6-OHDA Toxin Model in Mouse

Disrupted basal ganglia output during movement preparation in hemiparkinsonian mice is consistent with behavioral deficits

Parkinsonian motor deficits are associated with elevated inhibitory output from the basal ganglia (BG). However, several features of Parkinson's disease (PD) have not been accounted for by this simple "classical rate model" framework, including the observation in patients with PD that movements guided by external stimuli are less impaired than otherwise identical movements generated based on internal goals. Is this difference due to divergent processing within the BG itself or due to the recruitment of extra-BG pathways by sensory processing? In addition, surprisingly little is known about precisely when, in the sequence from selecting to executing movements, BG output is altered by PD. Here, we address these questions by recording activity in the substantia nigra pars reticulata (SNr), a key BG output nucleus, in hemiparkinsonian mice performing a well-controlled behavioral task requiring stimulus-guided and internally specified directional movements. We found that hemiparkinsonian mice exhibited a bias ipsilateral to the side of dopaminergic cell loss that was stronger when movements were internally specified rather than stimulus guided, consistent with clinical observations in patients with Parkinson's disease. We further found that changes in parkinsonian SNr activity during movement preparation were consistent with the ipsilateral behavioral bias, as well as its greater magnitude for internally specified movements. Although these findings are inconsistent with some aspects of the classical rate model, they are accounted for by a related "directional rate model" positing that SNr output phasically overinhibits motor output in a direction-specific manner. These results suggest that parkinsonian changes in BG output underlying movement preparation contribute to the greater deficit in internally specified than stimulus-guided movements.NEW & NOTEWORTHY Movements of patients with Parkinson's disease are often less impaired when guided by external stimuli than when generated based on internal goals. Whether this effect is due to distinct processing in the basal ganglia (BG) or due to compensation from other motor pathways is an open question with therapeutic implications. We recorded BG output in behaving parkinsonian mice and found that BG activity during movement preparation was consistent with the differences between these forms of movement.

Engraftable Induced Pluripotent Stem Cell-Derived Neural Precursors for Brain Repair

Stem cell transplantation has attracted great interest for treatment of neurodegenerative diseases to provide neuroprotection, repair the lesioned neuronal network and restore functionality. Parkinson's disease (PD), in particular, has been a preferred target because motor disability that constitutes a core pathology of the disease is associated with local loss of dopaminergic neurons in a specific brain area, the substantia nigra pars compacta. These cells project to the striatum where they deliver the neurotransmitter dopamine that is involved in control of many aspects of motor behavior. Therefore, cell transplantation approaches in PD aim to replenish dopamine deficiency in the striatum. A major challenge in developing cell therapy approaches is the ability to generate large numbers of transplantable cells in a reliable and reproducible manner. In recent years the technological breakthrough of induced pluripotent stem cells (iPSCs) has demonstrated that this is possible at a preclinical level, accelerating clinical translation. A second important issue is to efficiently differentiate iPSCs into dopaminergic neuronal progenitors with restricted proliferation potential in order to avoid cellular overgrowth in vivo and minimize the risk of tumorigenesis. Here we describe an effective protocol that includes human iPSC differentiation to the dopaminergic lineage and enrichment in neuronal precursor cells expressing the polysialylated form of the neural cell adhesion molecule PSA-NCAM, through magnetically activated cell sorting. The resulting cells are transplanted and shown to survive, differentiate, and integrate within a striatal lesion model generated by unilateral 6-hydroxydopamine administration in mice of the NOD/SCID strain that supports xenografts.

The Amphetamine Induced Rotation Test: A Re-Assessment of Its Use as a Tool to Monitor Motor Impairment and Functional Recovery in Rodent Models of Parkinson's Disease

Rats and mice with unilateral damage to the nigrostriatal dopamine system—induced by neurotoxins, such as 6-hydroxydopamine, overexpression of α-synuclein, or injections of toxic synuclein protofibrils—are widely used as experimental models to mimic the loss of dopamine neurons seen in Parkinson’s disease. The amphetamine rotation test is commonly used to monitor the extent of motor impairment induced by the lesion, and this test has also become the standard tool to demonstrate transplant-induced functional recovery or the efficacy of neuroprotective interventions aimed to preserve or restore DA neuron function. Although the amphetamine-induced rotation test is highly useful for this purpose it has some important pitfalls and the interpretation of the data may not always be straightforward. Unless the test is applied properly and the data are displayed and interpreted appropriately the conclusions may be misleading or simply totally wrong. The purpose of this review is to draw attention to the potential problems and pitfalls involved in the use of drug-induced rotation tests, and to provide recommendations and advice on how to avoid them.

Renoprotective and neuroprotective effects of enteric hydrogen generation from Si-based agent

We have developed Si-based agent which can generate a large amount of hydrogen. Si-based agent continues generating hydrogen for more than 24 h by the reaction with water under conditions similar to those in bowels, i.e., pH8.3 and 36 °C, and generates ~400 mL hydrogen. To investigate beneficial effects for diseases associated with oxidative stress, Si-based agent is administered to remnant kidney rats and Parkinson's disease mice. Rats are fed with control or Si-based agent-containing diet for 8 weeks. Si-based agent is found to greatly suppress the development of renal failure and the parameters of oxidative stress. Treatment with Si-based agent in a mouse model of hemi-Parkinson's disease induced by 6-hydroxydopamine attenuated degeneration of dopaminergic neurons and prevented impairment of motor balance and coordination. These findings indicate that the Si-based agent shows renoprotective and neuroprotective effects presumably via suppression of oxidative stress by generation of hydrogen.