Early specification of GAD67 subventricular derived olfactory interneurons

Area of Science:

• Neuroscience
• Developmental Biology

Background:

• Olfactory bulb interneurons originate from the subventricular zone (SVZ).
• These neurons migrate via the rostral migratory stream (RMS) to the olfactory bulb (OB).
• GABAergic interneurons, crucial for OB function, are derived from SVZ progenitors.

Purpose of the Study:

• To investigate the timing of GABAergic differentiation in migrating neuroblasts.
• To compare the expression patterns of GAD65 and GAD67 in SVZ-derived cells.
• To determine when SVZ-derived neuroblasts acquire GABAergic identity.

Main Methods:

• Utilized a transgenic mouse model expressing green fluorescent protein (GFP) under the GAD67 promoter.
• Employed Doublecortin (DCX) as a marker for migrating neuroblasts.
• Assessed cell proliferation using bromodeoxyuridine (BrdU) incorporation.

Main Results:

• GAD67-GFP expression was observed in migratory cells within the SVZ and RMS.
• GAD67-GFP positive cells co-expressed DCX and incorporated BrdU, confirming they are neuroblasts.
• GAD65 and GAD67 transgenes are expressed early in migration, with minimal protein production before reaching the OB.

Conclusions:

• Migrating neuroblasts from the SVZ express GABAergic markers, including GAD67, during their journey.
• GABAergic identity is acquired by SVZ-derived neuroblasts prior to their arrival in the olfactory bulb.
• This early expression contrasts with the later expression seen in dopaminergic interneurons.