Long-term imaging of dorsal root ganglia in awake behaving mice

Chao Chen,Wen-Biao Gan,Guang Yang,Peifu Tang,Yiling Zhang,Linlin Sun,Jinhui Zhang

doi:10.1038/s41467-019-11158-0

Chao Chen, Wen-Biao Gan + Show 5 more

Open Access

https://doi.org/10.1038/s41467-019-11158-0

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Abstract

The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation. Due to technical difficulties, DRG neuronal activity in awake behaving animals remains unknown. Here, we develop a method for imaging DRG at cellular and subcellular resolution over weeks in awake mice. The method involves the installation of an intervertebral fusion mount to reduce spinal movement, and the implantation of a vertebral glass window without interfering animals’ motor and sensory functions. In vivo two-photon calcium imaging shows that DRG neuronal activity is higher in awake than anesthetized animals. Immediately after plantar formalin injection, DRG neuronal activity increases substantially and this activity upsurge correlates with animals’ phasic pain behavior. Repeated imaging of DRG over 5 weeks after formalin injection reveals persistent neuronal hyperactivity associated with ongoing pain. The method described here provides an important means for in vivo studies of DRG functions in sensory perception and disorders.

Highlights

The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation
The mounting plates consisted of prongs that could be inserted alongside the lateral aspects of the vertebral column (Fig. 1c), with the short and long plates aligned to the opposite sides of the targeted DRG, respectively (Fig. 1e, f)
We showed that the structure and activity of sensory neurons in the DRG of awake mice can be reliably imaged over extended periods of time through an implanted vertebral window, without compromising the animals’ motor and sensory functions

Summary

Introduction

The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation. We develop a method for imaging DRG at cellular and subcellular resolution over weeks in awake mice. The activity of DRG cells in awake behaving animals remains unclear due to the lack of suitable methods of measurement. Previous studies have reported that following laminectomy, sensory neurons in the DRG could be imaged in anesthetized mice while their breathing is being suppressed[11]. This method restricts the duration of image collection to

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