Asymmetrically lesioned mesencephalon in healthy rodents: call for caution
Elsa Y Pioli1, Sandra Dovero, Bernard H Bioulac
1Basal Gang, Laboratoire de Physiologie et Physiopathologie de la Signalisation Cellulaire, CNRS UMR 5543, Université Victor Segalen, 146 rue Léo Saignat, 33076 Bordeaux Cedex, France.
Abstract:
Stereological counting of tyrosine-hydroxylase immunoreactive (TH-IR) neurons in the mesencephalon is a pivotal parameter in assessing the extent of lesioning in animal models of Parkinson's disease. We here show that the number of TH-IR neurons often appears abnormally decreased in healthy--commercially available--mice and rats, although both the number of Nissl-stained cells and the striatal dopaminergic innervation are unaffected. This potential bias in assessing extent of neurotoxin-induced lesion and subsequent protection by pharmacological manipulation prompts us to call for caution in setting up experimental designs.
Insights
Tyrosine-hydroxylase immunoreactive (TH-IR) neuron counts in the mesencephalon may be misleading in Parkinson
Area of Science:
- Neuroscience
- Parkinson's Disease Research
- Stereology
Background:
- Stereological counting of tyrosine-hydroxylase immunoreactive (TH-IR) neurons in the mesencephalon is crucial for Parkinson's disease (PD) animal models.
- Accurate assessment of dopaminergic neuron loss is vital for evaluating neurotoxin-induced lesions and potential therapeutic interventions.
Purpose of the Study:
- To investigate potential biases in stereological counting of TH-IR neurons in healthy control animals.
- To determine if apparent decreases in TH-IR neurons in healthy animals affect lesion assessment.
Main Methods:
- Stereological counting of TH-IR neurons in the mesencephalon of commercially available healthy mice and rats.
- Assessment of Nissl-stained cells and striatal dopaminergic innervation in the same animals.
Main Results:
- A decreased number of TH-IR neurons was observed in healthy mice and rats.
- Nissl-stained cell counts and striatal dopaminergic innervation remained unaffected in these healthy animals.
Conclusions:
- Apparent reductions in TH-IR neurons in healthy animals can create a bias in Parkinson's disease research.
- Caution is advised when designing experiments involving stereological assessment of TH-IR neurons to avoid misinterpretation of results.
