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Embryonic dopaminergic neuron transplants in MPTP lesioned mouse striatum
1Istituto Internazionale di Genetica e Biofisica, CNR, Naples, Italy.
Abstract:
The aim of this work is to study CNS development and plasticity, and to study the mechanisms that allow exogenous embryonic dopaminergic neurons to restore transmitter function in the experimental parkinsonism. Recently, we have developed a new method that produces a selective degeneration of the dopaminergic nigrostriatal system in mice by a combined acetaldehyde/MPTP treatment. This procedure results in a selective and irreversible loss of substantia nigra dopaminergic neurons in C57BL mice, while other dopaminergic areas of the brain are spared. MPTP alone results instead only in a temporary, reversible damage of nigro- striatal dopaminergic functions. Embryonic dopaminergic neurons from ventral mesencephalon or hypothalamus are implanted in lesioned or normal right striata or lateral ventricles. The mesencephalic neurons implanted in a lesioned host form a dense network of fibers which establish functional reinnervation of the striatum (or caudate-putamen complex). After several months about the entire striatal parenchyma appears reinnervated; on average, 20% of the grafted mesencephalic dopaminergic cells survive. Implants of embryonic HYP neurons instead, show little or no survival. Moreover, dopaminergic mesencephalic neurons in control non-lesioned animals show a poor development with little fiber outgrowth. These data indicate that interactions between embryonic dopaminergic neurons and adult striatal neurons is specific. They also suggest that this specificity is sustained by trophic and/or tropic factors possibly produced by the lesioned striatum and by putative inhibitory mechanisms of cell migration and neuritic outgrowth.
Insights
Embryonic dopaminergic neurons successfully reinnervated the striatum in a mouse model of Parkinson
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Neurodegenerative Diseases
Background:
- Parkinson's disease involves the loss of dopaminergic neurons.
- Current treatments offer symptomatic relief but do not restore lost neurons.
- Developing methods to replace lost dopaminergic neurons is crucial.
Purpose of the Study:
- To investigate the potential of embryonic dopaminergic neurons for functional recovery in experimental parkinsonism.
- To understand the mechanisms underlying neural plasticity and cell integration in the adult brain.
- To identify factors influencing the survival and integration of transplanted neurons.
Main Methods:
- A novel method using combined acetaldehyde/MPTP treatment to induce selective dopaminergic neurodegeneration in mice.
- Implantation of embryonic dopaminergic neurons from the ventral mesencephalon or hypothalamus into lesioned or normal mouse striata.
- Assessment of neuronal survival, fiber outgrowth, and functional reinnervation using histological and functional analyses.
Main Results:
- Combined acetaldehyde/MPTP treatment selectively and irreversibly damaged nigrostriatal dopaminergic neurons.
- Implanted mesencephalic dopaminergic neurons survived and formed extensive fiber networks, functionally reinnervating the lesioned striatum.
- Approximately 20% of grafted mesencephalic neurons survived long-term, while hypothalamic neuron implants showed poor survival.
- Non-lesioned hosts supported less development of grafted dopaminergic neurons, suggesting a role for host-derived factors.
Conclusions:
- Embryonic mesencephalic dopaminergic neurons can functionally restore transmitter function in experimental parkinsonism.
- The lesioned striatum provides a more permissive environment for grafted neuron survival and outgrowth compared to normal striata.
- Trophic/tropic factors from the lesioned host and inhibitory mechanisms in non-lesioned hosts likely regulate transplanted neuron development and integration.