An artery-specific fluorescent dye for studying neurovascular coupling

Area of Science:

• Neuroscience
• Vascular Biology
• Biomedical Imaging

Background:

• Neocortical arteries and arterioles are crucial for brain function.
• Accurate measurement of vascular dynamics is essential for understanding brain activity.
• Existing imaging techniques may face challenges in resolving fine vascular structures.

Purpose of the Study:

• To evaluate Alexa Fluor 633 hydrazide as a selective label for neocortical vasculature.
• To investigate sensory stimulus-evoked arteriole dilation dynamics in vivo.
• To identify potential artifacts introduced by Alexa Fluor 633 during functional imaging.

Main Methods:

• Utilized Alexa Fluor 633 hydrazide to label elastin fibers in neocortical arteries and arterioles.
• Measured arteriole dilation dynamics in response to sensory stimuli in mouse, rat, and cat visual cortex.
• Simultaneously recorded neuronal activity using calcium indicators and blood flow using fluorescein dextran.

Main Results:

• Alexa Fluor 633 demonstrated selective labeling of neocortical arteries and arterioles.
• Arteriole dilation dynamics were successfully measured in response to stimuli.
• Decreased fluorescence from underlying neurons during arteriole dilation was observed, indicating a potential artifact.

Conclusions:

• Alexa Fluor 633 is a valuable tool for selectively visualizing neocortical vasculature.
• The observed artifact necessitates careful consideration during functional imaging experiments.
• This finding impacts the interpretation of neuronal activity measurements in conjunction with vascular imaging.