This study aimed to evaluate the effects of two different protocols for physical exercise (strength and aerobic training) on mitochondrial and inflammatory parameters in the 6-OHDA experimental model of Parkinson’s disease. Six experimental groups were used (
Parkinson’s disease (PD) is a progressive neurodegenerative disease with a global prevalence of 1%–3% in the population aged over 55 years [
Several recent experimental studies have indicated a role for mitochondrial dysfunction [
Treatment with levodopa and dopamine agonists effectively manages the early motor symptoms of PD; however, the progressive and irreversible nature of the disease, where dopaminergic neurons continue to die, makes these drugs ineffective for treating the symptoms of involuntary movement. Some forms of rehabilitation, such as physical exercise, have been effective at alleviating these symptoms through neuroprotection. Previous studies by our group have shown that exercise modulates the neurochemical status of the striatum and hippocampus in a rodent model of PD, most likely by increasing the levels of regulatory neurotrophins and reducing oxidative stress [
Adult male C57BL/6 mice (age: 2 months; weight: 25–30 g) were obtained from our own breeding colony. Mice were housed five per cage, on a 12/12 h light/dark cycle (lights on at 07:00) with free access to food (Nuvilab CR1, NuvitalNutrientes S/A, Brazil) and water. All experimental procedures were carried out in accordance with the Brazilian Guidelines for the Care and Use of Animals for scientific and didactic purposes (DOU 27/5/13, MCTI, p.7) and the study was approved by the local ethics committee. Six experimental groups were used (
All mice were habituated on a nine-channel, motor-driven treadmill at a speed of 10 m·min−1 for 10 min/day for 1 week to reduce their stress in response to the new environment. The mice did not receive any stimulus to run. The exercise groups performed an incremental running program to obtain progressive levels of intensity (13–17 m·min−1, no incline) on 3 or 4 days/week for 8 weeks, for a total period of 60 days. Each session was 50 min in duration and there was a 48 h interval between sessions.
This exercise entailed the mice climbing a 1 m ladder with a 2 cm grid inclined at 85° [
Twenty-four hours after the final physical training session, mice were anesthetized with Equithesin (3 mL/kg, i.p.) and placed on a stereotaxic frame. Eight micrograms of 6-OHDA was administered to each mouse (2
Mice were killed by cervical dislocation, and the striatum and hippocampus were surgically removed. One aliquot of each sample was homogenized in a buffer containing 1% Triton X-100, Tris 100 mM (pH 7.4), sodium pyrophosphate 100 mM, EDTA 100 mM, sodium vanadate 10 mM, phenylmethanesulfonyl fluoride 2 mM, and aprotinin 0.1 mg/mL at 4°C for intracellular protein analyses by western blot. The homogenate was centrifuged at 11000 rpm for 40 min to remove insoluble material. The supernatant was collected and the protein concentration was determined using the Bradford method [
The activity of complex I was determined as previously described [
Proteins were denatured by boiling in sample buffer containing 100 mM DTT [
Striatal and hippocampal samples were homogenized in phosphate buffer containing 0.05% Tween 20, 0.1 mM phenylmethylsulfonyl fluoride, 0.1 mM benzethonium chloride, 10 mM ethylenediaminetetraacetic acid, and 20 IU aprotinin. The homogenate was centrifuged at 3000 ×g for 10 min and the supernatants were stored at −70°C for later analysis. The concentration of tumor necrosis factor alpha (TNF-
All data are presented as mean ± standard error of the mean (SEM). Differences between experimental groups were determined using two-way analysis of variance (ANOVA) followed by Tukey’s post hoc test. A
TH levels in the striatum and hippocampus are presented in Figures
The effects of two physical training protocols on TH levels (a and b) in the striatum and hippocampus of mice exposed to 6-OHDA. Protein levels were assayed by western blotting. Values are expressed as mean ± SEM (
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The effects of two physical training protocols on Sirt1 levels (a and b,
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Striatal and hippocampal NO were increased in the U + 6-OHDA group compared with the Sham group. When mice were subjected to treadmill physical training (TTR + 6-OHDA), NO levels were significantly decreased compared with the U + 6-OHDA group (Figures
The effects of two physical training protocols on nitric oxide (a and b,
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There were high levels of proinflammatory cytokines in the mice that underwent either type of physical training. There was no significant difference in the level of TNF-
The effects of two physical training protocols on TNF-
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This study was designed to investigate the effects of two different physical training protocols (aerobic treadmill training and strength training) on markers of mitochondrial function and regulatory mechanisms for neuroinflammation in the striatum and hippocampus of mice exposed to the 6-OHDA experimental model of PD. The striatum and hippocampus are two cerebral structures that respond positively to the neuroprotective effects of physical exercise, particularly in relation to mitochondrial function, oxidative stress, and neuroinflammation [
The efficacy of the experimental model was determined by measuring the TH levels, which is indicative of the neurodegeneration induced by 6-OHDA [
Several experimental studies have shown that there is mitochondrial dysfunction in PD, particularly resulting from a reduction in mitochondrial complex I activity [
Exercise may affect brain respiratory chain complexes, particularly complex I,
Neuroinflammation is important in the pathogenesis of PD [
The results presented here show that the levels of total NF-
The high levels of proinflammatory cytokines that were observed in this study, such as IFN-
Another possible mechanism responsible for the elevated levels of proinflammatory cytokines in the hippocampus and striatum of PD animal models could be increased nitric oxide production. Glial cells can generate nitric oxide at neurotoxic levels following stimulation from high levels of IFN-
In summary, 6-OHDA induced different changes in the hippocampus and striatum, particularly in the levels of IL-17 and TGF-
The authors declare that they have no conflict of interests.
Talita Tuon designed and performed the study and wrote the paper. Priscila S. Souza, Giulia S. Pedroso, Thais F. Luciano, Claudio T. De Souza, Rafael C. Dutra, and Paulo C. L. Silveira performed the assays, and Ricardo A. Pinho supervised the experiment and helped write the paper.
The authors thank Heron Sangaletti Pereira and Deivid Borges for their assistance in the treatment and care of animals. This research was supported by Grants from UNESC, CNPq, FAPESC, and NENASC projects (PRONEX Program CNPq/FAPESC) (Brazil).