# Functional and transcriptomic profiling of synaptically connected dorsal horn neurons

> **NIH NIH R21** · UNIVERSITY OF MINNESOTA · 2020 · $224,714

## Abstract

Project Summary
Spinal interneurons integrate noxious and innocuous sensory inputs to the dorsal horn and gate their access to
spinal projection neurons. Although specific cells within dorsal horn circuits have been identified and
characterized, the diversity of interneuron subtypes, together with limited knowledge on their neurochemistry
and connectivity, currently precludes comprehensive network mapping. Our long-term objective is to define
changes in dorsal horn circuits under conditions of chronic pain. The objective of this exploratory project is to
identify and comprehensively characterize interneurons that are presynaptic to nociceptive-specific (high-
threshold, HT) and wide dynamic range (WDR) projection neurons. We will employ a novel approach that
combines the following components: 1) Monosynaptic transfer of non-toxic modified rabies virus (SiR) will be
used to induce expression of fluorescent reporter genes and calcium indicators in synaptically connected
neurons. 2) Calcium imaging in spinal cord slices with attached dorsal roots (DR) will be used to monitor
responses of identified dorsal horn neurons to defined primary afferent input. 3) Dual patch-clamp recording
from identified synaptically connected neurons will be integrated with Patch-seq methodology for single-cell
transcriptome analysis. Information regarding the complement of inhibitory and excitatory neurons synapsing
on dorsal horn projection neurons is limited. Further, data on differences in this complement based on the
functionality (HT, WDR) of projection neurons is lacking. Such knowledge would expand our understanding of
excitatory/inhibitory balance in modality-specific dorsal horn circuits converging on projection neurons and
increase the possiblilty of circuit-specific neuromodulation for the treatment of chronic pain. The central
hypothesis of this proposal is that HT and WDR projection neurons receive synaptic input from distinct
subpopulations of interneurons. In Aim 1, we will define subpopulations of interneurons that synapse on
projection neurons using monosynaptic SiR transfer, imaging of calcium responses to dorsal root stimulation in
spinal cord slices, and CLARITY-based neuroanatomical analysis. In Aim 2, we will test the hypothesis that
subpopulations of interneurons synapsing on HT and WDR projection neurons can be distinguished by
transcriptomic analysis. Following delivery of SiR to projection neurons and its monosynaptic transfer to their
presynaptic partners, excitatory and inhibitory connections between synaptic pairs will be characterized using
patch-clamp electrophysiology in spinal cord slices and patch-seq methodology will be employed for single-cell
RNAseq transcriptomic analysis of recorded neurons.
This project will generate critical new data on the connectivity of spinal projection neurons to the network of
interneurons that process primary afferent inputs and will lay the groundwork for comprehensive anatomical
and functional mapping of ...

## Key facts

- **NIH application ID:** 9941159
- **Project number:** 5R21NS112886-02
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** Suhasa B Kodandaramaiah
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $224,714
- **Award type:** 5
- **Project period:** 2019-07-01 → 2022-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9941159

## Citation

> US National Institutes of Health, RePORTER application 9941159, Functional and transcriptomic profiling of synaptically connected dorsal horn neurons (5R21NS112886-02). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/9941159. Licensed CC0.

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