Figure 3

Parvalbumin neurons can be localized in brain sections using DAB colorimetric staining.

(A) 50 μm sections of cleared adult mouse brain labeled with anti-parvalbumin primary and horseradish peroxidase-labeled secondary antibodies, followed by incubation with DAB substrate. The neuronal cell bodies stain with brown color, cell bodies are labeled with arrows and axonal processes are labeled with asterisks. (B) 50 μm section of cleared adult mouse brain labeled with parvalbumin primary and Alexa 594-labeled secondary antibody. Cell bodies and neuronal processes are visualized; the axonal processes appear indistinct due to out-of-focus fluorescence from the thick section. (C) Control 50 μm section labeled with only HRP-labeled secondary antibody followed by DAB substrate (no primary antibody). As expected, no neurons retain label. (D) 100 μm sections of cleared adult mouse brain labeled with anti-parvalbumin primary and HRP-labeled secondary antibodies, followed by incubation with DAB substrate. Cell bodies and axonal processes retain brown-colored DAB label; selected cell bodies are labeled with arrows and identifiable axonal processes are labeled with arrowheads. (E) 100 μm sections of cleared adult mouse brain labeled with anti-parvalbumin primary and Alexa 594-labeled secondary antibody. (F) Control 100 μm section labeled as described in C. Scale bars = 50 μm.