# Validation of Therapeutic Target and Underlying Biology

> **NIH NIH U19** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2024 · $953,058

## Abstract

ABSTRACT
Research Component (RC) 1 includes the validation of novel therapeutic targets for pain and the study of their
biology. In our previous work, we discovered an ensemble of neurons in the amygdala that encodes pain
unpleasantness across pain modalities (heat, cold, mechanical) and pain types (acute, chronic neuropathic).
Furthermore, altering the activity of these amygdalar neurons using artificially expressed GPCRs (DREADDs,
Roth lab) significantly diminished pain affective-motivational behaviors in mice, in both acute and chronic
neuropathic pain models, and without altering withdrawal reflexes, anxiety or reward. Consequently, engaging a
target in the nociceptive amygdalar neurons that produce pain unpleasantness may be an effective approach to
manage many, if not all, pain types, including those with different peripheral localizations and mechanisms, those
of CNS origin, and even those for which we lack sufficient mechanistic understanding to treat the pain at its
source. Building on these exciting findings, we launched an analgesic target discovery project in which we
combined mouse genetic tools, single-cell RNA sequencing, and bioinformatics methods to label, sequence, and
catalog GPCRs present in nociceptive amygdalar neurons. After generating this catalog, we validated expression
of a dozen of GPCRs in the mouse amygdala using spatial transcriptomics. Next, we conducted a behavioral
screen in mice to test the ability of known ligands for these GPCRs, either purchased or synthesized by our
team, to reduce pain affective-motivational behaviors. This screen identified five amygdalar GPCRs with
antinociceptive properties. Among these, we focused our attention on neurotensin receptor 1 (NTSR1) because
previous studies have established that NTSR1 agonists are not rewarding and that engaging NTSR1 can even
reduce addictive behaviors in rodents. Both PD149163, a balanced/unbiased, brain-penetrant neurotensin (NTS)
peptide fragment 8-13 analog, and SBI-553, an NTSR1 negative allosteric modulator (NAM) at Gq and weaker
positive allosteric modulator with intrinsic agonist activity at beta-arrestin (PAM-agonist), reduced pain affective-
motivational behaviors in male mice. However, balanced/unbiased activation of NTSR1 with NTS or PD149163
produces dose-limiting side effects that could both confound antinociceptive readouts and hinder translation. In
contrast, SBI-553 lacks these side effects. We thus continued our evaluation of NTSR1 as an antinociceptive
target with SBI-553, and found that SBI-553 antinociceptive properties were lost in NTSR1 knockout mice,
validating on-target antinociceptive activity. In RC1, we expand validation studies to include other pain models
and further elucidate the biology of our target, NTSR1, focusing on signaling and expression in the human brain,
to inform optimized novel small molecule development and testing in RCs 3–5 and evaluate translation potential.
In Aim 1, we validate NTSR1 antinociceptive properti...

## Key facts

- **NIH application ID:** 10974395
- **Project number:** 1U19NS138975-01
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Gregory Scherrer
- **Activity code:** U19 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $953,058
- **Award type:** 1
- **Project period:** 2024-09-19 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10974395

## Citation

> US National Institutes of Health, RePORTER application 10974395, Validation of Therapeutic Target and Underlying Biology (1U19NS138975-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10974395. Licensed CC0.

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