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Heterogeneous development of calbindin-D28K expression in the striatal matrix
1Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
The Journal of Comparative Neurology
|June 15, 1992
Summary
The study reveals that calbindin expression in the developing rat striatal matrix is not initially complementary to dopamine islands. This suggests dynamic postnatal processes shape the final complementary relationship between striosomes and the matrix.
Area of Science:
- Neuroscience
- Developmental Biology
- Neuroanatomy
Background:
- The striatal matrix and striosomes are key compartments within the basal ganglia, involved in motor control and reward processing.
- Calbindin-D28K (calbindin) is a calcium-binding protein selectively expressed in medium-sized neurons of the striatal matrix in mature rats.
- Tyrosine hydroxylase (TH)-immunostained dopamine islands represent future striosomes, providing anatomical landmarks for studying striatal development.
Purpose of the Study:
- To trace the developmental trajectory of the striatal matrix by examining the ontogenetic expression of calbindin.
- To investigate the spatial and temporal relationship between calbindin-positive matrix neurons and TH-immunostained dopamine islands during development.
- To understand the developmental origins of the complementary relationship between the striatal matrix and striosomes.
Main Methods:
- Immunohistochemical analysis of calbindin and tyrosine hydroxylase (TH) expression in serial sections of developing rat brains from embryonic day 20 (E20) to adulthood.
- Documentation of the localization and distribution of calbindin-positive neurons and TH-immunostained dopamine islands within the caudoputamen.
- Comparative analysis of the spatial overlap and developmental timing of calbindin-rich/poor zones and dopamine islands.
Main Results:
- Calbindin-positive medium-sized neurons first appeared in the striatum at E20, exhibiting heterogeneous distributions and forming a lattice-like pattern.
- By postnatal day 7 (P7), a mosaic pattern emerged with calbindin-rich surrounds and circumscript calbindin-poor pockets, which expanded over time.
- Dopamine islands were consistently located within calbindin-poor zones, but these zones often extended beyond the dopamine islands, indicating a lack of initial complementarity.
Conclusions:
- The developing striatal matrix exhibits significant neurochemical heterogeneity, with distinct calbindin-rich and calbindin-poor compartments.
- Calbindin expression in the matrix does not originate as a system complementary to dopamine islands, challenging previous assumptions.
- The final complementary relationship between striosomes and the matrix likely results from dynamic developmental processes occurring during early postnatal life.