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First trimester development of the human nigrostriatal dopamine system
P M Almqvist1, E Akesson, L U Wahlberg
1Department of Clinical Neuroscience, Section of Neurosurgery, Karolinska Institute, Stockholm, Sweden.
Experimental Neurology
|June 1, 1996
Summary
Human mesencephalic dopaminergic neurons appear and differentiate early in the first trimester. Tyrosine hydroxylase (TH) expression and dopamine (DA) content increase significantly, indicating early functional development.
Area of Science:
- Neuroscience
- Developmental Biology
- Embryology
Background:
- Mesencephalic dopaminergic (mDA) neurons are crucial for motor control.
- Understanding their early development in humans is essential for insights into neurodevelopmental disorders.
Purpose of the Study:
- To characterize the morphological and neurochemical differentiation of human embryonic mDA neurons during the first trimester.
Main Methods:
- Immunohistochemistry and Western blot for tyrosine hydroxylase (TH) expression.
- High-performance liquid chromatography with electrochemical detection (HPLC-ED) for endogenous dopamine (DA) content analysis.
Main Results:
- TH expression detected as early as 3.5 weeks gestational age (Carnegie stage 11).
- TH-immunoreactive neurons and axonal projections to the neostriatum observed by mid-first trimester.
- Dopamine (DA) detected at 5.5 weeks gestational age, with levels increasing exponentially by 7.5 weeks.
Conclusions:
- Human mDA neurons exhibit early morphological and neurochemical differentiation within the first trimester.
- These findings provide evidence for the early migration, differentiation, and functional development of mDA neurons and their projections.