Development of a Unilaterally-lesioned 6-OHDA Mouse Model of Parkinson's Disease

Abstract

The unilaterally lesioned 6-hyroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD) has proved to be invaluable in advancing our understanding of the mechanisms underlying parkinsonian symptoms, since it recapitulates the changes in basal ganglia circuitry and pharmacology observed in parkinsonian patients [1][2][3][4] . However, the precise cellular and molecular changes occurring at cortico-striatal synapses of the output pathways within the striatum, which is the major input region of the basal ganglia remain elusive, and this is believed to be site where pathological abnormalities underlying parkinsonian symptoms arise 3,5 .In PD, understanding the mechanisms underlying changes in basal ganglia circuitry following degeneration of the nigro-striatal pathway has been greatly advanced by the development of bacterial artificial chromosome (BAC) mice over-expressing green fluorescent proteins driven by promoters specific for the two striatal output pathways (direct pathway: eGFP-D1; indirect pathway: eGFP-D2 and eGFP-A2a) 8 , allowing them to be studied in isolation. For example, recent studies have suggested that there are pathological changes in synaptic plasticity in parkinsonian mice 9,10 . However, these studies utilised juvenile mice and acute models of parkinsonism. It is unclear whether the changes described in adult rats with stable 6-OHDA lesions also occur in these models. Other groups have attempted to generate a stable unilaterally-lesioned 6-OHDA adult mouse model of PD by lesioning the medial forebrain bundle (MFB), unfortunately, the mortality rate in this study was extremely high, with only 14% surviving the surgery for 21 days or longer 11 . More recent studies have generated intra-nigral lesions with both a low mortality rate >80% loss of dopaminergic neurons, however expression of L-DOPA induced dyskinesia 11,12,13,14 was variable in these studies. Another well established mouse model of PD is the MPTP-lesioned mouse 15 . Whilst this model has proven useful in the assessment of potential neuroprotective agents 16 , it is less suitable for understanding mechanisms underlying symptoms of PD, as this model often fails to induce motor deï¬cits, and shows a wide variability in the extent of lesion 17, 18 .Here we have developed a stable unilateral 6-OHDA-lesioned mouse model of PD by direct administration of 6-OHDA into the MFB, which consistently causes >95% loss of striatal dopamine (as measured by HPLC), as well as producing the behavioural imbalances observed in the well characterised unilateral 6-OHDA-lesioned rat model of PD. This newly developed mouse model of PD will prove a valuable tool in understanding the mechanisms underlying generation of parkinsonian symptoms. Video LinkThe video component of this article can be found at http://www.jove.com/video/3234/ Protocol 1. Housing and preparation of mice 1. Maintain a colony of bacterial artificial chromosome (BAC) driven transgenic mice 8 (Mutant Mouse Regional Resource Center (MMRRC) FVB in a 12:12 h light-dark cycle ...

A partial lesion model of Parkinson's disease in mice – Characterization of a 6-OHDA-induced medial forebrain bundle lesion

“…In mice, 6-OHDA has been stereotaxically injected into different brain areas along the nigrostriatal pathways, such as the striatum [9][10][11], the SNpc [12,13] and the medial forebrain bundle (MFB) [14,15], leading to different types of degeneration and motor symptoms [13][14][15][16][17][18][19][20][21]. Injections into the MFB have been extensively used in rats (reviewed in [4,22,23]) but to a much lesser extent in mice [14,[16][17][18][19]21].…”

Depletion of nucleus accumbens dopamine leads to impaired reward and aversion processing in mice: Relevance to motivation pathologies

“…All procedures were conducted under a permit for animal experimentation (No. 170/2012) Denmark) to block 6-OHDA uptake by noradrenaline and serotonin neurons, respectively (Tanaka et al, 2012;Thiele et al, 2012). Mice were anaesthetised with a cocktail of fentanyl 0.04 mg/kg, midazolam 4 mg/kg and medetomidine 0.4 mg/kg, i.p..…”

Lymphocytes reduce nigrostriatal deficits in the 6-hydroxydopamine mouse model of Parkinson’s disease

“…T-cells into the SN. An explanation could be that we performed immunohistochemical analysis several weeks after 6-OHDA injection, because we wanted to see the full range of neurodegeneration that has been described to emerge after 21 days (Thiele et al 2012). Microglia activation in this model has been observed to occur already within the first few days (Marinova-Mutafchieva et al 2009), so we speculate that infiltration of T-cells might appear within the first few days after 6-OHDA delivery as well when the blood brain barrier is still leaky.…”

“…0.2 ll of 5 mg/ml 6-OHDA or 0.9 % NaCl (sham) containing 0.02 % ascorbic acid was unilaterally injected in a rate of 0.1 ll/min (1 lg total) into the right MFB according to the mouse brain atlas of Paxinos and Franklin (Paxinos and Franklin, The Mouse Brain in Stereotaxic Coordinates, Second Edition, 2001), using the coordinates: AP -1-2 mm; ML -1.1 mm; DV -5 mm. This protocol has been described to generate a stable, reproducible 6-OHDA lesion (Thiele et al 2012). We adapted this protocol by using 1/3 of the proposed 6-OHDA concentration, since the original 15 mg/ml solution caused high mortality in RAG-1 -/-mice.…”

“…6-OHDA toxicity is mediated by oxidative injury due to cytotoxic mediators such as hydrogen peroxidase, hydroxyl radicals and superoxide anions (Zigmond et al 1992) and impaired mitochondrial function (Kupsch et al 2014). Only recently, the 6-OHDA model has been successfully transferred to mice, allowing us to analyze the impact of 6-OHDA toxicity in genetically modified strains (Thiele et al 2012;Boix et al 2015). To unravel the role of the adaptive immune system in this model, we examined the effect of 6-OHDA injection into the medial forebrain bundle (MFB) of immunecompromised (lymphocyte-deficient) mice by means of behavioral analysis and histopathology.…”