nIRCat characterization and acute brain slice imaging

Dopamine neuromodulation of neural synapses is a process implicated in a
number of critical brain functions and diseases. Development of protocols
to visualize this dynamic process is essential to understanding how
dopamine modulates neurochemical brain function. We have developed a
non-genetically encoded, near infrared (nIR) catecholamine nanosensor
(nIRCat) capable of identifying ~2 µm dopamine release hotspots in the
dorsal striatal brain slices. This platform is readily introduced into
both genetically tractable and intractable organisms and is compatible
with a number of dopamine receptor agonist and antagonists. In the
following work, we describe the synthesis, characterization, and
implementation of nIRCat in brain slices. We show how to image
electrically and optogenetically stimulated dopamine release using nIRCat,
and how these imaging protocols can be adapted to study the effects of
dopamine receptor pharmacology. We also detail the development of
video-analysis software to identify and track the location and kinetics of
dopamine release hot spots over the course of nIRCat imaging experiments.
Altogether, synthesis and characterization of nIRCat takes 5 hours and
imaging live brain slices takes 6 hours.