Fluorescent neuroactive probes based on stilbazolium dyes.

Area of Science:

• Neuroscience
• Chemical Biology
• Molecular Imaging

Background:

• Developing selective probes for neurotransmitter transporters is crucial for understanding neuronal function and dysfunction.
• Stilbazolium dyes offer potential as imaging agents due to their spectral diversity and charge.
• Monoamine transporters play key roles in neurotransmission and are targets for neurological drug development.

Purpose of the Study:

• To identify and characterize spectrally diverse stilbazolium dyes for imaging cells expressing monoamine transporters.
• To investigate the selective uptake and interaction of novel dyes with specific transporters, including norepinephrine transporter (NET).
• To evaluate the utility of these dyes for imaging distinct cell populations in live brain tissue.

Main Methods:

• Uptake assays were performed using cultured chick brainstem and cerebellum cells, and HEK-293 cells expressing specific monoamine transporters.
• Indatraline pretreatment was used to identify dyes interacting with monoamine transporters.
• Two spectrally distinct dyes, NEP+ and HNEP+, were selected for detailed investigation.
• HEK-293 cells expressing dopamine, norepinephrine, or serotonin transporters were used to assess transporter selectivity.
• Live brain tissue explants were imaged to assess in situ cell population visualization.
• Uptake experiments in the presence and absence of desipramine confirmed HNEP+ selectivity for NET.

Main Results:

• A set of spectrally diverse stilbazolium dyes was identified.
• HNEP+ was selectively accumulated by catecholamine transporters, particularly the norepinephrine transporter (NET).
• NEP+ showed possible binding but was not transported by the tested transporters.
• The differential interactions of NEP+ and HNEP+ allow for imaging of distinct cell populations.
• HNEP+ uptake preference for NET was confirmed using desipramine, a NET inhibitor.

Conclusions:

• Spectrally distinct stilbazolium dyes, NEP+ and HNEP+, can be used to image different cell populations in the brain.
• HNEP+ is a selective probe for the norepinephrine transporter (NET), enabling visualization of NET-expressing cells.
• These novel probes have potential applications in neuroscience research for studying neuronal circuits and transporter function.