Striatal cholinergic interneurons: birthdates predict compartmental localization

Area of Science:

• Neuroscience
• Developmental Neurobiology
• Striatal Circuitry

Background:

• Striatal neurons exhibit distinct compartmentalization into patch and matrix based on their birthdates.
• Cholinergic interneurons, born early in neurogenesis, are unexpectedly distributed throughout the striatum, with a preference for the matrix.
• Understanding the factors influencing cholinergic interneuron localization is crucial for deciphering striatal function.

Purpose of the Study:

• To investigate whether neuronal birthdate predicts the final compartmental localization of striatal cholinergic interneurons.
• To compare the birthdate-compartment relationship of cholinergic neurons with other striatal neuron populations.

Main Methods:

• Maternal injection of bromodeoxyuridine (BrdU) to label postmitotic neurons at specific embryonic days (E13, E15, E17).
• Retrograde tracer (True Blue) injection into the substantia nigra to label the patch compartment.
• Triple labeling for BrdU, choline acetyltransferase (cholinergic marker), and True Blue in adult rats (P40).

Main Results:

• Cholinergic neurons born at E13 showed a higher probability of localization in the patch compartment.
• Cholinergic neurons born at E17 were more likely to be found in the matrix compartment, including the intermediate zone.
• The birthdate-dependent localization pattern for cholinergic neurons mirrors that of other striatal neuron types.

Conclusions:

• Neuronal birthdate is a significant predictor of compartmental localization for striatal cholinergic interneurons.
• The distribution of cholinergic interneurons, including those in the intermediate zone, follows a birthdate-dependent gradient.
• While absolute birthdates are earlier, cholinergic neurons exhibit the same relative birthdate/compartment relationship as other striatal neurons.