Application of hairless mouse strain to bioluminescence imaging of Arc expression in mouse brain

Hironori Izumi,Hisashi Mori,Tetsuya Ishimoto,Hiroshi Yamamoto

doi:10.1186/s12868-017-0335-6

Abstract

BackgroundBioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain. However, the black fur, skin pigmentation and hair regrowth after depilation of mouse interfere with BLI during developmental and daily examination. The aim of this study was to extend the application of Arc-Luc transgenic (Tg) mice to the BLI of neuronal activity in the mouse brain by introducing the hairless (HL) gene and to examine Arc-Luc expression at various developmental stages without interference from black fur, skin pigmentation, and hair regrowth.ResultsThe Arc-Luc Tg HL mice were established by crossing the Tg C57BL/6 mouse strain with the HL mouse strain. Under physiological and pathological conditions, BLI was performed to detect the signal intensity changes at various developmental stages and at an interval of <7 days. The established Arc-Luc Tg HL mice exhibited clear and stable photon signals from the brain without interference during development. After surgical monocular deprivation during visual-critical period, large signal intensity changes in bioluminescence were observed in the mouse visual cortex. Exposure of mice to a novel object changed the photon distribution in the caudal and rostral cerebral areas. The temporal pattern of kainic-acid-induced Arc-Luc expression showed biphasic changes in signal intensity over 24 h.ConclusionsThis study showed the advantages of using the mutant HL gene in BLI of Arc expression in the mouse brain at various developmental stages. Thus, the use of the Arc-Luc Tg HL mice enabled the tracking of neuronal-activity-dependent processes over a wide range from a focal area to the entire brain area with various time windows.

Highlights

Bioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain
Using cooled CCD camera systems, we detected bioluminescence signals in areas around the nose, brain, paws, kidneys, and testes in the activity-regulated cytoskeleton-associated protein gene (Arc)-luciferase gene (Luc) Tg HL mice (Fig. 2a). The distribution of these signals was consistent with those previously reported for Arc expression and public database from transcriptome analysis [14]
We examined the expression levels of Luc and endogenous Arc proteins by western blot analysis and found that they were slightly higher in the cerebral cortex at 4 weeks of age than at 8 weeks of age (Fig. 2b, Additional file 1: Table S2)

Summary

Introduction

Bioluminescence imaging (BLI) is a powerful technique for monitoring the temporal and spatial dynamics of gene expression in the mouse brain. The aim of this study was to extend the application of Arc-Luc transgenic (Tg) mice to the BLI of neuronal activity in the mouse brain by introducing the hairless (HL) gene and to examine Arc-Luc expression at various developmental stages without interference from black fur, skin pigmentation, and hair regrowth. Bioluminescence imaging (BLI) is a powerful research technique based on detection of light emission produced by oxidation of luciferin by luciferase [1, 2] The advantages of this technique in studies of small living animals are the following: high signal-to-noise (S/N) ratio with low background signal intensities, low limit and simplicity of detection, wide dynamic range of signal intensities, and applicability to genetic manipulation as well as continuous and quantitative analyses. The periods of BLI were restricted less than 24 h and at an interval of more than 4 weeks [11]

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