Visualization of GABA in Brain of Adult Drosophila Melanogaster by Mass Spectrometry Imaging

Introduction

The Drosophila melanogaster (hereinafter, Drosophila) is known as a model animal which is used in various fields of biology. Among its advantages as a model animal, it has a short life cycle of about 10 days, gene recombination techniques have already been established, breeding and creation of new models are inexpensive, and there are no issues from the viewpoint of animal ethics. In particular, Drosophila is widely used as a model organism for researches on neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS), because genetic knowledge and gene recombination techniques have been established. Neurotransmitters play important roles in neurodegenerative diseases. For example, it is known that γ-aminobutyric acid (GABA) influences various biological behaviors and neurodegenerative diseases as an inhibitory neurotransmitter. Investigation of not only the concentration of GABA in the brain, but also its spatial localization, is essential for determining the functions of GABA in the brain. For this reason, we believe that information on the localization of GABA in the head of Drosophila is critical for understanding the functions of GABA in various disease models. Although imaging techniques utilizing immunohistochemical staining and fluorescent labeling have been used to investigate the spatial localization information of GABA in the head of Drosophila, these conventional methods visualize the distribution of GABA indirectly, as they mainly visualize the GABAforming enzyme GAD1 or GABA transporters. Therefore, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which enables direct detection of target molecules by mass spectrometry, has attracted attention in recent years as a technique for visualization of biomolecules in nonmammalian model organisms.

March 6, 2020 GMT