Decreased GABA levels during development result in increased connectivity in the larval zebrafish tectum
Year: 2024
Type: preprint
Abstract: γ-aminobutyric acid (GABA) is an abundant neurotransmitter that plays multiple roles in the vertebrate central nervous system (CNS). In the early developing CNS, GABAergic signaling acts to depolarize cells. It mediates several aspects of neural development, including cell proliferation, neuronal migration, neurite growth, and synapse formation, as well as the development of critical periods. Later in CNS development, GABAergic signaling acts in an inhibitory manner when it becomes the predominant inhibitory neurotransmitter in the brain. This behavior switch occurs due to changes in chloride/cation transporter expression. Abnormalities of GABAergic signaling appear to underlie several human neurological conditions, including seizure disorders. However, the impact of reduced GABAergic signaling on brain development has been challenging to study in mammals. Here we take advantage of zebrafish and light sheet imaging to assess the impact of reduced GABAergic signaling on the functional circuitry in the larval zebrafish optic tectum. Zebrafish have three gad genes: two gad1 paralogs known as gad1a and gad1b , and gad2. The gad1b and gad2 genes are expressed in the developing optic tectum. Null mutations in gad1b significantly reduce GABA levels in the brain and increase electrophysiological activity in the optic tectum. Fast light sheet imaging of genetically encoded calcium indicator (GCaMP)-expressing gab1b null larval zebrafish revealed patterns of neural activity that were different than either gad1b-normal larvae or gad1b -normal larvae acutely exposed to pentylenetetrazole (PTZ). These results demonstrate that reduced GABAergic signaling during development increases functional connectivity and concomitantly hyper-synchronization of neuronal networks. Significance Statement Understanding the impact of reduced GABAergic signaling on vertebrate brain development and function will help elucidate the etiology of seizure initiation and propagation and other neurological disorders due to the altered formation of neural circuits. Here, we used fast light sheet imaging of larval zebrafish that neuronally expressed a genetically encoded calcium indicator (GCaMP) to assess the impact of reduced GABA levels through null mutation of gad1b during brain development. We show that reduced GABA levels during development result in increased functional connectivity in the brain.
Institution: University of Georgia
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Awards: AMPS: Scalable Graph Models for Anomaly Detection in Large-Scale Smart Grids, CRCNS: Quantum of Network Dysfunction in Epilepsy-Understanding the Inhibitory Restraint, Subcellular Resolution Light Sheet Microscope with a Large Field of View, ATD: Quantum algorithms for spatiotemporal models with applications to threat detection, Novel Analytical and Computational Approaches for Fusion and Analysis of Multi-Level and Multi-Scale Networks Data, Collaborative Research: Novel Statistical Tools for Metagenomics and Metabolomics Data, CAREER: IDBR: Super Resolution Deep Imaging, ATD: Inductive Spatiotemporal Graph Encoding for Interpretable and Transferable Deep Learning with Application in Human Dynamics, ATD: Nonparametric Testing and Fast Computing Methods for Spatiotemporal Models with Applications to Threat Detection, Collaborative Research: DMS/NIGMS 2: Novel machine-learning framework for AFMscanner in DNA-protein interaction detection
OpenAlex ID: W4402716343