# Melatonin Signaling in Photoreceptors

> **NIH NIH R21** · MOREHOUSE SCHOOL OF MEDICINE · 2022 · $206,610

## Abstract

Melatonin is an important player in the regulation of many physiological functions within the body and
within the retina. Several studies have shown that melatonin synthesis in the retina primarily occurs
during the night and its levels are low during the day. Melatonin exerts its influence by binding to G
protein-coupled receptors named melatonin receptor type 1 (MT1) and type 2 (MT2). MT1 and MT2
receptors activate a wide variety of signaling pathways and both receptors are present in the
vertebrate photoreceptors where they may form MT1/MT2 heteromers (MT1/2h). Previous studies have
also demonstrated that melatonin may play an important role in protecting photoreceptors from
oxidative stress and can protect photoreceptors from apoptosis. Critically, melatonin signaling is
involved in the modulation of photoreceptor functioning and viability during aging. Finally, new
experimental evidence indicates that high fat diet (HFD) leads to a significant decrease in the
amplitude of a- and b-wave of the scotopic ERGs in mice lacking MT1 signaling. The goal of this
application is to elucidate the role of melatonin signaling plays in in the modulation of photoreceptor
functioning and to determine if melatonin may represent a useful tool in the fight against retinal
disorders. The present application comprises two specific aims. In specific aim 1 we will produce a
rod specific MT1 knock out mice in a melatonin proficient genetic background. In specific aim 2 we
will investigate the mechanism(s) by which MT1/2h signaling protects photoreceptor cells HFD. In our
research, we will use a wide array of new and technologically advanced techniques as well as we will
develop new lines of transgenic mice. Our proposal will provide important insights about the role of
melatonin signaling in the modulation of photoreceptor health.

## Key facts

- **NIH application ID:** 10398209
- **Project number:** 5R21EY031821-02
- **Recipient organization:** MOREHOUSE SCHOOL OF MEDICINE
- **Principal Investigator:** Gianluca Tosini
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $206,610
- **Award type:** 5
- **Project period:** 2021-05-01 → 2024-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10398209

## Citation

> US National Institutes of Health, RePORTER application 10398209, Melatonin Signaling in Photoreceptors (5R21EY031821-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10398209. Licensed CC0.

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