Relaxin-3 neurons of the zebrafish periaqueductal gray mediate behavioral responses evoked by darkness
- 1Department of Molecular Biology, Umea University, Sweden
Abstract
Ambient illumination influences many aspects of brain function, including responses to threats. One brain region proposed to mediate these effects is the periaqueductal gray (PAG), an evolutionarily conserved midbrain structure that contains multiple subpopulations of peptidergic neurons. Here we ask which cell types in the larval zebrafish PAG respond to changes in ambient illumination. By registering post hoc gene expression to neurons recorded during exposure to sensory stimuli, we show that GABAergic PAG neurons expressing the neuropeptide Relaxin-3 (rln3a+) are persistently activated by darkness, while a neighboring subpopulation of GABAergic PAG neurons expressing penka is not. Zebrafish lacking rln3a show a reduction in locomotion during darkness. We propose that darkness recruits Relaxin-3-releasing PAG neurons to promote vigilance and potentiate defense circuits. These results identify a specific peptidergic population of PAG neurons that are potentially relevant to behavioral state dysregulation associated with excessive darkness.
Related
- Integration of audiovisual danger stimuli in the zebrafish tectum is linked with premotor and behavioral enhancements
- Unpredictable chronic stress produces a mixed depression/anxiety behavioral profile in zebrafish
- Effects of β-Glucans on Pro-Inflammatory Markers and Behavioral Phenotype in a Valproic Acid (VPA)-Induced Autism Model in Zebrafish
- Characterization and Behavioral Responses of Volatile Organic Compounds in Commercial Cockroach Baits
- Host behavioral responses to perceived risk shape spatial disease dynamics
BibTeX
@misc{chia2026relaxin3,
title = {{Relaxin-3 neurons of the zebrafish periaqueductal gray mediate behavioral responses evoked by darkness}},
author = {J. S. M. Chia and M. Martin and G. M. Padilla and J. Jefferson and V. Krishna and G. Vanwalleghem and R.-K. Cheng and S. Krishnan and M. Lovett-Barron and T. R. Thiele and S. Jesuthasan},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.26.754586},
url = {https://www.biorxiv.org/content/10.64898/2026.09.26.754586v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Relaxin-3 neurons of the zebrafish periaqueductal gray mediate behavioral responses evoked by darkness
AU - J. S. M. Chia
AU - M. Martin
AU - G. M. Padilla
AU - J. Jefferson
AU - V. Krishna
AU - G. Vanwalleghem
AU - R.-K. Cheng
AU - S. Krishnan
AU - M. Lovett-Barron
AU - T. R. Thiele
AU - S. Jesuthasan
PY - 2026
DA - 2026/09/26
PB - bioRxiv
DO - 10.64898/2026.09.26.754586
UR - https://www.biorxiv.org/content/10.64898/2026.09.26.754586v1
AB - Ambient illumination influences many aspects of brain function, including responses to threats. One brain region proposed to mediate these effects is the periaqueductal gray (PAG), an evolutionarily conserved midbrain structure that contains multiple subpopulations of peptidergic neurons. Here we ask which cell types in the larval zebrafish PAG respond to changes in ambient illumination. By registering post hoc gene expression to neurons recorded during exposure to sensory stimuli, we show that GABAergic PAG neurons expressing the neuropeptide Relaxin-3 (rln3a+) are persistently activated by darkness, while a neighboring subpopulation of GABAergic PAG neurons expressing penka is not. Zebrafish lacking rln3a show a reduction in locomotion during darkness. We propose that darkness recruits Relaxin-3-releasing PAG neurons to promote vigilance and potentiate defense circuits. These results identify a specific peptidergic population of PAG neurons that are potentially relevant to behavioral state dysregulation associated with excessive darkness.
ER -