# Neuron-Astrocyte Interactions in Developmental Lead Exposure

> **NIH NIH K00** · EMORY UNIVERSITY · 2020 · $84,750

## Abstract

Abstract
 Serotonergic neurons extensively innervate the visual system of the fruit fly Drosophila melanogaster,
yet the role of serotonin signaling in visual processing is unknown. Identification of individual cells expressing
serotonin receptors in visual system circuits will allow us to determine the contribution of serotonergic
modulation to visual processing computations. Five genetically distinct serotonin receptors are expressed
throughout the optic lobe and we identified specific neurons and visual processing pathways targeted by
serotonin neuromodulation. Single-cell labeling mapped serotonin receptors to specific visual processing
neurons: L2, L4, L5, T1, Lawf1, and Lawf2. Lamina monopolar cell 2 (L2) receives direct input from
photoreceptors and expresses the serotonin receptor 5-HT2B. Calcium imaging confirmed an increase in
baseline calcium in response to bath-applied serotonin in L2 and its electrically coupled partner, L1. L1 and L2
are the first-order neurons in the light-ON and light-OFF pathways, respectively, and both information streams
feed into motion detection circuits. L1 neurons do not express serotonin receptors, demonstrating that indirect
mechanisms such as gap junctions enable neuromodulators to influence cells in the absence of receptors. We
tested whether serotonin modulates visual responses in L2 neurons and found that serotonin increased the
magnitude of visually induced calcium transients. This suggests that neuromodulation may regulate salience to
specific visual stimuli in the light-OFF pathway. In this work we tested acute effects of serotonin signaling and I
propose to advance these findings by measuring physiological and transcriptomic changes in L2 neurons
following chronic increases in serotonin signaling. Together, these data will allow us to compare serotonin
modulation over multiple timescales. Additionally, these experiments will reveal molecular pathways and
transcriptional programs downstream of serotonin signaling cascades that are important for long-term
neuromodulation and may be relevant to mood elevation in humans. This work explores the molecular
mechanisms of neuromodulation and will contribute to the understanding of how neuromodulatory signaling is
integrated into sensory circuits.

## Key facts

- **NIH application ID:** 10226572
- **Project number:** 8K00ES033033-02
- **Recipient organization:** EMORY UNIVERSITY
- **Principal Investigator:** Maureen McGuirk Sampson
- **Activity code:** K00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $84,750
- **Award type:** 8
- **Project period:** 2020-09-16 → 2024-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10226572

## Citation

> US National Institutes of Health, RePORTER application 10226572, Neuron-Astrocyte Interactions in Developmental Lead Exposure (8K00ES033033-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10226572. Licensed CC0.

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