The Effect Of Brain Iron Overload On Parkinson’s Disease Induced By MPTP

As well as other organs, iron plays an important role in the process of life activity of brain; however, excessive or scant level of iron would also harm the function of brain. Therefore, the level of iron should be strictly regulated, including uptake, transport, storage and release of iron in cellular and systems levels. Any problem in these processes will destruct the stabilization of iron in brain and result in a variety of diseases.Oxidative stress is considered to be a major cause of destruction and death of neurons in neurodegenerative diseases, such as PD and AD. Under oxidative stress, excess amount of ROS in cells would be produced, consequently damage the structure of membranes, proteins and nucleic acids, and lead to cell necrosis ultimately. Different degree of iron accumulation in patient’s brain was found in these diseases. Also, excess iron deposition would generate massive ROS to exacerbate oxidative stress through the Fenton reaction.Ceruloplasmin-knockout mouse is usually used in progressive deposition of iron in organ. Along with aging, iron deposition will arise on knockout mouse’s brain. In addition, model of increased level of iron in mouse’s brain is made by injecting ferric citrate into lateral ventricle. PD model is produced through intraperitoneal injection of MPTP to explore if variation of iron levels in brain may influence the behavior in mice, iron levels in the part of the substantia nigra, the amount of TH-positive neurons and oxidative stress. The study present here will provide a theoretical basis for the effects of the iron level on PD, as well as drug development for PD treatment.Results:1. The behavioral detection show that the time on the wheel of CP-/- MPTP group had significant declined, compared with CP+/+ Con group.2. CP-knockout mice substantia nigra iron distribution detected by SR-XRF show that the content of iron in CP-/- MPTP group has raised significantly, and clustered intensively. Also, sedimentary phenomena of iron occurred.3. Immunofluorescence double staining showed that, in CP-knockout mice model substantia nigra, comparing to the CP+/+ Con group, the number of TH positive cell has declined significantly in CP+/+ MPTP group. Compared with other three groups, the double-labeled Ferritin increased significantly in CP-/- MPTP group and the signal was observed in TH positive cell, as well as other region. In the model of increased level of iron in mouse’s brain made by injecting ferric citrate into lateral ventricle, compared with the control group, the number of TH positive cell in FAC+MPTP group has significantly decreased. The double-labeled Ferritin positive signal has increased mainly appearing in the TH positive cells.4. The results of Western-blot indicate that, in mouse substantia nigra, compared with saline+MPTP and saline+saline groups, the level of Ferritin-L protein in FAC+MPTP group increased significantly, and the expression of TH protein decreased significantly. In striatum, compared with the saline+MPTP and saline+saline groups, the level of Ferritin-L protein increased significantly, comparing to the saline+saline group, the expression of TH protein decreased significantly, but show no difference comparing to the saline+MPTP group.5. The number of TUNEL positive cells in substantia nigra has increased significantly in CP-/- MPTP group, compared with CP+/+ MPTP and CP+/+ Con groups.6. Compared with CP+/+ MPTP and CP+/+ Con groups, the content of SOD in substantia nigra has declined significantly in CP-/- MPTP group, and MDA has remarkable risen.Conclusions:1. Lack of equilibrium as a feature of PD which is induced by MPTP is aggravate by increasing of brain iron levels, and cause more serious dyspraxia.2. In mouse substantia nigra, iron levels rise clearly with the incidence of PD, and Ferritin protein levels significantly higher than the control group’s. Meanwhile, we observe that iron deposition mainly in the dopaminergic neurons and their surrounding area.3. In MPTP-injected mice, death of dopaminergic neurons in the substantia nigra is on account of rise of brain iron levels. At the same time, there is a significant reduction in TH expression in the substantia nigra, and damage of the function of dopaminergic neurons.4. At the high level of brain iron, the apoptosis of cells which is induced by injection of MPTP in the substantia nigra increased clearly, companying with markers of apoptosis.5. At the high level of brain iron, ROS is increased obviously in the substantia nigra after injecting MPTP, which maybe the important reason of the increased apoptosis.