Im lebenden Organismus Calcium-Bildgebung neuronaler Ensembles in Netzwerken primärer sensorischer Neurone in intakten dorsalen Wurzelganglien

Overview

This protocol describes a surgical technique to expose the dorsal root ganglion (DRG) for GCaMP3 (genetically-encoded calcium indicator) imaging in Pirt-GCaMP3 mice. The study investigates neural responses in primary sensory neurons to various stimuli applied to the ipsilateral hind paw, providing insights into calcium transients associated with pain and allodynia.

Key Study Components

Area of Science

• Neuroscience
• Neuroimaging
• Pain Physiology

Background

• Dorsal root ganglia house primary sensory neurons involved in pain sensation.
• GCaMP3 imaging allows real-time monitoring of calcium dynamics in neurons.
• This approach can elucidate mechanisms underlying pain hypersensitivity.
• Older methodologies are less suited for expansive neural network analysis.

Purpose of Study

• To demonstrate a comprehensive method for visualizing calcium transients in sensory neurons.
• To assess neuronal ensemble responses to nociceptive stimuli.
• To adapt methodologies for applications in trigeminal or other ganglia studies.

Methods Used

• Surgical exposure of the lumbar L5 DRG was performed on Pirt-GCaMP3 mice.
• Calcium imaging was conducted using upright confocal microscopy.
• A variety of stimuli were applied to the hind paw, including mechanical and thermal stimuli.
• Specific imaging protocols were utilized to capture spontaneous and stimulus-evoked calcium activity.

Main Results

• The imaging technique enabled real-time observation of up to 1,800 primary sensory neurons simultaneously.
• Calcium responses increased significantly during strong stimuli or heat exposure.
• Observations included calcium transients in the absence of external stimuli, suggesting a baseline level of activity.
• A systematic process for creating high-quality imaging was established, enhancing data reliability.

Conclusions

• This protocol provides a robust framework for studying the dynamics of sensory neurons in response to pain stimuli.
• The findings enhance our understanding of neuronal mechanisms related to pain hypersensitivity.
• Potential applications include evaluating therapeutic interventions for conditions such as allodynia.

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