# Novel fluorescent sensors for imaging neuromodulation

> **NIH NIH U01** · UNIVERSITY OF CALIFORNIA BERKELEY · 2021 · $1,002,861

## Abstract

SUMMARY
 Animal behaviors are orchestrated by the sophisticated nervous system, which is
dynamically regulated by neuromodulators including lipids and neuropeptides. Endocannabinoids
(eCBs) are neurolipids exist broadly in the brain and regulate learning and memory, addiction,
pain sensation, and food intake. Among neuropeptides, cholecystokinin (CCK) is involved in
nutrient sensing, food intake, and sleep regulation, and oxytocin (OXT) and vasopressin (AVP)
play important roles in various aspects of social behaviors. However, how and when lipid and
neuropeptide transmission occur in the brain are largely unclear. Existing methods (e.g.
microdialysis) that measures brain chemical content suffer from low temporal and spatial
resolution. Additionally, since neurolipid and neuropeptide releases often require repetitive
neuronal firing and can occur at both axonal and dendritic sites, activity of the neuromodulator-
releasing neurons cannot reliably predict where and when neurolipids and neuropeptides are
released.
 Here we propose to develop a set of new tools for long-term monitoring of neurolipids
and neuropeptides. Our strategy taps into their natural receptors, human G protein-coupled
receptors (GPCRs), which are coupled to GFP. In the presence of neurolipids or neuropeptides,
these GPCR Activation-Based (GRAB) sensors transform ligand binding-induced
conformational changes into rapid fluorescent signals. We aim to develop and optimize
neurolipid and neuropeptide GRAB sensors with >500% fluorescence change (dF/F) and 10-
nanomolar affinity in vitro and validate these novel tools in brain slices ex vivo and mouse
behavioral paradigms in vivo. In Aim 1, we will develop GRAB sensors for endocannabinoids,
CCK, vasopressin, and OXT by systematically varying key sites involved in ligand binding,
conformational change, etc. In Aim 2, we will validate the performance of these sensors in brain
slice following long-term expression using viral tools. In Aim 3, we will use three different
imaging methods (fiber photometry, epifluorescence and 2-photon imaging coupled with GRIN
lens) in different behavioral paradigms to test in vivo performance of the novel GRAB sensors in
mice. Feedback from experiments in Aims 2-3 will guide iterative optimization in Aim 1.
Successful completion of our proposal will yield a suite of powerful tools and technical
approaches, which will greatly facilitate studies of neurolipids and neuropeptides under both
physiological and pathological conditions, helping reveal disease mechanisms, providing
therapeutic guidance, and eventually benefiting human health.

## Key facts

- **NIH application ID:** 10201786
- **Project number:** 5U01NS113358-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA BERKELEY
- **Principal Investigator:** Yang DAN
- **Activity code:** U01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $1,002,861
- **Award type:** 5
- **Project period:** 2019-08-15 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10201786

## Citation

> US National Institutes of Health, RePORTER application 10201786, Novel fluorescent sensors for imaging neuromodulation (5U01NS113358-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10201786. Licensed CC0.

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