Cholinergic Stimulation of the Adult Zebrafish Brain Induces Phosphorylation of Glycogen Synthase Kinase-3 β and Extracellular Signal-Regulated Kinase in the Telencephalon

Abstract

The sequencing of the zebrafish genome, the emergence of powerful gene-editing tools, and the development of in vivo imaging techniques have propelled the economical zebrafish into prominence as a biomedical research model. Neurodegenerative disorders with a cholinergic component, such as Alzheimer’s and Parkinson’s diseases, are currently modeled using zebrafish. Still, the utility of zebrafish as a research model will not be fully realized until their neurophysiological properties are thoroughly characterized. In mammals, the coupling of cholinergic receptors to the phosphorylation of glycogen synthase kinase-3 β (GSK3β) and extracellular signal-regulated kinase 1/2 (ERK1/2) is of critical importance to cognitive processes and imparts protection against neuropathogenic events. Similarly, it is known that cholinergic receptors are required for learning and memory in zebrafish and that in vivo activation of cholinergic receptors induces transient changes in evoked synaptic transmission in the telencephalon. However, the intracellular events mediating cholinergic processes in zebrafish have yet to be elucidated. In the current study, an ex vivo drug treatment assay was used to demonstrate that carbachol (CCh)-mediated cholinergic stimulation of the intact adult zebrafish brain induces phosphorylation of GSK3β and ERK1/2 in the zebrafish telencephalon. These findings suggest GSK3β and ERK1/2 may underly cognitive processes in zebrafish.

An acetylcholinesterase inhibitor, donepezil, increases anxiety and cortisol levels in adult zebrafish

“…The zebrafish ( Danio rerio ) is a small teleost fish commonly used in CNS drug screening (Khan et al, 2017; Parng et al, 2002; Stewart et al, 2015), and may also be utilized for testing donepezil. Demonstrating high genetic and physiological homology to humans and rodents (Howe et al, 2013), zebrafish possess generally conserved CNS drug receptors, transporters, and enzymes (Bertuzzi and Ampatzis, 2018; Mans et al, 2019), including a well-developed cholinergic system (Clemente et al, 2004; Mueller et al, 2004). Several studies have already demonstrated the cognitive improvement of donepezil in adult and larvae zebrafish (Best et al, 2008; Dumitru et al, 2019; Muthuraman et al, 2019).…”

The Brilliance of the Zebrafish Model: Perception on Behavior and Alzheimer’s Disease

“…The telencephalon is a key area in the zebrafish brain for memory consolidation ( Flood et al, 1976 ). The presence of cholinergic neurotransmission pathways has been validated in zebrafish by previous research as well ( Williams and Messer, 2004 ; Mans et al, 2019 ). Studies using electrophysiological methods, histological methods, and antibody binding methods have indicated that the cholinergic system is widely distributed in the zebrafish brain ( Mueller et al, 2004 ).…”

Cholinergic signaling impairs cardiomyocyte cohesion

“…In the cardiomyocytes, cholinergic signaling is known to engage other signaling pathways such as PI3K/AKT, cGMP, PKG, and Ca/Calmodulin‐dependent protein kinase II 16,17,26 . In mouse or zebrafish brain, in vivo administration of agents which increase cholinergic stimulation or block NMDA receptors led to an increase in the inhibitory phosphorylation site of GSK‐3β at serine 9 27–29 . The desmosomal protein DP was shown to act as a scaffold for GSK‐3β in cardiomyocytes.…”