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The 6-hydroxydopamine Rat Model of Parkinson's Disease
In This Article
Summary
The 6-hydroxydopamine (6-OHDA) model has been used for decades to advance the understanding of Parkinson's Disease. In this protocol, we demonstrate how to perform unilateral nigrostriatal lesions in the rat by injecting 6-OHDA in the medial forebrain bundle, assess motor deficits, and predict lesions using the stepping test.
Abstract
Motor symptoms of Parkinson's disease (PD)-bradykinesia, akinesia, and tremor at rest-are consequences of the neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) and dopaminergic striatal deficit. Animal models have been widely used to simulate human pathology in the laboratory. Rodents are the most used animal models for PD due to their ease of handling and maintenance. Moreover, the anatomy and molecular, cellular, and pharmacological mechanisms of PD are similar in rodents and humans. The infusion of the neurotoxin, 6-hydroxydopamine (6-OHDA), into a medial forebrain bundle (MFB) of rats reproduces the severe destruction of dopaminergic neurons and simulates PD symptoms. This protocol demonstrates how to perform the unilateral microinjection of 6-OHDA in the MFB in a rat model of PD and shows the motor deficits induced by 6-OHDA and predicted dopaminergic lesions through the stepping test. The 6-OHDA causes significant impairment in the number of steps performed with the contralateral forelimb.
Introduction
The main neuropathological characteristics of PD are the chronic progressive neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) and the presence of Lewy bodies containing α-synuclein protein1. As SNc dopaminergic neurons project their axons into the striatum through the nigrostriatal pathway, neurodegeneration of neurons in SNc results in a dopaminergic deficit in the striatum2. The absence of dopamine in the striatum causes an imbalance in the activities of the direct and indirect motor control pathways, which is responsible for the main motor symptoms of PD: akinesia (slow moveme....
Protocol
All procedures involving animals followed the ethical principles of the National Council for the Control of Animal Experimentation (CONCEA) and the Arouca Law (Law 11.794/2008) and were approved by the local ethics committee (CEUA-FFCLRP/USP (18.5.35.59.5).
1. Preparation of drugs
- Anesthesia with Ketamine/Xylazine
NOTE: The dose of ketamine used is 70 mg/kg, and the dose of xylazine is 10 mg/kg.- To prepare 1 mL of anesthetic using ketamine 100 mg.......
Representative Results
Dopaminergic lesion assessment
The stepping test enables the assessment of the akinesia of the anterior limb contralateral to the lesion and the selection of animals with a possible lesion of the nigrostriatal pathway induced by 6-OHDA infusion (Figure 1). The comparison of the performance of the contralateral forelimb stepping test presurgery and 2 weeks and 4 weeks after surgery revealed interaction (F2,74 = 93.63; p < 0.0001; two-way repeated-measures.......
Discussion
This paper describes a protocol for performing surgery for unilateral microinfusion of 6-OHDA in the MFB, capable of causing robust lesions in the neurons of the nigrostriatal pathway and generating akinesia in the animal. Also described is the protocol for performing the stepping test, an easily applicable and noninvasive test that can be used to prove the success of the lesions and assess forelimb akinesia. As presented in the representative results, animals receiving 6-OHDA showed a reduction in the number of adjustin.......
Acknowledgements
This work was supported by São Paulo Research Foundation (FAPESP, grant 2017/00003-0). We are grateful for the Coordination for the Improvement of Higher Education Personnel (CAPES). We thank Dr. Anthony R. West, Dr. Heinz Steiner, and Dr. Kuei Y. Tseng for support and mentoring.
....Materials
| Name | Company | Catalog Number | Comments |
| 6-OHDA | Sigma Aldrich | H4381 | https://www.sigmaaldrich.com/catalog/product/sigma/h4381?lang=pt®ion=BR&cm_sp=Insite-_-caSrpResults_srpRecs_srpModel _6-ohda-_-srpRecs3-1 |
| 70% Alcohol | |||
| Ascorbic acid | Sigma Aldrich | 795437 | https://www.sigmaaldrich.com/catalog/product/sial/795437?lang=pt®ion=BR&gclid= Cj0KCQjw4cOEBhDMARIsAA3XD RipyOnxOxkKAm3J1PxvIsvw09 _kfaS2jYcD9E5OyuHYr4n89kO 6yicaAot6EALw_wcB |
| Cotton | |||
| Drill or tap | |||
| Gauze | |||
| Hamilton syringe 50 uL | Hamilton | 80539 | https://www.hamiltoncompany.com/laboratory-products/syringes/80539 |
| Imipramine | Alfa Aeser | J63723 | https://www.alfa.com/pt/catalog/J63723/ |
| Infusion pump | Insight | EFF-311 | https://insightltda.com.br/produto/eff-311-bomba-de-infusao-2-seringas/ |
| Ketamine (Dopalen) | Ceva | https://www.ceva.com.br/Produtos/Lista-de-Produtos/DOPALEN | |
| Machine for trichotomy | |||
| Meloxicam (Maxicam 2% Ourofino) | Ourofino | https://terrazoo.com.br/produto/maxicam-injetavel-2-50ml-ouro-fino/ | |
| Metal Disposal | |||
| Paper towels | |||
| Pentabiotic | Zoetis | https://www.zoetis.com.br/pentabiotico-veterinario.aspx | |
| Plastic waste garbage can | |||
| Poly-antibiotic | Pentabiotic (Wealth) | ||
| Povidone-iodine | |||
| Scalpel and blades | |||
| Scissors | |||
| Scraper | |||
| Stereotaxic apparatus | Insight | EFF-331 | https://insightltda.com.br/produto/eff-331-estereotaxico-1-torre/ |
| Sterile saline solution | |||
| Swabs | |||
| Temperature probe | |||
| Timer | |||
| Tweezers | |||
| Xylazine (Anasedan) | Ceva | https://www.ceva.com.br/Produtos/Lista-de-Produtos/ANASEDAN |
References
- Gibb, W. R., Lees, A. J. The relevance of the Lewy body to the pathogenesis of idiopathic Parkinson's disease. Journal of Neurology, Neurosurgery, and Psychiatry. 51 (6), 745-752 (1988).
- Albin, R. L., Young, A. B., Penney, J. B.
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