAT-IR fibers, whereas curcumin administered once a day for 7 days improved the TH positive neuronal in the SN and DAT-IR fibers in the striatum to 82% and 36% of MPTP+curcumin-treatedmice, respectively.(3) Curcumin inhibits astrocyte activation in miceImmunoreactivity of GFAP results showed that MPTP+vehicle-treated mice exhibited 2.5 times more activated astrocytes than the vehicle control mice. MPTP+ curcumin treatment significantly attenuated the MPTP-induced increase in the number of activated astrocytes.(4) Inhibitory effects of curcumin on MPTP-induced activation of JNK, c-Jun and caspase-3 in mouse substantia nigraOur immunoBlotting results showed that MPTP induced a robust increase in phosphorylated forms of both JNK1 and JNK2, the key molecules in the JNK pathways, in the SN. Interestingly, curcumin treatment (50 mg/kg i.p.q.d. for 7 days) significantly inhibited MPTP-induced JNK1/2 phosphorylation,the activation of c-Jun and cleaved caspase-3.(5) Curcumin attenuates MPP+-induced SH-SY5Y cell deathMTT assay shown:SH-SY5Y cells treated with MPP+(0-5 mM) showed a dose-and time-dependent reduction in the levels of cell viability a 50% reduction in cell viability was obtained when cells were treated with 3 mM MPP+for 18 h. The MTT assay also showed that curcumin (0-5μM) and SP600125 (0-10μM) did not exhibit significant toxic effects on the cells. When the cells were pretreated with 1μM curcumin and 5μM SP600125 for 2 h prior to the addition of MPP+, the cell viability was significantly increased.Hoechst 33258 staining showed that distinct nuclear condensation was observed in MPP+-treated cells. This phenomenon was inhibited when curcumin was added prior to MPP+treatment.(6) Curcumin inhibits JNK pathway activation in SH-SY5Y cellsOur immunoBlotting results showed that the phosphorylated forms of both JNK1 and JNK2 were increased significantly in response to MPP+stimuli. The expression levels of JNK1 and JNK2 phosphorylation were inhibited by pretreatment with 1μM curcumin, and 5μM SP600125. The changes in the expression levels of MKK4 phosphorylation, an upstream molecule of JNK protein, were similar to that of JNK protein, i.e. curcumin could also inhibit MPP+-induced MKK4 activation in SH-SY5Y cells. Coincident with the result of JNK phosphorylation, MPP+-induced c-Jun phosphorylation was inhibited by curcumin in SH-SY5Y cells, which is similar to the effect of SP600125 on c-Jun activation.2,The protective effect of curcumin to the neuron of APP/PS1 transgenic mice model(1) Curcumin change behavior abnormalities in APP/PS1 transgenic miceMorris water maze test:In hidden platform tests, the escape latency has a downward trend in three groups of mice. Movement trail of Wild-type mice and mice of fed curcumin focused on the appropriate platform location, while control APP/PS1 mice almost along the pool wall and away from the platform location. Results showed, the escape latency on the second and fourth day of the hidden platform test was shorter than control mice, suggesting that curcumin-treated improved spatial learning and memory ability, but not reach normal levels. In the probe trial on the fifth day, the curcumin-treated APP/PS1 mice traveled into the third quadrant, where the hidden platform was previously placed, significantly more times than controls.Step Down Test:compared to wild-type mice, control transgenic mice reaction time, error frequency increased; The curcumin fed group compared with control group, curcumin can shorten the reaction time, improved learning ability, at the same time reduce the number of errors, improve memory performance.(2) Curcumin protect the burden of senile plaques in APP/PS1 transgenic miceIHC results showed that senile plaque formation was significantly decreased and the area of senile plaques was also significantly reduced in the brain of curcumin fedding mice.Quantification showed that curcumin treatment reduced senile plaque number in the hippocampus and cortex to 34% and 24% respectively.(3) Curcumin effect APP and Tau protein in APP/PS1 transgenic mice brainWestern blot results showed that APP has not significant difference between curcumin fed and control transgenic mice. p-Tau protein levels in the brain of curcumin feeding group mice lower than control transgenic mice but higher than wild-type mice.Conclusion1. The administration of intraperitoneal injection curcumin can significantly improve behavior of mice, while the number of nigrostriatal dopaminergic neurons and fibers increased, the active ingredient of MKK4, JNK, c-Jun, caspase-3 reduced in substantia nigra, the number of GFAP reduction which indicates that cucumin play a role in anti-apoptosis and thus alleviate neuronal damage by inhibiting the JNK pathway2. MPP+as an endogenous toxin can induce apoptosis in SH-SY5Y cells, while curcumin could inhibit the active ingredient of JNK to delay the occurrence of apoptosis, and its inhibitory effect is similar to the specific JNK inhibitor SP600125, which further confirmed that curcumin protected neurons by inhibiting the JNK pathway.3. Oral curcumin can improve memory and learning ability of transgenic mice, reduce the burden of senile plaques in brain of transgenic mice, and decrease the content of p-Tau. These results confirm the neuroprotective effect of curcumin in AD transgenic mouse brain.