Differential Modulation of the Central and Peripheral Monoaminergic Neurochemicals by Deprenyl in Zebrafish Larvae.

Marina Bellot,Melissa Faria,Cristian Gómez-Canela,Helena Bartolomé,Demetrio Raldúa

doi:10.3390/toxics9060116

Abstract

Zebrafish embryos and larvae are vertebrate models increasingly used in translational neuroscience research. Behavioral impairment induced by the exposure to neuroactive or neurotoxic compounds is commonly linked to changes in modulatory neurotransmitters in the brain. Although different analytical methods for determining monoaminergic neurochemicals in zebrafish larvae have been developed, these methods have been used only on whole larvae, as the dissection of the brain of hundreds of larvae is not feasible. This raises a key question: Are the changes in the monoaminergic profile of the whole larvae predictive of the changes in the brain? In this study, the levels of ten monoaminergic neurotransmitters were determined in the head, trunk, and the whole body of zebrafish larvae in a control group and in those treated for 24 h with 5 M deprenyl, a prototypic monoamine-oxidase B inhibitor, eight days post-fertilization. In control larvae, most of the monoaminergic neurochemicals were found at higher levels in the head than in the trunk. Significant changes were found in the distribution of some neurochemicals after deprenyl-treatment, with serotonin and norepinephrine increasing in both the head and the trunk, whereas dopamine, L-DOPA, and homovanillic acid levels were only modulated in the head. In fact, the highly significant increase in dopamine levels observed in the head after deprenyl-treatment was not detected in the whole-body analysis. These results indicate that the analysis of neurotransmitters in the zebrafish larvae whole-body should not be used as a general surrogate of the brain.

Highlights

Neurotransmission, the basis of neuronal communication, is critical for a normal neural function [1]
Serotonin is abundant in the intestine, where it is produced largely by enterochromaffin cells (EC) and by enteric neurons; it is involved in gut motility and enteric neuron development [7,8]
When data were normalized by larva (Supplementary Figure S2A), all the selected neurochemicals exhibited higher levels in the head, with levels ranging from 56.1% of tyrosine to 79.6% of L-DOPA

Summary

Introduction

Neurotransmission, the basis of neuronal communication, is critical for a normal neural function [1]. Especially the catecholamines dopamine and norepinephrine as well as the tryptamine serotonin, are major modulatory mechanisms in the vertebrate brain related with motor control, emotion, stress, and cognition [1,2]. The modulatory role of monoaminergic neurotransmitters is not restricted to the brain or the central nervous system (CNS), as these neurochemicals are involved in important signaling functions throughout our body. Dopamine and norepinephrine produced by enteric neurons are involved in gut motility and secretory reflexes [7]. Serotonin is abundant in the intestine (about 90% of the serotonin in the body), where it is produced largely by enterochromaffin cells (EC) and by enteric neurons; it is involved in gut motility and enteric neuron development [7,8]

Methods

Results

Conclusion